WO2017125287A1

WO2017125287A1 - Multi-stage extraction testing system for food products

Info

Publication number: WO2017125287A1
Application number: PCT/EP2017/050430
Authority: WO
Inventors: Jean-Luc Sauvageat; Romain STOUDMANN; Alice MORONI
Original assignee: Nestec SA
Current assignee: Nestec SA
Priority date: 2016-01-20
Filing date: 2017-01-10
Publication date: 2017-07-27
Anticipated expiration: 2018-07-20

Abstract

A food or plant material extraction testing system, apparatus and method are disclosed. The system comprises a chamber with a first opening for allowing food or plant material to be added and a second opening for allowing material to be removed. The chamber comprises an outer wall, comprising a water inlet, and an inner wall. The walls define a cavity therebetween, the cavity for receiving heated water through the inlet to heat the chamber. The system further comprises: a thermometer for sensing temperature within the chamber; a mixer for mixing, within the chamber, food or plant material, an enzyme and a solvent to produce a mixture; a gas inlet for allowing pressurised gas into the chamber to compress the mixture; a plunger for compressing the mixture within the chamber; a sealable outlet for allowing solution to exit the chamber; and a filter across the sealable outlet, for filtering the mixture.

Description

MULTI-STAGE EXTRACTION TESTING SYSTEM FOR FOOD PRODUCTS

Field

The present disclosure relates to a system, apparatus and method for testing parameters of the extraction of soluble and solubilised material from plant or food raw material. In particular, but not exclusively, the present disclosure relates to a system, apparatus and method for determining optimal conditions such as choice of enzymes, pressure, temperature profile, raw materials and ratios of raw materials, for extracting soluble material from different plant or food raw material.

Background Enzymatic reactions are used in the food industry. For example, enzymes are used in bakery, brewing, dairy, meat, sugar, vegetable or fruit processing.

Enzymatic hydrolysis influences the flavour, aroma, appearance, texture, colour and nutrients of food materials.

To produce an enzymatic solubilised extract by hydrolysis, a material is hydrolysed in water, by the action of an enzyme or combination of enzymes. The product to be extracted is then extracted using a solvent, such as water (in the case of a hydrosoluble product) or an organic solvent. The result of this reaction is solvent with soluble matter, i.e. carbohydrates, dissolved in it. The solvent can be evaporated to yield the extract.

For example, to produce malt extract, a malted grain is hydrolysed in water, by the action of one or more enzymes, to make carbohydrates in the grain more susceptible to being dissolved in water (i.e. they are solubilised). Then, water is used to extract the carbohydrates. This liquid, with the solubilised carbohydrates dissolved in it, is known as "wort". The wort is then processed to evaporate the water, yielding malt extract.

For production of hydrolysed food or plant material on an industrial scale, even small increases in yield by optimisation of the process, or the discovery of lower-cost raw materials for the reaction, can greatly reduce the cost of production of the extract. Using existing industrial equipment, experimenting with plant or food material for the production of hydrolysed soluble material can be, however, inconvenient and expensive.

If the equipment used for testing is not located near the intended site of manufacture of the extract, food or plant material which is readily available at the manufacturing site may not be readily available at the testing location. This means that large quantities of a given food or plant material may be difficult to obtain for testing.

Alternatively or additionally, a food or plant material variety (such as a grain variety, in the case of malt extraction) to be tested may not be widely available until it has been proven to be a suitable starting-point for the extraction. This also means that large quantities of a given food or plant material variety may be difficult to obtain for testing.

In the case of malt extraction, the length of time for which a grain is malted can affect the efficiency and quality of malt extraction. Some grains are malted for a number of days, and it may be desirable to test the extraction yield of such grains. Since the grains are time-consuming to prepare, large quantities of such grains may not be readily available. Experimenting with enzymes for the production of extract can also be inconvenient and expensive.

In order to identify an enzyme, or combination of enzymes, that provides sufficiently high performance and in order to achieve an extraction result of sufficiently high performance, testing of several enzymes with several parameters of extraction is typically required. Enzymes can be costly. Furthermore, large quantities of a particular enzyme may not be readily available. It is not uncommon for an enzyme producer to release only 10 grams (0.01kg) of a new prototype enzyme to a particular customer in a given year. The number of tests that can be run using a particular enzyme, or combination of enzymes, can therefore be limited not only by the cost of the enzymes but by the quantity of the enzymes available.

Any reference to other documents in this specification is not to be considered an admission that such documents or any teachings therein are widely known or form part of the common general knowledge in the field. Summary

Particular aspects and embodiments are set out in the appended independent and dependent claims.

From one perspective, a food or plant material extraction testing system, apparatus and method can be provided. The system comprises a chamber with a first opening for allowing food or plant material to be added and a second opening for allowing material to be removed. The chamber comprises an outer wall, comprising a water inlet, and an inner wall. The walls define a cavity therebetween, the cavity for receiving heated water through the inlet to heat the chamber. The system further comprises: a thermometer for sensing temperature within the chamber; a mixer for mixing, within the chamber, food or plant material, an enzyme and a solvent to produce a mixture; a gas inlet for allowing pressurised gas into the chamber to compress the mixture; a plunger for compressing the mixture within the chamber; a sealable outlet for allowing solution to exit the chamber; and a filter across the sealable outlet, for filtering the mixture. Viewed from a first aspect there can be provided a multi-stage extraction testing system, the system comprising: a multi-purpose heating, mixing, compression and filtration chamber, the chamber comprising first and second sealable openings, the first sealable opening arranged to allow plant or food material, at least one enzyme and at least one solvent to be added to the chamber, and the second sealable opening arranged to allow undissolved material to be removed from the chamber, the chamber further comprising a first, outer, wall and a second, inner, wall, the first and second walls defining a cavity therebetween, the first wall comprising a water inlet, the cavity arranged to receive heated water through the water inlet thereby to heat the chamber; a temperature sensor at least partially within the chamber and arranged to sense the temperature within the chamber; a mixer arranged to be at least partially inserted into the first sealable opening and to mix at least one enzyme, plant or food material and solvent within the chamber to produce a mixture; a gas inlet arranged to allow pressurised gas into the chamber to compress the mixture; a plunger arranged to be at least partially inserted into the first sealable opening and to compress the mixture; a sealable solution outlet arranged to allow, when not sealed, a solution of a solvent and an extract extracted by the solvent to exit the channber therethrough; and a filter across the sealable solution outlet, the filter arranged to filter the mixture.

Since the system comprises a multi-purpose heating, mixing, compression and filtration chamber, the system provides a self-contained extraction system. In being self- contained, the system does not require separate mixing, compression and filtration vessels, such that it can be made more compact than industrial extraction systems.

Since the chamber comprises a first, outer, wall and a second, inner, wall, the first and second walls defining a cavity therebetween, the first wall comprising a water inlet, the cavity arranged to receive heated water through the water inlet thereby to heat the chamber, the chamber can be efficiently heated. These features also allow for accurate temperature control of the chamber, since the temperature can be determined by the temperature of the water supplied to the water inlet. Materials within the chamber can thus be heated to a specific temperature and, when necessary, held at this temperature. This allows an enzymatic reaction with the material added to the chamber to take place at a controlled temperature. Temperature control is particularly relevant in the hydrolysis process since the enzymes used to promote hydrolysis of the food or plant material are typically very temperature-sensitive. Temperature control is also relevant according to the type of material to be extracted. Temperature differences of just 2°C to 3°C can have a significant impact on how well an enzyme works to hydrolyse the material.

The temperature sensor, being at least partially within the chamber and arranged to sense the temperature within the chamber, provides for an accurate determination of the temperature within the chamber. In particular, it allows a more accurate determination of the temperature within the chamber to be made than if the determination were based solely on the temperature of the water supplied to the cavity defined by the chamber walls. Thus, the temperature sensor allows for an accurate determination of the temperature at which the hydrolysis reaction takes place.

The mixer allows plant or food material and solvent to be mixed to produce a mixture. When the mixture is a mixture of water, one or more enzymes, and malted grain, it is known as "mash".. Since the mixer is arranged to be at least partially inserted into the first sealable opening, mixing can be performed within the chamber. This means that there is no need to mix the food or plant material and solvent in a separate vessel (in the context of malt extraction, this mixing vessel is often called a "tun" or "mash tun"). Thus, the mixture does not need to be transferred from a mixing vessel to the multipurpose chamber for the next steps of extraction to take place. This means that substantially no (or very little) mixture is lost between the mixing step and the next step in extraction. This allows for more accurate determination of the masses of food or plant material, solvent and enzyme reacted and, in particular, the ratio of food or plant material to solvent in the mixture. This is because the mixture is not homogeneous, can be hot and very viscous, and contains solids which tend to settle. When mixture is transferred from a mixing to a vessel in which the next step of the extraction process is to take place, solids can therefore be left behind. Thus, the mixture to be processed in fact contains less food or plant material than was measured in before mixing. By providing a multi- purpose chamber and a mixer arranged to be at least partially inserted into the chamber and to mix food or plant material and solvent within the chamber to produce a mixture, the system therefore allows for a significant reduction in experimental errors in extraction testing, and greater repeatability of the test.

The gas inlet allows pressurised gas to be introduced into the chamber. This increases the pressure within the chamber and forces a solution of solvent and extract extracted by the solvent out of the mixture and through the filter (as will be discussed further below). The gas inlet thus allows for more of the solution to be taken from the mixture than if the solution were drained from the mixture under gravity alone. Thus, the quantity of extract yielded from the mixture is increased. The plunger allows the mixture to be further compressed (that is, compressed further after having been compressed by the pressurised gas) and can thus squeeze more solution out of the mixture and through the filter. This further increases the quantity of extract yielded from the mixture. The plunger, in being arranged to compress the mixture, can be used to form a "cake". As used herein, a "cake" is the undissolved food or plant material that is left after a solution of solvent and extract extracted by the solvent has been taken from the mixture, compressed to form a compacted mass. The formation of a cake allows for yet further extraction of extract, as will be discussed below.

The provision of a first sealable opening through which the mixer and plunger are arranged to be at least partially inserted into the chamber makes the system simpler than one in which the mixture is mixed and compressed in separate chambers, or in which it is mixed and compressed in the same chamber but using devices arranged to be inserted into the chamber through separate openings.

The first sealable opening also allows solvent to be added into the chamber once the mixture has been compressed using the plunger and a cake has been formed. In this way, the food or plant material in the cake can be washed (that is, have solvent passed through it), and further extract collected from the solvent that has run through the cake (and has therefore dissolved additional solubilised matter from the food or plant material). The compression of the mixture by the plunger to form a cake means that solvent flows through the food or plant material cake in a more uniform manner than if the mixture had not been compressed. In other words, the washing solvent reaches more of the food or plant material when the mixture has been compressed than it otherwise would. Thus, more extract can be extracted.

The sealable solution outlet arranged to allow, when not sealed, a solution of the solvent and an extract extracted by the solvent to exit the chamber therethrough provides an outlet for the solution of the solvent and an extract extracted by the solvent pressed out of the mixture by compressed gas entering through the gas inlet or by the plunger, or for the solution draining from a cake when it is washed with solvent introduced via the first sealable opening. Since this solution carries dissolved material, it can thus be processed to produce concentrated extract.

