NL8600936A - Amylose prodn. from starch - by treatment with alpha-1,6-glucosidase and alpha-amylase - Google Patents

Abstract

Prodn. of amylose is effected by (a) treating a starch soln. with an alpha-1,6-glucosidase under conditions such that the DE remains below 2, (b) treating the soln. with alpha-amylase for a short time under conditions such that the DE remains below 5, and (c) pptg. long-chain amylose (LCA) from the soln. and opt. then pptg. short-chain amylose (SCA).

Description

VO 8161 Inventors: Frederik Simon Kaper

Jan Aten

Title: Method for preparing amylose 1

The invention relates to a process for preparing long-chain and short-chain amylose from amylose-containing starches.

Most starches consist of a mixture of about 25 weight percent substantially linear amylose molecules and 75 weight highly branched amylopectin molecules. A relatively large number of methods are known to separate amylose and amylopectin.

However, none of these methods proved to be economically viable on an industrial scale. Amylopectin can be obtained in an almost pure state, in the form of the waxy starches. However, no starches exclusively consisting of amylose have yet been discovered in nature. Amylose has excellent film-forming and gelling properties and is ideally suited for a wide range of applications. Thus, there is a great need for an economically feasible method for the preparation of amylose from starch. The present invention aims to provide a process for the preparation of long-chain and short-chain amylose from starch. The process according to the invention is characterized in that a starch solution is treated with an alpha-1,6-glucosidase such that the DE (Dextrose Equivalent) remains below 2 »the reaction mixture is then briefly treated with alpha-amylase such that the DE of the starch hydrolyzate remains below 5, then precipitates the long chain amylose from the solution and separates the precipitate from the solution. If the long-chain amylose precipitates and separates, the short-chain amylose can also be precipitated and separated from the solution.

However, it is also possible to further process the solution remaining after the separation of the long-chain amylose in its entirety (for example by drying and / or further hydrolysis) without separate separation of the short-chain amylose.

-2-

In principle, all amylose-containing starches can be used as starting material. However, for the method according to the invention preference is given to the tuber and root starches. especially to potato starch. Potato starch has a very low fat content and contains amylose with a relatively high degree of polymerization.

A. and. another is described by J.J.M. Sinkels in Starch / Starke, 37 (1985), Ir. 1, p. 1-5.

The starch can be gelatinized and dissolved in water according to the known techniques, for instance by means of a steam injection device (jet cooker) at 100-200 ° C. The starch concentration of the resulting starch solution is at. preferably 10-30 weight percent.

Before adding the alpha-1,6-glucosidase, the starch solution is allowed to cool to the temperature suitable for the enzyme in question. Usually this temperature is between itO and 70 ° C. Alpha-1, β-glucosidase is also often referred to as the branching enzyme. Among the alpha-1,6 glucusidases, both the isoamylases and the pullulanases are included. Alpha-1,6 glucosidases are capable of hydrolyzing the 1,6-glucosidic bonds (branching points) of the amylo-pectin molecules. As a result, the amylo-pectin is largely converted into short linear chains with a degree of polymerization of 10-60. This degree of polymerization is very low compared to that of the long-chain amylose, usually between 200 and 5000.

The short linear chains are referred to herein as short chain amylose. In principle, all alpha-1,6 glucosidases can be used in the method according to the invention. Particularly suitable is the alpha-1,6 glucosidase isolated from the bacterium Bacillus acidopullulyticus, which is also still at a relatively high temperature of 60 ° C. is working. Because one can work at a relatively high temperature, the starch solution is less viscous and less retrogradation occurs. The action of the alpha-1,6 glucosidase preferably lasts for 1-5 hours.

-3-

The DE of the hydrolyzate is then less than 2 and preferably less than 1. Thereafter, alpha-amylase is briefly allowed to act on the solution, such that the DE of the hydrolyzate is preferably not more than 5 amounts. This decreases the viscosity of the solution and facilitates precipitation and separation of the amylose fractions. Hydrolysis by alpha amylase is stopped by inactivating the enzyme by pH reduction or heating. The solution is then left to stand for several hours, whereby the long-chain amylose fraction first precipitates.

