CN115747262A

CN115747262A - Method for producing ethanol by using wheat

Info

Publication number: CN115747262A
Application number: CN202111032420.4A
Authority: CN
Inventors: 杜伟彦; 于斌; 熊强; 刘小辰; 刘劲松; 林海龙
Original assignee: Sdic Biotechnology Investment Co ltd
Current assignee: Sdic Biotechnology Investment Co ltd
Priority date: 2021-09-03
Filing date: 2021-09-03
Publication date: 2023-03-07

Abstract

The invention relates to the field of ethanol production, and discloses a method for producing ethanol by using wheat, which comprises the following steps: crushing wheat to obtain a crushed product; in the presence of xylanase and/or beta-glucanase, pulping and liquefying the crushed product to obtain liquefied liquid; inoculating the strain into the liquefied liquid for fermentation to obtain mature mash; distilling the mature mash to obtain ethanol and waste mash; the fermentation results in a five carbon sugar utilization of 60% or more, based on the total weight of arabinose and xylose. By adopting the scheme of the invention, the solid content of the clear liquid can be reduced, so that the post-treatment of the clear liquid is facilitated, the evaporation difficulty and the evaporation energy consumption are reduced, the syrup viscosity is reduced, the return consumption of the clear liquid is increased, the ethanol yield can be increased, and the rectification energy consumption is reduced.

Description

Method for producing ethanol by using wheat

Technical Field

The invention relates to the field of ethanol production, and particularly relates to a method for producing ethanol by using wheat.

Background

Because wheat and the like are emerging fuel ethanol raw materials, no fuel ethanol process special for the wheat raw materials is provided at home. The existing process flow is mostly improved in the process of producing fuel ethanol by using cassava or corn as raw materials. However, when the fuel ethanol is produced by using the wheat raw material, the components of the wheat have low starch content and high non-starch polysaccharides NSPs content, and the protein content and the fiber content are relatively high.

In particular non-starch polysaccharides, form a gel when they come into contact with water, which causes a significant increase in the viscosity of the material in the entire system for the production of ethanol, in particular the serum and syrup viscosities, from about 600cP for the syrup obtained from corn to about 3000cP today. The syrup viscosity rises, the evaporation capacity is seriously reduced, and the load of the whole wheat flow device is reduced to 50 to 60 percent. Moreover, due to the high viscosity of the syrup, the evaporator unit needs to be shut down and cleaned periodically. And the proportion of the recycled clear liquid is reduced, the amount of the clear liquid to be evaporated is increased, and the capacity required by evaporation is increased by 10-20 percent, so that the whole evaporation system becomes the bottleneck of the device. Plant capacity using corn feedstock is reduced to around 50%.

Disclosure of Invention

The invention aims to solve the problems of high clear liquid concentration, high syrup viscosity, difficult evaporation, low clear liquid recycling amount and the like in the process of producing ethanol by taking wheat as a raw material in the prior art, and provides a method for producing ethanol by utilizing wheat.

In order to achieve the above object, the present invention provides a method for producing ethanol using wheat, the method comprising:

(1) Crushing wheat to obtain a crushed product;

(2) In the presence of xylanase and/or beta-glucanase, pulping and liquefying the crushed product to obtain liquefied liquid;

(3) Inoculating strains into the liquefied liquid for fermentation to obtain mature mash;

(4) Distilling the mature mash to obtain ethanol and waste mash;

wherein the fermentation enables the utilization rate of the pentose to be more than 60% based on the total weight of the arabinose and the xylose.

Preferably, the method further comprises: and carrying out first separation on the waste mash to obtain a first clear liquid and a first wet cake, and carrying out second separation on the first clear liquid to obtain a second clear liquid and a second wet cake.

Preferably, the method further comprises: and evaporating the second clear liquid to obtain syrup and an evaporation condensate.

Preferably, the syrup is recycled to the first separation step as at least part of the feed to the first separation.

Preferably, at least part of the evaporative condensate is recycled to the size mixing step as part of the size mixing water.