The filter arranged to filter the mixture allows the solution of the solvent and an extract extracted by the solvent to exit the chamber but retains undissolved material. In this way, extract can be taken from the system while the undissolved material, in the form of a food or plant material cake, is retained for further processing steps. For example, when the mixture is compressed using compressed gas from the gas inlet, the solution of the solvent and an extract extracted by the solvent exits the chamber through the filter and the sealable solution outlet, but the food or plant material cake remains within the chamber where it can be further compressed by the plunger and then washed by solvent from the first sealable opening. There is no need to extract the mixture from the chamber and filter it outside the chamber. The filter thus allows several steps of the extraction process to take place within the same chamber.

The second sealable opening allows non-solubilised material to be removed from the chamber after those steps of the extraction process that take place within the chamber are complete. The properties of the non-solubilised material, the cake, can thus be studied.

The first sealable opening may be arranged to be at the top of the chamber when the system is in normal use.

The second, inner, wall of the chamber may be substantially tubular. The second, inner, wall of the chamber may be tubular. The second, inner, wall of the chamber may be substantially circular in cross-section. The second, inner, wall of the chamber may be circular in cross-section. In this way, the chamber can be easily manufactured and cleaned.

The temperature sensor may be a resistance thermometer. The temperature sensor may be a platinum resistance thermometer.

Resistance thermometers are, in general, more accurate and less prone to drift (i.e. decreasing accuracy over time) than thermocouples. In examples in which the temperature sensor is a resistance thermometer, therefore, the temperature sensor is accurate and its measurements repeatable. The system may further comprise a water heater arranged to heat water supplied to the cavity through the water inlet. The system may further comprise a temperature controller arranged to control the water heater to control the temperature to which the water is heated. The temperature sensor may be arranged to send signals to the temperature controller, the signals indicative of the temperature within the chamber. The temperature controller may be arranged to receive signals from the temperature controller, the signals indicative of the temperature within the chamber. The temperature controller may be arranged to control the water heater to control the temperature to which the water is heated, based on signals received from the temperature controller, the signals indicative of the temperature within the chamber.

When the system comprises a water heater and a temperature controller arranged to control the water heater to control the temperature to which the water is heated, based on signals received from the temperature controller, the signals indicative of the temperature within the chamber, the temperature within the chamber can be more precisely controlled. This means that the temperature at which an extraction test is to be performed using the system can be set more accurately, and thus also allows for greater repeatability of the test.

The second, inner, wall may be of metal. In this way, heat is efficiently conducted between water supplied to the cavity and the chamber.

The mixer may be a rotary mixer. The mixer may be a screw mixer. The system may comprise a mixer controller. The mixer controller may be arranged to control a speed of the mixer. The mixer controller may be arranged to control a speed of rotation of the mixer. The mixer controller may be arranged to control the mixer to rotate at a plurality of speeds.

When the system comprises a mixer controller that is arranged to control a speed of the mixer, the speed at which the material and solvent within the chamber are mixed can be controlled. This allows for a more accurate simulation of industrial conditions within the chamber, and also allows the influence of mixing speed on the yield of extraction to be determined. In particular, when the mixer controller is arranged to control the mixer to rotate at a plurality of speeds, the mixer controller can be used to control the viscosity of the mixture by setting a particular speed of rotation of the mixer, and to control how the viscosity of the mixture changes during a reaction within the chamber by controlling the mixer to rotate at different speeds at different times during the reaction. The mixer may be arranged to be at least partially inserted into the first sealable opening so that the inserted part is substantially co-axial with the chamber. The mixer may be arranged to be at least partially inserted into the first sealable opening so that the inserted part it is co-axial with the chamber. This allows for even mixing of food or plant material and solvent within the chamber.

The mixer may be of a length such that when it is inserted into the first sealable opening, it reaches substantially the bottom of the chamber. In this way, substantially all of the mixture of food or plant material with enzymes and solvent is reached by the mixer, allowing for even mixing. Thus, the solvent, food or plant material and at least one enzyme come more evenly into contact with one another and extraction tests using the system are more reproducible. When the mixer is of a length such that when it is inserted into the first sealable opening, it reaches substantially the bottom of the chamber, the mixer also allows for greater reproducibility of extraction tests using the system by maintaining the mixture at a more homogeneous temperature. This is because the mixture is more evenly heated by the heated water in the cavity.

The system may comprise an actuator arranged to drive the plunger into the chamber. The actuator may be a pneumatic actuator. The plunger may comprise a head arranged to contact mixture within the chamber. The head may be shaped so as to have substantially the same cross-section as the second, inner, wall of the chamber. In this way, the head fits tightly within the chamber so that mixture does not escape around it. The plunger may be arranged to seal the first sealable opening. At least the area of the head that, in use, contacts the second, inner, wall of the chamber may be of plastic. At least the area of the head that, in use, contacts the second, inner, wall of the chamber may be of polyether ether ketone (PEEK). This provides for a smooth interface between the plunger head and the second, inner, wall of the chamber, such that wear to the plunger head and the second, inner, wall is minimised.

The plunger may be arranged to seal the first sealable opening. The plunger may be arranged to seal the first sealable opening so that it is substantially air-tight. In this way, when gas is added to the chamber via the gas inlet, it does not escape via the first sealable opening. This makes compression of mixture in the chamber more effective. Thus, more solution can be driven out of the mixture by the compressed gas, leading to the extraction of more extract from the mixture.

The plunger may comprise a scale marked on a component of the plunger. The scale may be arranged to show, in use, how far the plunger has been driven into the chamber.

In this way, a user can read off from the scale how far the plunger has been driven into the chamber, and thus calculate the pressure applied to mixture within the chamber, and also the expected height of the cake produced by compressing the mixture with the plunger. The plunger may comprise a marker arranged to slide along the scale. The plunger may comprise a marker arranged to slide along the component of the plunger on which the scale is marked. The marker may be arranged to show, in use, how far the plunger has been driven into the chamber. The marker may be arranged to slide along the scale when the plunger is driven into the chamber. The marker may be arranged to be stationary with respect to the scale when the plunger is retracted from the chamber.

In this way, even once the plunger is pulled away from the mixture, i.e. retracted from the chamber, the maximum distance which the plunger reached within the chamber can be read off from the scale by a user. This reading can thus be taken at the end of a test, and the pressure applied to mixture within the chamber, and also the expected height of the cake produced by compressing the mixture with the plunger, can be calculated based on it.

The sealable solution outlet may be arranged to be at the bottom of the chamber when the system is in normal use. In this way, no solution, mixture or undissolved material can pool below the sealable solution outlet, increasing the volume of solution that can be extracted from the undissolved material. The sealable solution outlet may be at least partially defined by a base of the chamber.

The sealable solution outlet may comprise a valve. The valve may be arranged to open and to seal the sealable solution outlet. The sealable solution outlet may be arranged to be sealed so that substantially no solvent can pass through it. The valve may be arranged to seal the sealable solution outlet so that substantially no solution can pass through the sealable solution outlet. In this way, the sealable solution outlet and/or valve can retain mixture within the chamber while it is being mixed, and be opened to allow a solution of the solvent and an extract extracted by the solvent out of the chamber after mixing and when the mixture is being compressed.

The filter may be of a mesh. The filter may be of a substantially inert material. The filter may be of polypropylene, nylon, composite plastic material, or paper. The filter may comprise a filter support. The filter support may be arranged to support the filter. The filter support may be of a mesh. The filter support may be of a substantially inert material. The filter support may be of stainless steel, nylon or composite plastic material. In this way, a delicate filter can be used to filter the mixture while reducing the risk of the filter sagging or being damaged due to the pressure applied to the mash.

The second sealable opening may be arranged to be at the bottom of the chamber when the system is in normal use. The second sealable opening may comprise a removable base arranged to seal the second sealable opening. The removable base may be arranged to be removed and thereby to open the second sealable opening.

When the second sealable opening is open, this therefore allows non-soluble or undissolved materials, which, when compressed, form a cake, to be removed from the chamber under gravity. This makes use of the system simpler, since no additional tools are required to remove the non-soluble or undissolved materials.

The second sealable opening may be defined by the second, inner, wall of the chamber. In this way, the diameter of a cake produced by compressing mixture within the chamber is no greater than the diameter of the second sealable opening. Thus, when the second sealable opening is opened, a cake can be removed from the chamber substantially intact. In other words, it is not damaged by being removed through an opening that is smaller than the cake. Thus, properties of the cake such as its height and its appearance can be more accurately determined after its removal from the chamber. The extraction testing apparatus may for example be a lab-scale device having a chamber with a capacity of less than 1000 cm³, for example less than 500 cm³.

Viewed from a second aspect, there can be provided a multi-stage plant or food material extraction testing apparatus, the apparatus comprising: a multi-purpose heating, mixing, compression and filtration chamber, the chamber comprising first and second sealable openings, the first sealable opening arranged to allow plant or food material, at least one enzyme and at least one solvent to be added to the chamber, and the second sealable opening arranged to allow undissolved material to be removed from the chamber, the chamber further comprising a first, outer, wall and a second, inner, wall, the first and second walls defining a cavity therebetween, the first wall comprising a water inlet, the cavity arranged to receive heated water through the water inlet thereby to heat the chamber; a temperature sensor at least partially within the chamber and arranged to sense the temperature within the chamber; a gas inlet arranged to allow pressurised gas into the chamber to compress a mixture of the food or plant material, at least one enzyme and at least one solvent; a sealable solution outlet arranged to allow, when not sealed, a solution of the solvent and an extract extracted by the solvent to exit the chamber therethrough; and a filter across the sealable solution outlet, the filter arranged to filter the mixture; wherein the first sealable opening is arranged to receive: a mixer arranged to be at least partially inserted into the opening and to mix food or plant material and solvent within the chamber to produce a mixture; and a plunger arranged to be at least partially inserted into the opening and to compress the mixture. The extraction testing apparatus may for example be a lab-scale device having a chamber with a capacity of less than 1000 cm³, for example less than 500 cm³.

Viewed from a third aspect, there can be provided a multi-stage plant or food material extraction testing method, the method comprising: heating a multi-purpose heating, mixing, compression and filtration chamber by supplying heated water through a water inlet in a first, outer, wall of the chamber to a cavity defined by the first, outer, wall and a second, inner, wall; adding plant or food material to the chamber through a first sealable opening in the chamber; adding at least one enzyme to the chamber through the first sealable opening in the chamber; adding a solvent into the chamber through the first sealable opening; with a temperature sensor at least partially within the chamber, sensing the temperature within the chamber; at least partially inserting a mixer into the first sealable opening and to mix the plant or food material, at least one enzyme and solvent within the chamber to produce a mixture; sealing the first sealable opening; opening a sealable solution outlet to allow a solution of solvent and extract extracted by the solvent to exit the chamber therethrough and through a filter across the sealable solution outlet; adding pressurised gas into the chamber through a gas inlet to compress the mixture; at least partially inserting a plunger into the first sealable opening to compress the mixture; adding further solvent into the chamber through the first sealable opening; removing undissolved material from the chamber via a second sealable opening in the chamber.

The method may comprise heating water to be supplied to cavity of the multi-purpose heating, mixing, compression and filtration chamber. The method may comprise controlling the temperature to which the water is heated. The method may comprise controlling the temperature to which the water is heated based on signals output by the temperature sensor, the signals indicative of the temperature within the chamber.

