阅读说明：本技术 以谷物为原料生产乙醇的方法 (Method for producing ethanol by using grains as raw materials ) 是由 岳军 屈海峰 马丹 惠继星 宁艳春 徐友海 胡世洋 王继艳 金刚 于 2018-05-29 设计创作，主要内容包括：本发明提供了一种以谷物为原料生产乙醇的方法。该方法包括以下步骤：将谷物粉碎后,制成淀粉浆；将淀粉浆采用液化工艺进行液化得到液化醪,液化过程中添加的酶包括第一纤维素酶、甘露聚糖酶、果胶酶及耐酸性液化酶；将液化醪进行发酵,得到乙醇。本方法实现了谷物原料高浓度乙醇的发酵,可以减少蒸汽以及水的消耗,增加设备利用率。(The invention provides a method for producing ethanol by using grains as raw materials. The method comprises the following steps: pulverizing grain, and making into starch slurry; liquefying the starch slurry by a liquefying process to obtain liquefied mash, wherein the enzymes added in the liquefying process comprise first cellulase, mannase, pectinase and acid-resistant liquefying enzyme; fermenting the liquefied mash to obtain ethanol. The method realizes fermentation of high-concentration ethanol in grain raw material, can reduce consumption of steam and water, and increases equipment utilization rate.)

1. A method for producing ethanol by taking grains as raw materials is characterized by comprising the following steps:

a, crushing the grains to prepare starch slurry;

b, liquefying the starch slurry by adopting a liquefying process to obtain liquefied mash, wherein the enzymes added in the liquefying process comprise first cellulase, mannase, pectinase and acid-resistant liquefying enzyme;

And c, fermenting the liquefied mash to obtain the ethanol.

2. The method of claim 1, wherein in step b, the liquefaction process is a two-stage liquefaction process.

3. The method of claim 2, wherein the acid-resistant liquefying enzyme comprises a first acid-resistant liquefying enzyme and a second acid-resistant liquefying enzyme; in the two-stage liquefaction process, the enzymes added in the first stage liquefaction process comprise the first cellulase, the mannanase, the pectinase and the first acid-resistant liquefaction enzyme, and the enzymes added in the second stage liquefaction process comprise the second acid-resistant liquefaction enzyme.

4. The method of claim 3, wherein in the first stage liquefaction process, the first cellulase enzyme is present in an amount of 1.5 to 3u/g, the mannanase is present in an amount of 5 to 10u/g, the pectinase is present in an amount of 5 to 10u/g, and the first acid-resistant liquefaction enzyme is present in an amount of 6 to 10 u/g.

5. The method of claim 3, wherein the second acid-resistant liquefying enzyme is used in an amount of 7.5 to 12u/g grain material in the second-stage liquefying process.

6. The method according to claim 2, wherein the liquefaction temperature in the first stage liquefaction process is 55 ℃ to 60 ℃; the liquefaction temperature in the second-stage liquefaction process is 85-95 ℃; preferably, the liquefaction time in the first stage liquefaction process is 30-60 min; the liquefaction time in the second stage of liquefaction process is 60-90 min.

7. The method according to any one of claims 1 to 6, wherein in step a, the cereal is ground to below 20 mesh.

8. The method according to any one of claims 1 to 6, wherein in step a, the starch slurry has a weight concentration of 29 to 32%.

9. The method according to any one of claims 1 to 6, wherein in step b, after liquefaction, the liquefied mash is cooled, preferably to 30-35 ℃.

10. The method according to any one of claims 1 to 6, wherein in step c, yeast is added multiple times during the fermentation; preferably, a saccharifying enzyme, a second cellulase, an acid protease, a first yeast and a second yeast are added to the liquefied mash to perform the fermentation process.

11. The method according to claim 10, wherein the saccharifying enzyme is used in an amount of 150 to 200u/g of the cereal raw material, the second cellulase is used in an amount of 1.2 to 2.5u/g of the cereal raw material, the acidic protease is used in an amount of 3 to 7u/g of the cereal raw material, the first yeast is used in an amount of 0.02 to 0.03% by mass of the cereal raw material, and the second yeast is used in an amount of 0.01 to 0.02% by mass of the cereal raw material.

12. The method according to claim 11, wherein the second cellulase, the acid protease and the first yeast are added to the liquefied mash during the fermentation process, and then air is introduced into the liquefied mash, wherein the aeration rate is 0.02vvm to 0.1vvm, and the aeration time is 8h to 12 h.