The scheme of the invention degrades non-starch polysaccharide by adding xylanase and/or beta-glucanase in a size mixing process (preferably high-temperature size mixing) to generate C5 sugar (comprising monosaccharide and polysaccharide); the fermentation process reduces the solid content of the clear liquid through the co-fermentation of C5 sugar and C6 sugar (including monosaccharide and polysaccharide), thereby being beneficial to the post-treatment of the clear liquid, reducing the evaporation difficulty and the evaporation energy consumption, reducing the syrup viscosity, increasing the return dosage of the clear liquid, increasing the ethanol yield (reaching 2 percent) and reducing the rectification energy consumption (2 to 5 percent).

In the preferred technical scheme of the invention, the clear liquid adopts a twice separation process, and the material separated for the first time is used for obtaining DDGS feed; the clear liquid of the first separation is separated for the second time, the wet grains produce high protein materials, and the clear liquid is separated for the second time, so that the solid content of the clear liquid is reduced, and the evaporation load is further reduced.

Drawings

FIG. 1 is a flow chart of the present invention for producing ethanol from wheat.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For numerical ranges, each range between its endpoints and individual point values, and each individual point value can be combined with each other to give one or more new numerical ranges, and such numerical ranges should be construed as specifically disclosed herein.

The invention provides a method for producing ethanol by using wheat, which comprises the following steps:

(1) Crushing wheat to obtain a crushed product;

(3) Inoculating a strain into the liquefied liquid for fermentation to obtain a mature mash;

(4) Distilling the mature mash to obtain ethanol and waste mash;

In the invention, the ethanol production by using wheat is that the wheat is used as a main raw material, the wheat can be completely used as the raw material for production, and other starchy raw materials such as rice, corn, cassava, sorghum and the like can also be doped.

In the present invention, the other starchy materials in the raw materials for producing ethanol do not exceed 50% by weight, that is, wheat is used in an amount of not less than 50% by weight.

It is understood that the terms "wheat", "corn", "rice", "tapioca" and "sorghum" do not refer to the entire plant itself, but to parts or organs thereof having a high starch content, i.e. wheat seeds, corn seeds, rice seeds, tapioca tubers, sorghum seeds, with or without husk.

In the present invention, unless otherwise specified, wheat is wheat grains, rice is brown rice, and corn is corn grains.

The pulverization method is not particularly limited, and various pulverization methods commonly used in the art may be used, and in order to improve the effect of the subsequent treatment, it is preferable that the pulverization conditions are such that 80% by weight or more of the pulverized product can pass through a 20-mesh sieve, more preferably at least 85%, and still more preferably at least 95% of the pulverized product can pass through a 20-mesh sieve.

In the present invention, the water for size mixing may be process water or material obtained in the production process (such as evaporation condensate obtained in the subsequent evaporation process).

In the present invention, it is preferable that the xylanase and the beta-glucanase have a property of tolerating a temperature of 90 ℃ or more.

When used alone, the xylanase is preferably used in an amount of 10 to 40U, more preferably 12 to 20U, relative to 1g of wheat, for example, 12U, 13U, 14U, 15U, 16U, 17U, 18U, 19U, 20U, and any value within the range of any two points. It is commercially available, for example, as Viscozyme HT from Novovin.

When used alone, the amount of the β -glucanase is preferably 5 to 20U, more preferably 10 to 18U, for example, 10U, 11U, 12U, 13U, 14U, 15U, 16U, 17U, 18U, or any value in the range of any two points, relative to 1g of wheat. It can be obtained commercially, for example, as a beta-glucanase from bort or from petaste.

When xylanase and beta-glucanase are used simultaneously, the xylanase is preferably used in an amount of 10-15U and the beta-glucanase in an amount of 1-2U, relative to 1g of wheat.

The inventors also tried adding cellulase for size mixing, but there was substantially no effect.

Preferably, the solids content of the material (generally referred to as starch slurry) in the size mixing process is 20-40 wt%, preferably 22-33 wt%, and may be, for example, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33 wt% or any value in the range of any two of these, more preferably 25-32 wt%.

