Method for improving fermentation stability of straw mixed sugar
By pretreating and enzymatically decomposing the straw, compound straw sugar is obtained as a carbon source for lactic acid fermentation, which solves the problem of fluctuations in the mass of straw sugar solution affecting fermentation stability, and achieves the effect of improving fermentation stability and lactic acid yield.
Patent Information
- Application Number
- CN202510245392.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-04
- Publication Date
- 2025-05-30
AI Technical Summary
In the prior art, the mass of straw sugar liquid fluctuates greatly, affecting the subsequent fermentation results of bacterial strains, resulting in insufficient fermentation stability.
By pretreating the plant straw into comprehensive fibers, enzymatically dissolved with cellulose complex enzyme, the enzymatic solution was obtained and then filtered to obtain plant-based straw sugar, and compounded with the finished sugar into compound straw sugar as a fermentation carbon source.
This method does not require evaporation and concentration of enzymatically filtered mixed sugars, shortening the sugar production process, reducing energy consumption, and improving the utilization rate of different types of straw sugars by strains during the fermentation process, increasing lactic acid production, and reducing fermentation costs.
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Figure CN120060387A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of lactic acid fermentation, and particularly relates to a method for improving the fermentation stability of straw mixed sugar. Background Art
[0002] Lactic acid is widely used as a bio-based chemical in the food industry, medical field, and biodegradable materials. At present, lactic acid fermentation production mainly uses corn starch of food crops as the main raw material, which forms competition in terms of human and livestock rations and agricultural land use. Using food raw materials for production has become a bottleneck in large-scale biomanufacturing.
[0003] Straw biomass is the most abundant renewable resource on the earth. After the cellulose and hemicellulose in straw raw materials are pretreated and saccharified with enzymes, a mixed sugar solution mainly composed of glucose and xylose can be obtained, which is an important raw material for the fermentation industry. It can be used for the production of various high-value chemicals. Using straw instead of starch to produce lactic acid can solve the food security problem and play an important supporting role in the development of carbon zero emissions and circular economy.
[0004] In the process of producing sugar from straw as raw material, due to the different types of straw, the quality of straw sugar solution fluctuates greatly, which directly affects the subsequent fermentation results of strains. Therefore, a method for improving the fermentation stability of straw mixed sugar is proposed. Summary of the Invention
[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a method for improving the fermentation stability of straw mixed sugar, which solves the problems in the prior art.
[0006] The purpose of the present invention can be achieved by the following technical solutions:
[0007] A method for improving the fermentation stability of straw mixed sugar includes the following steps:
[0008] Pre-treat plant straw to obtain holocellulose;
[0009] Use a cellulose complex enzyme to enzymatically hydrolyze the holocellulose to obtain an enzymatic hydrolysate;
[0010] Filter the enzymatic hydrolysate to obtain plant-based straw sugar;
[0011] Compound the straw sugar with finished sugar to form compound straw sugar;
[0012] Use the compound straw sugar as a fermentation carbon source to ferment and produce lactic acid.
[0013] Further, the plant straw is one or more of rice straw, corn straw, wheat straw, and cotton stalks.
[0014] Further, the process of pre-treating the plant straw is as follows: the plant straw is washed and then mechanically pulverized, then an alkaline solution is added for kneading and extrusion, and then washed to remove lignin, and finally dried.
[0015] Further, in the process of enzymatic hydrolysis of the comprehensive fiber, the addition amount of the cellulase complex is: 15 - 20 FPU / g, and the enzymatic hydrolysis temperature is 45 - 50 °C.
[0016] Further, the finished sugars used in the compound straw sugar include one or more of glucose, xylose, and arabinose.
[0017] Further, in the compound straw sugar, the concentration ratio of glucose, xylose, and arabinose is 8:2:0.5, and the total concentration of glucose, xylose, and arabinose is 100 g / L.
[0018] Further, the steps for fermenting to produce lactic acid are as follows:
[0019] 1) After activating and purifying the Bacillus coagulans glycerol tube, it is inoculated on a slant medium for enrichment culture, and an appropriate amount of colonies are picked and inoculated into a seed medium to obtain a seed solution;
[0020] 2) The seed solution is inoculated into a fermentation medium for mechanical fermentation.
