Method for mixed alcohol fermentation using rice and wheat

Abstract

The present application relates to the field of alcohol fermentation, and particularly relates to a method for mixed alcohol fermentation by using rice and wheat, which comprises the following steps: contacting mixed powder slurry containing rice and wheat with amylase and xylanase to liquefy the mixed powder slurry, so as to obtain a liquefied liquid; and inoculating yeast into the liquefied liquid to perform alcohol fermentation. The method can reduce the viscosity of the liquefied liquid, reduce the total residual sugar content after fermentation, reduce the viscosity of the fermentation liquid, and reduce the dry matter content of the waste beer supernatant.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of alcohol fermentation, in particular to a method for mixed alcohol fermentation using rice and wheat. BACKGROUND

[0002] The main raw materials for fuel ethanol fermentation include grain raw materials, potato raw materials, sugar raw materials, and cellulose raw materials, among which the starch raw materials mainly include corn, wheat, rice, and cassava. With the rapid development of the fuel ethanol industry, the raw materials are gradually changing from single raw materials to mixed raw materials. In recent years, with the increase in grain output, there is a huge inventory of aged rice and wheat in China, and a large amount of aged grain needs to be processed. The co-fermentation of multiple starch raw materials to produce fuel ethanol can achieve diversification of raw materials and effectively solve the problem of aged grain accumulation.

[0003] Aged wheat and rice are grains that have been stored for a long time (more than 3 years). Due to problems such as mold, mycotoxins, and excessive heavy metals, they are generally used for fuel ethanol production. The mixed use of wheat and rice raw materials can achieve flexible production of diversified raw materials, avoid excessive dependence on corn raw materials by enterprises, effectively alleviate the problem of tight raw material supply, form a pattern of substitution of multiple raw materials, enhance the vitality and market competitiveness of enterprises, and promote the healthy and rapid development of enterprises. Due to the low price of wheat and rice with excessive heavy metals, optimization and other methods can reduce production costs and achieve good economic benefits, while ensuring food security.

[0004] Currently, factories use rice and wheat for mixed fermentation. Since the starch content in wheat is higher than that in rice, increasing the addition ratio of wheat helps to increase the alcohol content. However, the high protein content in wheat and the large proportion of bran result in high viscosity of the liquefied liquid, high total residual sugar at the end of fermentation, high viscosity of the fermentation broth, and high dry matter content in the waste beer clear liquid. SUMMARY

[0005] The purpose of the present application is to overcome the above-mentioned problems in the prior art and provide a method for mixed alcohol fermentation using rice and wheat. This method can reduce the viscosity of the liquefied liquid, reduce the total residual sugar content after fermentation, reduce the viscosity of the fermentation broth, and reduce the dry matter content in the waste beer clear liquid.

[0006] To achieve the above-mentioned purpose, the present application provides a method for mixed alcohol fermentation using rice and wheat, which comprises: contacting a mixed powder slurry containing rice and wheat with amylase and xylanase to liquefy the mixed powder slurry and obtain a liquefied liquid; and then inoculating yeast into the liquefied liquid for alcohol fermentation.

[0007] The present application optimizes a set of processes suitable for mixing rice and wheat on the basis of original processes, i.e. using xylanase in the liquefaction stage, so that the viscosity of fermentation liquor, the viscosity of waste liquor, the total residual sugar and the dry matter content of waste liquor are all reduced. DETAILED DESCRIPTION

[0008] The endpoints of the ranges and any values described herein are not limited to the precise values stated. The endpoints of the ranges and the values stated are approximations that are used to illustrate conceptual endpoints. The endpoints of the ranges and the values stated are sufficiently flexible to include values approximating the value at either or both of the ends of the range or the values. For example, a range from 1-10 should be interpreted to include about 1 to about 10, and include individual values and sub-ranges within the indicated range.

[0009] Unless otherwise indicated herein, temperatures are set forth in degrees Celsius.

[0010] The present application provides a method for mixed alcohol fermentation using rice and wheat, which comprises: contacting mixed powder slurry containing rice and wheat with amylase and xylanase to liquefy the mixed powder slurry, to obtain a liquefied liquor; and inoculating yeast into the liquefied liquor to perform alcohol fermentation.

[0011] According to the present application, the rice is preferably aged rice.

[0012] According to the present application, the rice can be hulled or unhulled rice, and is preferably unhulled rice.

