CN104926949A - Preparation method for high purity amylose - Google Patents

Abstract

The invention relates to a preparation method for high purity amylose. The preparation method for the high purity amylose is characterized in that natural starch servers as a raw material, pretreatment is conducted on the natural starch through 0.4-0.6 mol/L aqueous alkali, pullulanase of 12.5-100 U/g starch is used for cutting amylopectin molecules in branch starch, normal butanol of a 40-70 ml/L starch solution is utilized to conduct complex-precipitation on the amylopectin molecules, extraction filtration, separation and precipitation are conducted, ethanol rinsing is conducted, and the prepared amylose solution is dried in a drying oven. Iodine colorimetry is utilized for determination, and the purity of the amylose can reach over 90%. According to the preparation method for the high purity amylose, the problems that in the prior art, the cost for purifying the amylose is high, the process is complex, and the yield and the purity are low are solved.

Description

A kind of preparation method of high-purity amylose

technical field

The invention relates to the field of natural polymer materials, in particular to a method for preparing high-purity amylose.

Background technique

With the rapid development of the polymer industry and the depletion of petroleum resources, human beings have faced two difficult problems: environmental pollution and resource shortage. In order to solve the global plastic environmental pollution and develop the sources of non-petroleum-based plastic raw materials, the research, development and promotion of environmentally friendly polymer materials have received worldwide attention. Starch, as a kind of natural polymer material, is regarded as an important potential substitute because of its rich source, low price and natural and fully degradable characteristics. Starch is not a single substance, but a mixture of amylose and amylopectin, where amylose is a polysaccharide with linear linear molecules and amylopectin is a highly branched polysaccharide. The content of amylose in ordinary starch is only 22% to 27%, while the content of amylose in high amylose is generally 40% to 70%. Due to its special structure and physical and chemical properties, amylose has more important potential applications in the field of materials than amylopectin. The high-strength starch film prepared by it can be applied to the field of fully degradable packaging materials. Studies have shown that the content of resistant starch is directly proportional to the content of amylose, so amylose shows potential health benefits, such as promoting improved glucose metabolism in diabetic patients. As a structural homologue of cyclodextrin, amylose molecules can wrap other compound molecules between molecular helices or in the central hydrophobic cavity. This important property can be applied to high value-added industries, including drug controlled release and food flavor packaging.

Although amylose has so many potentially important applications, its application and development are limited by its high price, especially for high-purity amylose. Because the purification of amylose is a complicated and costly process. At present, there are two methods for preparing the most commonly used high-purity amylose: (1) After gelatinizing and dispersing ordinary starch with water or alkaline solution, directly use n-butanol to complex and precipitate amylose molecules, and obtain high-purity amylose after centrifugation, washing and precipitation. Purity amylose. The problem with this method is that, due to the presence of amylopectin molecules, multiple precipitation and purification with n-butanol are required, the operation steps are complicated, the purity is limited, and the yield is low (Gao Weili et al., Research on the separation of crude amylose by butanol precipitation. Food Science, 2007(28):271-274; Hong Yan et al., Extraction and identification of pure amylose and amylopectin. Food Industry Science and Technology, 2004(6):86-87). (2) After the pullulan enzyme cuts amylopectin, the amylose molecule is precipitated by n-butanol complexation, and the high-purity amylose is obtained after centrifugation, washing and precipitation. The disadvantage of this method is that high-amylose starch replaces ordinary starch as a raw material, and the cost is high. High amylose starch needs to be gelatinized and dispersed under high temperature, high pressure and nitrogen protection, which is time-consuming and energy-consuming, and the process is complicated (Vorwerg W, et al., Carbohydrate Polymers, 2002(47):181-189).

Invention content:

In order to solve the deficiencies of the above-mentioned prior art, the present invention aims to provide an economical, efficient and simple method for preparing high amylose starch. The content of the amylose amylose prepared by the invention can reach more than 90%.