Preferably, the size mixing temperature is 90-105 ℃, more preferably 93-100 ℃, and under the preferable condition, the starch can be completely gelatinized, the starch in the material is fully released, good conditions are provided for subsequent liquefaction, and the increase of the ethanol concentration is facilitated.

Wherein, the size mixing process can also comprise a step of adjusting pH, and the adjusted pH is preferably 3-8, more preferably 4-7.

In the present invention, the purpose of the liquefaction is to convert the starch slurry into fermentable sugars. Therefore, any method conventionally used in the art to achieve the purpose of liquefaction treatment is suitable for the present invention.

Specifically, the liquefaction process can be performed separately after the size mixing step (for example, adding amylase to the starch slurry for liquefaction to obtain a liquefied liquid), or can be performed subsequently in the size mixing process, for example, adding amylase simultaneously with xylanase and/or beta-glucanase for size mixing.

Preferably, the method comprises: in the step (2), under the existence of xylanase and/or beta-glucanase and amylase, the crushed product is simultaneously subjected to size mixing and liquefaction to obtain liquefied liquid.

Preferably, the amylase is used in an amount of 10 to 80U, more preferably 18 to 40U, relative to 1g of the pulverized product.

It should be understood that the comminuted product herein may refer to wheat (when whole wheat is used for ethanol production) or a mixture of wheat and other starchy materials (when wheat and other starchy materials are used for ethanol production).

The amylase may be an amylase conventionally used in the art, and may be, for example, a thermostable alpha-amylase available from Jenenaceae.

Preferably, the conditions of liquefaction include: the temperature is 55-120 ℃, more preferably 70-105 ℃; a pH of 3 to 8, more preferably 4 to 7; the time is 0.2 to 10 hours, more preferably 1 to 5 hours.

It should be understood that when liquefaction and slurrying are performed substantially simultaneously, the temperature and pH of the liquefaction is maintained consistent with the slurrying process.

In the present invention, the fermentation is performed to produce an ethanol-containing fermented mash from the liquefied solution, and the separated ethanol-containing fermented mash is separated to obtain a mature mash. Therefore, methods conventionally used in the art to achieve fermentation purposes are suitable for the present invention.

During the fermentation process, C5 sugar (mainly arabinose and xylose) and C6 sugar (mainly glucose, fructose, maltose and the like) are simultaneously utilized for fermentation, and solid content and viscosity in clear liquid are reduced.

The bacterium used for fermentation may be a strain in the art capable of simultaneously fermentatively producing ethanol using C5 sugars and C6 sugars, preferably, the strain has an ethanol production efficiency using five carbon sugars of 60% or more, more preferably 70% or more, based on the total weight of arabinose and xylose. It will be appreciated that the utilization of pentoses on a large scale is lower than that of pilot or pilot scale ethanol production, i.e. the utilization of pentoses can be higher if it is on pilot or laboratory scale.

Generally, most starch is liquefied and saccharified and then hydrolyzed into small-molecular polysaccharides and glucose, and the strain can utilize the sugar to produce ethanol through fermentation, and residual sugar exists after the fermentation is finished.

Preferably, the fermentation is such that the content of residual total sugars is 2.5g/L or less. Wherein the residual total sugar is calculated by arabinose, xylose, glucose, fructose and maltose.

The content of residual total sugars can be determined by liquid chromatography.

In the invention, the strain can be activated and at least one stage of propagation before inoculation, the activation can be carried out in a shake flask, and the propagation can be carried out in the shake flask and/or a propagation tank. For example, activation and primary expanding culture can be performed in a shake flask, and secondary expanding culture can be performed in an expanding culture tank to obtain a seed solution.

The conditions of activation and each stage of propagation can include: the pH value is 2-7, preferably 3-6; the temperature is 25-40 ℃, preferably 30-35 ℃; the activation time is 12-24h; the time of each stage of propagation is 6-16h.

