WO1999006528A1 - Device and method for stabilising the tartrate index of wines - Google Patents

Abstract

The invention concerns an installation for stabilising wine tartrate index comprising: means (26, 28) for cooling the wine; a so-called crystallising device (10), including a removable metal support, with a large removable metal surface (30, 34) for crystallisation and retention of the wine tartaric acid salts; means (36, 38) for circulating wine through the crystallising device.

Description

 DEVICE AND METHOD FOR TARTARIC STABILIZATION OF

WINES

Technical Field The present invention relates to an installation and a process for tartaric stabilization of wines.

Wine generally contains tartaric acid, and in particular salts of potassium bitartrate and / or dissolved calcium tartrate. During the conservation of wine bottles, and especially when the bottles undergo a drop in temperature, the salts of tartaric acid precipitate and form small crystals. The deposit of these crystals in the bottles, although not presenting a danger for the consumer, is however interpreted negatively and harms the image of quality of the wine. Tartaric stabilization prevents precipitation of tartaric acid salts and therefore the formation of crystals in wine.

State of the art

At present, to avoid the presence of crystals in the wine, the wine is subjected to a so-called stabilization treatment, prior to bottling. This treatment consists of inducing crystallization of the potassium bitartrate (THK) and calcium tartrate (TCa) salts in the wine and then filtering the wine to remove the crystals.

The crystallization of these wine salts can be brought about, for example, by keeping the wine in tanks at a temperature of the order of -4 ° C for a period which can range from a few hours to a fortnight. It immediately appears that such treatment is too long and unsuitable for commercial wine production. Indeed, the immobilization of the tanks during the stabilization treatment, as well as the cooling of the wine, considerably increase the production costs.

To reduce the crystallization time, several techniques have been developed. For example, sowing with finely ground potassium bitartrate crystals (THK) and introduced into the tank containing the wine; which accelerates the crystallization of the salts of tartaric acid. Reference may be made to this subject in document (1), the reference of which is indicated at the end of this description.

However, such a process remains relatively expensive and the growth of the crystals is always too slow.

In addition, during refrigerated wine stabilization treatments, the tartrate crystals are removed either by decantation or by cyclone or filter systems. These techniques are mentioned, for example, in documents (2), (3) and (4), the references of which are given at the end of this description.

The separation of the crystals and the wine by simple decantation proves to be long and therefore also unsuitable for commercial wine production.

Furthermore, known filtering or cyclone systems are not provided or are not optimized to recover the tartrate crystals extracted from the wine in order to enhance them. However, it turns out that the tartrate crystals, which constitute a food-grade acidifier, are perfectly recoverable in the food industry. The crystals formed in wine can in fact be transformed into salts of edible tartaric acid, in the form of finely ground and purified crystals, also known as "cream of tartar".

Finally, there are known processes for stabilizing wine by electrodialysis. These methods consist in removing the tartrate and bitartrate ions from wine by causing these ions to migrate through a selective membrane, under the effect of an electric field. It appears for these processes that the treatment of very unstable wines, that is to say wines containing a large amount of tartaric acid, requires frequent maintenance of the membranes. Furthermore, to avoid a too low treatment rate, a very large membrane surface is required. Finally, electrodialysis does not make it possible to process wine online, just after the harvest, due to its high instability. Thus, this process is not well suited for the production of early wines.

Statement of the invention

An object of the present invention is to provide an installation and a method for tartaric stabilization of wine which does not have the limitations mentioned above. One goal is in particular to propose an installation making it possible to quickly and economically process a large quantity of wine in order to reduce the costs of the treatment. Another aim is also to provide an installation which is easy to maintain and which requires little maintenance.

Another goal is to offer an easily removable and transportable installation from one vinification unit to another.

Another aim is also to propose a tartaric stabilization of the wine which is not stressful for the wine and which does not alter its qualities. Finally, an object of the invention is to allow easy recovery of the tartrate crystals for their subsequent recovery, for example, in the food industry.

To achieve these aims, the invention more specifically relates to a tartaric stabilization installation for wine comprising:

- means for cooling the wine,

A device, known as a crystallization device, comprising at least one removable metal support, having a large surface for the crystallization and retention of the tartaric acid salts of the wine, and

- means for circulating the wine through the crystallization device.