[0021] Further, the inoculation mass ratio of the seed solution is 5 - 10%, the fermentation time is 36 - 48 h, the fermentation temperature is 45 - 50 °C, and the rotation speed is 100 - 120 rpm.
[0022] Further,
[0023] The components of the fermentation medium include: 100 g / L compound straw sugar, 5 g / L yeast extract powder, 0.03 g / L sodium chloride, 1.5 g / L ammonium sulfate, 0.6 g / L potassium dihydrogen phosphate, 0.6 g / L magnesium sulfate heptahydrate, 0.15 g / L manganese sulfate heptahydrate, 60 g / L calcium carbonate.
[0024] The components of the seed medium include: 50 g / L glucose, 10 g / L yeast extract powder, 0.01 g / L sodium chloride, 0.5 g / L ammonium chloride, 0.2 g / L potassium dihydrogen phosphate, 0.2 g / L magnesium sulfate heptahydrate, 30 g / L calcium carbonate.
[0025] Use of the above method for improving the fermentation stability of straw mixed sugar in the preparation of lactic acid.
[0026] Advantages of the present invention:
[0027] 1. In the process of preparing the straw-based carbon source in the present invention, it is not necessary to evaporate and concentrate the mixed sugar obtained by enzymatic hydrolysis and filtration, shortening the sugar-making link of enzymatic hydrolysis and reducing the energy consumption of sugar-making.
[0028] 2. The compound mixed sugar prepared by the present invention can reduce the utilization preference of strains for fermentation carbon sources, effectively improve the utilization rate of strains for mixed sugars prepared from different types of crop straws during the fermentation process, increase the lactic acid production at the same initial sugar concentration, and further reduce the lactic acid fermentation cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0030] Figure 1 is the process flow chart of the lactic acid fermentation of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.
[0032] As Figure 1 shown, a method for improving the fermentation stability of straw mixed sugar includes the following steps:
[0033] S1. Pretreat the plant straw to obtain comprehensive fibers;
[0034] S2. Enzymatically hydrolyze the comprehensive fibers with a cellulose complex enzyme to obtain an enzymatic hydrolysate;
[0035] S3. Filter the enzymatic hydrolysate to obtain plant-based straw sugar;
[0036] S4. Compound the straw sugar with a finished sugar to form a compound straw sugar;
[0037] S5. Use the compound straw sugar as a fermentation carbon source to ferment and produce lactic acid.
[0038] Among them, the plant straw is one or more of rice straw, corn straw, wheat straw, and cotton stalks.
[0039] In S1, the process of pretreating the plant straw is as follows: Wash the plant straw and then mechanically crush it, then add an alkaline solution (caustic soda solution) for kneading and extrusion, then wash to remove lignin, and then dry for standby.
[0040] In S2, the enzymatic hydrolysis process is carried out in an enzymatic hydrolysis tank. The addition amount of the cellulose complex enzyme is: 15 - 20 FPU / g, the solid content of the enzymatic hydrolysis solution is 15%, and the enzymatic hydrolysis temperature is 45 - 50 °C; the cellulose complex enzyme is cellulase + hemicellulase;
[0041] In S3, the enzymatic hydrolysate is filtered by a mechanical plate and frame to obtain plant-based straw sugar.
[0042] In S4, the compound straw sugar uses finished sugars including one or more of glucose, xylose, and arabinose. In the compound straw sugar, the concentration ratio of glucose, xylose, and arabinose is 8:2:0.5, and the total concentration of the trisaccharide (glucose + xylose + arabinose) reaches 100 g / L, which is used as the fermentation carbon source.
[0043] In S5, the steps for fermenting lactic acid are as follows:
[0044] 1) After activating and purifying the glycerol tube of Bacillus coagulans, inoculate it on a slant medium for enrichment culture, and pick an appropriate amount of colonies to inoculate into the seed medium to prepare a seed solution;
[0045] The components of the seed medium include: 50 g / L glucose, 10 g / L yeast extract powder, 0.01 g / L sodium chloride, 0.5 g / L ammonium chloride, 0.2 g / L potassium dihydrogen phosphate, 0.2 g / L magnesium sulfate heptahydrate, 30 g / L calcium carbonate.