The method may comprise adding a first solvent into the chamber through the first sealable opening and then adding a second solvent into the chamber through the first sealable opening. The step of adding further solvent into the chamber through the first sealable opening may comprise adding a different solvent into the chamber than the solvent added in the step of adding a solvent into the chamber through the first sealable opening.

This means that the method can be tailored to the plant or food material used. In particular, a substance to be extracted from the food or plant material might be made more soluble by enzymatic reaction with a first solvent and be soluble in a second, different, solvent. In this case, two such different solvents can be used. The step of adding further solvent into the chamber through the first sealable opening may comprise adding the same solvent into the chamber as the solvent added in the step of adding a solvent into the chamber through the first sealable opening. In particular, this is appropriate where a substance to be extracted from the food or plant material both can be made more soluble by enzymatic reaction with a solvent and is soluble in the same solvent.

Adding a solvent into the chamber through the first sealable opening may comprise adding water into the chamber through the first sealable opening. I n other words, the solvent added in this step may be water. This is appropriate where the substance to be extracted from the food or plant material can be hydrolysed. Adding further solvent into the chamber through the first sealable opening may comprise adding water into the chamber through the first sealable opening. This is appropriate where the substance to be extracted from the food or plant material is soluble in water.

The method may comprise heating the solvent to be added to the chamber through the first sealable opening. Heating the solvent to be added to the chamber through the first sealable opening may comprise controlling the temperature to which the solvent is heated.

When the method comprises controlling the temperature to which the solvent is heated, this allows the temperature solvent to be supplied to the chamber (to be mixed with the food or plant material) to be controlled. This means that the temperature at which the extraction method is to be performed can be set more accurately, and thus also allows for greater repeatability of the method.

The method may comprise controlling a speed of mixing of the mixer. The method may comprise controlling a rotational speed of the mixer. The method may comprise controlling a rotational speed of the mixer to be between 10 and 2000 rpm. The method may comprise controlling a rotational speed of the mixer to be between 10 and 500 rpm. The method may comprise controlling a rotational speed of the mixer to be between 10 and 200 rpm. When the food or plant material is a malted grain, the method may comprise controlling a rotational speed of the mixer to be between 10 and 200 rpm. Since the nnethod comprises the step of heating the multi-purpose heating, mixing, compression and filtration chamber by supplying heated water through a water inlet in a first, outer, wall of the chamber to a cavity defined by the first, outer, wall and a second, inner, wall, this can lead to a substantially uniform temperature of the second, inner, wall, particularly in examples in which the method also comprises controlling the temperature to which the water is heated. Accordingly, there is likely to be little or no need to mix the food or plant material, at least one enzyme and solvent particularly quickly to avoid localised overheating. The rotational speed of the mixer can therefore be controlled to be comparatively slow. Slow mixing of the food or plant material, at least one enzyme and solvent can inhibit or reduce the introduction of air into the mixture. It may be particularly appropriate to avoid introducing air into the mixture when the food or plant material is a malted grain and the method is a malt extraction testing method. By controlling the rotational speed of the mixer to be between 10 and 500 rpm, or between 10 and 200 rpm the method can limit the introduction of air into the mixture (with the volume of air introduced reducing with reducing rotational speed of the mixture), without overheating of the mixture.

The method may comprise inserting the mixer into the first sealable opening so that the mixer is substantially co-axial with the chamber. The method may comprise inserting the mixer into the first sealable opening so that the mixer is co-axial with the chamber. The method may comprise sealing the first sealable opening using the plunger. This avoids a need for an additional component to seal the opening, for example a stopper. It therefore allows the method to be used with a simpler system.

The step of adding pressurised gas into the chamber may comprise adding pressurised air into the chamber. This means the method can be performed at a lower cost than if other gases were used. The method may comprise supplying pressurised gas to an actuator to drive the plunger into the chamber. The method may comprise supplying pressurised air to an actuator to drive the plunger into the chamber. When the method comprises supplying pressurised air to an actuator to drive the plunger into the chamber and the step of adding pressurised gas into the chamber comprises adding pressurised air into the chamber, a single source of pressurised air can be used to carry out both steps, thereby making the multi-stage extraction testing method simpler.

The step of at least partially inserting a plunger into the first sealable opening to compress the mixture may comprise applying a pressure of between 40000 Pa (0.4 bar) and 300000 Pa (3 bar) to the mixture. The step of at least partially inserting a plunger into the first sealable opening to compress the mixture may comprise applying a pressure of between 40000 Pa (0.4 bar) and 100000 Pa (1 bar) to the mixture.

The method may comprise heating the solvent to be added to the chamber through the first sealable opening. Heating the solvent to be added to the chamber through the first sealable opening allows for further control of the temperature of the mixture (in addition to the control provided by heating the chamber by supplying heated water through the water inlet). It therefore allows for greater repeatability of the multi-stage plant or food material extraction testing method.

The method may comprise removing undissolved material from the chamber by removing a base of the chamber.

The method may comprise performing, in the following order, the steps of opening the sealable solution outlet to allow a solution of solvent and extract extracted by the solvent to exit the chamber therethrough and through the filter across the sealable solution outlet, adding pressurised gas into the chamber through a gas inlet to compress the mixture, at least partially inserting the plunger into the first sealable opening to compress the mixture, and adding further solvent into the chamber through the first sealable opening.

In this way, the mixture is initially compressed using the pressurised gas, which drives a solution of solvent and extract extracted by the solvent through the filter and the sealable solution outlet, before the mixture is further compressed using the plunger to drive out further solution. The further solvent is not added until the mixture has been further compressed using the plunger. Compressing the mixture using the plunger causes it to form a "cake", so that solvent will run through it more evenly, dissolving more of the extract to be extracted than if the mixture had not been compressed.

The method may comprise performing, in the following order, the steps of heating the multi-purpose heating, mixing, compression and filtration chamber, adding a solvent into the chamber, adding plant or food material to the chamber, sensing the temperature within the chamber and adding at least one enzyme to the chamber.

In this way, the multi-purpose heating, mixing, compression and filtration chamber is heated before receiving the plant or food raw material, at least one enzyme and solvent. Further, the temperature in the chamber is sensed before adding the at least one enzyme to the chamber, enabling a user to add the at least one enzyme only when the temperature is appropriate for an enzymatic reaction using the at least one enzyme.

The method may comprise, after the step of adding solvent into the chamber through the first sealable opening, repeating the steps of adding pressurised gas into the chamber through a gas inlet to compress the mixture, at least partially inserting the plunger into the first sealable opening to compress the mixture, before the step of removing undissolved material from the chamber via the second sealable opening in the chamber. In this way, further solution of the solvent and an extract extracted by the solvent can be extracted from the mixture even after it has been compressed by pressurised gas and the plunger a first time. This can therefore lead to a higher yield of extract. Optional features of each aspect are also optional features each other aspect, with changes of terminology being inferred by the skilled addressee where necessary for these to make sense.

As used in this specification, the words "comprises", "comprising", and similar words, are not to be interpreted in an exclusive or exhaustive sense. In other words, they are intended to mean "including, but not limited to.

Brief Description of the Figures Specific embodiments will be described below by way of example only and with reference to the accompanying drawings, in which:

Figure 1 shows an exploded view of a multi-stage extraction testing apparatus and a plunger; Figure 2 shows a perspective view of the multi-stage extraction testing apparatus and a mixer;

Figure 3 shows a cross-sectional view of the multi-stage extraction testing apparatus and the mixer;

Figure 4 shows a perspective view of the multi-stage extraction testing apparatus and the plunger;

Figure 5 shows a cross-sectional view of the multi-stage extraction testing apparatus and the plunger;

Figure 6 shows a flow diagram of a multi-stage extraction testing method; and

Figure 7 shows a view of a multi-stage extraction testing system. Detailed Description

The present teachings are further described with reference to the following examples. It will be appreciated that the claimed scope is not intended to be limited in any way by these examples.

Figure 1 shows an exploded view of a multi-stage extraction testing apparatus and a plunger. The multi-stage extraction testing apparatus is now described in overview, with reference to this figure. This embodiment of the multi-stage extraction testing apparatus will be described in relation to its use for testing malt extraction. In other embodiments, however, it is expected that the multi-stage extraction testing apparatus can be used to test other enzymatic reactions, in a similar manner, and with similar effects. The multi-stage extraction testing apparatus is, in this example, in the form of a bench- top extraction tool 10 (hereinafter, the "tool"). The tool 10 has a multi-purpose heating, mixing, compression and filtration chamber in the form of a reaction chamber 1. Since the tool 10 has a multi-purpose heating, mixing, compression and filtration chamber in the form of the reaction chamber 1, separate mixing, compression and filtration vessels are not required. The tool 10 can therefore be made more compact than industrial systems for extracting material.

In this example, the reaction chamber 1 has a first, outer, wall, in the form of a reaction chamber jacket 4, and a second, inner, wall in the form of a reaction chamber wall 5. The reaction chamber wall 5 and the reaction chamber jacket 4 are both tubular. This means that the reaction chamber wall 5 and reaction chamber jacket 4 can be easily manufactured and cleaned.

The diameter of the reaction chamber jacket 4 is greater than that of the reaction chamber wall 5 so that the reaction chamber jacket 4 sits radially outside the reaction chamber wall 5, substantially coaxial with it. The reaction chamber jacket 4 and the reaction chamber wall 5 define a cavity between them. The cavity is in the form of a heating water passage 6.

The reaction chamber jacket 4 defines a water inlet in the form of a heating water inlet 7b and also defines a heating water outlet 7a

Since the reaction chamber 1 has a reaction chamber jacket 4 and a reaction chamber wall 5 defining a heating water passage 6 between them, and since the reaction chamber jacket 4 defines a water inlet in the form of a heating water inlet 7b and also defines a heating water outlet 7a, the reaction chamber 1 can be heated by introducing heated water into the heating water inlet 7b, passing it through the heating water passage 6, and having it exit through the heating water outlet. In the present example, the water is heated using a water heater in the form of a water bath. These features allow for accurate temperature control of the chamber, since the temperature can be determined by the temperature of the water supplied to the water inlet. Raw materials within the chamber can thus be heated to a specific temperature and, when necessary, held at this temperature. This allows reaction of material added to the chamber to take place at a controlled temperature. In the present embodiment in which the apparatus is used for malt extraction, the solvent is water such that the reaction is hydrolysis. This is especially true in examples in which the water heater comprises a temperature controller. In such examples, the temperature at which an extraction test is to be performed can be set more accurately. This therefore allows for greater repeatability of the test.

As mentioned above, temperature control is particularly relevant in the hydrolysis process since the enzymes used to promote hydrolysis of the plant or food material are typically very temperature-sensitive. Temperature differences of just 2°C to 3°C can have a significant impact on how well an enzyme works to hydrolyse the plant or food material.