The purpose of the present invention is achieved by the following technical solutions:

A preparation method for high-purity amylose, comprising the steps of:

(1) starch solution pretreatment

Add lye with a concentration of 0.4-0.6mol/L to the starch suspension, stir gently, and let it stand for 5-20 minutes at 20-30 degrees to form a starch solution;

(2) Enzymatic cutting and branching treatment of starch solution

Neutralize the pretreated starch solution in step (1) with hydrochloric acid solution, so that the starch quality accounts for 4% to 6% in the total mass of starch solution and hydrochloric acid solution, gelatinize in a water bath at 60 to 80°C for 30 to 90 minutes, adjust The pH is 4-5, the temperature is 55-65°C, add an appropriate amount of pullulan enzyme for 10-20 minutes, heat to above 85°C, and inactivate the enzyme for 10-30 minutes;

(3) Purification and separation of amylose

Reduce the temperature of the starch solution treated in step (2) to 65-75°C, add a certain amount of n-butanol to complex and precipitate amylose molecules, stir for 45-75 minutes, then cool down to 40°C, and stir slowly for 18-24 hours, remove the supernatant, suction filter to obtain the precipitate, wash with absolute ethanol for 3 to 4 times, and dry in a blast oven at 50 to 70°C to obtain high-purity amylose;

Wherein, the amount of pullulanase in the step (2) is 12.5-100 U/g starch, and the amount of n-butanol in the step (3) is 40-70 ml/L starch solution.

The lye in the step (1) is sodium hydroxide or potassium hydroxide solution, the volume ratio of lye and starch suspension is 2:1, and the starch suspension is natural starch suspensions such as corn, soybean, potato and cassava , the mass fraction of starch is 15% to 25%.

Compared with the prior art, the present invention has the following advantages and beneficial effects

(1) Pretreatment of starch with lye to improve the sensitivity of starch to enzymes and improve the efficiency of enzymes.

(2) The natural starch is selected as the raw material, which is cheap and can be gelatinized in a water bath, and the operation is convenient and simple.

(3) Use pullulan enzyme to cut amylopectin molecules, eliminate the interference of branched chain molecules, and improve the purity of the product. One-time complexation of n-butanol precipitates straight-chain molecules without repeated precipitation, greatly improving the preparation efficiency and reducing product loss. . Short amylopectin molecules can be obtained after cutting the branched chain molecules, thereby increasing the yield.

(4) Separation by suction filtration replaces centrifugal separation, which simplifies the preparation operation.

Detailed ways

The following examples further describe the present invention, but the examples are only for illustrating the present invention rather than limiting the present invention.

Example 1

(1) Configure 100ml of natural cassava starch suspension (starch 25g) with a starch mass fraction of 25%, add 200ml of 0.5mol/L sodium hydroxide solution, stir slightly, and let it stand for 10 minutes. A pretreated starch solution is obtained.

(2) 200ml of 0.5mol/L hydrochloric acid neutralizes the starch solution in step (1), and gelatinizes in a water bath at 60°C for 45 minutes. Adjust the pH value to 4 and the solution temperature to 60°C. Add pullulanase 12.5U/g starch, cut branches for 15 minutes, heat to 85°C in a boiling water bath, and inactivate the enzyme for 20 minutes.

(3) When the starch solution in step (2) drops to 70° C., add 26 ml of n-butanol to precipitate and complex amylose molecules, and stir for 60 minutes. Then the temperature was lowered to 40°C and stirred slowly for 20 hours. The supernatant was removed, the precipitate was obtained by suction filtration, washed three times with absolute ethanol, and dried in a blast oven at 60°C to obtain 5.9 g of high-amylose starch with a yield of 23.6% and a linear chain content of 95.8%.

Example 2

(1) Configure 100ml of natural cassava starch suspension (starch 25g) with a starch mass fraction of 25%, add 200ml of 0.5mol/L sodium hydroxide solution, stir slightly, and let it stand for 10 minutes. A pretreated starch solution is obtained.

(2) 200ml of 0.5mol/L hydrochloric acid neutralizes the starch solution in step (1), and gelatinizes in a water bath at 60°C for 60 minutes. Adjust the pH value to 4.5, and the solution temperature to 60°C. Add pullulanase, 25U/g starch, cut branches for 15 minutes, heat to 90°C in a boiling water bath, and inactivate the enzyme for 15 minutes.