In the present invention, the inoculum size of the strain may be selected within a wide range, for example, the inoculum size of the strain may be 1X 10 per 1g of the liquefied liquid ⁴ -1×10 ⁷ cfu。

The culture medium used in the activation or expansion process may be the same or different, and may be an expansion medium conventionally used in the art, such as YEPX culture medium or zymolysis medium.

Wherein, YEPX culture medium can comprise 5-15g/L yeast extract, 15-25g/L peptone and 15-25g/L monosaccharide. Wherein the monosaccharide is at least one selected from glucose, arabinose and xylose.

The enzymolysis liquid culture medium can comprise enzymolysis liquid diluent, monosaccharide and corn steep liquor.

Preferably, the glucose amount is 2.5-3.5 parts by weight, the xylose content is 1-1.5 parts by weight, the corn steep liquor content is 0.1-0.2 part by weight, and the rest is the enzymolysis liquid diluent (the dilution multiple is preferably 1-2 times) relative to 100 parts by weight of the enzymolysis liquid culture medium, and under the preferable condition, the tolerance of the strain to the inhibitor contained in the enzymolysis liquid is improved.

Preferably, the expanding culture medium further comprises penicillin, and the amount of the penicillin is such that the content of the penicillin in the expanding culture medium is 5-20ppm, more preferably 8-15ppm.

In the present invention, the fermentation is performed such that the five-carbon sugar utilization rate is 60% or more, preferably 65% or more, more preferably 70% or more, based on the total weight of arabinose and xylose.

In the present invention, the utilization rate of pentose can be calculated according to the following formula, and the utilization rate (%) of pentose (= (pentose concentration at 0h fermentation-pentose concentration at the end of fermentation)/pentose concentration at 0h fermentation × 100%, wherein pentose is based on the total weight of arabinose and xylose.

The utilization rate of pentose is mainly influenced by strains, and therefore, it is preferable to select a strain capable of efficiently utilizing pentose in fermentation. Preferably, the strain is Saccharomyces cerevisiae CGMCC No.16830. It is understood that other strains capable of meeting five carbon sugar utilization may be used in the present invention.

Preferably, the conditions of the fermentation include: the pH value of the fermentation is 2-7, preferably 3-6; the temperature is 25-40 ℃, preferably 30-35 ℃; the time is 2-5 days.

In the present invention, saccharification and fermentation may be performed simultaneously, i.e., saccharification enzyme may be added to the liquefied liquid, wherein the saccharification enzyme may be one commonly used in the art, such as suzuo 474, which may be novacin.

The amount of the saccharifying enzyme can be selected within a wide range, and preferably 300 to 400U, preferably 320 to 380U, per 1g of the pulverized product.

Preferably, the method further comprises adding cellulase in at least one step of the conditioning, liquefaction and fermentation. In the preferred case, the clear liquid solid content can be further reduced, the syrup viscosity can be reduced, and the ethanol yield can be increased.

Preferably, the cellulase is used in an amount of 5 to 20U, preferably 10 to 18U, for example, 10U, 11U, 12U, 13U, 14U, 15U, 16U, 17U, 18U and any value within the range of any two points, relative to 1g of wheat. It can be obtained commercially, for example, cellulase available from bort or Persongjen.

In the present invention, the purpose of the distillation is to extract ethanol from the fermentation mash, preferably by means of a distillation comprising: performing rough distillation on the mature mash to obtain rough distillation fraction and waste mash; and rectifying the crude distillation fraction to obtain the ethanol.

The distillation can be carried out in a distillation system conventional in the art and can be selected by the person skilled in the art as desired.

For example, the crude distillation may be carried out in a crude distillation column, preferably, the operating conditions of the crude distillation column include: the temperature of the tower kettle is 65-85 ℃; the pressure of the tower kettle is-0.06 to-0.03 MPa; the temperature of the tower top is 40-60 ℃; the pressure at the top of the tower is-0.05 to-0.08 MPa; the reflux ratio is 0.5-5;

for example, the rectification may be performed in a rectification column, and preferably, the operating conditions of the rectification column include: the temperature of the tower kettle is 105-125 ℃; the pressure of the tower kettle is 0.07 to 0.3MPa; the temperature of the tower top is 85-98 ℃; the pressure at the top of the tower is 0.05 to 0.2MPa; the reflux ratio is 0.5-8.