Also forming part of the reaction chamber 1, a chamber cap 18 fits over the top edges of the reaction chamber wall 5 and reaction chamber jacket 4. The chamber cap 18 defines a first sealable opening in the form of a top opening 2. In other words, in this example, the first sealable opening is defined by the chamber cap 18. In other examples, the first sealable opening could conceivably be provided by the opening defined by the top of the reaction chamber wall 5. In such an example, the chamber cap 18 is not required. In use, the top opening 2 allows plant or food material, enzymes and solvent to be added to the reaction chamber 1. In particular, in this embodiment, in use, the top opening allows for malted grain, enzymes and solvent in the form of water to be added to the reaction chamber 1. The reaction chamber 1 also has a base in the form of a filter clamp 19. The filter clamp 19 is fitted to the bottom edges of the reaction chamber wall 5 and reaction chamber jacket 4. The reaction chamber wall 5 defines a second sealable opening in the form of a bottom opening 3. The bottom opening 3 allows undissolved material (in this case, malted grain from which malt extract has been extracted) to be removed from the reaction chamber 1 after those steps of the extraction process (described further below, with reference to Figure 6) that take place within the reaction chamber 1 are complete. The properties of the undissolved material may thus be studied.

Since the bottom opening 3 is at the bottom of the reaction chamber 1, the bottom opening allows, when it is open, undissolved material to be removed from the chamber under gravity. By providing for removal of the undissolved material under gravity, the apparatus avoids the complexity of additional undissolved material removal tools.

Since the bottom opening 3 is defined by the reaction chamber wall 5, which, as discussed above, is tubular, the diameter of a cake produced by compressing mixture (in this embodiment, called "mash", since the mixture is a mixture of water, enzymes and malted grain) within the reaction chamber 1 is no greater than the diameter of the bottom opening 3. Thus, when the bottom opening 3 is opened, a cake can be removed from the chamber substantially intact. In other words, the cake is not damaged by being removed through an opening that is smaller than the cake. Thus, properties of the cake such as its height can be more accurately determined after its removal from the reaction chamber 1.

The bottom opening 3 is sealed by the filter clamp 19. In examples in which it is not desired to be able to remove an intact cake of non-soluble material from the reaction chamber 1, the bottom opening can be defined by the filter clamp 19. The filter clamp 19 supports a filter 14a. Below the filter 14a, the filter clamp 19 has a sealable solution outlet in the form of a draining valve 31. The draining valve 31, when sealed, retains mixture, solvent and/or a solution of the solvent and extract extracted by the solvent (i.e. in this case mash, water and/or wort) within the reaction chamber 1. It thus prevents any mixture, solvent or solution from exiting the reaction chamber 1 while plant or food material and solvent (in this case malted grain and water) are being mixed together, as will be described further below, to form a mixture (called, in this example, a "mash").

The draining valve 31, when not sealed, allows solvent (in this case, water) to exit the chamber therethrough. It therefore provides an outlet for a solution of solvent with extract dissolved in it (i.e., in this case, wort) pressed out of the mash by compressed gas entering through a gas inlet or by a plunger (as will be described further below), or for a solution of solvent with extract dissolved in it (wort) draining from a cake when it is sparged with solvent (in this example water) introduced via the first sealable opening (as will also be described further below). This solution (wort) carries dissolved matter (in this example, malt extract) and can thus be processed to produce concentrated extracted material (in this example, concentrated malt extract).

Since the draining valve 31 is below the filter clamp 19 of the reaction chamber 1, and is therefore below the reaction chamber 1, no solution or mixture (wort or mash) can pool below the draining valve 31. Thus, the volume of solution (wort) that can be taken from a mixture (mash) within the reaction chamber 1 is increased.

The filter 14a, in conjunction with the draining valve 31, allows a solution of solvent and extract extracted by the solvent (wort) to exit the reaction chamber 1 while retaining non- soluble or undissolved material within the reaction chamber 1. In this way, solution (wort) can be taken from the tool 10 while the undissolved material is retained for further processing steps. For example, when a mixture of malted grain and water is compressed using compressed gas from a gas inlet (as will be described further below) wort exits the reaction chamber 1 through the filter 14a and the draining valve 31, but malted grain remains within the chamber where it can be further compressed by a plunger and then sparged by water from the first sealable opening (to be described further below). There thus is no need to extract the mixture (mash) from the reaction chamber 1 and to filter it outside the reaction chamber 1. The filter 14a thus allows several steps of the extraction process (described further below, with reference to Figure 6) to take place within the same reaction chamber 1. The tool 10 has a gas inlet 51. The gas inlet 51 is shown in Figure 1, but will be described in more detail below, with reference to Figure 5. The gas inlet 51 allows pressurised gas to be introduced into the reaction chamber 1. This increases the pressure within the reaction chamber 1 and, when the reaction chamber 1 contains mixture (mash) and the draining valve 31 is open, forces solution (wort) out of the mixture (mash) and through the filter 14a (as will be discussed further below). The gas inlet 51 thus allows for more solution (wort) to be taken from the mixture (mash) than if solution (wort) were drained from the mixture (mash) under gravity alone. Thus, the quantity of food or plant material extract (in this case, malt extract) yielded from the mixture (mash) is increased. The tool 10 also has a temperature sensor in the form of a thermometer 53 that extends into the reaction chamber 1. The thermometer 53 is also not shown in Figure 1, but will be described in more detail below, with reference to Figure 5.

The thermometer 53 allows the temperature within the reaction chamber 1 to be sensed. Since the thermometer 53 extends into the reaction chamber 1, it provides for an accurate determination of the temperature within the reaction chamber 1. In particular, the thermometer 53 allows a more accurate determination of the temperature within the reaction chamber 1 to be made than if the determination were based solely on the temperature of the water supplied to the heating water passage 6 defined by the reaction chamber wall 5 and reaction chamber jacket 6. Thus, the thermometer 53 allows for an accurate determination of the temperature at which a reaction and/or extraction takes place within the chamber.

The top opening 2 is arranged to receive each of: a mixer arranged to be at least partially inserted into the opening and to mix food or plant material (in this case, malted grain) and solvent (in this case, water) within the chamber to produce a mixture (mash); and, separately, a plunger arranged to be at least partially inserted into the opening and to compress the mixture (mash). The provision of a top opening 2 through which the mixer and plunger are arranged to be at least partially inserted into the reaction chamber 1 makes a system comprising the tool 10, mixer and plunger simpler than one in which mixture (mash) is mixed and compressed in separate chambers, or in which it is mixed and compressed in the same chamber but using devices arranged to be inserted into the chamber through separate openings.

Each of the above components shown in Figure 1 will now be described in more detail with continued reference to that figure. Further components shown in Figure 1 will now also be described.

The reaction chamber wall 5 is a tube made from a material that is expected to have low or no reactivity with the raw materials to be tested within the tool 10. In this example, the material is stainless steel. In other examples, the reaction chamber wall 5 can be made from other metals. In examples, such as the present example, in which the reaction chamber wall 5 is made of metal, heat is efficiently conducted between water supplied to the heating water passage 6 and the reaction chamber 1. As mentioned above, the reaction chamber jacket 4 is also tubular. The reaction chamber jacket 4 is positioned radially around the reaction chamber wall 5 so as to provide a heating water passage 6 about the reaction chamber wall 5. In the present example, the reaction chamber jacket 4 is coaxial with the reaction chamber wall 5. The reaction chamber wall 5 is supported on a support 15. The support 15 cooperates with the filter clamp 19 (which supports the filter 14a) to hold the filter 14a in place. This will be described further below. The support 15 of the present example is generally ring-shaped. In other words, the support 15 is disc-shaped, with a hole in its centre. The hole shape matches the shape of the filter 14a, as will be discussed in more detail below. In the present example, the hole is circular. The support 15 is made from a material that is expected to have low or no reactivity with the raw materials to be tested within the tool 10. In this example, the support 15 is made of the same material as the reaction chamber wall 5. This material is, in the present example, stainless steel. The support 15 has an inner diameter that is exactly the same as the inner diameter of the reaction chamber wall 5, and an outer diameter that is greater than the outer diameter of the reaction chamber jacket 4 so as to provide closure to the lower end of the heating water passage 6 and to provide partial closure to the reaction chamber 1.

The inner surface of the support 15 is stepped. In other words, a ledge extends radially inwards around the lower edge of the hole in the centre of the support 15. The hole in the centre of the support 15 and the ledge or step extending into the hole are proportioned so that the bottom edge of the reaction chamber wall 5 fits into the hole and rests on the ledge. The bottom edge of the reaction chamber wall 5 is sealed to the support 15, in the present example this sealing is provided by an O-ring 16a, although in other examples this seal could be provided by a tight tolerance physical fit, or by a joining approach such as welding, soldering or adhering the reaction channber wall 5 to the support 15.

The support 15 has a circular groove around its top surface. The circular groove has the same diameter as the reaction chamber jacket 4, so that the lower edge of the reaction chamber jacket 4 fits within the groove. The bottom edge of the reaction chamber jacket 4 is sealed to the support 15, in the present example this sealing is provided by an O-ring 16b, although in other examples the seal could be provided by a tight tolerance physical fit, or by a joining approach such as welding, soldering or adhering the reaction chamber jacket 4 to the support 15. Radially outside the reaction chamber jacket are a set of support rods. In the present example, three support rods 12a, 12b, 12c are provided. The three support rods 12a, 12b, 12c are spaced radially around the support 15. The radial spacing provides for the rods to be used to provide a clamping force between the chamber cap 18 and the support 15 with substantially even clamping force distribution around the perimeter or circumference of the reaction chamber jacket 4 and reaction chamber wall 5. In the present example, the support rods 12a, 12b, 12c are radially substantially equidistant from one another. The three support rods 12a, 12b, 12c extend parallel to the reaction chamber jacket 4 and the reaction chamber wall 5. Each of the three support rods 12a, 12b and 12c extends into a corresponding hole in the support 15. The holes in the support 15 are threaded bores into which a matching thread on the lower ends of each of the three support rods 12a, 12b and 12c can be screwed. This fixes the support rods 12a, 12b, 12c to the support 15.

The filter clamp 19 of the reaction chamber 1 is a disc of a material that is expected to have low or no reactivity with the raw materials to be tested within the tool 10. In this example, the filter clamp 19 is made of the same material as the reaction chamber wall 5 and support 15. In other words, in the present example, the filter clamp 19 is made of stainless steel. Its diameter is substantially the same as that of the support 15. The filter clamp 19 has an indentation in its upper surface. The indentation surrounds the hole in the middle of the filter clamp 19. The indentation is to receive a filter support in the form of a filter grille 14b. In the present example, the grille 14b and indentation are both circular. The indentation of the present example is substantially radially central on the filter clamp 19 so that the filter grille 14b covers the bottom of the reaction chamber wall 5 (as will be described below) The dimensions and radial alignment of the indentation are such that the filter grille 14b sits within the internal perimeter of the reaction chamber wall 5. In the present example, where the indentation and filter grille 14b are both circular and are radially central in the filter clamp 19, this alignment and dimensioning is achieved by making the diameter of the indentation and filter grille 14b approximately equal to the internal diameter of the reaction chamber wall 5.

The filter grille 14b is provided to support a filter material of a filter 14a that will rest on top of the filter grille 14b. This prevents a mass or pressure of materials within the reaction chamber 1 from distending or breaking pores in the filter material. In the present example the filter grille 14b is a circular piece of metal gauze. The filter grille 14b has a size just less than that of the indentation, so that it fits into the indentation.