13. The method of claim 12, wherein the second yeast is supplemented after the addition of the first yeast for at least 24 hours of fermentation.

14. The method according to any one of claims 1 to 6, wherein in step c, the fermentation time of the fermentation process is 45-60 h.

15. The method according to any one of claims 1 to 6, wherein the concentration of ethanol is 130 to 145 g/L.

Technical Field

The invention relates to the technical field of bioethanol production, in particular to a method for producing ethanol by using grains as raw materials.

Background

Since the human beings enter the industrial society, the resource and environment problems are increasingly highlighted, and especially the massive use of non-renewable fossil energy sources generates a series of resource and environment problems, wherein the greenhouse effect caused by the emission of a large amount of carbon dioxide becomes a great problem which cannot be avoided. The renewable and environment-friendly energy and resource is the direction of transformation and upgrading in the future.

The fuel ethanol is added into the gasoline, so that the nitrogen oxide in the automobile exhaust can be effectively reduced. Ethanol has a higher octane number, the octane number of gasoline can be increased after fuel ethanol is mixed in the gasoline, and the fuel ethanol replaces methyl tert-butyl ether (MTBE) to be used as an antiknock agent of the automotive gasoline.

Improving the ethanol concentration in the fermented mash is the development direction of the fuel ethanol industry. The fermentation with high substrate concentration can reduce the consumption of energy and water and increase the utilization rate of equipment. However, at high substrate concentration, the starch gelatinization phenomenon caused by the temperature rise of the material transportation, particularly in the early stage of cooking and liquefaction, leads to the increase of the viscosity of the material and the reduction of the fluidity, thereby causing certain influence on the production.

CN103773811A discloses a novel method for producing fuel ethanol by a corn low-temperature pretreatment mode. The invention carries out liquefaction at low temperature, can save energy, but causes the defects of overhigh consumption of the liquefying enzyme and overlong fermentation, and simultaneously does not solve the problem of viscosity increase. It is therefore desirable to provide a process for producing ethanol from a cereal material that has low energy consumption and short fermentation time, while addressing the problem of increased viscosity at high substrate concentrations.

Disclosure of Invention

The invention mainly aims to provide a method for producing ethanol by using grains as raw materials, which aims to solve the problems of high energy consumption, long fermentation time and starch gelatinization caused by viscosity increase in the prior art when the raw materials with high substrate concentration are adopted for fermentation.

To achieve the above object, according to one aspect of the present invention, there is provided a method for producing ethanol from a cereal material, comprising the steps of: a, crushing grains to prepare starch slurry; liquefying the starch slurry by adopting a liquefying process to obtain liquefied mash, wherein the enzymes added in the liquefying process comprise first cellulase, mannanase, pectinase and acid-resistant liquefying enzyme; and c, fermenting the liquefied mash to obtain the ethanol.

Further, in step b, the adopted liquefaction process is a two-stage liquefaction process.

Further, the acid-resistant liquefying enzyme includes a first acid-resistant liquefying enzyme and a second acid-resistant liquefying enzyme; in the two-stage liquefaction process, the enzymes added in the first stage of liquefaction process comprise first cellulase, mannanase, pectinase and first acid-resistant liquefaction enzyme, and the enzymes added in the second stage of liquefaction process comprise second acid-resistant liquefaction enzyme.

Furthermore, in the first stage of liquefaction process, the dosage of the first cellulase is 1.5-3 u/g of the grain raw material, the dosage of the mannanase is 5-10 u/g of the grain raw material, the dosage of the pectinase is 5-10 u/g of the grain raw material, and the dosage of the first acid-resistant liquefaction enzyme is 6-10 u/g of the grain raw material.

Furthermore, in the second stage of liquefaction process, the dosage of the second acid-resistant liquefying enzyme is 7.5-12 u/g of grain raw material.

Further, the liquefaction temperature in the first stage of liquefaction process is 55-60 ℃; the liquefaction temperature in the second stage of liquefaction process is 85-95 ℃; preferably, the liquefaction time in the first stage liquefaction process is 30min to 60 min; the liquefaction time in the second stage of liquefaction process is 60-90 min.

Further, in step a, the cereal raw material is pulverized to 20 mesh or less.

Further, in the step a, the weight concentration of the starch slurry is 29-32%.

