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CN-121975873-A - Method for preparing edible alcohol by fermenting wheat starch

CN121975873ACN 121975873 ACN121975873 ACN 121975873ACN-121975873-A

Abstract

The invention provides a method for preparing edible alcohol by fermenting wheat starch, which comprises the following steps of pretreatment, enzymolysis, complex flora fermentation and purification, wherein the pretreatment method comprises the steps of sieving wheat B starch with a 90-110 mesh sieve, adding water to prepare starch milk with the concentration of 32-35 wt%, adding a complex pre-oxidant, preserving heat for 40-50min under the condition of 46-50℃, pH 4.9.9-5.2, adding complex degrading enzyme, preserving heat for 20-25min, and finally realizing double improvement of product quality and production benefit, wherein the viscosity of the pretreated starch milk is 270-300cP, the reducing sugar of saccharified mash is 213-232g/L, the fermentation time is 48-52h, the total sugar of fermented mature mash residue is 1.5-1.7g/L, the purity of the prepared alcohol reaches 96.3-96.6%, the yield is 0.459-0.466L/kg starch, the normal content is 0.2-0.4mg/L, and the content of isobutyl alcohol and isoamyl alcohol is 0.3-6 mg/L.

Inventors

  • DU FANGLING
  • ZHOU PENGCHENG
  • ZONG AIZHEN
  • XU TONGCHENG
  • LI YANQI

Assignees

  • 山东省农业科学院

Dates

Publication Date
20260505
Application Date
20251215

Claims (10)

  1. 1. A method for preparing edible alcohol by fermenting wheat starch is characterized by comprising the following steps of pretreatment, enzymolysis, composite flora fermentation and purification; The pretreatment method comprises the steps of sieving wheat B starch with a 90-110 mesh sieve, adding water to prepare starch milk with the weight of 32-35%, adding a composite pre-oxidant, preserving heat for 40-50min under the condition of 46-50℃, pH and 4.9-5.2, and adding a composite degrading enzyme to preserve heat for 20-25min to obtain pretreated starch milk; the compound pre-oxidant consists of horseradish peroxidase and hydrogen peroxide solution; The composite degrading enzyme consists of xylanase, beta-glucanase and arabinofuranosidase.
  2. 2. The method for preparing edible alcohol by fermenting wheat starch according to claim 1, wherein the method comprises the following steps: the addition amount of horseradish peroxidase in the composite pre-oxidant is 100-120U/g starch, the addition amount of hydrogen peroxide solution is 2-3 mu L/g starch, and the concentration of the hydrogen peroxide solution is 10-12wt%.
  3. 3. The method for preparing edible alcohol by fermenting wheat starch according to claim 1, wherein the xylanase in the composite degrading enzyme is added in an amount of 105-120U/g starch, the beta-glucanase is added in an amount of 70-80U/g starch, and the arabinofuranosidase is added in an amount of 35-40U/g starch.
  4. 4. The method for preparing edible alcohol by fermenting wheat starch according to claim 1, wherein the enzymolysis method is characterized in that food-grade soybean lecithin is added into pretreated starch milk, alpha-amylase is added for hydrolysis after stirring and dispersing, the pH is adjusted to 5.4-5.8, the temperature is raised to 91-94 ℃, the temperature is kept for 110-125min, the temperature is lowered to 56-59 ℃ after the hydrolysis is finished, first part of saccharifying enzyme and acid proteinase are added, the pH value of the starch milk is controlled to be 3.8-4.2, the temperature is kept for 50-55 min, then the temperature is lowered to 30-32 ℃, second part of saccharifying enzyme is added, and the temperature is kept for 28-32min, so that saccharified mash is obtained.
  5. 5. The method for preparing edible alcohol by fermenting wheat starch according to claim 4, wherein the method comprises the following steps: the addition amount of the food-grade soybean lecithin is 0.12% -0.18% of the mass of the starch milk; The addition amount of the alpha-amylase is 26-30U/g of starch, the addition amount of the first part of saccharifying enzyme is 130-145U/g of starch, the addition amount of the acid protease is 12-18U/g of starch, and the addition amount of the second part of saccharifying enzyme is 32-38U/g of starch.
  6. 6. The method for preparing edible alcohol by fermenting wheat starch according to claim 1, wherein the method for fermenting the composite flora is characterized in that a composite microbial inoculum consisting of saccharomyces cerevisiae and candida utilis is inoculated into the mash, the total inoculation amount is 2.3% -3.2% of the mass of the mash, the sectional temperature change and pH cooperative regulation and fermentation are adopted, slow-release nutritional factors are added in 9 hours of fermentation, and the fermentation is finished to obtain the fermented mash.
  7. 7. The method for preparing edible alcohol by fermenting wheat starch according to claim 6, wherein the ratio of the number of viable bacteria of the Saccharomyces cerevisiae to the number of viable bacteria of the candida utilis in the composite microbial inoculum is 7:1.8-2.2.
  8. 8. The method for preparing the edible alcohol by fermenting the wheat starch according to claim 6, wherein the method for cooperatively regulating the sectional temperature and the pH is characterized in that the temperature is controlled to be 33-35 ℃ in the proliferation period of 0-9h, the pH is controlled to be 4.9-5.0, the temperature is controlled to be 29-31 ℃ in the wine producing period of 9-42h, the pH is controlled to be 4.6-4.7, the temperature is controlled to be 27-28 ℃ in the post-maturation period of 42h to the end, the pH is controlled to be 4.4-4.5, and slow-release nutritional factors are added in the fermentation period of 9h to supplement nitrogen sources required by fermentation.
  9. 9. The method for preparing edible alcohol by fermenting wheat starch according to claim 6, wherein the slow-release nutritional factors comprise inactivated candida utilis cells, ammonium sulfate and potassium dihydrogen phosphate, and the mass ratio of the inactivated candida utilis cells, the ammonium sulfate and the potassium dihydrogen phosphate is 5:1.8-2.2:0.9-1.1, and the addition amount is 0.4% -0.5% of the mass of the mash.
  10. 10. The method for preparing edible alcohol by fermenting wheat starch according to claim 1, wherein the purifying method is that the fermented mature mash is filtered, decolorized, distilled and dehydrated and purified by molecular sieve to obtain the edible alcohol.