A filter 14a is positioned axially above the filter grille 14b. In this example, the filter 14a is made of polypropylene, which is appropriate for malt extraction testing. In other examples, the filter 14a may be of nylon, composite plastic material, or paper. By choosing a filter material from one of these example materials, the filter 14a can be adapted to the material to be extracted. The filter 14a can be replaced after an extraction test has been performed, preventing clogging of the filter 14a over successive tests that would lead to reduced repeatability of a test.

The filter 14a is sized and shaped so as to extend over the hole in the filter clamp 19. In the present example, the filter 14a is disc-shaped and has a radius greater than that of the indentation. The filter 14a sits axially between the support 15 and the filter clamp 19.

The filter 14a is held between the support 15 and the filter clamp 19 by screws 20a, 20b and 20c which are fastened through corresponding threaded bores in the filter clamp 19 and support 15. In the present example, the screws 20a, 20b and 20c have heads with a diameter greater than that of the bores in the filter clamp 19 so that they do not pass through the filter clamp 19. In this way, the support rods 12a, 12b, 12c are fastened to the support 15 and the filter clamp 19 is in turn fastened to the support 15. The filter clamp 19 has an axial hole radially in its centre, as mentioned above. The axial hole is connected to a draining valve 31 (not visible in Figure 1) on the lower side of the filter clamp 19.

Axially distal from the support 15 - in other words, at the other end of the reaction chamber wall 5, reaction chamber jacket 4 and support rods 12a, 12b, 12c from the support 15 - there is a chamber cap 18. The chamber cap 18, like the support 15, is generally ring-shaped. The chamber cap 18 is made from a material that is expected to have low or no reactivity with the raw materials to be tested within the tool 10. In this example, the material is stainless steel. The chamber cap 18 has an inner diameter that is less than the inner diameter of the reaction chamber wall 5, and an outer diameter that is greater than the outer diameter of the reaction chamber jacket 4. Top edges of the reaction chamber wall 5 and reaction chamber jacket 4 cooperate with corresponding features on the lower surface of the chamber cap 18, just as the lower edges of the reaction chamber wall 5 and reaction chamber jacket 4 cooperate with corresponding features on the upper surface of the support 15 (as described above). Thus, the chamber cap 18 fits over the reaction chamber wall 5 and reaction chamber jacket 4. Any gap between the chamber cap 18 and the reaction chamber wall 5 is sealed, in the present example by an O-ring 16c. Other sealing approaches may be used as described above. Any gap between the chamber cap 18 and the reaction chamber jacket 4 is also sealed, in the present example by an O-ring 16d. In other examples, other sealing approaches may be used as described above. The chamber cap 18 differs from the support 15 in that the chamber cap 18 has a circular wall protruding axially from its top surface, providing an edge of a central top opening 2. Through this top opening 2, a mixer 21 can be inserted, as will be described further below, with reference to Figures 2 and 3. A plunger 17 can also be inserted through the top opening 2, as will be described further below with reference to Figures 4 and 5 With reference, now, to Figure 5, further features of the chamber cap 18 will now be described. The first of these features is the gas inlet 51. In the present example, the gas inlet 51 is a hole in the chamber cap 18. In this example, the gas inlet 51 is circular in profile for simplicity of forming. The gas inlet 51 is connected to a quick pneumatic connection 51a that can be controlled by a valve 51b in the pneumatic connection 51a. In other examples, the gas inlet need not be formed in the chamber cap 18. Instead, it can be formed in the reaction chamber wall 5. In the present example, however, the gas inlet 51 extends radially through the chamber cap 18, from the outer edge of the chamber cap 18 to the central top opening 2 of the chamber cap 2. In this way, gas supplied to the pneumatic connection 51a can pass from the outside of the reaction chamber 1, through the valve 51b and through the gas inlet 51 in the chamber cap 18 to the inside of the reaction chamber 1. The second of these features is the washing solvent inlet 52. The washing solvent inlet 52 allows solvent (in this case water) to be added into the reaction chamber 1 via the first sealable opening in the form of the top opening 2. Specifically, the washing solvent inlet 52 allows water to be added into the reaction chamber 1 once the mixture (mash) within the reaction chamber 1 has been compressed using a plunger (described further below) and a cake has thus been formed. In this way, the cake can be washed (that is, have solvent passed through it), and further soluble matter extract collected from the solvent that has run through the cake (and has therefore picked up soluble matter from it).

The washing solvent inlet 52 is a hole in the chamber cap 18. In this embodiment, it is circular in profile for simplicity of forming. The washing solvent inlet 52 is connected to a funnel 52a, with a valve 52b between the funnel 52a and the washing solvent inlet 52. The washing solvent inlet 52 extends radially through the chamber cap 18, from the outer edge of the chamber cap 18 to the central top opening 2 of the chamber cap 2. In other examples, the washing solvent inlet 52 is formed in the reaction chamber wall 5 instead of in the chamber cap 2. In this way, water supplied to the funnel 52a can pass from the outside of the chamber 1, through the valve 52b and washing solvent inlet 52 to the inside of the chamber 1. The washing solvent inlet 52 is located radially opposite the gas inlet 51. With continued reference to Figure 5, the thermometer 53 will now be described. The support 15 has a hole extending radially through it, from the outer edge of the support 15 to the hole in the centre of the support 15. In other words, the hole extends through the support 15, from the outside of the reaction chamber 1 to the inside of the reaction chamber 1. A thermometer 53 extends through the hole. In other examples, the thermometer 53 can extend through a hole formed in the reaction chamber wall 5 and not through the support 15. The thermometer 53 is, in this example, a platinum resistance thermometer. Resistance thermometers are, in general, more accurate and less prone to drift (i.e. decreasing accuracy over time) than thermocouples. In examples in which the temperature sensor is a resistance thermometer, therefore, the temperature sensor is accurate and its measurements repeatable. In other examples, however, it may be more convenient to use a thermocouple for the thermometer 52.

A probe of the thermometer 53 is located inside the reaction chamber 1. In this way, the thermometer 53 can sense the temperature inside the reaction chamber 1. The thermometer 53 is connected to a computer (not shown) such that the thermometer 53 can send signals to the computer which records these signals as the temperature sensed by the thermometer 53 over time.

With reference, once more, to Figure 1, as discussed above, the three support rods 12a, 12b, 12c extend axially, each through a corresponding hole in the support 15and are each secured in place by a thread on the support rod that screws into the respective hole in the support 15. This keeps the support 15, reaction chamber jacket 4, reaction chamber wall 5, chamber cap 18 and the O-rings 16a, 16b, 16c, 16d between them together to form the reaction chamber 1. In other examples, the support rods 12a, 12b, 12c are provided with an internal thread that extend. In these examples, screws are tightened into the ends of the support rods 12a, 12b, 12c instead of the nuts tightened onto their outsides.

The reaction chamber jacket 4 has a heating water inlet 7b and a heating water outlet 7a. The heating water inlet 7b is a through-hole located near the bottom of the of the reaction chamber jacket 4. The through-hole has a wall around it to enable it to be connected to a water pipe. In this example, the wall is circular in cross-section to make connecting the water inlet 7b to a tubular pipe easier. Similarly, the heating water outlet 7a is also a through-hole. The heating water outlet 7a also has a wall around it to enable it to be connected to a water pipe. In this example, the wall is circular in cross-section to make connecting the water outlet 7a to a tubular pipe easier. The heating water outlet 7a is located near the top of the of the reaction chamber jacket 4.

The reaction chamber 1 is supported on a stand 9. The stand 9 serves to keep the reaction chamber 1 upright and the filter clamp 19 away from the surface on which the tool 10 is placed. This provides a clearance between the draining valve 31 and the surface, such that a vessel, such as a beaker, for collecting wort from the reaction chamber 1 can be placed on the surface below the reaction chamber 1. In this example, the stand 9 has a U-shaped base 9a, which sits on a surface, and an upstand 9b perpendicular to the U- shaped base 9a, which stands upright when the U-shaped base is placed on a flat surface. The upstand 9b has a support bracket 11a connected to it. The support bracket 11a defines a vertical slot between it and the upstand 9b when it is connected to the upstand 9b. A bracket fixing lib connects to the chamber cap 18 with two screws, and fits into the vertical slot 11a defined by the support bracket. This connects that reaction chamber 1 to the stand 9. Other configurations of the stand are contemplated that keep the reaction chamber 1 substantially upright and the filter clamp 19 of the chamber away from a surface on which the tool 10 is placed. For example, the stand could be in the form of a bracket fixed to a wall, rather than a support resting on a surface.

The reaction chamber 1 can be used for mixing food or plant material, enzymes and solvent to produce a mixture. For example, the reaction chamber 1 can be used for mixing malted grain, enzymes and water to produce a mash. To produce a mixture, the impeller 33 of a mixer 21 is inserted into the reaction chamber 1.

Figure 2 shows the reaction chamber 1 and stand 9, as well as a mixer 21 with its impeller 33 (not visible in Figure 2) inserted through the top opening 2 into the reaction chamber 1. As can be seen from Figure 2, the mixer 21 has a motor housing 22. The motor housing 22 encases a motor 32, not visible in Figure 2. On the motor housing 22 is a mixer switch 23 for turning the mixer 21 on or off by completing or breaking a circuit supplying power to the motor 32. Also on the motor housing 22 is a mixer speed control dial 24. The mixer speed control dial 24 is an example of a mixer controller. When the mixer speed control dial 24 is turned, it controls the speed of rotation of the impeller 33. This allows for a more accurate simulation of industrial conditions within the chamber, and also allows the influence of mixing speed on the yield of extraction to be determined.

On the lower side of the motor housing 22 is a chuck 26 that holds a mixer shaft 25 of the impeller 33. The impeller 33 is not visible in Figure 2 since it is inside the reaction chamber 1. It will be described in more detail below, with reference to Figure 3. With continued reference to Figure 2, the motor housing 22 is mounted on an upstand attachment 27 which is in turn mounted on the upstand 9b of the stand 9. In this way, the motor housing 22 is positioned axially above the reaction chamber 1. The upstand attachment 27 is mounted to the upstand 9b of the stand 9 such that it can be slid vertically along the upstand 9b. This allows the mixer 21 to be moved up or down with respect to the reaction chamber 1. The motor housing 22 is dimensioned, and the chuck 26 is positioned on the motor housing 22, such that the mixer shaft 25 descends into the reaction chamber 1 substantially co-axially with the reaction chamber 1. This allows for even mixing of food or plant material and water within the reaction chamber 1. The upstand attachment 27 is mounted to the upstand 9b of the stand 9 such that it can be fixed stationary with respect to the upstand 9b. This allows the mixer 21 to be held in place once it has been put into a desired position.

Figure 3 shows a cross-sectional view of the reaction chamber 1 and mixer 21. The mixer 21 will now be described in more detail with reference to this figure. As mentioned above, the motor housing 22 houses a motor 32. It also houses gears that are arranged to transfer rotation of the motor 32 to the chuck 26. The motor 32 and gears are not shown in Figure 3 (they are in the shaded area marked within the motor housing 22). The motor 32, gears and chuck 26 are, in this example, of the sort found in electric power drills and could be adapted by a skilled person from these. A power source (not shown) is electrically connected to the motor 32 via the mixer switch 23 (also not shown in this figure). In this example, the power source is mains electricity. In other examples, the power source can be a battery.

