阅读说明：本技术 将玉米秸秆转化为还原糖和膳食纤维的方法 (Method for converting corn straws into reducing sugar and dietary fiber ) 是由 尹清强 刘超齐 王平 常娟 党晓伟 朱群 李茂龙 张瑞 李慧娟 耿启泉 于 2020-06-04 设计创作，主要内容包括：本发明涉及秸秆处理领域,具体而言,涉及一种将玉米秸秆转化为还原糖和膳食纤维的方法。本发明的将玉米秸秆转化为还原糖和膳食纤维的方法,包括以下步骤：将玉米秸秆和碱溶液的混合物进行蒸汽处理,再与酶混合进行酶解；所述碱溶液主要由氢氧化钠、氧化钙和水混合制备得到；所述酶包括纤维素酶和/或β-葡聚糖酶。本发明的方法得到的产品营养丰富,用作动物饲料可促进动物生长,调节肠道健康,对降低仔猪腹泻具有很好的效果。(The invention relates to the field of straw treatment, in particular to a method for converting corn straws into reducing sugar and dietary fiber. The method for converting the corn straws into the reducing sugar and the dietary fiber comprises the following steps: performing steam treatment on the mixture of the corn straws and the alkali solution, and mixing the mixture with enzyme for enzymolysis; the alkali solution is mainly prepared by mixing sodium hydroxide, calcium oxide and water; the enzyme comprises cellulase and/or beta-glucanase. The product obtained by the method is rich in nutrition, can promote animal growth and regulate intestinal health when being used as animal feed, and has a good effect of reducing piglet diarrhea.)

1. A method for converting corn stover into reducing sugars and dietary fiber, comprising the steps of:

performing steam treatment on the mixture of the corn straws and the alkali solution, and mixing the mixture with enzyme for enzymolysis;

the alkali solution is mainly prepared by mixing sodium hydroxide, calcium oxide and water;

the enzyme comprises cellulase and/or beta-glucanase.

2. The method for converting corn stover into reducing sugars and dietary fiber according to claim 1, wherein the mass ratio of the corn stover to the alkali solution is 1: (4-6).

3. The method for converting corn stover into reducing sugars and dietary fiber according to claim 1, wherein the concentration of sodium hydroxide in the alkali solution is 6.5-40 g/L;

preferably, the mass ratio of the sodium hydroxide to the calcium oxide is 1: (1-2).

4. The method for converting corn stover into reducing sugars and dietary fiber according to claim 1, wherein the steam treatment is performed for 0.5 to 2 hours.

5. The method for converting corn stalks into reducing sugar and dietary fiber according to claim 1, wherein the cellulase is added in an amount of 1.36 to 68.64FPU/g of stalks;

preferably, the addition amount of the beta-glucanase is 431.88-8168.12U/g straw.

6. The method for converting corn stalks into reducing sugar and dietary fiber according to claim 5, wherein the addition amount of the cellulase is 10-20 FPU/g of the stalks, and the addition amount of the beta-glucanase is 1800-2200U/g of the stalks.

7. The method for converting corn stalks into reducing sugar and dietary fiber according to claim 5, wherein the addition amount of the cellulase is 45-55 FPU/g of the stalks, and the addition amount of the beta-glucanase is 6000-6800U/g of the stalks.

8. The method for converting corn stalks into reducing sugar and dietary fiber according to claim 1, wherein the pH value in the enzymolysis process is adjusted to 4.5-5.5, the enzymolysis temperature is 40-60 ℃, and the enzymolysis time is 10-72 hours.

9. The method for converting corn stover into reducing sugars and dietary fiber of claim 1, wherein in the mixture of corn stover and alkali solution, the length of corn stover is 0.8 to 1.2 mm;

preferably, the mixture obtained after the steam treatment is subjected to drying and crushing treatment;

preferably, the drying temperature is 60-65 ℃;

preferably, the grain diameter of the corn straws after the crushing treatment is 40 meshes;

preferably, the mixture after enzymolysis is boiled in water for 50-70 min.