The operating principle of the installation is the direct crystallization of the salts of tartaric acid on a removable metal support. This support may possibly include seeds of crystallization, but these seeds are not essential.

As indicated above, according to an important characteristic of the invention, the crystallization means are formed essentially by the metal support of the crystallization device. So, when passing through an area where the removable metal support, the average distance between the tartrate ions and the crystals already fixed, and offered for growth, is small. In addition, the crystals formed are retained on the surface of the metal support. Filter and / or cyclone systems for recovering the crystals are therefore not necessary.

According to one aspect of the invention, the metal support of the crystallization device can comprise a stack of perforated or non-perforated metal plates. Such trays allow prolonged contact of the wine with the metallic surface.

According to another aspect of the invention, the metal support of the crystallization device can comprise metallic wool. The entanglement of the metallic threads of the wool offers a very large contact surface with the wine, and a very small distance between the tartrate ions and the crystals already fixed. According to a particular construction, the metal plates, previously mentioned, can be associated with metallic wool. In such a case, the metallic wool can be placed on the plates as a garnish. According to another advantageous aspect of the invention, the plates and / or the metallic wool are designed to be removably installed in the crystallization device. This characteristic facilitates maintenance of the installation and above all allows easy recovery of the tartrate crystals accumulated in the metallic wool. For example, when the trays and / or the metallic wool are extracted from the device, they can easily be subjected to rinsing and / or vibration to recover the tartrate crystals.

The wine cooling means may include a cooling group equipped with a heat exchanger.

In this case, according to a particular embodiment, the crystallization device can be designed to also form the essential part of the heat exchanger. Such an embodiment allows the wine to be cooled directly by the metallic crystallization surface, and particularly promotes the formation of crystals.

Alternatively, the cooling means may also include a circulation cooling group, through which the wine can flow.

According to a particular aspect of the invention, the installation may further comprise means for forming an electric field around said metal support. These means include, for example, a reference electrode in contact with the wine and a voltage source connected between the reference electrode and the metal support. Preferably, the voltage value is chosen to be low enough not to cause electrochemical reactions in the wine.

The invention also relates to a crystallization device for tartaric acid salts comprising a wine circuit, a set of metal trays arranged in the wine circuit, and a cooling fluid circuit in thermal contact with the wine circuit, by means of said metal plates. Finally, the invention relates to a process for the tartaric stabilization of wine in which the cooled wine is circulated on a metallic crystallization surface and in which a potential difference is applied between the metallic crystallization surface and a reference electrode in contact with the wine, so as to create an electric field around said crystallization surface. Other characteristics and advantages of the invention will emerge more clearly from the description which follows, with reference to the figures of the appended drawings. This description is given purely by way of non-limiting illustration.

Brief description of the figures

- Figure 1 shows schematically two different configurations of a tartaric stabilization installation with a crystallization device external to the tank containing the wine to be stabilized.

- Figure 2 shows in section and schematically, a tartaric stabilization installation with a crystallization device immersed in a tank containing the wine to be stabilized. - Figure 3 is a schematic section of a first particular embodiment of the crystallization device of Figure 1.

- Figure 4 is a schematic section of an alternative embodiment of the crystallization device of Figure 1.

- Figure 5 is an enlarged schematic section of a detail of an alternative embodiment of the device of Figure 4. Detailed description of methods of implementing the invention

The stabilization installation of FIG. 1 comprises a crystallization device 10, equipped with means for cooling the wine. These means are not shown in this figure for reasons of clarity. An input 12 of the crystallization device

10 is connected to a tank 14 of wine to be treated via a first pipe 16. An outlet 18 of the crystallization device is, according to a first configuration of the installation, also connected to the tank 14 of wine to be treated by a second pipe 20a. In this configuration, a pump 22, arranged, for example, on the first pipe 16, makes it possible to circulate the wine from the tank 14 of wine to be treated, through the crystallization device 10 to finally pour the treated wine into the same tank.

Such a configuration of the wine stabilization installation, known as a "batch" configuration, is suitable in particular for the treatment of wines with a high tartaric acid content, such as, for example, early wines.

A second configuration of the installation, which constitutes a variant of the first configuration, is also shown in FIG. 1, in broken lines.