The chuck 26 is, in this example, a drill chuck. It is arranged to hold the mixer shaft 25 in its centre. The mixer shaft 25 is a straight piece of metal that is circular in cross-section. The impeller 33 is located at the bottom of the mixer shaft 25 (that is, at the end of the mixer shaft 25 furthest from the end held in the chuck 26). The impeller 33 is of metal (for strength and durability). In this example, the impeller 33 is helical in shape. That is, the impeller 33 is a twist of metal, like a corkscrew, but on a larger scale. In this example, the impeller 33 has five coils. In other examples, the impeller can have paddles instead of coils, or be screw-shaped. In examples in which the impeller 33 has coils, it can have more or fewer than five coils. Each of the coils has a diameter that is less than the inner diameter of the reaction chamber wall 5 and less than the inner diameter of the top opening 2. The impeller 33 has an axial length (i.e. a height) that is less than the axial length (i.e. height) of the reaction chamber wall 5. In this way, the impeller fits within the reaction chamber 1. The impeller 33 and mixer shaft 25 are, however, long enough that the end of the impeller 33 reaches almost to the bottom of the chamber 1. The impeller can rotate clockwise or anti-clockwise.

The mixer allows food or plant material, enzymes and solvent to be mixed to produce a mixture. For example, it allows malted grain, enzymes and water to be mixed to produce a mash. Since the mixer is arranged to be at least partially inserted into the top opening 2, mixing can be performed within the reaction chamber 1. This means that there is no need to mix the food or plant material and water in a separate mixing vessel.

Thus, the mixture (mash) does not need to be transferred from a mixing vessel to the reaction chamber 1 for the next steps of extraction to take place. This means that substantially no (or very little) mixture is lost between the mixing step and the next step in extraction. This allows for more accurate determination of the masses of food or plant material, solvent and enzyme reacted and, in particular, the ratio of food or plant material to solvent in the mixture. This is because the mixture is often not homogeneous, but contains solids which tend to settle. When mash is transferred from a mixing vessel to a vessel in which the next step of the extraction process is to take place, solids can therefore be left behind. Thus, the mixture to be processed in fact contains less food or plant material than was measured in before mixing. By providing a reaction chamber 1 and a mixer arranged to be at least partially inserted into the chamber and to mix food or plant material and solvent within the chamber to produce a mixture, the system therefore allows for a significant reduction in experimental errors in food or plant material extraction testing, and greater repeatability of extraction tests.

The reaction chamber 1 can be used for compressing a mash to extract wort. To do this, a plunger attachment 44 is fitted to the reaction chamber 1 shown in Figure 1. Figure 5 shows, in cross-section, the reaction chamber 1 with the plunger attachment 44 fitted to its top.

Broadly, the plunger attachment 44 is made up of an actuator and a plunger 17. The actuator is made up of a cylindrical housing 44a, defining a cavity with in it, with part of a plunger shaft 52 within the cavity. The plunger 17 is made up of a plunger shaft 52 and a plunger head 56 on the end of the plunger shaft 52.

The plunger attachment 44 is fitted to the top opening 2 of the reaction chamber 1 by a fastening seal 43. The fastening seal 43 is a tri-clamp. In other words, the fastening seal 43 is a ring with a key to tighten it. The fastening seal 43fits around the wall around the top opening 2 of the reaction chamber 1, and also around the lower end of the cylindrical housing 44a. Turning the key of the fastening seal 43 secures the cylindrical housing 44a of the plunger attachment 44 to the reaction chamber 1.

The plunger shaft 52 is circular in cross-section, for ease of manufacturing. The plunger shaft 52 is of a material that is strong and durable, and has little or no reactivity with the raw materials tested in the reaction chamber 1. In this embodiment it is metal. The plunger shaft 52 is held co-axial with the reaction chamber 1. The diameter of the plunger shaft 52 is less than the inner diameter of the reaction chamber wall 5 and of the top opening 2 so that the plunger shaft 52 can move vertically through them. The plunger head 56 is circular in cross-section. The plunger head 56 has a diameter only slightly less than the inner diameter of the reaction chamber wall 5 so that it can effectively compress mash below it. The plunger head 56 is fixed to the bottom of the plunger shaft 52. In other examples, the plunger head is formed integrally with the plunger shaft. The plunger shaft 52 can be moved vertically upwards and downwards (using the actuator described further below). This moves the plunger head 56 up or down within the reaction chamber 1. The plunger 17 is shown in Figure 5 in a fully-descended state.

In this example, the plunger head 52 is made of polyether ether ketone (PEEK). This allows it to slide without excessive friction along the stainless steel reaction chamber wall 5, such that wear to the plunger head 52 and the reaction chamber wall 52 is minimised. In other examples, the plunger head 52 is made of other plastics that allow it to slide along the reaction chamber wall 5, or has a coating of such a plastic.

In this example, the actuator is a pneumatic actuator. In other words, the actuator drives the plunger 17 by compressed air. In other examples, the plunger 17 can be actuated in other ways, for example by pressing it down by hand. The cylindrical housing 44a has a first quick pneumatic connection 54a and a second quick pneumatic connection 54b. The first and second quick pneumatic connections 54a, 54b are each designed to receive pressurised air from a supply outside the cylindrical housing 44a (not shown) and allow the air into the cylindrical housing 44a. The first quick pneumatic connection 54a is located near the top of the cylindrical housing 44a. The second quick pneumatic connection 54b is located near the bottom of the cylindrical housing 44a. The plunger shaft 52 is formed with a sliding seal 55 around it. The sliding seal is a region of the plunger shaft with a diameter substantially equal to the inner diameter of the cylindrical housing 44a. The sliding seal 55 is located about half-way along the length of the plunger shaft 52. In this way, when air enters the first quick pneumatic connection 54a, it enters above the sliding seal 55. When the second quick pneumatic connection 54b is open, the air entering above the sliding seal 55 increases the pressure within the part of the cylindrical housing above the sliding seal 55. This forces the sliding seal 55 downwards. In turn, this pushes the plunger 52 down. When the first quick pneumatic connection 54a is open, and air enters the second quick pneumatic connection 54b, this increases the pressure within the part of the cylindrical housing above the sliding seal 55. This forces the sliding seal 55 upwards. In turn, this pushes the plunger 52 up.

Figure 4 shows a perspective view of the reaction channber 1 and stand 9, as well as a plunger attachment 44 fitted to the top of the reaction chamber 1. On one side of the plunger attachment 44 is a scale 42. The scale 42 is outside the cylindrical housing 44a and runs parallel to the axis of the cylindrical housing 44a. Since the scale 42 runs parallel to the axis of the cylindrical housing 44a, the scale 42 is vertical when the plunger attachment 44 is fixed to the top of the reaction chamber 1. The scale 42 is a tube with a vertical slot in it. There is a vertical row of markings at regular intervals beside the vertical slot. In this example, each marking is 1mm away from the next marking. There is a measuring rod 45 inside the scale 42. The top of the measuring rod 45 is just visible in Figure 4. The measuring rod 45 can better be seen in Figure 1. Also visible in Figure 1 is a marker 46. The marker 46 is a clip that clips through the vertical slot onto the measuring rod 45. The marker 46 is arranged to slide downwards when the measuring rod 45 moves downwards, to be stationary when the measuring rod 45 is stationary, and to be stationary when the measuring rod 45 moves upwards. As can be seen in Figure 4, the measuring rod 45 is connected at its top end via a connector to a plunger shaft 52. The measuring rod 45 therefore moves axially with the plunger shaft 52. Only the top of the plunger shaft 52 is visible in Figure 4. The plunger 17 allows mash within the reaction chamber 1 to be compressed further after having been compressed by pressurised gas introduced through the gas inlet 52. The plunger 17 can thus squeeze more wort out of the mash and through the filter 14a. This further increases the quantity of extract yielded from the mash.

The plunger 17 can also be used to form a cake. The formation of a cake allows for yet further extraction of soluble material (malt extract, in this example), by washing, as will be discussed below.

The marker 46 allows the maximum distance which the plunger head 56 reached within the reaction chamber 1 can be read off from the scale by a user. Since the marker 46 is arranged to slide downwards when the measuring rod 45 moves downwards, to be stationary when the nneasuring rod 45 is stationary, and to be stationary when the nneasuring rod 45 moves upwards, even once the plunger 17 is retracted from the reaction chamber 1, the maximum distance can still be read from the scale 42. This reading can thus be taken at the end of a test, and the pressure applied to mash within the reaction chamber 1, and also the expected height of the cake produced by compressing the mash with the plunger 17, can be calculated based on it.

Together, the bench-top extraction tool 10 (an example of a multi-stage plant or food material extraction apparatus), the mixer 21 and the plunger attachment 44 make up a multi-stage plant or food material extraction testing system 700. The system 700 is shown in Figure 7. In particular, Figure 7 shows a first view of the tool 10 with the mixer 21, a second view of the tool 10 alone, and a third view of the tool 10 with the plunger attachment 44. Each of these components is, in this example, as described above in relation to Figures 1 to 5, and so will be described no further here.

The tool 10, mixer 21 and plunger 17 (i.e. the system 700) can be used to perform a multi- stage plant or food material extraction testing method. In overview, the tool 10, along with the mixer 21 and the plunger 17, is used as follows:

(a) At least partially inserting a mixer into a first sealable opening. That is, in this example, inserting the impeller 33 of the mixer 21 into the top opening 2.

(b) Heating a multi-purpose heating, mixing, compression and filtration chamber by supplying heated water through a water inlet in a first, outer, wall of the chamber to a cavity defined by the first, outer, wall and second, inner, wall. That is, heating the reaction chamber 1 by supplying heated water through the heating water inlet 7b to the heating water passage 6.

(c) Adding plant or food material to the chamber through a first sealable opening in the chamber. That is, adding plant or food material to the reaction chamber 1 through the top opening 2.

(d) Adding at least one enzyme to the chamber through the first sealable opening in the chamber. That is, adding at least one enzyme to the reaction chamber 1 through the top opening 2. (e) Adding a solvent into the channber through the first sealable opening. That is, adding a solvent to the reaction channber 1 through the top opening 2.

(f) With a temperature sensor at least partially within the chamber, sensing the temperature within the chamber. That is, with the thermometer 53, sensing the temperature within the reaction chamber 1.

(g) Mixing the plant or food material, at least one enzyme and solvent within the chamber to produce a mixture. That is, mixing, with the mixer 21, the plant or food material, at least one enzyme and solvent within the reaction chamber 1 to produce a mixture. During this step, the enzymes and solvent act on the food or plant material to solubilise a substance to be extracted from the food or plant material. In examples in which the food or plant material is soluble in the solvent added, the substance to be extracted from the food or plant material will also begin to dissolve in the solvent.

(h) Sealing the first sealable opening. That is, removing mixer 21 and fitting the plunger attachment 44 to the tool 10 to seal the top opening 2.

(i) Opening a sealable solution outlet to allow a solution of solvent and extract extracted by the solvent to exit the chamber therethrough and through a filter across the sealable solution outlet. That is, opening the draining valve 31 to allow a solution of solvent and extract extracted by the solvent to exit the reaction chamber 1 through the draining valve 31 and the filter 14a.