In the present invention, the reflux ratio is the ratio of the amount of the withdrawn material to the amount of the material returned to the column.

The waste mash of the topping still, which is preferably < 0.04 wt.% ethanol, is discharged from the bottom of the tower and may be subjected to post-treatment, such as separation, evaporation and drying to give by-products.

In the present invention, the separation method may be performed using a technique conventional in the art, such as a method of centrifugation or filtration. It should be understood that the first separation is a coarse separation and the second separation is a fine separation.

Preferably, the conditions of the first separation are such that the dry matter content in the first clear liquid is 5-10 wt%.

Preferably, the conditions of the second separation are such that the dry matter content in the second clear liquid is 3.5 wt% or less.

In a preferred embodiment of the invention, the first separation mode is plate and frame filtration or centrifugation (rotation speed of 1500-2000 rpm).

In a preferred embodiment of the invention, the second separation mode is centrifugation (rotation speed of 2000-2500 rpm).

It will be appreciated that where the first and second separations are both centrifugal, the rotational speed of the second separation is higher than the rotational speed of the first separation.

And (3) concentrating the main component of the second clear liquid obtained after the second separation treatment to obtain syrup and evaporation condensate, wherein the main component of the second clear liquid is saccharide.

The concentration mode can be a conventional concentration mode in the field, and preferably, the method further comprises the following steps: and evaporating the second clear liquid to obtain syrup and an evaporation condensate.

In the present invention, the syrup may be sold directly as a by-product or may be further processed, preferably, the syrup is returned to the first separation step as at least part of the raw material for the first separation. The syrup can be returned to the first separation step and treated with waste mash together for producing by-products, thus improving economic benefits.

The skilled person can select the apparatus and parameters of evaporation as desired.

Since the first wet cake and the second wet cake also contain moisture, it is generally necessary to dry them to obtain DDGS and/or high protein material. Preferably, the method further comprises: and (3) drying the first wet cake and/or the second wet cake to obtain DDGS and/or high-protein materials and drying waste gas.

Wherein the DDGS refers to distillers' grain protein, and can be used for producing feed products. The protein content of the high protein material is in the range of 40-60 wt%, and can also be used as high quality feed.

In the present invention, the drying method may be a technique conventionally used in the art, and may be drying by a dryer, for example. The temperature and time of drying can be adjusted as desired by one skilled in the art.

Preferably, the drying exhaust gas serves as a heat source for the evaporation step and/or the drying step.

The drying condensate obtained after the heat exchange of the drying waste gas can be used as at least part of water for size mixing.

In the present invention, the ethanol obtained by rectification may be subjected to post-treatment to obtain an ethanol product, and a person skilled in the art may select a suitable purification process as required, which is not described herein again.

In the present invention, unless otherwise specified, the pressures are gauge pressures.

The method of the present invention may be performed in a system that may include:

the crushing unit is used for crushing the wheat to obtain a crushed product;

the size mixing unit is used for mixing the crushed product to obtain starch size;

the liquefaction unit is used for carrying out enzymolysis on the starch slurry to obtain liquefied liquid;

the fermentation unit is used for fermenting the liquefied liquid to obtain mature mash;

and the distillation unit is used for distilling and separating the mature mash to obtain ethanol and waste mash.

Preferably, the system further comprises a separation unit for performing a first separation of the spent mash to obtain a first clear liquid and a first wet cake, and performing a second separation of the first clear liquid to obtain a second clear liquid and a second wet cake.

Preferably, the system further comprises an evaporation unit, and the second clear liquid is subjected to evaporation treatment to obtain syrup and evaporation condensate.

Preferably, the evaporation unit is further connected to a separation unit via a conduit for returning the syrup to the first separation step as at least part of the feed to the first separation.

Preferably, the evaporation unit is further connected with the size mixing unit through a pipeline and is used for circulating at least part of the evaporation condensate to the size mixing step to be used as part of size mixing water.

