WO2015067472A1 - Method for obtaining starch - Google Patents

Abstract

The invention relates to a method for obtaining starch from green bananas containing starch, which method comprises at least the following steps: 100) providing green bananas, 200) peeling the green bananas in order to obtain the banana flesh; 300) mixing the banana flesh from step 200) with water; 400) adding an enzyme that causes a disintegration of the fiber and cell structure of the banana flesh to the flesh/water mixture from step 300); 500) allowing the enzyme to act for an action time T; and 700) separating the enzyme/flesh/water mixture from step 700) into a higher-starch and lower-water starch suspension a lower-starch and higher-water water/fiber suspension.

Description

 Process for obtaining starch

The invention relates to a process for obtaining starch from green bananas. Methods for obtaining starch from starchy plants are known per se, such as WO 2013/143986 A2.

Thus, in the extraction of starch from potatoes, these are first placed in a washing and de-stoning plant. This is followed by a crushing of the potatoes. This can be done by disintegration, for example by means of a crusher or a grater. After grating the potatoes, an optional desanding can take place. Subsequently, if necessary, after a centrifugal separation of amniotic fluid, vegetable fibers are separated from the starch milk by separation, in particular sieving. This corresponds to a separation of the comminuted plants into a high-strength fiber fraction and a low-strength fiber fraction, wherein the high-starch fiber fraction is the starch milk and the low-strength fiber fraction is the vegetable fibers. This is followed by dewatering of the plant fibers, which are subsequently removed from the process as fiber pulp. The starch milk, on the other hand, is further processed into starch, in particular by starch washing. If necessary, a fine-fiber sieving is carried out and the washed starch milk is subsequently freed from most of the water in a starch drainage.

For this purpose, WO 2013/143986 A2 also proposes that even the low-strength fiber fraction be further processed. For this purpose, the low-strength fiber fraction is placed under high pressure to achieve further cell disruption and further release of starch by high-pressure cell disruption to a pressure of at least 10 bar, which is then recovered in addition. The known method has proven itself, but is essentially suitable for the products potatoes, cassava roots or legumes. For green bananas, however, the known method is not meaningful applicable.

Against this background, it is the object of the invention to provide a method by which starch can be obtained from green bananas in a relatively simple manner on an industrial scale. The invention achieves this goal by the method of claim 1.

Advantageous embodiments of the invention can be found in the dependent claims. By adding an enzyme, in particular pectinase, the pectin contained in the cell walls is broken up so that the starch clumps are released and can be separated from the previously produced pulp / water mixture. An enzyme within the meaning of claim 1 is understood to mean an enzyme alone or else the addition of an enzyme cocktail which is preferably pectinase-containing (and / or protease-containing) and contains two or more different enzymes.

Although the use of pectinase is known, for example, from the production of fruit juices or the field of wine production. The use of this enzyme in the field of starch production from bananas, however, has not yet been considered, but surprisingly brings in the field of bananas the desired result with it, that it is possible to separate the starch in a simple manner after a certain exposure time can. This separation / classification can be carried out, for example, by means of hydrocyclones or by means of one or more sieves or by means of a decanter. There is the known range of separators from the field of conventional starch production in the field of potatoes available. The invention will be described in more detail with reference to the drawing with reference to an embodiment.

1 shows a flowchart to illustrate an exemplary method according to the invention.

According to the exemplary method of FIG. 1, green bananas are initially provided in a step 100.

These green bananas of step 100 are then peeled in a step 200 to obtain the "pulp" separated from the trays. The starch content of this pulp is high. For example, it was found in an experiment that the starch content of this pulp is, for example, 22 grams of starch in 100 grams of pulp.

The pulp obtained in step 200 is then preferably added with water in a step 300, with or without stirring the pulp / water mixture.

The addition of the water is preferably carried out at a temperature of less than 35 ° C, in particular less than 30 ° C, preferably 20 to 25 ° C. In the experiment, for example, 100 g of pulp were added to 700 g of water. Preferably, at least five parts of water or more are added to a portion of pulp.

The pulp-water mixture from step 300 is then further comminuted in step 400. This can be done in one step, for example by shearing or, for example, in two steps by rasping and shearing. The crushing can also be done in other ways.

Then, a single enzyme or an enzyme cocktail is added to the minced water-pulp mixture from step 400 in a step 500. As this enzyme, an enzyme which breaks down the pulp and / or cell structure is used.

It has been found that, especially with the enzyme pectinase excellent results are achieved in terms of the subsequent starch production. Without the addition of the enzyme, a starch production on an industrial scale is virtually impossible to represent.

After adding the enzyme pectinase this should act for a certain time before further processing takes place. Preferably, this action is accompanied by stirring at a temperature of preferably more than 15 ° C, more preferably more than 25 ° C, especially more than 30 ° C, most preferably 37 ° C and preferably less than 40 ° C. The exposure time during stirring in step 600 is preferably more than 10 minutes, in particular more than 20 minutes, most preferably 30 minutes or more.