(j) Adding pressurised gas into the chamber through a gas inlet to compress the mixture. That is, connecting a supply of pressurized air to the pneumatic connection 51a and opening the valve 51b such that pressurised air enters the reaction chamber 1 through the gas inlet 51. This compresses the mixture.

(k) At least partially inserting a plunger into the first sealable opening to compress the mixture. That is, decompressing the reaction chamber 1 and pushing down the plunger head 56 is to further compress the mixture. Additional solution exits the reaction chamber 1 through the draining valve 31. A cake is formed by this compression.

(I) Adding further solvent into the chamber through the first sealable opening. That is, inverting the pressure within the actuator housing 44a so that the plunger head 56 rises, and adding further solvent, washing solvent, to the reaction chamber 1 through the funnel 52a and water inlet 52. This washes the cake. A solution of this solvent and extract extracted by the solvent exits the reaction chamber 1 through the draining valve 31.

In this example, the step (k) of at least partially inserting a plunger into the first sealable opening to compress the mixture is repeated. That is, the plunger head 56 is pushed down to further compress the mixture. Liquid remaining in the cake is expressed through the draining valve 31. Step (I) of adding further solvent into the chamber through the first sealable opening is also repeated in this example. That is, the pressure within the actuator housing 44a is inverted so that the plunger head 56 rises, and washing solvent is added to the reaction chamber 1 through the funnel 52a and water inlet 52. A solution of this solvent and extract extracted by the solvent exits the reaction chamber 1 through the draining valve 31. In other examples, steps (k) and (I) can be repeated any number of times. In yet other examples, steps (k) and (I) are each performed only once.

(m) Removing undissolved material from the chamber via a second sealable opening in the chamber. That is, removing the cake from the reaction chamber 1 via the bottom opening 3 by removing the filter clamp 19 along with the filter 14a and filter support 14b so that the cake can drop from the reaction chamber 1 under gravity.

Figure 6 shows a flow diagram of an example of such a multi-stage extraction testing method 60 that uses the tool 10 described above. In this example, the multi-stage extraction testing method is a method for testing malt extraction. In particular, the food or plant material is malted barley, and the testing method 60 is performed to determine whether adding rice hulls to the malted hull-less barley improves the yield of malt extracted, using alpha amylase as an enzyme. In other examples, it is expected that the method outlined above can be used with other food or plant materials. For example, it is expected that the method can be used to make substances in any of the following raw materials more soluble, and then to dissolve those substances: other grains, such as wheat or oats; cocoa; coffee; algae; vegetables; fruit; or meat. In other words, in a multi-stage plant or food material extraction testing method, the plant or food material may be grain. The plant or food material may be barley. The plant or food material may be wheat, oats, rice or rye. The plant or food material may be malted grain. The method may be a malt extraction testing method. The plant or food material may be malted barley, malted wheat, malted rice or malted rye. This present example method 60 for testing malt extraction has the following steps, which will now be described with reference to Figure 6:

First, the mixer impeller 33 is inserted at step 61 into the top opening 2. This corresponds to step (a) in the overview of the method given above. To insert 61 the mixer impeller 33 into the top opening 2, the upstand attachment 27 of the mixer 21 is mounted to the upstand 9b of the stand 9. In this way, the motor housing 22 is positioned axially above the reaction chamber 10. Next, the upstand attachment 27 is pushed downwards so that it slides down the upstand 9b of the stand 9. Since the motor housing 22 is positioned axially above the reaction chamber 10, the impeller 33 enters the top opening 2 of the reactor chamber. When the impeller 33 of the mixer is completely within the reaction chamber 1, the upstand attachment 27 is fixed in place relative to the upstand 9b of the stand 9.

Then, water to be added to the heating water passage 6 is heated at step 62 in a water bath (not shown) with a thermostat. In this example, the water is heated to 75°C. In other examples, the water is heated to other temperatures, depending on the conditions that a user of the tool 1 wishes to test.

Next, the reaction chamber 1 is heated at step 63 by supplying the heated water through the heating water inlet 7b to the heating water passage 6. This corresponds to step (b) in the above overview of the method 60. To heat 63 the reaction chamber 1, the heated water is supplied via a water supply line (not shown) to the heating water inlet 7b. The heated water enters the heating water inlet 7b and runs into the heating water passage 6. Since the heating water passage 6 contains water at 75°C (or just below that temperature, since the water loses heat when it is transferred from the water bath), and since, as mentioned above, the reaction chamber wall 5 is of stainless steel and is therefore a good thermal conductor, the reaction chamber 1 is heated 63. A second water line is connected to the heating water outlet 7a, so that water flows out of the heating water passage 6 through the heating water outlet 7a.

The malted barley, rice hulls, water and alpha amylase are weighed out at step 64 using a balance (not shown). For this test, 90g (0.09kg) of barley, 5g (0.005kg) of rice hulls, 210g (0.210kg) of water and 0.2g (0.0002kg) of alpha amylase are weighed out. When the method is used with other food or plant materials, other raw materials, enzymes and solvents can be used. For example, if the substance to be extracted from the food or plant material is not susceptible to being made more soluble by enzymatic hydrolysis, or is not soluble in water, the solvent used for the enzymatic reaction and/or the solvent used for the extraction could be ethanol, oil, an organic solvent, or a deep eutectic solvent.

Next, the weighed-out water is added at step 65 to the reaction chamber 1 by pouring it through the funnel into the top opening 2 of the reaction chamber 1, into the reaction chamber 1. This corresponds to step (e) in the overview of the method outlined above. The mixer switch 23 is pressed. This turns the mixer 21 on by completing the circuit supplying power to the motor 32. Thus, the motor 32 turns the impeller 33. In this example the speed of the impeller is initially set at 200 rpm. Once the impeller 33 is turning, the rice hulls and malted barley are added at step 66 into the chamber 1 by pouring them through a funnel into the top opening 2 of the reaction chamber 1, into the reaction chamber 1. This corresponds to step (c) in the above overview of the method. The temperature within the reaction chamber is measured, or sensed, at step 67, using the thermometer 53. This corresponds to step (f) in the overview given above of the method. The thermometer 53 senses the temperature within the chamber to determine the temperature of the raw materials within the reaction chamber 1. As mentioned above, the thermometer 53 is connected to a computer. Temperature sensing 67 is repeated throughout the method, with the thermometer 53 sensing the temperature within the reaction chamber 1 as the method 60 is being carried out and sending signals indicative of this temperature to the computer, which records the temperature within the reaction chamber 1 as the method 60 is carried out. In this example, the sensed temperature is used to control the temperature of the water supplied to the heating water inlet 7b to control the temperature within the reaction chamber 1.

When the desired temperature is reached, alpha amylase is added at step 68 to the reaction chamber 1 through the top opening 2. In this example, the desired temperature is 75°C, since alpha amylase works well at this temperature. In other embodiments, the reaction chamber 1 is heated to other temperatures, according to the enzyme used. Where, in other embodiments, an amylase is used as the enzyme, the temperature to which the reaction chamber 1 is heated can be between 50°C and 80°C. This step corresponds to step (d) in the above overview of the method.

Once the alpha amylase has been added 68 to the reaction chamber 1, enzymatic hydrolysis of carbohydrates in the malted barley begins at step 69. Mixing the malted barley, alpha amylase, rice hulls and water in the reaction chamber 1 produces a mash with rice hulls mixed through it.

The time for which the impeller 33 rotates is measured. After 60 minutes of mixing, the rotational speed of the mixer impeller 33 is reduced in this example to 100 rpm. In this example, the mixer 21 is switched off after 120 minutes by pressing the mixer switch 23. After mixing has been performed and the mixer impeller 33 stops turning, the upstand attachment 27 is pulled upwards so that it slides up the upstand 9b of the stand 9. This withdraws the impeller 33 from the reaction chamber 1. When the impeller 33 is fully outside the reaction chamber 1, the upstand attachment 27 is removed from the upstand 9b.

A beaker (not shown) is placed below the draining valve 31 to collect wort. The draining valve 31 is turned so that the draining valve 31 opens. Some wort from the mash will run through the filter 14a and out of the draining valve 31 under the force of gravity.

The plunger attachment 44 is attached at step 70 to the tool 10 with the seal 43. This seals the top opening 2. This step corresponds to step (h) in the above overview of the method. To attach the plunger attachment 44, the plunger attachment 44 is fitted to the top opening 2 of the reaction chamber 1. This is done by lowering the plunger attachment 44 onto the reaction chamber 1 so that the fastening seal is around the wall around the top opening 2 of the reaction chamber 1, and then turning the key on the fastening seal 43 to tighten it. Sealing the top opening 2 using the plunger 17 removes the need for an additional component to seal the top opening 2, for example a stopper. It therefore allows the method to be used with a simpler system than a system requiring a stopper. In other examples, however, a stopper can be used instead of a plunger to seal the top opening 2.

In order to extract wort from the mash, the gas inlet 51 is connected to a supply of pressurised gas so that gas is added at step 71 to the chamber to compress the mash. This corresponds to step (j) in the above overview of the method. In this example the supply is of pressurised air. This means the method can be performed at a lower cost than if other gases were used. In other examples, however, other gases can be used. In this example, a single supply of pressurised air is used both to actuate the plunger 17 and to add 71 pressurised air to the reaction chamber 1. This makes the method simpler than if a different gas supply is used to actuate the plunger from that used to add pressurised gas to the reaction chamber.

The supply of pressurised air is switched on so that pressurised air is added 71 into the reaction chamber 1. In this example, when the pressure within the reaction chamber 1 is at 40000Pa, the supply of pressurised air to the reaction chamber 1 is stopped. The pressure within the reaction chamber 1 is determined by a manometer at the gas inlet 51, and by a correspondence table which shows the relationship between pressure measured by the manometer and the pressure within the reaction chamber 1. Since the top opening 2 has been sealed, when gas is added to the chamber via the gas inlet 51, it does not escape via the top opening 2.

The increased pressure within the reaction chamber 1 compresses the mash. Wort is thereby forced out of the mash through the filter 14a and out of the draining valve 31 into the beaker below the draining valve 31. This initial extraction of wort is at step 72 in Figure 6.

Next, the chamber is depressurised at step 73 to later allow the plunger to enter the reaction chamber 1.

The mash is then compressed at step 74 with the plunger head 56. This corresponds to step (k) in the above overview of the method 60. To compress 74 the mash with the plunger head 56, the first quick pneumatic connection 54a in the housing 44a of the plunger attachment 44 is fitted to a pressurised air supply line. The supply of pressurised air is turned on so that pressurised air is supplied to the cavity defined by the cylindrical housing 44a. This pushes the sliding seal 55 downward. This causes the plunger shaft 52 to descend until the plunger head 56 contacts the top of the mash. The supply of pressurised air to the cavity defined by the cylindrical housing 44a is continued so that the plunger head 56 compresses the mash. More wort therefore passes through the filter 14a and out of the draining valve 31 into the beaker below. The depth to which the plunger head 56 has descended within the reaction chamber 1 is indicated on the scale 42 marked on the outside of the cylindrical housing 44a. From this, height of the cake can be estimated.

The pressure applied to the plunger is measured. In this example, a conversion table is used to calculate the pressure applied to the mash. For example, in the present example, it is known that when the pressure applied to the plunger is 200000 Pa (2 bar), the pressure in the reaction chamber has reached around 122000 Pa (1.22 bar). After the mash has been compressed 74 with the plunger head 56, the mash remaining in the reaction chamber 1 has had most of the water extracted from it. In this compressed, drier, form, the mash is known as a "cake".