According to the second configuration, the wine leaving the crystallization device is not directed towards the tank 14 of wine to be treated but towards a second tank 24 of treated wine. To this end, a line 20b connects the outlet 18 of the crystallization device to the second tank. This configuration of the installation is referred to as "continuous processing configuration". A third configuration of the installation, known as an immersed crystallization device, is shown in FIG. 2.

In this configuration, the crystallization device 10 is directly immersed in the tank 14 of wine to be treated. It can be noted that the cooling of the wine, in the installation of FIG. 2, does not take place directly in the crystallization device but is caused by a heat exchanger 26, immersed in the tank 14 and connected to a cooling group. 28. The cooling group is designed to cool the wine to a temperature preferably between 0 and -4 ° C.

It can be noted that the crystallization device 10 comprises a certain number of metal plates 30, for example made of stainless steel, fixed on a casing 32 according to an arrangement in baffles. The plates 30 are further provided with pads 34 of stainless steel wool.

The plates 30, as well as the metal pads 34, have a metal surface which allows the crystallization of the tartaric acid salts.

A propeller 36, connected to motor means, not shown, by a drive shaft 38, makes it possible to circulate the wine through the crystallization device from openings 40 made in the upper part of the casing 32 up to an opening lower 42 of the casing. The circulation of the wine along the plates 30 and through the pads of metallic wool allows both prolonged contact of the wine with the metallic crystallization surface and makes it possible to reduce the average distance separating a tartrate ion from the crystallization surface.

These measures allow efficient and rapid stabilization of the wine. The mesh of the metallic wool of the pads 34 is chosen sufficiently fine and rough to favor the formation of the tartrate crystals produced during the crystallization of the tartaric acid salts.

The reference 50 in FIG. 2 designates an adjustable voltage source. A first terminal of the source 50 is connected to a reference electrode 52 in contact with the wine and a second terminal of the source is connected to the plates 30 which constitute a second electrode. The voltage source creates an electric field around metal surfaces and promotes the formation of crystals. The source voltage is, for example, of the order of

200 mV. The value of the tension, as well as its polarity can be adjusted according to the wine treated so as to optimize crystallization. However, it is preferably chosen to be low enough not to induce electrochemical reactions in the wine.

The reference electrode 52, brought into contact with the wine is made of a material such as stainless steel or graphite, for example.

A more detailed description of the crystallization devices is given with reference to FIGS. 3 and 4. These figures do not however relate to crystallization devices intended to be immersed but to be used in installation configurations in accordance with Figure 1.

The crystallization device 100 of FIG. 3 comprises a reservoir delimited by a wall 101 which is essentially cylindrical and having in its upper part a mouth 102 for the arrival of wine to be treated. The device also has a central chimney 104 which leads to an outlet 106 for the treated wine.

The chimney 104 and the outer wall 101 define an annular space in which a number of circular plates 130a, 130b are formed. These plates 130a, 130b are arranged perpendicular to the chimney 104 and are arranged in baffles.

The wine, circulated by a pump external to the device (not shown in the figure) enters the tank by the arrival of wine 102. It then passes into the part of the tank comprising the trays 130a and 130b and goes up into the chimney central 104 to leave the tank through a tube 106 which forms the outlet for the treated wine. The tube 106 passes concentrically through a dispensing nozzle 108 of the wine inlet 102.

The uniform distribution of the wine in the tank is ensured by a set of openings 110 made in the dispensing nozzle 108 of the wine arrival. The plates 130a, 130b are for example eight in number.

They have a bottom 131 which is permeable to wine. The bottom 131 is pierced with wine passage holes or is made, for example, by a mesh. The plates also have a rim 132. Each plate 130a, 130b is lined with one or more layers of metallic wool 134, for example made of food steel. The layers of metallic wool, arranged on the bottom 131 of the plates are essentially retained by their edge 132.

As can be seen in Figure 3, the device has two types of plates 130a and 130b of equal width but of different diameters.

The plates 130a, of the first type, have an internal diameter adjusted to the diameter of the central chimney 104 and an external diameter less than the diameter of the wall 101 of the tank. The trays 130b of the second type have an inner diameter greater than the diameter of the central chimney 104 and have an outer diameter adjusted to the diameter of the wall 101 of the tank. The first plates 130a rest on lugs 135a fixed on the central chimney and the second plates 130b rest on lugs 135b secured to the wall 101 of the tank.