The precipitate can be separated from the solution by the usual methods, for example by decanting, filtering or centrifuging. The precipitate can be washed with water and then dried. The yield of the long-chain amylose fraction is 10-25% by weight of the starch starting material (based on the dry matter).

The product consists of more than 70% by weight of long-chain amylose molecules with a degree of polymerization of, for example, 100 to 1500 and an average degree of polymerization of, for example, about 500.

After the separation of the long-chain amylose fraction, a solution remains, from which the short-chain amylose precipitates on further storage at a reduced temperature. The precipitate obtained can be separated from the solution by decantation, filtration or centrifugation, washed with cold water and finally dried. The remaining solution still contains more or less branched dextrins of relatively low molecular weight. This solution can be dried, for example, by spray drying.

The long-chain amylose fraction or derivatives thereof can be used in packaging materials (amylose film) as a coating on fruits, food and pharmaceuticals, in noodles and other pasta, as a strengthening agent for glass fibers and other fibers, as a complexing agent for various substances, in capsules (gelatin replacement) and tablets (filler and binder) · * · * -lf- and as a gelling agent in food, pharmaceuticals and cosmetics. Furthermore, the long-chain amylose fraction or derivatives thereof is suitable as a component in tablets, capsules and the like for the controlled release (substained release) of active substances.

The short-chain amylose can be used in various foods such as baked goods.

Example

A suspension of potato starch in water (23% by weight of dry matter by weight) was gelatinized by means of a jet cooker at 155 ° C. After cooling to 58 ° C, 5.2 alpha-1,6-glucosidase (isolated - from Baxillus acidopululyticus) was allowed to act on the starch solution for 3 hours at pK. Here, the amylopectin fraction was largely converted into low molecular weight (short chain) amylose.

The increase in reducing power was very small (DE-below T), indicating that the alpha-1,6-glucosidase preparation does not produce alpha-amylase act under these conditions. possession. Then alpha-amylase was allowed to act on the solution for 10 minutes at 50 ° C and at pH 5.5.

Almost immediately after the addition of the alpha amylase, a milky structure arose and the viscosity dropped rapidly.

The alpha amylase was inactivated by lowering the pH to 3. The DE of the starch hydrolyzate was 3. Then the long chain amylose was precipitated from the solution at 10 ° C for 10 hours. The precipitate was then filtered off, washed with water and dried. The amount of isolated long chain amylose fraction was 18 weight percent of the weight of the potato starch (calculated on dry matter). The fraction contained 75 weight percent amylose molecules with an average degree of polymerization of 700. After the long chain amylose fraction was separated, the remaining solution was allowed to cool to 20 ° C.

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A precipitate of short-chain amylose had formed in the solution for 8 hours. This precipitate was separated by filtration, washed with cold water and finally dried.

The amount of isolated short chain amylose fraction was 50 weight percent of the weight of the potato starch (based on dry matter).

This fraction contained 80 weight percent amylose molecules with an average degree of polymerization of 20. In the solution remaining after the separation of the short chain amylose fraction, there were still lower sugars and branched dextrin molecules. This solution was spray dried.

Claims (3)

A process for preparing amylose from starch, characterized in that a starch solution is treated with an alpha-1,6-glucosidase such that the DE "remains below 2, then the reaction mixture is briefly treated with alpha-amylase such that the The starch hydrolyzate remains below 5, then precipitates the long chain amylose from the solution and separates the precipitate from the solution. » 2. Process according to claim 1, characterized in that after the separation of the long-chain amylose, the short-chain amylose is subsequently precipitated from the remaining solution and the precipitate is separated from the solution. 3. Process according to claim 1, characterized in that alpha-1,6-glucosidase from Bacillus acidopullulyticus is used. * »*,