[0013] According to the present application, the wheat is preferably aged wheat.

[0014] According to the present application, the wheat can be hulled or unhulled wheat, and is preferably hulled but not peeled wheat.

[0015] Unless otherwise specified herein, "aging" refers to the storage time of grain being more than 3 years.

[0016] According to the present application, the preparation method of the mixed powder slurry comprises: mixing a mixture of rice crushing product and wheat crushing product with a mixing liquid to obtain the mixed powder slurry.

[0017] The mixing of the starchy raw material with the mixing liquid to obtain the powder slurry is referred to as mixing, and the mixing liquid can be various mixing liquids commonly used, for example, can include but is not limited to tap water, process water, for example, waste water generated in an ethanol fermentation process, such as condensate, clear liquid, etc.

[0018] According to the present application, the dry content of the mixed flour paste can be a conventional content, preferably 30-40% by weight, for example, can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40% by weight.

[0019] According to the present application, the pH value of the mixed flour paste is preferably acidic, more preferably 5-6, for example, can be 5, 5.2, 5.4, 5.6, 5.8, 6.

[0020] Among them, the pH value of the mixed flour paste can be adjusted by using conventional acid-base regulators, such as dilute hydrochloric acid, dilute sulfuric acid, phosphoric acid, citric acid, sodium hydroxide, ammonia, etc.

[0021] According to the present application, the use ratio of rice and wheat can be adjusted within a wide range, but the inventors of the present application have found that in order to further improve the fermentation performance of the present application, the use ratio of rice and wheat is preferably 1:0.25-1.5 by dry weight, for example, can be 1:0.25, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5; more preferably 1:0.3-0.8.

[0022] According to the present application, the xylanase can be various xylanases commonly used in the art, which can be high-temperature resistant xylanase or ordinary xylanase, preferably high-temperature resistant xylanase. The "high-temperature resistant xylanase" refers to a xylanase with an enzyme activity of not less than 20000 U / mL at a temperature of not less than 70°C. In terms of acidity, it can be an acidic xylanase or an alkaline xylanase, preferably an acidic xylanase. According to a preferred embodiment of the present application, the xylanase is a high-temperature resistant acidic xylanase, which is commercially available, for example, from Xiasen Industrial Group Co., Ltd., with the product code FDG-2234.

[0023] Among them, the amount of xylanase can be selected within a wide range, in order to further improve the fermentation performance of the present application, preferably, the amount of xylanase is 0.05-0.5 kg per ton of mixed flour paste by dry weight, for example, can be 0.05 kg, 0.1 kg, 0.2 kg, 0.3 kg, 0.4 kg, 0.5 kg, preferably 0.2-0.4 kg.

[0024] According to the present invention, preferably, to further improve the fermentation effect, the amylase contains thermostable α-amylase and protease, and the enzyme activity, calculated as α-amylase, is not less than 140,000 U / mL. The thermostable α-amylase refers to an α-amylase with an enzyme activity of not less than 140,000 U / mL at a temperature not lower than 70°C. The protease is preferably an acidic protease. According to a preferred embodiment of the present invention, the amylase is commercially available, specifically a super-strong compound amylase (Avantec CN) (containing thermostable amylase and acidic protease) purchased from Novozymes (China) Biotechnology Co., Ltd., with an enzyme activity of 140,000 U / mL.

[0025] The amount of amylase can be selected within a wide range. In order to further improve the fermentation performance of the present invention, preferably, the amount of amylase is 0.1-0.5 kg per ton of mixed slurry on a dry weight basis. For example, it can be 0.1 kg, 0.2 kg, 0.3 kg, 0.4 kg, or 0.5 kg, preferably 0.2-0.4 kg.

[0026] In this invention, liquefaction refers to the process of hydrolyzing starchy raw materials into small molecule substances (dextrin, oligosaccharides, etc.), and liquefaction can be carried out using conventional liquefaction methods in the art. However, to further improve fermentation performance, preferably, the liquefaction conditions include maintaining a temperature of 80-100℃ (e.g., 80℃, 82℃, 84℃, 86℃, 88℃, 90℃, 92℃, 94℃, 96℃, 98℃, 100℃) for 1-4 hours (e.g., 1 hour, 1.3 hours, 1.5 hours, 1.8 hours, 2 hours, 2.2 hours, 2.5 hours, 2.8 hours, 3 hours, 3.3 hours, 3.5 hours, 3.8 hours, 4 hours) to obtain the liquefied liquid.