The pins 135a, 135b are preferably three in number for each plate and distributed angularly at an angle of the order of 120 ° in planes perpendicular to the figure.

The plates have grooves corresponding respectively to the lugs in order to be able to remove them from the tank by adjusting the position of the grooves on that of the lugs.

It can be noted that the upper part of the wall 101 of the tank is made in the form of a removable cover to allow removal of the trays 130a, 130b. The seal between the cover and the remaining part of the tank is ensured by an annular flange 136, and a central joint 138 disposed between the top part of the chimney 104 and the nozzle 108 of the wine inlet.

The wine is cooled by a cooling circuit constituted for example by a jacket 140 surrounding the wall 101 of the tank. The cooling circuit has in the lower part of the jacket 140 an inlet 142 for cooling fluid and in its upper part an outlet 144 for the fluid.

The cooling fluid inlet and outlet are respectively connected to a cooling refrigeration unit not shown in the figure. One can notice in the cooling circuit the presence of deflectors 146 which are preferably arranged in a helix to promote and homogenize the heat exchange.

Thus, the salts of tartaric acid, of wine cooled to a temperature of -2 ° C ± 2 ° C, crystallize on the trays and on the metallic wool where they are retained. The possibility of removing the trays 130a,

130b allows quick and convenient recovery of the crystals formed.

According to a particularly interesting aspect of the device as shown in Figure 3, the plates 130b and the outer wall of the tank are in thermal contact with the cooling circuit and thus constitute a heat exchanger. Cooling of trays and metallic wool can thus be used to promote the crystallization of tartaric acid salts.

The reference 145 in Figure 3 designates a drain valve of the crystallization device. This valve, shown very schematically, allows the wine contained in the device to be removed after use.

Figure 4 shows another embodiment of the crystallization device. For the sake of convenience, identical references to which 100 have been added denote parts which are identical or similar to the parts of the device in FIG. 3 described above.

The device 200 comprises a tank, substantially cylindrical, delimited by a wall 201.

An annular space 203 is defined between the wall 201 of the tank and a central chimney 204 which channels the treated wine.

The wine to be treated which arrives in the tank 200 by a wine inlet 202, is distributed in the annular space by a distributor 208 which is in the form of a torus pierced with holes, in particular on its lower part.

The wine, the circulation of which is ensured by an external pump not shown, is then directed to trays 230 in the form of grids. These trays are lined with metallic wool pads 234. The wine passes through the trays 230 and the metallic wool before being extracted from the tank 201. Unlike the device of FIG. 3, the trays 230 are not arranged horizontally, but vertically. Note also that unlike the device of Figure 3 where the plates are arranged in series in the wine circuit, the trays of the device of Figure 4 are arranged in parallel in the wine circuit.

The plates are held in the lower part of the tank 200 by supports 235. It can be noted that the lower part of the tank is connected to the upper part of the tank by means of a seal 236, so that it can be dismantled in order to remove the trays and the metallic wool pads.

In the same way, a seal 238 connects in a leaktight but removable manner an upper part and a lower part of the central chimney 204.

The removal of the metallic wool makes it possible to recover the crystals of tartaric acid salts which have formed.

The crystallization device of FIG. 4 is equipped with a cooling circuit 240, in contact with the wall 201 of the reservoir 200. This circuit makes it possible to cool the wine before it reaches the metallic crystallization surface formed by the metallic trays 230 and metallic wool 234.

As a variant, the cooling circuit 240 can also be constituted by a set of tubes 262 wound in a spiral in the annular space between the cylindrical ferrules 201 and 204, and in which the refrigerant circulates. This set of tubes constitutes an efficient exchanger 260.

This variant is shown in FIG. 5. According to another particularly advantageous aspect of the device, a heat exchanger 250 is provided in the upper part of the tank, just under the distributor 208. The ^heat exchanger consists of a set of tubes 252 wound in a spiral and which connect the top part 254 of the central chimney 204 to a wine outlet 206 of the device. Untreated wine admitted to the device since the arrival of wine, passes through the heat exchanger 250 before reaching the metallic crystallization surfaces.

Thus, the treated wine, which has been cooled by the cooling circuit 240, and which has passed over the metallic crystallization surfaces, circulates through the tubes 252 of the heat exchanger 250 and transfers its calories to the newly admitted wine.

Such an arrangement allows significant energy savings for cooling the wine.