[0046] 2) According to the inoculation mass ratio of 5 - 10%, inoculate the seed solution into the fermentation medium and ferment for 36 - 48 h, the fermentation temperature is 45 - 50 °C, the rotation speed is 100 - 120 rpm. After fermentation is completed, detect the lactic acid content in the final fermentation broth.
[0047] The components of the fermentation medium include: 100 g / L compound straw sugar, 5 g / L yeast extract powder, 0.03 g / L sodium chloride, 1.5 g / L ammonium sulfate, 0.6 g / L potassium dihydrogen phosphate, 0.6 g / L magnesium sulfate heptahydrate, 0.15 g / L manganese sulfate heptahydrate, 60 g / L calcium carbonate.
[0048] The technical solution of the present invention will be verified in detail through the following examples and comparative examples;
[0049] Example 1
[0050] In S1, the rice straw is washed and mechanically crushed, then alkaline solution (caustic soda solution) is added and kneaded and extruded, and then washed to remove lignin, and then dried for standby.
[0051] S2. Add enzymatic hydrolysis buffer (citric acid buffer solution) (pH adjusted to 5) to the dried comprehensive fiber, with a solid content of 15%, and add 15 FPU / g of cellulose complex enzyme (cellulase + hemicellulase). Hydrolyze in an enzymatic hydrolysis tank at an enzymatic hydrolysis temperature of 50 °C and an enzymatic hydrolysis rotation speed of 150 r / min for 52 h to obtain an enzymatic hydrolysate.
[0052] S3. The enzymatic hydrolysate is filtered through a mechanical plate and frame to obtain a mixed sugar solution.
[0053] S4. Use a high-pressure liquid chromatograph to detect the concentrations of glucose, xylose, and arabinose in the rice mixed sugar solution, and compound them with industrial glucose, industrial xylose, and industrial arabinose to obtain a rice compound sugar, where the concentration ratio of glucose, xylose, and arabinose is 8:2:0.5; the total concentration of the trisaccharide reaches 100 g / L, which is used as a fermentation carbon source.
[0054] S5. Activate and purify the Bacillus coagulans glycerol tube and inoculate it on a slant medium for enrichment culture. Pick an appropriate amount of colonies and inoculate them into a seed medium to prepare a seed solution. The components of the seed medium include: 50 g / L glucose, 10 g / L yeast extract powder, 0.01 g / L sodium chloride, 0.5 g / L ammonium chloride, 0.2 g / L potassium dihydrogen phosphate, 0.2 g / L magnesium sulfate heptahydrate, 30 g / L calcium carbonate.
[0055] S6. Inoculate the seed solution into the fermentation medium according to an inoculation mass ratio of 5% and ferment for 48 h at a fermentation temperature of 50 °C and a rotation speed of 120 rpm, and detect the lactic acid content in the final fermentation broth. The components of the fermentation medium include: 100 g / L rice compound sugar, 5 g / L yeast extract powder, 0.03 g / L sodium chloride, 1.5 g / L ammonium sulfate, 0.6 g / L potassium dihydrogen phosphate, 0.6 g / L magnesium sulfate heptahydrate, 0.15 g / L manganese sulfate heptahydrate, 60 g / L calcium carbonate.
[0056] Example 2
[0057] S1. Wash and mechanically crush wheat straw, add an alkaline solution (caustic soda solution), knead and extrude, then wash to remove lignin, and then dry for standby.
[0058] S2. Add enzymatic hydrolysis buffer (citric acid buffer solution) (pH adjusted to 5) to the dried comprehensive fiber, with a solid content of 15%, and add 15 FPU / g of cellulose complex enzyme (cellulase + hemicellulase). Hydrolyze in an enzymatic hydrolysis tank at an enzymatic hydrolysis temperature of 50 °C and an enzymatic hydrolysis rotation speed of 150 r / min for 52 h to obtain an enzymatic hydrolysate.