[0027] More preferably, the liquefaction is carried out under stirring conditions, and the stirring speed can be 150-250 rpm.

[0028] Fermentation refers to the process by which microorganisms, under aerobic or anaerobic conditions, produce the microbial cells themselves, or their direct or secondary metabolites. Fermentation can be carried out using methods conventionally used in the art. However, the inventors of this invention have discovered that using saccharifying yeast during fermentation can reduce the residual sugar content after fermentation, decrease the viscosity of the fermentation broth, reduce the dry matter content of the fermentation waste mash, and increase the alcohol content. This method is particularly suitable for fermenting unhulled aged rice and wheat as raw materials to produce ethanol. Therefore, preferably, the yeast is saccharifying yeast, which is commercially available, for example, from Angel Yeast Co., Ltd., with a total yeast count ≥ 2 × 10⁻⁶. 10 per g.

[0029] According to the present application, the yeast inoculation ratio is preferably 0.05-0.2% by weight, more preferably 0.05-0.1% by weight, based on the dry powder.

[0030] According to the present application, the fermentation conditions can be performed according to the conventional methods in the art, but in order to further improve the fermentation performance of the present application, preferably, the present application is performed by two-stage fermentation as follows:

[0031] The first-stage fermentation is performed from the start of fermentation to 6-10 hours after the start of fermentation, and the temperature of the first-stage fermentation is 25-33°C;

[0032] The second-stage fermentation is performed from 6-10 hours after the start of fermentation to the end of fermentation, and the temperature of the second-stage fermentation is 33-40°C;

[0033] wherein the temperature of the first-stage fermentation is lower than the temperature of the second-stage fermentation, preferably 1-5°C, for example, 3°C.

[0034] According to the present application, the fermentation time can be 60-80 hours.

[0035] According to the present application, in order to further improve the fermentation performance of the present application, preferably, the method further comprises adding at least one of ammonium sulfate, saccharifying enzyme, acid protease and bactericide to the liquefied liquid;

[0036] Preferably, the method further comprises adding ammonium sulfate, saccharifying enzyme, acid protease and bactericide to the liquefied liquid.

[0037] wherein the amount of the ammonium sulfate added is preferably 5-10 kg, more preferably 8-9 kg, per ton of the liquefied liquid in dry weight.

[0038] wherein the amount of the saccharifying enzyme added is preferably 0.1-1 kg, more preferably 0.5-0.8 kg, per ton of the liquefied liquid in dry weight, which can be commercially available, for example, from Shandong Longda Biological Engineering Co., Ltd., with an enzyme activity of 260000 U / g, and the definition of enzyme activity can be found in the instruction manual thereof.

[0039] wherein the amount of the acid protease added is preferably 0.01-0.1 kg, more preferably 0.05-0.07 kg, per ton of the liquefied liquid in dry weight, which can be commercially available, for example, from Guangxi Lejiang Biological Technology Co., Ltd., with an enzyme activity of 20000 U / g, and the definition of enzyme activity can be found in the instruction manual thereof.

[0040] wherein the amount of the bactericide added is preferably such that the final concentration thereof is 1-10 ppm, more preferably 4-6 ppm.

[0041] The bactericide can be various bactericides commonly used in the alcohol fermentation process, for example, can include but are not limited to, Agotan, penicillin, Bactocon, Agon, preferably, the bactericide is Agotan.

[0042] According to the present application, preferably, the method further comprises distilling the fermentation liquor obtained by fermentation to obtain alcohol and waste liquor; and then performing solid-liquid separation on the waste liquor to obtain clear liquor and wet grains.

[0043] The distillation refers to a step of separating ethanol from the fermentation liquor, and can be separated by using a separation method commonly used in the art. The waste liquor after distillation can be filtered by using a plate and frame filter cloth to obtain clear liquor.

[0044] According to a particularly preferred embodiment of the present application, a method for mixed alcohol fermentation using rice and wheat

[0045] (1) The aged rice and the aged wheat are crushed and mixed at a ratio of 1:0.6-0.7 on a dry basis, then a mixing liquid (25-35 wt% clear liquor, 65-75 wt% process water) is added so that the dry matter of the slurry is 31-33 wt%, and the pH value of the slurry is adjusted to 5-6.