Preferably, the system further comprises a drying unit for drying the first wet-cake and the second wet-cake from the separation unit to obtain the DDGS and the high protein material.

It should be understood that the slurrying unit and the liquefaction unit may be the same unit or different units.

The equipment and connection mode thereof contained in each unit can be equipment and connection mode which are conventional in the field, and the equipment and connection mode can be selected by a person skilled in the art according to needs, and the operation condition can also be the operation condition which is conventional in the field without special description.

According to a particularly preferred embodiment of the present invention, there is provided a process for producing fuel ethanol from wheat feedstock, the process comprising:

(1) Crushing wheat to obtain a crushed product; wherein the pulverization conditions are such that 80% by weight or more of the pulverized product can pass through a 20-mesh screen;

(2) Mixing the crushed product with xylanase, beta-glucanase, alpha-amylase and water for size mixing, and then carrying out size mixing and liquefaction to obtain liquefied liquid; wherein, the conditions of size mixing and liquefaction comprise that the temperature is 93-98 ℃, the pH is 4-6, the time is 1-3h, and the solid content of the materials in the size mixing and liquefaction process is 25-32 wt% by using the amount of size mixing water; wherein the water for size mixing comprises process water, evaporation condensate and drying condensate; wherein, compared with 1g of wheat, the dosage of xylanase is 10-15U, and the dosage of beta-glucanase is 1-2U; the amount of the amylase is 18-25U relative to 1g of the pulverized product;

(3) Inoculating a strain into the liquefied liquid for fermentation in the presence of saccharifying enzyme to obtain mature mash; wherein the fermentation enables the utilization rate of the pentose to be more than 60% based on the total weight of the arabinose and the xylose; the fermentation is carried out so that the content of residual total sugar is below 2.5g/L, wherein the residual total sugar is calculated by arabinose, xylose, glucose, fructose and maltose; the inoculum size of the strain is 1 × 10 relative to 1g of the liquefied solution ⁴ -1×10 ⁶ cfu, the conditions of fermentation are as follows: the fermentation temperature is 30-34 ℃, the pH is 3.5-4.5, and the fermentation time is 60-72h; wherein, the dosage of saccharifying enzyme is 320-380U relative to 1g of pulverized product;

(4) Roughly distilling the mature mash to obtain waste mash and a roughly distilled fraction, and rectifying the roughly distilled fraction to obtain ethanol;

(5) Carrying out first separation on the waste mash to obtain a first wet cake and a first clear solution; carrying out second separation on the first clear liquid to obtain a second wet cake and a second clear liquid, and carrying out evaporation concentration on the second clear liquid to obtain syrup and an evaporation condensate; drying the first wet cake and the second wet cake to obtain DDGS, a high-protein material and a drying condensate; the evaporation condensate and the dry condensate flow back to the size mixing step to be used as part of size mixing water; wherein the first separation conditions are such that the dry matter content in the first clear liquid is 5-10 wt.%, and the second separation conditions are such that the dry matter content in the second clear liquid is 3.5 wt.% or less.

Wherein, the wheat can be used for producing the ethanol together with other starchy raw materials (in the raw materials for producing the ethanol, the other starchy raw materials are not more than 50 weight percent), and the whole wheat can also be used for producing the ethanol.

The present invention will be described in detail below by way of examples.

In the following examples and comparative examples, unless otherwise specified, reagents and materials used were all commercially available.

Unless otherwise stated, all equipment involved is conventional in the art and can be selected and operated by one skilled in the art according to the actual circumstances.

The xylanase is Viscozyme HT purchased from Novovin;

the beta-glucanase is a beta-glucanase from Baismith corporation;

alpha-amylase a thermostable alpha-amylase available from jenenaceae;

saccharifying enzymes were purchased from sumacro 474 of novacin.

The Saccharomyces cerevisiae is Saccharomyces cerevisiae (Saccharomyces cerevisiae) CGMCC No.16830.

YEPX medium: yeast extract 10g/L, peptone 20g/L, xylose 20g/L, penicillin 10ppm.