Then the mixture from step 500, which consists of the comminuted pulp-water mixture, was added to the pectinase, which time was allowed to act while stirring, placed in a separator. In the separation device, a separation / classification of a starch suspension takes place from the remaining cell structure material in the retentate / upper run. As a separating device in step 700, in particular a sieve can be used. Alternatively, hydrocyclones or a decanter are used. The sieve preferably allows a separation of particles which are larger than 50 μm.

Preferably, the reaction time of the enzyme in step 500) is such that the cell structures destroyed by the enzyme are substantially more than 20% larger than the starch granules.

Individual starch granules should be free, i. without the cell substance enclosing the starch granules or without the starch granules enclosing pectin chains,

An optimal enzyme effect would be achieved if all starch granules were present individually. In practice, however, a proportion of starch in Siebrückstand remain in starch granule associations, so that it is advantageous to post-treat this suspension in Siebrückstand of starch granules associations, so by means of one or both measures: mechanical action (shear, extruder, high pressure or the like.) And Adding / allowing for a single enzyme or enzyme cocktail.

Starch granules usually have sizes from 2 to about 5 or more than 5 starch granules, depending on the enzyme efficiency. These can be e.g. different treatment or differentiation.

In a laboratory experiment in which in one step 300 100 g of pulp without skins were added to 700 g of water, it was found that after the addition of pectin (preferably up to 2 ml, in particular up to 1, 5 ml, in experiment 0, 1 ml of enzyme, in each case based on 1 00 g of banana (without shell), a starch suspension is obtained in the separation / classification of step 700, which amounts to about 100 g. Starch grains of a size of about 40 to 45 μm are obtained.

For separation, various devices such as sieves, hydrocyclones, decanters or the like can be used. The proportion of the retentate / headwaters containing the even larger starch granules is, on the other hand, 700 g. If necessary, this retentate can be comminuted in a step 710, wherein in a further step 720 the water content is reduced. The reduced retentate in the water content can then be recycled to the mixing process with the enzyme pectinase of step 500. This is not mandatory but purely optional.

The starch suspension obtained in the separation step is then processed further as it is known per se from the field of industrial starch production. So it is possible to wash them once or three times to reduce the water content. With a subsequent drying, it is then possible to gain an industrially exploitable strength. In one experiment, it has been found that this starch has a purity of 85 percent. 4.5 g of industrially utilizable starch were recovered. This value can be increased by the mentioned recycling and re-treatment of the sieve residue.

Undoubtedly, the enzymes cause the fibers to be disrupted in step 500. Care must be taken to choose the residence time of the enzyme so that sufficient starch is released on all sides and, on the other hand, there is no destruction of the fibers so extensive that they can pass through a sieve of 50 μm. Importantly, the action time of the enzyme pectinase is such that in the mixing step and stirring and reaction step 600 the fibers are destroyed only so far that they can still be separated in separation step 700 substantially from the water-pulp-pectinase mixture , Preferably, the temperature in the process steps between 20 ° C and 40 ° C, in particular 37 ° C.

Claims

claims Process for obtaining starch from starchy green bananas, characterized by at least the following steps:  100) providing green bananas,  200) peeling the green bananas to obtain the banana pulp; 300) mixing the banana fruit meat from step 200) with water;  400) adding an enzyme which reduces the fiber and cell structure of the banana fruit meat to the pulp / water mixture from step 300);  500) exposing the enzyme to an exposure time T; and  700) separating / classifying the enzyme / pulp / water mixture from step 700) into a starchy and less watery starch suspension and a starch-containing and water-containing water / fiber suspension. A method according to claim 1, characterized in that as the enzyme added in step 400 pectinase is used. A method according to claim 1 or 2, characterized in that the separation takes place in step 700 with a sieve, wherein a screen residue remains. A method according to claim 3, characterized in that the mesh size of the sieve is at most 50 μιτι. Method according to claim 1 or 2, characterized in that the separation / classification takes place in step 700 in the centrifugal field with a decanter or hydrocyclone. A method according to claim 3, 4 or 5, characterized in that the remaining during separation / classification phase with larger starch granules associations, in particular the screen residue, is subjected to further treatment by means of enzymes. A method according to claim 6, characterized in that the remaining during separation / classification phase with larger starch granules associations, in particular the screen residue is subjected to a further treatment by means of a mechanical Einwirkverfahrens. 8. The method according to any one of the preceding claims, characterized in that the separation in step 700 in the centrifugal field, in particular by means of hydrocyclones, takes place. 9. The method according to any one of the preceding claims, characterized in that the contact time of the enzyme in step 500) is dimensioned such that the cell structures destroyed by the enzyme are substantially more than 20% larger than the starch granules. 10. The method according to any one of the preceding claims, characterized in that during the action of the enzyme in a step 600, a stirring of the enzyme / water-starch / pulp mixture takes place. 1 1. Method according to one of the preceding claims, characterized in that between the step 200) and the step 500) a single or multi-stage mechanical comminution of pulp structures takes place, preferably by means of shearing or by acting with a homogenizer or extruder. 12. The method according to any one of the preceding claims, characterized in that the further processing of the starch suspension from the separation step 700 to strength comprises one or more of the following steps in the following order:  D.1 starch washing (6);  D.2 starch drainage (10); and or  D.3 drying (1 1).