[0046] (2) The obtained slurry is added with super compounded amylase (added amount is 0.3-0.4 kg / t of grain) and xylanase (added amount is 0.3-0.4 kg / t of grain), and heated to 88-92°C for 2-3 h, and the rotation speed is maintained at 150-250 rpm to obtain a liquefied mash.

[0047] (3) The obtained liquefied mash is added with ammonium sulfate (added amount is 8.2-8.6 kg / t of raw materials), saccharifying enzyme (added amount is 0.65-0.7 kg / t of raw materials), acid protease (added amount is 0.055-0.065 kg / t of raw materials), and Agotan (final concentration is 5-5.5 ppm) to prepare an ethanol fermentation medium, and the inoculation amount of dry saccharifying yeast powder is 0.05-0.1 wt%. From the start of fermentation to 7.5-8.5 hours of fermentation, the fermentation temperature is controlled at 30-32°C; from 8.5-9.5 hours of fermentation to the end of fermentation, the fermentation temperature is controlled at 33-35°C, and the total fermentation time is 68-72 h to obtain a fermentation mash.

[0048] (4) The obtained fermentation mash in step (3) is evaporated and condensed by a distillation device to obtain a distillation liquid containing alcohol and waste liquor, and the waste liquor is filtered by a plate and frame cloth to obtain clear liquor.

[0049] The present application will be described in detail below through examples.

[0050] Alpha-amylase, Genencor amylase, purchased from Genencor (China) Bioengineering Co., Ltd., enzyme activity is 140000 U / mL,

[0051] Ultra-strong compound amylase was purchased from Novozymes (China) Biotechnology Co., Ltd., with enzyme activity of 140000 U / mL as α-amylase;

[0052] Xylanase was an acid xylanase, purchased from Xiasheng Industrial Group Co., Ltd., with product number FDG-2234 and enzyme activity of 20000 U / g;

[0053] Glucoamylase was purchased from Shandong Longda Biological Engineering Co., Ltd., with enzyme activity of 260000 U / g;

[0054] Protease was an acid protease, purchased from Guangxi Leferm Biological Technology Co., Ltd., with enzyme activity of 20000 U / g;

[0055] Aged rice was aged rice stored for 3 years, with starch content of 52.4% (w / w) and moisture content of 11% (w / w);

[0056] Aged wheat was aged wheat stored for 3 years, with starch content of 57.2% (w / w) and moisture content of 12% (w / w);

[0057] Anjuntai was purchased from Liuzhou Longtai Technology Co., Ltd., with a commercially available product with a fungicidal rate of 85%;

[0058] Both of the dry powder of Saccharomyces fermentati and the dry powder of saccharomyces cerevisiae were purchased from Angel Yeast Co., Ltd., with total yeast number ≥2×10 10

[0059] Reducing sugar refers to the reducing sugar in the liquefied mash obtained after liquefaction, and the determination method is Fehling reagent method;

[0060] Total sugar refers to the total sugar (including reducing sugar, disaccharide, starch, etc.) in the liquefied mash obtained after liquefaction, and the determination method is Fehling reagent method;

[0061] DE value refers to the percentage of reducing sugar (calculated as glucose) in the dry matter of sugar syrup, and the determination method of reducing sugar and sugar syrup is Fehling reagent method;

[0062] Residual reducing sugar refers to the residual reducing sugar in the fermentation mash obtained after the end of ethanol fermentation, and the determination method is Fehling reagent method;

[0063] Residual total sugar refers to the residual sugar (including reducing sugar, disaccharide, starch, etc.) in the fermentation mash obtained after the end of ethanol fermentation, and the determination method is Fehling reagent method;

[0064] Residual starch refers to the residual starch in the fermentation mash obtained after the end of ethanol fermentation, which is obtained by subtracting the total sugar after filtration from the total sugar;

[0065] Alcohol content refers to the degree of alcohol distilled by a distillation device from the fermentation mash obtained after the end of ethanol fermentation;​

[0066] Acidity refers to the molar mass of NaOH consumed for neutralizing the acidic substances (including inorganic acids, organic acids, strong acid weak base salts, etc.) in per liter of liquefied mash, and the determination method is acid-base neutralization method;

[0067] Waste mash liquid filtration rate refers to the filtration rate of waste mash liquid through plate and frame cloth after distillation of fermentation mash;

[0068] Filter dry matter refers to the solid content of the filtrate of waste mash liquid after plate and frame cloth filtration, which is determined by a rapid moisture meter.