[0059] S3. The enzymatic hydrolysate is filtered through a mechanical plate and frame to obtain a mixed sugar solution.
[0060] S4. Use a high - performance liquid chromatograph to detect the concentrations of glucose, xylose, and arabinose in the wheat mixed sugar solution. Use industrial glucose, industrial xylose, and industrial arabinose to compound it to obtain wheat compound sugar, where the concentration ratio of glucose, xylose, and arabinose is 8:2:0.5; the total concentration of the trisaccharide reaches 100 g / L and is used as the fermentation carbon source.
[0061] S5. After activating and purifying the Bacillus coagulans glycerol tube, inoculate it on a slant medium for enrichment culture. Pick an appropriate amount of colonies and inoculate them into the seed medium to prepare the seed liquid. The components of the seed medium include: 50 g / L glucose, 10 g / L yeast extract powder, 0.01 g / L sodium chloride, 0.5 g / L ammonium chloride, 0.2 g / L potassium dihydrogen phosphate, 0.2 g / L magnesium sulfate heptahydrate, and 30 g / L calcium carbonate.
[0062] S6. Inoculate the seed liquid into the fermentation medium according to the inoculation mass ratio of 5% and ferment for 48 h at a fermentation temperature of 50 °C and a rotation speed of 120 rpm, and detect the lactic acid content in the final fermentation broth. The components of the fermentation medium include: 100 g / L wheat compound sugar, 5 g / L yeast extract powder, 0.03 g / L sodium chloride, 1.5 g / L ammonium sulfate, 0.6 g / L potassium dihydrogen phosphate, 0.6 g / L magnesium sulfate heptahydrate, 0.15 g / L manganese sulfate heptahydrate, and 60 g / L calcium carbonate.
[0063] Example 3
[0064] S1. Wash the corn straw and mechanically crush it. Add an alkaline solution (caustic soda solution) and then knead and extrude it. Then wash to remove lignin and dry for later use.
[0065] S2. Add an enzymatic hydrolysis buffer (citric acid buffer solution) (pH adjusted to 5) to the dried holocellulose, with a solid content of 15%. The addition amount of the cellulose complex enzyme (cellulase + hemicellulase) is 15 FPU / g. Under the conditions of an enzymatic hydrolysis temperature of 50 °C and an enzymatic hydrolysis rotation speed of 150 r / min, perform enzymatic hydrolysis in an enzymatic hydrolysis tank for 52 h to obtain an enzymatic hydrolysate.
[0066] S3. The enzymatic hydrolysate is filtered through a mechanical plate - and - frame filter to obtain a mixed sugar solution.
[0067] S4. Use a high - performance liquid chromatograph to detect the concentrations of glucose, xylose, and arabinose in the corn mixed sugar solution. Use industrial glucose, industrial xylose, and industrial arabinose to compound it to obtain corn compound sugar, where the concentration ratio of glucose, xylose, and arabinose is 8:2:0.5. The total concentration of the trisaccharide reaches 100 g / L and is used as the fermentation carbon source.
[0068] S5. After activating and purifying the Bacillus coagulans glycerol tube, inoculate it on a slant medium for enrichment culture. Pick an appropriate amount of colonies and inoculate them into a seed medium to prepare a seed solution. The components of the seed medium include: 50 g / L glucose, 10 g / L yeast extract powder, 0.01 g / L sodium chloride, 0.5 g / L ammonium chloride, 0.2 g / L potassium dihydrogen phosphate, 0.2 g / L magnesium sulfate heptahydrate, and 30 g / L calcium carbonate.
[0069] S6. According to the inoculation mass ratio of 5%, inoculate the seed solution into a fermentation medium and ferment for 48 h at a fermentation temperature of 50 °C and a rotation speed of 120 rpm. Detect the lactic acid content in the final fermentation broth. The components of the fermentation medium include: 100 g / L corn complex sugar, 5 g / L yeast extract powder, 0.03 g / L sodium chloride, 1.5 g / L ammonium sulfate, 0.6 g / L potassium dihydrogen phosphate, 0.6 g / L magnesium sulfate heptahydrate, 0.15 g / L manganese sulfate heptahydrate, and 60 g / L calcium carbonate.
