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CN-118020863-B - Soybean protein isolate membrane and preparation method thereof

CN118020863BCN 118020863 BCN118020863 BCN 118020863BCN-118020863-B

Abstract

The invention relates to a soybean isolated protein film and a preparation method thereof, comprising the following steps of S1, taking active dry yeast for activation to obtain yeast liquid, S2, mixing the yeast liquid with wheat gluten for fermentation to obtain a fermented WG sample, S3, uniformly mixing the fermented WG sample with soybean isolated protein SPI, water and an alcohol solvent, regulating pH of the solution to be more than 7 by alkaline water to obtain a protein film-forming liquid, S4, pouring the protein film-forming liquid on a template after defoaming, and drying to obtain the soybean isolated protein film. The method can improve mechanical property, thermal stability, hydrophobic property and the like of the soybean protein isolate membrane, improve the comprehensive performance of the soybean protein isolate membrane, and promote the soybean protein isolate membrane to be better popularized and applied.

Inventors

  • WENG WUYIN
  • Jiang Ruizhao

Assignees

  • 集美大学

Dates

Publication Date
20260512
Application Date
20240130

Claims (12)

  1. 1. A preparation method of a soybean protein isolate membrane is characterized by comprising the following steps: S1, activating active dry yeast to obtain a yeast liquid, wherein the yeast content of the yeast liquid is 1-3wt%; S2, mixing the yeast liquid and wheat gluten in a ratio of (0.5-3 mL) of 1 g, and fermenting under the conditions of 20-30 ℃ and relative humidity of 60-80% for 2-5 h to obtain a fermented WG sample; S3, uniformly mixing the fermented WG sample with the soy protein isolate SPI, water and a food-grade plasticizer, wherein the mass ratio of the fermented WG sample to the soy protein isolate SPI is (1-5) (6-10), regulating the pH value of the solution to be more than 7 by using alkaline water to obtain a protein film forming solution, wherein the alkaline water is a polymerized phosphate aqueous solution containing Na 2 CO 3 and K 2 CO 3 , the concentration of Na 2 CO 3 in the alkaline water is 0.5-3% (w/v), the concentration of K 2 CO 3 is 0.1-1% (w/v), and the concentration of polymerized phosphate is 0.1-1% (w/v); S4, pouring the protein film forming liquid on a template after defoaming, and drying to obtain a soybean protein isolate film, wherein the elongation at break of the soybean protein isolate film is 90-95%, the tensile strength is 4-5 MPa, and the water vapor transmittance is (1.3-2.5) multiplied by 10 10 g m 1 s 1 pa 1 The contact angle of water is 80-105 degrees, and the solubility is 20-30 percent.
  2. 2. The method for preparing a soy protein isolate membrane according to claim 1, wherein the activating step S1 is carried out by taking active dry yeast and white granulated sugar, dispersing the active dry yeast and white granulated sugar in distilled water, and activating the active dry yeast and white granulated sugar, wherein the yeast content of the obtained yeast liquid is 1-3wt%.
  3. 3. The method for producing a soy protein isolate film according to claim 1, wherein the fermentation time of S2 is 3 to 5 hours.
  4. 4. The method for producing a soy protein isolate film according to claim 3, wherein the fermentation time of S2 is 4 hours.
  5. 5. The method of producing a soy protein isolate membrane according to any one of claims 1 to 4, wherein the mass ratio of the fermented WG sample to the soy protein isolate SPI in S3 is (1-2): 8-10.
  6. 6. The method of producing a soy protein isolate membrane according to claim 5, wherein the mass ratio of the fermented WG sample to the soy protein isolate SPI in S3 is (1-2): 9-10.
  7. 7. The method of preparing a soy protein isolate film according to any of claims 1 to 4, wherein the food-grade plasticizer in S3 is any one of glycerol, sorbitol, and polyethylene glycol.
  8. 8. The method for preparing a soy protein isolate membrane according to any one of claims 1 to 4, wherein the alkaline water adjusting solution in S3 has pH=8 to 10.
  9. 9. The method for preparing a soy protein isolate membrane according to claim 8, wherein the alkaline water adjusting solution in S3 has pH=9.
  10. 10. The method for preparing a soy protein isolate film according to any one of claims 1 to 4, wherein S3 is followed by uniformly mixing the protein film-forming liquid with soybean oil to obtain a film-forming emulsion, and correspondingly S4 is followed by deaeration of the film-forming emulsion and casting on a template, and drying to obtain the soy protein isolate film.
  11. 11. The method for preparing a soybean protein isolate film according to claim 10, wherein the mass ratio of the protein film-forming liquid to the soybean oil is 10 (0.1-0.3).
  12. 12. The isolated soy protein film of claims 1-11, wherein the isolated soy protein film is prepared by a process comprising at least one of the following steps (1) - (5): (1) The tensile strength is 4-5 MPa; (2) The elongation at break is 90-95%; (3) The water vapor transmittance is (1.3-2.5) x 10 10 g m 1 s 1 pa 1 ; (4) The contact angle of water is 80-105 degrees; (5) The solubility is 20-30%.