[0069] Process water is cooling water and the like in the alcohol process.

[0070] Clear liquid is supernatant after solid-liquid separation of waste mash liquid after alcohol evaporation in the alcohol process, and the COD in the clear liquid is ≤60000 mg / L.

[0071] Example 1

[0072] This example is used to illustrate the method for mixed alcohol fermentation using rice and wheat provided by the present application

[0073] (1) The aged rice and aged wheat were crushed and mixed at a dry basis ratio of 1:0.67, then a mixing liquid (30% by weight of clear liquid and 70% by weight of process water) was added so that the dry matter of the slurry was 32% by weight, and the pH value of the slurry was adjusted to 5.6.

[0074] (2) Super compounded amylase (added amount: 0.3 kg / t of grain) and xylanase (added amount: 0.3 kg / t of grain) were added to the obtained slurry, which was maintained at 60°C for 30 min, then the temperature was increased to 90°C and maintained for 2 h, and the rotation speed was maintained at 200 rpm, to obtain a liquefied mash. The viscosity, reducing sugar, total sugar and DE value of the liquefied mash were determined, and the results are shown in Table 1.

[0075] (3) Ammonium sulfate (added amount: 8.4 kg / t of raw materials), saccharifying enzyme (added amount: 0.68 kg / t of raw materials), acid protease (added amount: 0.06 kg / t of raw materials) and Anjuntai (final concentration: 5 ppm) were added to the obtained liquefied mash to prepare an ethanol fermentation medium, and the inoculation amount of dry saccharifying yeast powder was 0.05% by weight. From the start of fermentation to the 8th hour of fermentation, the fermentation temperature was controlled at 30°C; from the 9th hour of fermentation to the end of fermentation, the fermentation temperature was controlled at 33°C, and the total fermentation time was 70 h, to obtain a fermentation mash. The residual reducing sugar, residual total sugar, residual starch and viscosity in the fermentation mash were determined, and the results are shown in Table 2.

[0076] (4) The fermentation mash obtained in step (3) was evaporated and condensed by a distillation device to obtain a distillation liquid containing alcohol and waste mash liquid, and the clear liquid was obtained after the waste mash liquid was filtered by a plate and frame cloth. The alcohol content, acidity, waste mash liquid filtration rate and clear liquid dry matter were determined, and the results are shown in Table 2.

[0077] Example 2

[0078] This example is used to illustrate the method for mixed alcohol fermentation using rice and wheat provided by the present application

[0079] (1) The aged rice and aged wheat were crushed and mixed in a dry weight ratio of 1:0.5, then a mixing liquid (30% by weight of clear liquid, 70% by weight of process water) was added so that the dry matter of the slurry was 34% by weight, and the pH of the slurry was adjusted to 5.

[0080] (2) Super strong compound amylase (added in an amount of 0.4 kg / t of grain) and xylanase (added in an amount of 0.4 kg / t of grain) were added to the obtained slurry, maintained at 55°C for 40 min, raised to 95°C for 1.5 h, and the rotation speed was maintained at 150 rpm to obtain a liquefied mash. The viscosity, reducing sugar, total sugar, and DE value of the liquefied mash were determined, and the results are shown in Table 1.

[0081] (3) Ammonium sulfate (added in an amount of 8 kg / t of raw materials), saccharifying enzyme (added in an amount of 0.8 kg / t of raw materials), acid protease (added in an amount of 0.05 kg / t of raw materials), and Anjuntai (final concentration of 6 ppm) were added to the obtained liquefied mash to prepare an ethanol fermentation medium, and the inoculation amount of dry saccharifying yeast powder was 0.08% by weight. The fermentation temperature was controlled at 28°C from the start of fermentation to 7 hours of fermentation, and the fermentation temperature was controlled at 33°C from 8 hours of fermentation to the end of fermentation, and the total fermentation time was 70 h to obtain a fermented mash. The residual reducing sugar, residual total sugar, residual starch, and viscosity in the fermented mash were determined, and the results are shown in Table 2.