10. The method for adjusting the content of reducing sugar and cellulose by adopting the method for converting corn stalks into the reducing sugar and the dietary fiber as claimed in any one of claims 1 to 9, wherein the corn stalks with different contents of the reducing sugar and the cellulose are obtained by adjusting the conditions of the enzymolysis;

preferably, when the addition amount of cellulase is 10-20 FPU/g straw, the addition amount of beta-glucanase is 1800-2200U/g straw, the enzymolysis time is 10-14 h, the total amount of reducing sugar in the obtained corn straw is 250-300mg/g, and the content of cellulose is 10-15%;

preferably, when the addition amount of the cellulase is 45-55 FPU/g of straw, the addition amount of the beta-glucanase is 6000-6800U/g of straw, and the enzymolysis time is 35-45 h, the total amount of reducing sugar in the obtained corn straw is more than or equal to 400mg/g, and the content of cellulose is less than or equal to 7%;

preferably, the multivariate quadratic regression fitting equation of the cellulose content and the enzymolysis conditions is as follows:

Y₁＝16.3610-0.1143X₁-2.2175X₂-0.2506X₃+4.3136X₁X₂+1.0954X₁X₃-1.9418X₂X₃+4.1250X₁ ²-1.5580X₂ ²+2.6779X₃ ²；

the multivariate quadratic regression fitting equation of the total amount of the reducing sugar and the enzymolysis conditions is as follows:

Y₂＝144.4376+3.4097X₁+0.01251X₂+6.5663X₃-0.0002X₁X₂-0.0086X₁X₃+0.0002X₂X₃-0.0191X₁ ²+0.000001X₂ ²-0.0895X₃ ²；

wherein, Y₁Represents the cellulose content, Y₂Represents the total amount of reducing sugars, X₁Represents the amount of cellulase added, X₂Represents the addition amount of β -glucanase, X₃Representing the time of the enzymatic hydrolysis.

Technical Field

The invention relates to the field of straw treatment, in particular to a method for converting corn straws into reducing sugar and dietary fiber.

Background

Lignocellulose is the most abundant renewable natural resource on the earth, wherein crop straws occupy a large part, and the annual output of China is about 6 to 7 hundred million tons. The corn stalks are the most typical representatives of the crop stalks, and the yield of the corn stalks reaches about 35 percent of the crop stalk yield. The corn stalks are only utilized by less than 50 percent and are mostly burnt, buried and rotten, thereby not only causing resource waste and environmental pollution, but also being not beneficial to the growth of crops. The main component of the corn straw is lignocellulose consisting of cellulose, hemicellulose and lignin, wherein the cellulose is macromolecular polysaccharide formed by connecting glucose through beta-1, 4-glycosidic bonds and is a key substrate for converting the cellulose into energy substances or feed resources. Cellulose is tightly wrapped inside by hemicellulose and lignin and is difficult to contact with external cellulose hydrolase, and the intractable construction of the structure makes the maize straw difficult to be recycled. In the prior art, the treatment method of the straws is complex, and the obtained nutritional ingredients after treatment are poor, so that the healthy growth of animals is difficult to promote.

In view of the above, the present invention is particularly proposed.

Disclosure of Invention

According to one aspect of the present invention, the present invention relates to a process for converting corn stover to reducing sugars and dietary fiber comprising the steps of:

performing steam treatment on the mixture of the corn straws and the alkali solution, and mixing the mixture with enzyme for enzymolysis;

the alkali solution comprises a mixed solution of sodium hydroxide and calcium oxide;

the enzyme comprises cellulase and/or beta-glucanase.

According to the invention, sodium hydroxide and calcium oxide are used as chemical reagents for pretreatment, the pretreatment effect of the corn straws is studied by combining the steam action, and then cellulase and beta-glucanase are selected to carry out enzymolysis study on the pretreated corn straws, so as to obtain products with different reducing sugar and dietary fiber contents. The method is simple and easy to implement. The product obtained by the method is rich in nutrition, and can be used as animal feed for promoting animal growth, regulating intestinal health, and reducing diarrhea of piglets.

According to another aspect of the invention, the invention also relates to a method for adjusting the content of reducing sugar and cellulose by adopting the method for converting the corn straws into the reducing sugar and the dietary fiber, and the corn straws with different contents of the reducing sugar and the cellulose are obtained by adjusting the conditions of the enzymolysis.

The present invention obtains different types of reducing sugars and cellulose by adjusting the reducing sugar and cellulose contents using the method of converting corn stover into reducing sugars and dietary fibers as described above, and thus has different effects when it is used for animal feed.

Compared with the prior art, the invention has the beneficial effects that:

(1) according to the invention, sodium hydroxide and calcium oxide are used as chemical reagents for pretreatment, the pretreatment effect of the corn straws is studied by combining the steam action, and then cellulase and beta-glucanase are selected to carry out enzymolysis study on the pretreated corn straws, so as to obtain products with different reducing sugar and dietary fiber contents. The method is simple and easy to implement. The corn stalks contain rich cellulose components and are converted into monosaccharide and dietary fiber which can be utilized by animals, so that the aim of changing waste into valuable is fulfilled. In the process of converting the cellulose into the animal feed resources, it is necessary to decompose and convert the cellulose into saccharides and maintain proper cellulose content, so that the produced product has a nutritional function and an effect of regulating the intestinal health of animals, and the method has important social and economic benefits for developing and utilizing the cellulose resources in the corn straws. The product obtained by the method is rich in nutrition, and can be used as animal feed for promoting animal growth, regulating intestinal health, and reducing diarrhea of piglets.