This cake can be washed (or "sparged") to extract further malt extract. This is done by adding, at step 76, further water into the reaction chamber 1. This corresponds to step (I) in the above overview of the method 60.

Before adding 76 the water, the plunger head 56 is raised at step 75 by inverting the pressure in the cavity defined by the cylindrical housing 44a of the plunger attachment 44 to draw the sliding seal 55 upwards and thus raise the plunger head 56. The water is then heated in a water bath (not shown) to a controlled temperature. The controlled temperature can be set using, for example, a thermostat. In this example, the water is heated to 48°C.

After heating the water, the water is weighed out, for example using a balance (not shown). For this test, 210g (0.210kg) of water is weighed out. This water is poured into the washing funnel 52a and the valve 52b is opened so that water flows through the washing solvent inlet 52. From here, the water enters the reaction chamber 1 and pours onto the cake.

The mash is, in this example, compressed once again, by adding, at step 77, pressurised air to the reaction chamber 1. This corresponds to a repetition of step (j) as described in the above overview of the method 60. The addition 77 of pressurised air is performed as described above for the first iteration of this step.

This second compression by adding 77 pressurised air forces water through the cake. As the water filters through the cake, malt extract dissolves in it. Then, as wort, it passes through the filter 14a and out of the draining valve 31 into the beaker below. Thus, more wort is extracted, at step 78, from the reaction chamber.

In examples in which the substance to be extracted from the food or plant material is not water soluble, but can be hydrolysed to make it more soluble, water can be used for the initial step of adding solvent to the chamber, and a solvent other than water (for example ethanol, oil, an organic solvent, or a deep eutectic solvent) can be used for the washing step to extract the substance. In other examples in which the substance cannot be satisfactorily hydrolysed, a solvent other than water can be used for the initial step of adding solvent to the chamber.

The compression of the mash to form a cake means that the washing solvent flows through the malted grain in a more uniform manner than if the mash had not been compressed. In other words, the washing solvent reaches more of the malted grain when the mash has been compressed than it otherwise would. Thus, more malt extract can be extracted.

In this example, the mash is compressed 74 with the plunger head 56 again, water is added 76 again, and the mixture is compressed by adding 77 pressurised air again. That is, the steps described above from depressurising 73 the reaction chamber 1 to allow the plunger head 56 to enter the reaction chamber 1 to the extraction 78 of more wort from the reaction chamber are performed again. Each repeated step is performed as described above in relation to its first iteration.

In this example, the reaction chamber 1 is then decompressed once more, at step 79. The mash is compressed, at step 80, for a final time with the plunger head 56, as described above. A final extraction of wort from the reaction chamber is carried out at step 81. In other examples, the step of decompressing 73 the chamber to the step of extracting 78 further wort may be repeated any number of additional times. By repeating these steps, even more wort can be extracted from the mash.

In this example, after the repetition described above, the cake is removed at step 82. This corresponds to step (m) in the above overview of the method 60. The filter clamp 19 of the reaction chamber 1 is removed by unfastening the screws 20a, 20b, 20c. This leaves the bottom opening 3 defined by the inner diameter of the support 15 open. The cake is therefore no longer retained by the bottom part of the reaction chamber 1 so as to be able to slide out under gravity, or, if it does not slide out, to be pushed out by supplying more pressurised air through the first quick pneumatic connection 54a to the cavity defined by the cylindrical housing 44a such that the plunger head 52 descends further in the reaction chamber 1 and pushes the cake out.

Once the method 60 is complete, the wort is analysed to determine its soluble matter content, that is, how much malt extract it contains. This allows the yield of the experiment to be determined. The following example parameters can then be analysed: the temperature of the chamber; the mass of malted grain, of water and of enzymes added to the reaction chamber; the type of grain used; the type of enzyme used; the mass and type of any additional raw materials (such as the rice hulls in the above-described example); the time for which the mash was mixed; the speed at which it was mixed; the pressure within the chamber when gas is added; the pressure within the chamber when the plunger compresses the mash; the mass of washing solvent; and the number of times any steps were repeated.

In examples where the method is used on food or plant material other than malted grain, the solution extracted from the material can similarly by analysed to determine its soluble matter content. Example parameters that can be analysed in these examples include: the temperature of the chamber; the mass of food or plant material, of solvent and of enzymes added to the reaction chamber; the type of food or plant material used; the type or types of enzyme used; the mass and type of any additional raw materials (such as the rice hulls in the above-described example); the time for which the mixture was mixed; the speed at which it was mixed; the pressure within the chamber when gas is added; the pressure within the chamber when the plunger compresses the mash; the mass of washing solvent; and the number of times any steps were repeated.

By comparing these and the yield of soluble matter against other iterations of the method in which the parameters were different, improved parameters for extracting a substance from food or plant material can be determined.

Although the present techniques have been described by way of example, it should be appreciated that variations and modifications may be made without departing from the spirit and scope as defined in the claims. Furthermore, where known equivalents exist to specific features, such equivalents are incorporated as if specifically referred in this specification.

Claims

1. A multi-stage extraction testing system, the system comprising: a multi-purpose heating, mixing, compression and filtration chamber, the chamber comprising first and second sealable openings, the first sealable opening arranged to allow food or plant material, at least one enzyme and at least one solvent to be added to the chamber, and the second sealable opening arranged to allow undissolved material to be removed from the chamber, the chamber further comprising a first, outer, wall and a second, inner, wall, the first and second walls defining a cavity therebetween, the first wall comprising a water inlet, the cavity arranged to receive heated water through the water inlet thereby to heat the chamber; a temperature sensor at least partially within the chamber and arranged to sense the temperature within the chamber; a mixer arranged to be at least partially inserted into the first sealable opening and to mix at least one enzyme, food or plant material and solvent within the chamber to produce a mixture; a gas inlet arranged to allow pressurised gas into the chamber to compress the mixture; a plunger arranged to be at least partially inserted into the first sealable opening and to compress the mixture; a sealable solution outlet arranged to allow, when not sealed, a solution of a solvent and an extract extracted by the solvent to exit the chamber therethrough; and a filter across the sealable solution outlet, the filter arranged to filter the mash.

2. The multi-stage extraction testing system as claimed in claim 1, wherein the system further comprises a water heater arranged to heat water supplied to the cavity through the water inlet and a temperature controller arranged to control the water heater to control the temperature to which the water is heated.

3. The multi-stage extraction testing system as claimed in claim 2, wherein the temperature controller is arranged to control the water heater to control the temperature to which the water is heated, based on signals received from the temperature controller, the signals indicative of the temperature within the chamber.

4. The multi-stage extraction testing system as claimed in any one of the preceding claims, the system comprising a pneumatic actuator arranged to drive the plunger into the chamber.

5. The multi-stage extraction testing system as claimed in any one of the preceding claims, wherein the plunger comprises a scale marked on a component of the plunger, the marker arranged to slide along the scale when the plunger is driven into the chamber and to stay still with respect to the scale when the plunger is retracted from the chamber, the marker arranged to show, in use, how far the plunger has been driven into the chamber.

6. The multi-stage extraction testing system as claimed in any one of the preceding claims, wherein the second sealable opening is defined by the second, inner, wall of the chamber.

7. A multi-stage extraction testing method, the method comprising:

heating a multi-purpose heating, mixing, compression and filtration chamber by supplying heated water through a water inlet in a first, outer, wall of the chamber to a cavity defined by a first, outer, wall and a second, inner wall; adding food or plant material to the chamber through a first sealable opening in the chamber; adding at least one enzynne to the channber through the first sealable opening in the chamber; adding a solvent into the chamber through the first sealable opening in the chamber; with a temperature sensor at least partially within the chamber, sensing the temperature within the chamber; at least partially inserting a mixer into the first sealable opening and to mix the food or plant material, at least one enzyme and solvent within the chamber to produce a mixture; sealing the first sealable opening; opening a sealable solution outlet to allow a solution of a solvent and an extract extracted by the solvent to exit the chamber therethrough and through a filter across the sealable solution outlet; adding pressurised gas into the chamber through a gas inlet to compress the mash; at least partially inserting a plunger into the first sealable opening to compress the mash; adding further solvent into the chamber through the first sealable opening; removing undissolved material from the chamber via a second sealable opening in the chamber.

8. The method as claimed in claim 7, wherein the method is a malt extraction testing method and the food or plant material is malted grain.

9. The method as claimed in claim 7 or claim 8, wherein the solvent added into the chamber through the first sealable opening is a first solvent and wherein the further solvent added into the chamber through the first sealable opening is a second solvent.

10. The method as claimed in any one of claims 7, 8 or 9, wherein the method comprises controlling a rotational speed of the mixer to be a speed selected from the group comprising: between 10 and 2000 rpm; between 10 to 500 rpm; and between 20 and 200 rpm.

11. The method as claimed in any one of claims 7 to 10, the method comprising removing undissolved material from the chamber by removing a base of the chamber.

12. The method as claimed in any one of claims 7 to 11, wherein the method comprises performing, in the following order, the steps of opening the sealable solution outlet to allow a solution of solvent and extract extracted by the solvent to exit the chamber therethrough and through the filter across the sealable solution outlet, adding pressurised gas into the chamber through the gas inlet to compress the mash, at least partially inserting the plunger into the first sealable opening to compress the mash, and adding solvent into the chamber through the first sealable opening.

13. The method as claimed in claim 12, the method comprising, after the step of adding solvent into the chamber through the first sealable opening, repeating the steps of adding pressurised gas into the chamber through a gas inlet to compress the mash, at least partially inserting the plunger into the first sealable opening to compress the mash, before the step of removing grain from the chamber via the second sealable opening in the chamber.

14. The method as claimed in any one of claims 1 to 13, the method comprising performing, in the following order, the steps of heating the multi-purpose heating, mixing, compression and filtration chamber, adding a solvent into the chamber, adding plant or food material to the chamber, sensing the temperature within the chamber and adding at least one enzyme to the chamber.

15. A multi-stage plant or food material extraction testing apparatus, the apparatus comprising:

a multi-purpose heating, mixing, compression and filtration chamber, the chamber comprising first and second sealable openings, the first sealable opening arranged to allow food or plant material, at least one enzyme and at least one solvent to be added to the chamber, and the second sealable opening arranged to allow undissolved material to be removed from the chamber, the chamber further comprising a first, outer, wall and a second, inner, wall, the first and second walls defining a cavity therebetween, the first wall comprising a water inlet, the cavity arranged to receive heated water through the water inlet thereby to heat the chamber; a temperature sensor at least partially within the chamber and arranged to sense the temperature within the chamber; a gas inlet arranged to allow pressurised gas into the chamber to compress a mixture of food or plant material, at least one enzyme and solvent; a sealable solution outlet arranged to allow, when not sealed, a solution of a solvent and an extract extracted by the solvent to exit the chamber therethrough; and a filter across the sealable solution outlet, the filter arranged to filter the mixture; wherein the first sealable opening is arranged to receive: a mixer arranged to be at least partially inserted into the opening and to mix food or vegetal material and water within the chamber to produce the mixture; and a plunger arranged to be at least partially inserted into the opening and connpress the mixture.