[0082] (4) The fermented mash obtained in step (3) was evaporated and condensed by a distillation device to obtain a distillation liquid containing alcohol and a waste mash liquid, and the waste mash liquid was filtered by a plate and frame cloth to obtain a clear liquid. The alcohol content, acidity, filtration speed of the waste mash liquid, and dry matter of the clear liquid were determined, and the results are shown in Table 2.

[0083] Example 3

[0084] This example is used to illustrate the method for mixed alcohol fermentation using rice and wheat provided by the present application

[0085] (1) The aged rice and aged wheat were crushed and mixed in a dry weight ratio of 1:0.8, then a mixing liquid (30% by weight of clear liquid, 70% by weight of process water) was added so that the dry matter of the slurry was 36% by weight, and the pH of the slurry was adjusted to 6.

[0086] (2) Super strong compound amylase (added in an amount of 0.25 kg / t of grain) and xylanase (added in an amount of 0.25 kg / t of grain) were added to the obtained slurry, maintained at 65°C for 20 min, raised to 80°C for 3 h, and the rotation speed was maintained at 250 rpm to obtain a liquefied mash. The viscosity, reducing sugar, total sugar, and DE value of the liquefied mash were determined, and the results are shown in Table 1.

[0087] (3) The obtained liquefied mash was added with ammonium sulfate (added amount 9 kg / t raw material), saccharifying enzyme (added amount 0.5 kg / t raw material), acid protease (added amount 0.07 kg / t raw material), and Anfungtai (final concentration 4 ppm) to prepare an ethanol fermentation medium, and the fermentation was inoculated with 0.1 wt% of dry saccharifying yeast. The fermentation temperature was controlled at 32°C from the start of the fermentation to the 9th hour of the fermentation, and the fermentation temperature was controlled at 34°C from the 10th hour of the fermentation to the end of the fermentation, and the total fermentation time was 70 h to obtain a fermentation mash. The residual reducing sugar, residual total sugar, residual starch, and viscosity in the fermentation mash were determined, and the results are shown in Table 2.

[0088] (4) The fermentation mash obtained in step (3) was evaporated and condensed by a distillation device to obtain a distillation liquid containing alcohol and a waste mash liquid, and the waste mash liquid was filtered by a plate and frame cloth filter to obtain a clear liquid. The alcohol content, acidity, filtration rate of the waste mash liquid, and dry matter of the clear liquid were determined, and the results are shown in Table 2.

[0089] Example 4

[0090] This example is used to illustrate the method for mixed alcohol fermentation using rice and wheat provided by the present application

[0091] The fermentation was carried out according to the method of Example 1, except that the liquefaction did not include the step of maintaining at 60°C for 30 min, but directly maintained at 90°C for 2.5 h, and the results are shown in Tables 1 and 2.

[0092] Example 5

[0093] This example is used to illustrate the method for mixed alcohol fermentation using rice and wheat provided by the present application

[0094] The fermentation was carried out according to the method of Example 1, except that in step (2), the super compounded amylase was replaced with an equal amount of α-amylase (Genscript amylase was purchased from Genscript (China) Bioengineering Co., Ltd., with an enzyme activity of 140000 U / mL), and no xylanase was added; and in step (3), the saccharifying yeast was replaced with an equal amount of fermenting yeast. The results are shown in Tables 1 and 2.

[0095] Comparative Example 1

[0096] This comparative example is used to illustrate a reference method for mixed alcohol fermentation using rice and wheat

[0097] The fermentation was carried out according to the method of Example 1, except that in step (2), the super compounded amylase was replaced with an equal amount of α-amylase (Genscript amylase was purchased from Genscript (China) Bioengineering Co., Ltd., with an enzyme activity of 140000 U / mL), and no xylanase was added; and in step (3), the saccharifying yeast was replaced with an equal amount of fermenting yeast. The results are shown in Tables 1 and 2.

[0098] Comparative Example 2

[0099] This comparative example is used to illustrate a reference method for mixed alcohol fermentation using rice and wheat

[0100] The fermentation was carried out according to the method of Example 1, except that in step (2), no xylanase was added; and in step (3), the saccharogenic yeast was replaced with an equal amount of fermenting yeast. The results are shown in Tables 1 and 2.