(2) The present invention obtains different types of reducing sugars and cellulose by adjusting the reducing sugar and cellulose contents using the method of converting corn stover into reducing sugars and dietary fibers as described above, and thus has different effects when it is used for animal feed.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a graph showing the trend of the optimization of cellulose content by different factors (cellulase and. beta. -glucanase) according to the present invention;

FIG. 2 is a graph showing the optimization trend of different factors (cellulase and enzymolysis time) to the cellulose content in the present invention;

FIG. 3 is a graph showing the trend of the optimization of cellulose content by different factors (beta-glucanase and enzymolysis time) according to the present invention;

FIG. 4 is a graph of the optimization trend of different factors (cellulase and. beta. -glucanase) for total reducing sugars;

FIG. 5 is a graph of the optimization trend of different factors (cellulase and enzymolysis time) on total reducing sugar;

FIG. 6 is a graph of the optimization trend of different factors (beta-glucanase and enzymolysis time) on total reducing sugar;

FIG. 7 is a scanning electron microscope image of untreated corn stover;

FIG. 8 is a scanning electron microscope image of alkali + steam treated corn stover;

FIG. 9 is a scanning electron microscope image of fiber corn stover in medium sugar;

FIG. 10 is a scanning electron microscope image of high sugar low fiber corn stover.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

According to one aspect of the present invention, the present invention relates to a process for converting corn stover to reducing sugars and dietary fiber comprising the steps of:

performing steam treatment on the mixture of the corn straws and the alkali solution, and mixing the mixture with enzyme for enzymolysis;

the alkali solution comprises a mixed solution of sodium hydroxide and calcium oxide;

the enzyme comprises cellulase and/or beta-glucanase.

Cellulases and beta-glucanases were purchased from Shandong Zesheng Biotechnology Ltd. Cellulase activity and beta-glucanase activity were determined according to the American renewable energy laboratory (NREL) NREL/TP-510-42628 and the agricultural industry Standard NY/T911-2004 of the people's republic of China. The cellulase activity is 322.37FPU/g, and the beta-glucanase activity is 10000U/g.

The corn straws are pretreated by alkali and steam to break the structure of lignocellulose and break the connection of hemicellulose, lignin and cellulose, so that gaps appear on the surface, the cellulose is exposed, the contact area of enzyme is increased, the hydrolysis of the enzyme is facilitated, and after the exposed cellulose is hydrolyzed by the enzyme, the structure collapses, the atrophy appears, and the gaps grow. In addition, the enzymolysis can obviously reduce the crystallinity of the cellulose and the surface area of the straw.

Preferably, the mass ratio of the corn straws to the alkali solution is 1: (4-6);

in one embodiment, the mass ratio of the corn stover to the alkali solution is 1: (4.5-6), and 1:4.5, 1:5.0 or 1:5.5 can be selected.

Preferably, the concentration of sodium hydroxide in the alkali solution is 6.5-40 g/L;

in one embodiment, the concentration of sodium hydroxide in the alkali solution is 6.5-40 g/L, and may be selected from 7g/L, 8g/L, 9g/L, 10g/L, 12g/L, 15g/L, 18g/L, 20g/L, 25g/L, 28g/L, 30g/L, 35g/L or 38 g/L.

Preferably, the mass ratio of the sodium hydroxide to the calcium oxide is 1: (1-2).

In one embodiment, the mass ratio of the sodium hydroxide to the calcium oxide is 1: (1-2), optionally 1: 1.1, 1: 1.2, 1: 1.5, 1: 1.7 or 1: 1.9.

preferably, the time of the steam treatment is 0.5-2 h.

Preferably, the addition amount of the cellulase is 1.36-68.64FPU/g straw;

preferably, the addition amount of the beta-glucanase is 431.88-8168.12U/g straw.

Preferably, the addition amount of the cellulase is 10-20 FPU/g of straw, and the addition amount of the beta-glucanase is 1800-2200U/g of straw.

Preferably, the addition amount of the cellulase is 45-55 FPU/g of straw, and the addition amount of the beta-glucanase is 6000-6800U/g of straw.

Preferably, the pH value is adjusted to be 4.5-5.5 in the enzymolysis process, the enzymolysis temperature is 40-60 ℃, and the enzymolysis time is 10-96 hours.