[0070] Control Example 1
[0071] S1. Wash the rice straw and mechanically crush it. Add an alkaline solution (caustic soda solution) and then knead and extrude it. Then wash to remove lignin and dry for later use.
[0072] S2. Add an enzymatic hydrolysis buffer (citric acid buffer solution) (pH adjusted to 5) to the dried holocellulose with a solid content of 15%. The addition amount of the cellulase complex (cellulase + hemicellulase) is 15 FPU / g. Enzymatically hydrolyze in an enzymatic hydrolysis tank for 52 h at an enzymatic hydrolysis temperature of 50 °C and an enzymatic hydrolysis rotation speed of 150 r / min to obtain an enzymatic hydrolysate.
[0073] S3. Filter the enzymatic hydrolysate through a mechanical plate and frame to obtain a mixed sugar solution.
[0074] S4. Use a high-pressure liquid chromatograph to detect the concentrations of glucose, xylose, and arabinose in the rice mixed sugar solution. Without changing the trisaccharide ratio, appropriately concentrate it to make the total sugar concentration reach 100 g / L as the fermentation carbon source.
[0075] S5. After activating and purifying the Bacillus coagulans glycerol tube, inoculate it on a slant medium for enrichment culture. Pick an appropriate amount of colonies and inoculate them into a seed medium to prepare a seed solution. The components of the seed medium include: 50 g / L glucose, 10 g / L yeast extract powder, 0.01 g / L sodium chloride, 0.5 g / L ammonium chloride, 0.2 g / L potassium dihydrogen phosphate, 0.2 g / L magnesium sulfate heptahydrate, and 30 g / L calcium carbonate.
[0076] S6. Inoculate the seed liquid into the fermentation medium at an inoculation mass ratio of 5% and ferment for 48 h at a fermentation temperature of 50 °C and a rotation speed of 120 rpm, and detect the lactic acid content in the final fermentation broth. The components of the fermentation medium include: 100 g / L rice mixed sugars, 5 g / L yeast extract powder, 0.03 g / L sodium chloride, 1.5 g / L ammonium sulfate, 0.6 g / L potassium dihydrogen phosphate, 0.6 g / L magnesium sulfate heptahydrate, 0.15 g / L manganese sulfate heptahydrate, and 60 g / L calcium carbonate.
[0077] Comparative Example 2
[0078] S1. Wash and mechanically crush wheat straw, add an alkaline solution (caustic soda solution), knead and extrude, then wash to remove lignin, and then dry for later use.
[0079] S2. Add an enzymatic hydrolysis buffer (citric acid buffer solution) (pH adjusted to 5) to the dried holocellulose, with a solid content of 15%, and add 15 FPU / g of a cellulose complex enzyme (cellulase + hemicellulase). Carry out enzymatic hydrolysis in an enzymatic hydrolysis tank for 52 h at an enzymatic hydrolysis temperature of 50 °C and an enzymatic hydrolysis rotation speed of 150 r / min to obtain an enzymatic hydrolysate.
[0080] S3. Filter the enzymatic hydrolysate through a mechanical plate and frame to obtain a mixed sugar solution.
[0081] S4. Use a high-pressure liquid chromatograph to detect the concentrations of glucose, xylose, and arabinose in the wheat mixed sugar solution, without changing the trisaccharide ratio, and appropriately concentrate it to make the total sugar concentration reach 100 g / L as the fermentation carbon source.
[0082] S5. Activate and purify the Bacillus coagulans glycerol tube and inoculate it on a slant medium for enrichment culture. Pick an appropriate amount of colonies and inoculate them into a seed medium to prepare a seed liquid. The components of the seed medium include: 50 g / L glucose, 10 g / L yeast extract powder, 0.01 g / L sodium chloride, 0.5 g / L ammonium chloride, 0.2 g / L potassium dihydrogen phosphate, 0.2 g / L magnesium sulfate heptahydrate, and 30 g / L calcium carbonate.