Further, in the step b, after liquefaction, the temperature of the liquefied mash is reduced, preferably to 30-35 ℃.

Further, in step c, yeast is added for a plurality of times during the fermentation; preferably, the fermentation process is carried out by adding saccharifying enzyme, second cellulase, acid protease, first yeast and second yeast to the liquefied mash.

Furthermore, the dosage of the saccharifying enzyme is 150-200 u/g of the grain raw material, the dosage of the second cellulase is 1.2-2.5 u/g of the grain raw material, the dosage of the acid protease is 3-7 u/g of the grain raw material, the dosage of the first yeast is 0.02-0.03 percent of the mass of the grain raw material, and the dosage of the second yeast is 0.01-0.02 percent of the mass of the grain raw material.

Further, in the fermentation process, the second cellulase, the acid protease and the first yeast are added into the liquefied mash, then air is introduced, the air flow is 0.02 vvm-0.1 vvm, and the air introduction time is 8 h-12 h.

Further, the second yeast is supplemented after the addition of the first yeast for fermentation for at least 24 h.

Further, in the step c, the fermentation time in the fermentation process is 45-60 h.

Furthermore, the concentration of the ethanol is 130 g/L-145 g/L.

by applying the technical scheme of the invention, a saccharification process and a spraying process are cancelled, a liquefaction process is changed, and cellulase, mannase, pectinase and acid-resistant liquefaction enzyme are added, so that starch in grains is quickly changed into fermentable sugar which can be fermented by yeast under the action of various enzymes, thereby realizing the fermentation of high-concentration ethanol in grain raw materials, reducing the consumption of steam and water and increasing the utilization rate of equipment.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.

As described in the background section, increasing the ethanol concentration in the fermentation mash is the direction of development in the fuel ethanol industry, which requires fermentation of high concentration substrates, not only to reduce energy and water consumption, but also to increase equipment utilization. However, the high concentration of substrate causes gelatinization of the starch during cooking. To solve this problem, the present invention provides a method for producing ethanol from a cereal material, comprising the steps of: a, crushing grains to prepare starch slurry; liquefying the starch slurry by adopting a liquefying process to obtain liquefied mash, wherein the enzymes added in the liquefying process comprise first cellulase, mannanase, pectinase and acid-resistant liquefying enzyme; and c, fermenting the liquefied mash to obtain the ethanol.

The invention changes the liquefaction process, adds the first cellulase, mannase, pectinase and acid-resistant liquefaction enzyme in the liquefaction process, and quickly changes starch in grains into fermentable sugar which can be fermented by yeast under the action of various enzymes, thereby realizing the fermentation of high-concentration ethanol in the grain raw material, reducing the consumption of steam and water and increasing the utilization rate of equipment.

In a preferred embodiment, in step b, the liquefaction process employed is a two-stage liquefaction process. The invention adopts two-stage liquefaction process in the starch slurry liquefaction process, so that the starch is liquefied more fully, the starch viscosity is reduced, and the starch gelatinization phenomenon can be reduced.

In a preferred embodiment, the acid-resistant liquefying enzyme comprises a first acid-resistant liquefying enzyme and a second acid-resistant liquefying enzyme; in the two-stage liquefaction process, the enzymes added in the first stage of liquefaction process comprise first cellulase, mannanase, pectinase and first acid-resistant liquefaction enzyme, and the enzymes added in the second stage of liquefaction process comprise second acid-resistant liquefaction enzyme. A plurality of enzymes are added in the first section of liquefaction process, different substances in the grains can be hydrolyzed into fermentation sugar which can be fermented by yeast, meanwhile, the viscosity of the starch slurry can also be reduced, and acid-resistant liquefying enzyme is added again in the second section of liquefaction process, so that the starch is hydrolyzed more fully.

In a preferred embodiment, in the first stage liquefaction process, the first cellulase is present in an amount of 1.5 to 3u/g, the mannanase is present in an amount of 5 to 10u/g, the pectinase is present in an amount of 5 to 10u/g, and the first acid-resistant liquefying enzyme is present in an amount of 6 to 10 u/g. Controlling the dosage of the enzyme within the range can improve the utilization rate of the enzyme and reduce the cost.

In a preferred embodiment, the second acid-resistant liquefying enzyme is used in an amount of 7.5 to 12u/g of the cereal material in the second-stage liquefying process. Acid-resistant liquefying enzyme is further added in the second stage of liquefying process, so that the hydrolysis rate of the grain starch is further improved.