(3) When the starch solution in step (2) drops to 70° C., add 26 ml of n-butanol to precipitate and complex amylose molecules, and stir for 60 minutes. Then the temperature was lowered to 40°C and stirred slowly for 20 hours. The supernatant was removed, the precipitate was obtained by suction filtration, washed 4 times with absolute ethanol, and dried in a blast oven at 60°C to obtain 5.9 g of high-amylose starch with a yield of 23.6% and an amylose content of 98.5%.

Example 3

(1) Configure 100ml of natural cassava starch suspension (starch 25g) with a starch mass fraction of 25%, add 200ml of 0.4mol/L sodium hydroxide solution, stir slightly, and let it stand for 10 minutes. A pretreated starch solution is obtained.

(2) 200ml of 0.4mol/L hydrochloric acid neutralizes the starch solution in step (1), and gelatinizes in a water bath at 60°C for 45 minutes. Adjust the pH value to 4.5, and the solution temperature to 60°C. Add pullulanase 25U/g starch, cut branches for 15 minutes, heat to 85°C in a boiling water bath, and inactivate the enzyme for 20 minutes.

(3) When the starch solution in step (2) drops to 70° C., add 26 ml of n-butanol to precipitate and complex amylose molecules, and stir for 60 minutes. Then the temperature was lowered to 40°C and stirred slowly for 20 hours. The supernatant was removed, the precipitate was obtained by suction filtration, washed three times with absolute ethanol, and dried in a blast oven at 60° C. to obtain 5.3 g of high-amylose starch with a yield of 21.2% and an amylose content of 97.1%.

Although the present invention has been described in detail and some specific examples have been cited, it will be obvious for those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention.

The comparison of the example sample prepared by the present invention with the existing method in table 1

By comparison, it can be found that the yield and amylose content of the high-purity amylose prepared by the method are improved, especially the yield is significantly improved. This shows that the present invention is practical and effective.

Claims (3)

1. a preparation method for high-purity linear-chain starch, is characterized in that, described method comprises the steps:

(1) starch solution pre-treatment

Be that the alkali lye of 0.4 ~ 0.6mol/L joins in starch suspension by concentration, gentle agitation, leaves standstill effect 5 ~ 20 minutes at 20 ~ 30 DEG C, forms starch solution;

(2) enzyme cuts a process starch solution

With the starch solution that hydrochloric acid soln neutralization procedure (1) is pretreated, starch quality is made to account for 4% ~ 6% in the total mass of starch solution and hydrochloric acid soln, in 60 ~ 80 DEG C of water-bath gelatinizations 30 ~ 90 minutes, pH is regulated to be 4 ~ 5, temperature is 55 ~ 65 DEG C, adding appropriate Pullulanase cuts after 10 ~ 20 minutes, is heated to more than 85 DEG C, and go out ferment treatment 10 ~ 30 minutes;

(3) purification & isolation of amylose starch

After the starch solution temperature that step (2) processed is down to 65 ~ 75 DEG C, add a certain amount of propyl carbinol complex-precipitation amylose molecule, stir after 45 ~ 75 minutes, be cooled to 40 DEG C, slowly stir 18 ~ 24 hours, remove supernatant liquid, suction filtration is precipitated thing, absolute ethanol washing 3 ~ 4 times, in convection oven, 50 ~ 70 DEG C of oven dry, can obtain highly purified amylose starch;

Wherein, the Pullulanase consumption in described step (2) is 12.5 ~ 100U/g starch, and the propyl carbinol consumption in described step (3) is 40 ~ 70ml/L starch solution.

2. the preparation method of high-purity linear-chain starch as claimed in claim 1, it is characterized in that, the alkali lye in described method steps (1) is sodium hydroxide solution or potassium hydroxide solution, and the volume ratio of alkali lye and starch suspension is 2:1.

3. the preparation method of high-purity linear-chain starch as claimed in claim 1, it is characterized in that, starch suspension in described method steps (1) is the one in corn, soybean, potato or cassava native starch suspension, and starch shared massfraction in suspension is 15% ~ 25%.