[0101] Comparative Example 3

[0102] This comparative example is used to illustrate a reference method for mixed alcohol fermentation using rice and wheat

[0103] The fermentation was carried out according to the method of Example 1, except that in step (2), the super compounded amylase was replaced with an equal amount of a-amylase (Genencor amylase was purchased from Genencor (China) Bioengineering Co., Ltd., with an enzyme activity of 140000 U / mL), and no xylanase was added. The results are shown in Tables 1 and 2.

[0104] Comparative Example 4

[0105] This comparative example is used to illustrate a reference method for alcohol fermentation using wheat

[0106] The fermentation was carried out according to the method of Comparative Example 1, except that instead of using aged rice, 100% wheat was used. The results are shown in Tables 1 and 2.

[0107] Comparative Example 5

[0108] This comparative example is used to illustrate a reference method for alcohol fermentation using rice

[0109] The fermentation was carried out according to the method of Comparative Example 1, except that instead of using aged wheat, 100% rice was used. The results are shown in Tables 1 and 2.

[0110] Table 1

[0111] Viscosity (mPa.s) Reducing sugars (%) Total sugars (%) DE value Example 1 130 7.81 22.50 24.41 Example 2 140 8.21 23.68 24.14 Example 3 170 8.71 25.31 24.19 Example 4 116 7.93 22.51 24.78 Example 5 146 6.91 22.30 21.60 Comparative Example 1 449 6.75 22.31 21.09 Comparative Example 2 372 7.80 22.42 24.38 Comparative Example 3 449 6.75 22.31 21.09 Comparative Example 4 1022 8.32 24.00 26.00 Comparative Example 5 220 5.50 21.63 17.19

[0112] Table 2

[0113]

[0114] As can be seen from the results of Tables 1 and 2, by adding xylanase, the viscosity of the liquefied liquid, the viscosity of the fermentation liquid, the total residual sugar, and the dry matter content of the waste mash supernatant are all reduced, and preferably by using the combined process of "using xylanase in the liquefaction stage and using saccharogenic yeast in the fermentation stage with an enzyme activity of not less than 140000 U / mL of a-amylase", the viscosity of the liquefied liquid, the viscosity of the fermentation liquid, the total residual sugar, and the dry matter content of the waste mash supernatant are all further reduced, and the alcohol content is significantly increased.

[0115] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A method for reducing the viscosity of liquefied liquid and fermentation liquid, total residual sugar, and dry matter content of waste mash in mixed alcoholic fermentation using rice and wheat, and increasing the alcohol content, characterized in that, The method comprises: (1) crushing aged rice and aged wheat, and mixing them at a dry basis ratio of 1:0.6-0.7, then adding a mixing liquid to make the dry matter content of the slurry 31-33% by weight, and adjusting the pH value of the slurry to 5-6; wherein the mixing liquid comprises 25-35% by weight of clear liquid and 65-75% by weight of process water; (2) adding super strong compound amylase and xylanase to the obtained slurry, heating to 88-92°C for 2-3h, and maintaining the rotation speed at 150-250rpm to obtain a liquefied liquid; wherein the amount of super strong compound amylase added is 0.3-0.4kg per ton of the mixed slurry in dry weight, and the amount of xylanase added is 0.3-0.4kg per ton of the mixed slurry in dry weight; (3) adding ammonium sulfate, saccharifying enzyme, acid protease, and Anjuntai to the obtained liquefied liquid to prepare an ethanol fermentation medium, and inoculating saccharifying yeast; from the start of fermentation to 7.5-8.5h of fermentation, the fermentation temperature is controlled at 30-32°C; from 8.5-9.5h of fermentation to the end of fermentation, the fermentation temperature is controlled at 33-35°C, and the total fermentation time is 68-72h to obtain a fermented mash; wherein the amount of ammonium sulfate added is 8.2-8.6kg per ton of the liquefied liquid in dry weight, the amount of saccharifying enzyme added is 0.65-0.7kg per ton of the liquefied liquid in dry weight, and the amount of acid protease added is 0.055-0.065kg per ton of the liquefied liquid in dry weight; wherein the amount of Anjuntai added is to make the final concentration 5-5.5ppm; wherein the inoculation amount of saccharifying yeast in dry powder is 0.05-0.1% by weight; (4) evaporating and condensing the obtained fermented mash by a distillation device to obtain a distillation liquid containing wine and a waste mash liquid, and filtering the waste mash liquid by a plate and frame cloth filter to obtain a clear liquid.

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