Description

Method for preparing edible alcohol by fermenting wheat starch Technical Field The invention belongs to the technical field of ethanol production, and relates to a method for preparing edible alcohol by fermenting wheat starch. Background Wheat is one of main grain crops in China, has higher starch content, and is a high-quality raw material for preparing edible alcohol. Wheat starch is processed into two types, one is in the shape of a large disc with a diameter of about 20-35nm, and the other is in the shape of a small sphere with a diameter of about 2-10nm, and is starch B. The wheat B starch is used as a byproduct of wheat flour milling, and the alcohol is produced by using the B starch, so that the comprehensive utilization of the wheat can be improved, and the economic value is increased. Compared with wheat A starch, the wheat B starch has smaller grain size, is easy to be mixed and stuck together with non-starch polysaccharide, structural protein and the like, and is difficult to purify by a common separation method, so that the wheat B starch contains a certain amount of non-starch polysaccharide, protein, lipid and other impurities, and various problems are caused in the process of preparing alcohol by fermentation. Polysaccharide such as arabinoxylan and beta-glucan contained in the starch B is covalently crosslinked with protein and fat through phenolic acid such as ferulic acid to form a compact cellulose-protein complex network, and starch particles are coated. When the starch milk concentration is raised to a level that is commercially economical, such as above 30%, the viscosity increases dramatically to above 900 cP. The high viscosity severely limits the stirring efficiency, prevents mass transfer and heat transfer, greatly reduces the contact efficiency of subsequent liquefying and saccharifying enzymes and substrates, forces the industrial production to only adopt low-concentration starch milk, and has low equipment utilization rate and high energy consumption. The high-viscosity environment can prevent mass transfer of a fermentation system, uneven nutrition supply of yeast, abnormal metabolism, acceleration of decarboxylation of amino acid to produce fusel oil, and meanwhile, if non-starch polysaccharide remains, the yeast can not efficiently utilize carbohydrate, the yeast can turn to metabolism of protein or amino acid, the fusel oil can be increased, and the quality of alcohol is reduced. The dense network wrapped outside the starch granules forms a strong steric hindrance effect on degrading enzymes such as saccharifying enzyme, and enzyme molecules are difficult to effectively contact and act on substrates of the degrading enzymes. More importantly, the covalent crosslinks that make up the network backbone are not cleavable by conventional hydrolases. In order to reduce the viscosity, the skilled person tries to pretreat by adopting a complex enzyme method consisting of saccharifying enzyme, xylanase and pullulanase, and the DE value reaches 90 percent, but the required saccharifying time reaches 40 hours, so that the process time is greatly prolonged, and the production efficiency is low. In addition, some of the proposals have attempted to use a strong oxidizing agent, which is capable of breaking chemical bonds, but has problems such as severe reaction, difficult control of conditions, and easy generation of by-products that inhibit yeasts. In addition, the prior art generally adopts Saccharomyces cerevisiae with single function for fermentation, and has remarkable limitations in metabolic balance, substrate utilization breadth and environmental adaptability. Meanwhile, the single flora lacks functional complementation and synergy when facing high osmotic pressure and ethanol stress, so that the fermentation period is prolonged, the control of end-point residual sugar is not ideal, and the improvement of the whole fermentation efficiency and the product quality is finally restricted. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a method for preparing edible alcohol by fermenting wheat starch, which realizes the following aims of realizing high-efficiency and high-purity alcohol production through pre-oxidation-enzymolysis coupling and adaptive fermentation regulation. In order to achieve the above purpose, the invention adopts the following technical scheme: A method for preparing edible alcohol by fermenting wheat B starch comprises pretreating, performing enzymolysis, fermenting with compound bacteria, and purifying; (1) Pre-treating, namely sieving wheat B starch with a 90-110 mesh sieve, adding water to prepare starch milk with the weight of 32-35%, adding a composite pre-oxidant, preserving heat for 40-50min under the condition of 46-50℃, pH < 4.9-5.2 >, and adding a composite degrading enzyme to preserve heat for 20-25min to obtain pre-treated starch milk; the wheat B starch contains 3-4.5wt% of protein, 1.2-1.8wt% of fat and 3-4w