A steam generator is adopted to generate fresh steam of 0.80MPaG, and a heat source is provided for the rectifying tower.

The method for measuring the solid content in the clear liquid adopts a drying method, and the solid content = the weight of the solid phase after drying/the weight of the clear liquid before drying.

The viscosity was measured using a viscometer.

Xylose is a commercial product of Shanghai Huishi Biochemical reagent company Limited with the brand number of D-xylose.

Arabinose is a commercial product of Michelin company with the trade name of L-arabinose.

Utilization ratio of pentose (%) = (pentose concentration at 0h fermentation-pentose concentration at end of fermentation)/pentose concentration at 0h fermentation × 100%, in which pentose is based on the total weight of arabinose and xylose.

The content of residual total sugars, calculated as arabinose, xylose, glucose, fructose and maltose, can be determined by liquid chromatography.

In the following examples, the ethanol production scale was 15 ten thousand t/year.

Unless otherwise stated, the values referred to below all fluctuate within the expected range in the art.

Example 1

This example illustrates the method of the present invention for producing ethanol from wheat.

According to the flow chart shown in fig. 1, the production of fuel ethanol is carried out by taking whole wheat as a raw material, and the specific operations are as follows:

and (3) crushing the wheat to obtain a crushed product. Wherein the pulverization conditions are such that 80% by weight or more of the pulverized product can pass through a 20-mesh screen.

Mixing the crushed product with water for size mixing, xylanase, beta-glucanase and alpha-amylase for size mixing and liquefying to obtain liquefied liquid; wherein, the conditions of size mixing and liquefaction comprise: the temperature was 95 ℃ for 90 minutes and the pH 5. The amount of the water used for size mixing was such that the solids content in the obtained material was 28 wt.%, the water used for size mixing included process water, evaporation condensate and drying condensate. Wherein, compared with 1g of wheat, the dosage of xylanase is 12U, and the dosage of beta-glucanase is 1.5U; the amount of the alpha-amylase used was 20U relative to 1g of the pulverized product.

And (3) activating and expanding the saccharomyces cerevisiae by using a YEPX culture medium to obtain a seed solution. Wherein the activation conditions include: the temperature is 30 ℃, the initial pH is 5, and the time is 20h; the expanding culture conditions comprise: the temperature was 30 ℃ and the initial pH 5 for 12h. Mixing saccharifying enzyme, liquefied solution and seed solution, and fermenting, wherein the inoculation amount of the alcohol yeast is 10 per 1g of the liquefied solution ⁵ cfu, conditions of fermentation: fermenting at 32 deg.C and pH of 4.2 for 65 hr to obtain fermented mash, and filtering to obtain mature mash. Wherein the amount of the saccharifying enzyme is 350U per 1g of the pulverized product. The utilization rate of the pentose is calculated to be 74.3%; the residual total sugar content was 1.5g/L.

And carrying out rough distillation on the mature mash in a rough distillation tower to obtain waste mash and rough distillation fraction, and rectifying the obtained rough distillation fraction in a rectifying tower to obtain ethanol. Wherein, the conditions of the rough distillation comprise: the temperature of the tower kettle is 80 ℃; the pressure of the tower kettle is-0.045 Ma; the temperature at the top of the tower is 53 ℃; the pressure at the top of the tower is-0.065 MPa; the reflux ratio was 0.8. The rectification conditions include: the temperature of the tower kettle is 105 ℃; the pressure of the tower kettle is 0.13MPa; the temperature at the top of the tower is 92 ℃; the pressure at the top of the tower is 0.07MPa; the reflux ratio was 3.

Carrying out first separation on the waste mash in a plate and frame filter to obtain a first wet cake and a first clear liquid; performing secondary separation (the rotating speed is 2000 rpm) on the first clear liquid in a disc centrifuge to obtain a second wet cake and a second clear liquid, and performing evaporation concentration on the second clear liquid to obtain syrup and an evaporation condensate; and drying the first wet cake and the second wet cake to obtain the DDGS, the high-protein material and the drying condensate. The evaporation condensate and the drying condensate are refluxed to the size mixing step to be used as part of size mixing water. Wherein the dry matter content in the first clear liquid is 6.7 wt%; the dry matter content in the second clear solution decreased to 3.1 wt%.