[0083] S6. Inoculate the seed liquid into the fermentation medium at an inoculation mass ratio of 5% and ferment for 48 h at a fermentation temperature of 50 °C and a rotation speed of 120 rpm, and detect the lactic acid content in the final fermentation broth. The components of the fermentation medium include: 100 g / L wheat mixed sugars, 5 g / L yeast extract powder, 0.03 g / L sodium chloride, 1.5 g / L ammonium sulfate, 0.6 g / L potassium dihydrogen phosphate, 0.6 g / L magnesium sulfate heptahydrate, 0.15 g / L manganese sulfate heptahydrate, and 60 g / L calcium carbonate.
[0084] Comparative Example 3
[0085] S1. Wash the corn straw and mechanically crush it. Add an alkaline solution (caustic soda solution), then knead, extrude, wash to remove lignin, and then dry for later use.
[0086] S2. Add an enzymatic hydrolysis buffer (citric acid buffer solution, pH adjusted to 5) to the dried holocellulose, with a solid content of 15%. Add 15 FPU / g of a cellulase complex (cellulase + hemicellulase). Under the conditions of an enzymatic hydrolysis temperature of 50 °C and an enzymatic hydrolysis rotation speed of 150 r / min, perform enzymatic hydrolysis in an enzymatic hydrolysis tank for 52 h to obtain an enzymatic hydrolysate.
[0087] S3. Filter the enzymatic hydrolysate through a mechanical plate and frame to obtain a mixed sugar solution.
[0088] S4. Use a high-performance liquid chromatograph to detect the concentrations of glucose, xylose, and arabinose in the corn mixed sugar solution. Without changing the trisaccharide ratio, appropriately concentrate it to make the total sugar concentration reach 100 g / L as the fermentation carbon source.
[0089] S5. Activate and purify the glycerol tube of Bacillus coagulans and inoculate it on a slant medium for enrichment culture. Pick an appropriate amount of colonies and inoculate them into a seed medium to prepare a seed solution. The components of the seed medium include: 50 g / L glucose, 10 g / L yeast extract powder, 0.01 g / L sodium chloride, 0.5 g / L ammonium chloride, 0.2 g / L potassium dihydrogen phosphate, 0.2 g / L magnesium sulfate heptahydrate, 30 g / L calcium carbonate.
[0090] S6. Inoculate the seed solution into the fermentation medium at an inoculation mass ratio of 5% and ferment for 48 h at a fermentation temperature of 50 °C and a rotation speed of 120 rpm. Detect the lactic acid content in the final fermentation broth. The components of the fermentation medium include: 100 g / L corn mixed sugar, 5 g / L yeast extract powder, 0.03 g / L sodium chloride, 1.5 g / L ammonium sulfate, 0.6 g / L potassium dihydrogen phosphate, 0.6 g / L magnesium sulfate heptahydrate, 0.15 g / L manganese sulfate heptahydrate, 60 g / L calcium carbonate.
[0091] Detect the lactic acid production after fermentation in Examples 1 - 3 and Comparative Examples 1 - 3. Specifically, use a liquid chromatograph (model Shimadzu LC-20A) to detect the lactic acid content in the fermentation broth;
[0092] The detection results are shown in Table 1 below:
[0093] Table 1 Fermentation acid production results of Examples 1 - 3 and Comparative Examples 1 - 3
[0094] Example / Comparative Example Fermentation Time (h) Lactic Acid Yield (g / L) Example 1 48 92 Example 2 48 90 Example 3 48 89 Comparative Example 1 48 77 Comparative Example 2 48 72 Comparative Example 3 48 68
[0095] According to Table 1, combined with the fermentation results of Examples 1-3, it can be found that the sugar solutions prepared from three different crop straws, after being compounded with industrial sugar in a certain proportion, have little difference in the final acid production effect after 48 hours of fermentation. At the same time, it can be seen from Comparative Examples 1-3 that for the uncompounded straw mixed sugar solution, due to the different types of crop straws, the utilization of the mixed sugar obtained by enzymatic hydrolysis of the strain is different. This is mainly because in the mixed sugar prepared from different straws, the proportions of the three main sugars are different, and coupled with the preference of the strain for the carbon source and its proportion, the utilization effect of the strain on it is different, reducing the utilization efficiency of the straw mixed sugar.