In a preferred embodiment, the liquefaction temperature in the first stage liquefaction process is between 55 ℃ and 60 ℃; the liquefaction temperature in the second stage of liquefaction process is 85-95 ℃; preferably, the liquefaction time in the first stage liquefaction process is 30min to 60 min; the liquefaction time in the second stage of liquefaction process is 60-90 min. In the first stage of liquefaction process, low temperature is adopted for liquefaction, the gelatinization phenomenon of starch can be reduced, so that the fluidity of the material is improved, in the second stage of liquefaction process, the liquefaction temperature is increased, and the activity of the enzyme in the liquefaction process reaches the optimal state due to the change of the activity of the enzyme along with the change of the temperature, so that the liquefaction effect is better. The liquefaction time is controlled within the range, so that the liquefaction effect is met, the resources can be effectively utilized, and the cost is saved.

In a preferred embodiment, in step a, the cereal material is comminuted to less than 20 mesh. The grain raw material is crushed to be below 20 meshes, so that grains can be dispersed more uniformly, and the liquefaction effect is better.

In a preferred embodiment, the concentration of starch slurry in step a is 29 to 32% by weight. The concentration of the starch slurry is controlled within the range, so that the utilization rate of the raw materials can be greatly improved, the gelatinization phenomenon is reduced, and the content of byproducts is effectively reduced.

In a preferred embodiment, in step b, after liquefaction, the temperature of the liquefied mash is reduced to 30-35 ℃. When the temperature of the liquefied mash is reduced to the temperature, the next fermentation process of the yeast is facilitated.

In a preferred embodiment, in step c, yeast is added for a plurality of times during the fermentation process, wherein the yeast can be dry saccharomyces cerevisiae, and the yeast is added for a plurality of times during the fermentation process, so that the liquefied mash is fermented more fully, and the yield of the ethanol is improved.

In a preferred embodiment, the fermentation process is carried out by adding saccharifying enzyme, second cellulase, acid protease, first yeast and second yeast to the liquefied mash. In the fermentation process, saccharifying enzyme, cellulase, acid protease and the like are added again, and unhydrolyzed starch and other substances in the liquefaction process can be further changed into fermentable sugar which can be fermented by yeast.

In a preferred embodiment, the saccharifying enzyme is used in an amount of 150 to 200u/g of the cereal raw material, the second cellulase is used in an amount of 1.2 to 2.5u/g of the cereal raw material, the acid protease is used in an amount of 3 to 7u/g of the cereal raw material, the first yeast is used in an amount of 0.02 to 0.03 percent by mass of the cereal raw material, and the second yeast is used in an amount of 0.01 to 0.02 percent by mass of the cereal raw material. Controlling the dosage of the enzyme and the yeast within the above range can improve the yield of ethanol by using the action of the enzyme and the yeast.

In a preferred embodiment, the second cellulase, the acid protease and the first yeast are added into the liquefied mash in the fermentation process, and then air is introduced, wherein the air flow is 0.02 vvm-0.1 vvm, and the air introduction time is 8 h-12 h. Controlling the ventilation amount and the ventilation time within the above range, promoting the growth and reproduction of yeast, increasing the concentration of yeast during fermentation, and improving the fermentation efficiency.

In a preferred embodiment, the second yeast is supplemented after at least 24 hours of fermentation by the addition of the first yeast. The yeast is added in the fermentation process, so that the concentration of the yeast can be further improved, and the fermentation efficiency is improved.

In a preferred embodiment, in step c, the fermentation time is 45h to 60 h. The fermentation time is controlled within the range, the fermentation efficiency is better, and the yield of the ethanol is higher.

In a preferred embodiment, the concentration of ethanol is from 130g/L to 145 g/L.

The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.

The source of the enzyme may be as follows: the first cellulase and the second cellulase (CEL-01, Ningxia Shengshi group Co., Ltd.), mannanase (10000 u/g, Ningxia Shengshi group Co., Ltd.), pectinase (60000 u/mL, Shandong Longmao bioengineering Co., Ltd.), acid-resistant liquefying enzyme (Tenemamyl SC), saccharifying enzyme (Jenenke OPTIMAX 4060VHP), and acid protease (100000 u/mL, Shandong Longmao bioengineering Co., Ltd.).