Measuring the solid content and the viscosity of the first clear liquid, the second clear liquid and the syrup, and obtaining specific results shown in the table 1; the alcohol results are shown in Table 1.

Example 2

The procedure was followed as described in example 1, except that 15U/g wheat xylanase was used instead of xylanase and beta-glucanase.

Measuring the solid content and the viscosity of the first clear liquid, the second clear liquid and the syrup, and specifically, the results are shown in the table 1; the alcohol results are shown in Table 1.

Example 3

This example illustrates the production of ethanol from wheat according to the invention.

The procedure was followed as described in example 1, except that 15U/g of wheat beta-glucanase was used instead of xylanase and beta-glucanase.

Example 4

The procedure is as described in example 1, except that the slurrying and liquefaction temperature is 70 ℃.

Comparative example 1

This comparative example serves to illustrate a reference process for the production of ethanol from wheat.

The procedure was followed as described in example 1 except that the yeast used for the fermentation was essentially a Farkia farkia yeast which was not capable of fermenting with arabinose and xylose.

Comparative example 2

The procedure was followed as described in example 1, except that no xylanase and no beta-glucanase were added.

TABLE 1

The results in Table 1 show that the technical scheme of the invention can obviously reduce the solid content of the clear liquid and the viscosity of the syrup, can also improve the alcohol content, and can obtain obviously better effect under the optimal condition (simultaneously using xylanase and/or beta-glucanase; optimal pulp mixing temperature): low solid content in clear liquid, high alcohol content and low viscosity of materials. The problem of material transportation and the serious jam of evaporimeter is solved to energy saving and consumption reduction does benefit to the steady operation of device.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including various technical features being combined in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A method for producing ethanol from wheat, comprising:

(1) Crushing wheat to obtain a crushed product;

(4) Distilling the mature mash to obtain ethanol and waste mash;

2. The method according to claim 1, wherein in the step (1), when xylanase is used alone, the dosage of the xylanase is 10-40U relative to 1g of wheat; and/or

When the beta-glucanase is used alone, the dosage of the beta-glucanase is 5-20U relative to 1g of wheat; and/or

When xylanase and beta-glucanase are used simultaneously, the dosage of xylanase is 10-15U and the dosage of beta-glucanase is 1-2U relative to 1g of wheat.

3. The method of claim 1 or 2, wherein the method further comprises: adding amylase in the steps of size mixing and/or liquefying;

wherein the amount of the amylase is 10-80U relative to 1g of the pulverized product.

4. The method according to claim 1, wherein the pulverization conditions are such that 80% by weight or more of the pulverized product can pass through a 20-mesh sieve.

5. The method of claim 1, wherein the solids content of the material during the size mixing process is 20-40 wt%.

6. The method of claim 1, wherein the temperature of the conditioning is 90-105 ℃; and/or

The conditions of the liquefaction include: the temperature is 55-120 ℃; the pH is 3-8; the time is 0.2-10h.

7. The method of claim 1, wherein the conditions of the fermentation comprise: the pH value is 2-7, preferably 3-6; the temperature is 25-40 ℃, preferably 30-35 ℃; the time is 2-5 days.

8. The method of claim 1 or 5, wherein the manner of distilling comprises: performing rough distillation on the mature mash to obtain rough distillation fraction and waste mash; and rectifying the crude distillation fraction to obtain the ethanol.

9. The method of claim 8, wherein the method further comprises: and carrying out first separation on the waste mash to obtain a first clear liquid and a first wet cake, and carrying out second separation on the first clear liquid to obtain a second clear liquid and a second wet cake.

10. The method of claim 9, wherein the method further comprises: evaporating the second clear liquid to obtain syrup and an evaporation condensate;

preferably, the syrup is refluxed to the first separation step as at least part of the feed to the first separation;