It can be noted that a passage 256, fitted with a valve 258 also makes it possible, if necessary, to directly connect the top part 254 of the central chimney 204 to the wine outlet 206. In FIG. 4, the reference 245 finally designates a drain valve of the crystallization device. As mentioned above, the devices in FIGS. 3 and 4 are more specifically adapted for use in an installation in accordance with FIG. 1.

These devices described above allow large quantities of wine to be treated quickly and with a particularly reduced energy cost. They can be used either in a "batch" configuration or in a continuous processing configuration.

Furthermore, the removable nature of the elements constituting the crystallization surfaces, allow not only easy maintenance but also to recover and therefore enhance the crystals of the tartaric acid salts formed.

CITES DOCUMENT

(1)

FR-A-0 975 575, (2) FR-A-2 623 518, (3)

EP-A-0 299 597, (4)

FR-A-2 589 163.

Claims

1. Tartaric stabilization installation of wine comprising: - means (26, 28, 140, 240) for cooling the wine, equipped with a heat exchanger - A device (10, 100, 200) called crystallization, comprising at least one removable metal support, having a large surface (30, 34, 130a, 130b, 134, 230, 234) for the crystallization and the retention of salts of tartaric acid in wine, and - Means (36, 38, 102, 106) for circulating the wine through the crystallization device, in which the crystallization device (100) essentially forms the heat exchanger. 2. Installation according to claim 1, wherein the metal support of the crystallization device comprises metal plates (130, 130a, 130b, 230) for crystallization and retention of tartaric acid salts. 3. Installation according to claim 1, wherein the metal support of the crystallization device comprises metallic wool for the crystallization and the retention of tartaric acid salts. 4. Installation according to claim 2, wherein at least one metal tray has a lining (34, 134, 234) of metallic wool. 5. Installation according to claim 1 wherein the cooling means further comprises a circulation cooling group, through which the wine can circulate. 6. Installation according to claim 1, wherein the surface of the metallic crystallization support has seeds of crystallization. 7. Installation according to claim 1, further comprising a wine tank, the crystallization device being able to be, at least in part, immersed in the wine tank (14). 8. Installation according to claim 1, further comprising a first wine tank (14) intended to contain wine to be stabilized and a second wine tank (24) intended to collect the stabilized wine, the means for circulating the wine to through the crystallization device being provided for sucking wine into the first tank and pouring it into the second tank after passing through the crystallization device. 9. Installation according to claim 1 further comprising a wine tank (14), the means for circulating the wine through the crystallization device being provided for sucking wine in the wine tank and pouring it back into the tank after passage in the crystallization device. 10. Tartaric wine stabilization installation comprising: - means (26, 28, 140, 240) for cooling the wine, equipped with a heat exchanger - A device (10, 100, 200) called crystallization, comprising at least one removable metal support, having a large surface (30, 34, 130a, 130b, 134, 230, 234) for the crystallization and the retention of salts of wine tartaric acid, means for forming an electric field around said metallic support, and - Means (36, 38, 102, 106) for circulating the wine through the crystallization device. 11. Installation according to claim 10, in which the means for forming an electric field comprise a reference electrode and a voltage source connected between the reference electrode and the metal support. 12. Device for crystallizing tartaric acid salts from wine comprising a wine circuit (120, 104, 106, 202, 203, 204, 206), a set of metal trays (130a, 130b, 230) arranged in the circuit of wine and a coolant circuit (140, 240, 260) in thermal contact with the wine circuit, via said metal trays. 13. Device according to claim 12, in which the plates (30, 130a, 130b, 230) have a lining of metallic wool (34, 134, 234). 14. Device according to claim 12, comprising a heat exchanger (250) for bringing into thermal contact the wine circulating in the device upstream of the metal plates (230) and the wine circulating downstream of the metal plates (230). 15. A method of tartaric stabilization of wine according to which the cooled wine is circulated through a set of metallic wires (34, 134, 234) forming a crystallization surface and according to which a positive potential difference is applied between the surface of crystallization and a reference electrode in contact with the wine, so as to create an electric field around said crystallization surface. 16. The method of claim 15, wherein the metallic crystallization surface is cooled. 17. The method of claim 15, wherein the wine is circulated on a plurality of trays equipped with a woolen lining of metal son (34, 134, 234).