Description

Soybean protein isolate membrane and preparation method thereof Technical Field The invention relates to the technical field of protein edible films, in particular to a soybean isolated protein film and a preparation method thereof. Background Isolated soy protein (soy protein isolate, SPI) is a by-product of soybean oil extraction, which is a soy protein with a protein content of over 90% obtained by high refining with defatted soy flour. Beta-conglycinin (7S) and glycinin (11S) are major components of SPI, which can be tightly connected by hydrophobic interactions, hydrogen bonds and disulfide bonds to form a stable network structure. Therefore, SPI has good film forming properties, but its barrier properties after film formation are general. In order to expand the application range of the SPI film, improvement of the water vapor barrier property of the film is necessary. Currently, the water vapor barrier performance improvement of SPI films is mostly achieved by increasing the content of hydrophobic substances in the film matrix. For example, chinese patent No. CN104262654B discloses a method for preparing a composite membrane of soy protein isolate and modified zein. The preparation method comprises the specific steps of a, preparing a protein composite liquid by adopting a solution blending method, b, adding a plasticizer and a cross-linking agent, c, adjusting the pH value to enable the solution to be alkaline, d, heating in a water bath, e, drying at a constant temperature to prepare the protein film. The protein composite membrane prepared by the scheme is pollution-free, degradable, and has higher mechanical property and higher barrier property after being abandoned. However, according to the scheme, the zein needs to be subjected to phosphorylation modification to obtain the phosphorylated zein, the phosphorylated zein is dissolved in distilled water to prepare a phosphorylated zein solution, and the phosphorylated zein solution is subjected to microwave modification treatment to obtain the microwave modified phosphorylated zein solution, so that the operation is complex, the dependence on the zein is high, and the popularization and the application of the phosphorylated zein solution are limited. Disclosure of Invention The invention aims to solve the problem of insufficient performance of the existing soybean protein isolate after film formation, and provides a preparation method of a soybean protein isolate film, which utilizes Wheat Gluten (WG) to improve a soybean protein isolate (soy protein isolate, SPI) film. Gluten powder mainly comprises wheat gluten rich in nonpolar amino acids and wheat gliadin, is gluten powder remained after starch and soluble substances are washed out of wheat flour, and has good hydrophobicity. The addition of WG with proper fermentation treatment can improve partial physicochemical properties of SPI film and emulsion film. Furthermore, the invention also utilizes alkaline water to treat wheat gluten, the alkaline water is an alkaline salt solution containing a mixture of Na 2CO3 and K 2CO3, and the alkaline water is a common material in the process of making foods such as noodles, guangdong cakes and the like. The WG for the alkaline water pretreatment is properly added to further improve part of physical properties of the SPI film. The specific scheme is as follows: A method for preparing a soy protein isolate film comprising the steps of: s1, activating active dry yeast to obtain a yeast liquid; S2, mixing the saccharomycete liquid with wheat gluten, and fermenting to obtain a fermented WG sample; S3, uniformly mixing the fermented WG sample with soy protein isolate SPI, water and a food-grade plasticizer, and regulating the pH value of the solution to be more than 7 by alkaline water to obtain a protein film-forming solution; s4, pouring the protein film forming liquid on a template after defoaming, and drying to obtain the soybean isolated protein film. Further, in the step S1, active dry yeast and white granulated sugar are taken and dispersed in distilled water for activation, and the yeast content of the obtained yeast liquid is 1-3wt%. Further, the ratio of the yeast liquid to the wheat gluten in S2 is (0.5-3 mL) to 1g. Further, the conditions of the fermentation in S2 are that the fermentation is carried out for 2 to 24 hours, preferably 3 to 5 hours, more preferably 4 hours under the conditions of 20 to 30 ℃ and the relative humidity of 60 to 80%. Further, the mass ratio of the fermented WG sample to the isolated soy protein SPI in S3 is (1-5) to (6-10), preferably (1-2) to (8-10), and more preferably (1-2) to (9-10). Further, the food-grade plasticizer in S3 is any one of glycerol, sorbitol, and polyethylene glycol. Further, in the step S3, the alkaline water is a polymerized phosphate aqueous solution containing Na 2CO3 and K 2CO3, preferably, the concentration of Na 2CO3 in the alkaline water is 0.5-3% (w/v), the concentration of K 2CO3 is 0.1-1% (w/