[0096] In the process of preparing the straw-based carbon source, the mixed sugar obtained by enzymatic hydrolysis filtration is compounded with the finished sugar in an appropriate proportion, effectively improving the utilization rate of the mixed sugar prepared from different types of crop straws by the strain during fermentation. At the same initial sugar concentration, the lactic acid yield is increased. In addition, the sugar production link by enzymatic hydrolysis is shortened, the sugar production energy consumption is reduced, and the lactic acid fermentation cost is further reduced.
[0097] In the description of this specification, the description with reference to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.
[0098] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and the above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.
Claims
1. A method for improving the fermentation stability of straw mixed sugar, characterized in that: The following steps are involved: Pre-treating plant straw to obtain hodgkin fibers; Using cellulose complex enzyme to enzymolyze the holocellulose to obtain enzymolysis solution; The enzymatic hydrolysate is filtered to obtain plant-based straw sugar; The straw sugar is compounded with the finished sugar to form compound straw sugar; Compound straw sugar is used as a fermentation carbon source to produce lactic acid.
2. A method for improving the fermentation stability of straw mixed sugar according to claim 1, characterized in that: The plant straw is one or more of rice straw, corn straw, wheat straw and cotton straw.
3. A method for improving the fermentation stability of straw mixed sugar according to claim 1, characterized in that: The plant straw pretreatment process is: the plant straw is cleaned and then mechanically crushed, then an alkaline solution is added to knead and squeeze it, then washed to remove lignin, and finally dried.
4. The method for improving the fermentation stability of straw mixed sugar according to claim 1, characterized in that: In the process of enzymatic hydrolysis of holocellulose, the addition amount of cellulose complex enzyme is: 15-20FPU / g, and the enzymatic hydrolysis temperature is 45-50℃.
5. The method for improving the fermentation stability of straw mixed sugar according to claim 1, characterized in that: The compound straw sugar uses finished sugars including one or more of glucose, xylose and arabinose.
6. A method for improving the fermentation stability of straw mixed sugar according to claim 1 or 5, characterized in that: In the compound straw sugar, the concentration ratio of glucose, xylose and arabinose is 8:2:0.5, and the total concentration of glucose, xylose and arabinose is 100 g / L.
7. The method for improving the fermentation stability of straw mixed sugar according to claim 1, characterized in that: The steps for producing lactic acid by fermentation are: 1) Activating and purifying the Bacillus coagulans glycerol tube, inoculating it on a slant culture medium for enrichment culture, picking an appropriate amount of colonies and inoculating them on a seed culture medium to prepare a seed solution; 2) Inoculate the seed liquid into the fermentation medium for mechanical fermentation.
8. A method for improving the fermentation stability of straw mixed sugar according to claim 7, characterized in that: The inoculation mass proportion of the seed liquid is 5-10%, the fermentation time is 36-48h, the fermentation temperature is 45-50°C, and the rotation speed is 100-120rpm.
9. The method for improving the fermentation stability of straw mixed sugar according to claim 7, characterized in that: The fermentation medium comprises: 100 g / L compound straw sugar, 5 g / L yeast extract powder, 0.03 g / L sodium chloride, 1.5 g / L ammonium sulfate, 0.6 g / L potassium dihydrogen phosphate, 0.6 g / L magnesium sulfate heptahydrate, 0.15 g / L manganese sulfate heptahydrate, and 60 g / L calcium carbonate. The components of the seed culture medium include: 50 g / L glucose, 10 g / L yeast extract powder, 0.01 g / L sodium chloride, 0.5 g / L ammonium chloride, 0.2 g / L potassium dihydrogen phosphate, 0.2 g / L magnesium sulfate heptahydrate, and 30 g / L calcium carbonate.
10. Use of the method for improving the fermentation stability of straw mixed sugar according to any one of claims 1 to 9 in the preparation of lactic acid.