Preferably, in the mixture of the corn straws and the alkali solution, the length of the corn straws is 0.8-1.2 mm;

in one embodiment, the length of the corn stalks is 0.8-1.2 mm, and 0.9mm, 1mm and 1.1mm can be selected.

Preferably, the mixture obtained after the steam treatment is subjected to drying and crushing treatment;

preferably, the drying temperature is 55-70 ℃;

preferably, the grain diameter of the corn straws after the crushing treatment is 40 meshes.

Preferably, the mixture after enzymolysis is boiled in water for 50-70 min.

The method for regulating the content of the reducing sugar and the cellulose by adopting the method for converting the corn straws into the reducing sugar and the dietary fiber is adopted, and the corn straws with different contents of the reducing sugar and the cellulose are obtained by regulating the enzymolysis condition;

preferably, when the addition amount of cellulase is 10-20 FPU/g straw, the addition amount of beta-glucanase is 1800-2200U/g straw, the enzymolysis time is 12-14 h, the total amount of reducing sugar in the obtained corn straw is 250-300mg/g, and the content of cellulose is 10-15%;

preferably, when the addition amount of the cellulase is 45-55 FPU/g of straw, the addition amount of the beta-glucanase is 6000-6800U/g of straw, and the enzymolysis time is 35-45 h, the total amount of reducing sugar in the obtained corn straw is more than or equal to 400mg/g, and the content of cellulose is less than or equal to 7%.

The corn stalks contain rich cellulose components and are converted into monosaccharide and dietary fiber which can be utilized by animals, so that the aim of changing waste into valuable is fulfilled. In the process of converting the cellulose into the animal feed resources, it is necessary to decompose and convert the cellulose into saccharides and maintain proper cellulose content, so that the produced product has a nutritional function and an effect of regulating the intestinal health of animals, and the method has important social and economic benefits for developing and utilizing the cellulose resources in the corn straws. The two specific types of products of the invention, i.e. medium-sugar medium-fiber and high-sugar low-fiber, can exert different efficacies as animal feeds and have different applications.

Preferably, the multivariate quadratic regression fitting equation of the cellulose content and the enzymolysis conditions is as follows:

Y₁＝16.3610-0.1143X₁-2.2175X₂-0.2506X₃+4.3136X₁X₂+1.0954X₁X₃-1.9418X₂X₃+4.1250X₁ ²-1.5580X₂ ²+2.6779X₃ ²；

the multivariate quadratic regression fitting equation of the total amount of the reducing sugar and the enzymolysis conditions is as follows:

Y₂＝144.4376+3.4097X₁+0.01251X₂+6.5663X₃-0.0002X₁X₂-0.0086X₁X₃+0.0002X₂X₃-0.0191X₁ ²+0.000001X₂ ²-0.0895X₃ ²；

wherein, Y₁Represents the cellulose content, Y₂Represents the total amount of reducing sugars, X₁Represents the amount of cellulase added, X₂Represents the addition amount of β -glucanase, X₃Representing the time of the enzymatic hydrolysis.

The coefficient of determination for the two regression models is R²0.9411 and 0.9838 with correction for R²The better the fit of the regression equation, 0.8653 and 0.9629, the better the change in the model can be reflected. Therefore, the regression model can be used for analyzing and predicting the enzymolysis effect of the pretreated corn straws.

In a preferred embodiment, the enzymatic hydrolysis protocol for the fiber in the sugar of the present invention is: 15FPU/g of cellulase, 2000U/g of beta-glucanase and 12 hours of enzymolysis, wherein the total reducing sugar content and the cellulose content are respectively 288.30mg/g and 11.64%.

In a preferred embodiment, the high sugar low fiber enzymatic protocol is: the cellulose 52.39FPU/g straw, the beta-glucanase 6599.99U/g straw and the enzymolysis time are 40h, and the highest total reducing sugar content and the lowest cellulose content are 493.74mg/g and 6.57% respectively.

The corn stalks of the invention come from the Shanghai city of Henan province. The air-dried corn stalks are crushed to about 1mm by a hammer mill and stored at room temperature for later use.

The test instrument apparatus includes: a hammer mill (9FQ-420 type Zhengzhou Qianding mechanical equipment Co., Ltd.), a three-layer steamer (Zhejiang Poll Co., Ltd.), an electronic balance (AB204-N), an ultraviolet visible spectrophotometer (752 type Shanghai Cyanin science and technology Co., Ltd.), a magnetic heating stirrer (79-1 large instrument factory in Jintan City), a pH meter (PHS-2C acidimeter), filter paper (Whatman 4), a constant temperature shaking table (Shanghai Xin Miao instruments Co., Ltd.), and an oven (Tester instruments Co., Tianjin City).

The invention will be further explained with reference to specific examples.