Pretreatment and material supplementing method for promoting enzymolysis of bamboo shoot shells
By optimizing the enzymatic hydrolysis of bamboo shoot shells through hot alkali pretreatment and batch feeding, the problem of low enzymatic hydrolysis efficiency under high solid content was solved, achieving high-efficiency enzymatic hydrolysis, improving sugar concentration and production efficiency, and making it suitable for large-scale application.
Patent Information
- Application Number
- CN202510983974.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2025-06-26
- Filing Date
- 2025-07-17
- Publication Date
- 2025-10-17
AI Technical Summary
Existing technologies have low enzymatic hydrolysis efficiency and poor mass transfer under high solids content conditions, resulting in low equipment utilization and poor economic feasibility. In addition, the sugar concentration in conventional enzymatic hydrolysis systems is low, which affects the hydrolysis efficiency.
After pretreating bamboo shoot shells with hot alkali, enzymatic hydrolysis was carried out under high solid content using a batch feeding method. The pretreatment conditions and feeding time were optimized. Bamboo shoot shells were treated with alkaline solutions such as NaOH. The batch feeding method was combined with a simplex centroid design model to improve the efficiency of enzymatic hydrolysis.
Under conditions of 45% w/v high solids content, the glucose yield reached 95.32%, the xylose yield reached 57.54%, and the total sugar concentration reached 268.7 g/L. This improved the enzymatic hydrolysis efficiency, reduced the difficulty of mass transfer and mixing, and was simple to operate, low in cost, and suitable for large-scale production.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of lignocellulose enzymolysis, and particularly relates to a pretreatment and feeding method for promoting enzymolysis of bamboo shoot shell. BACKGROUND
[0002] The rapid consumption of fossil fuels has triggered serious environmental problems and energy crisis, and people are increasingly concerned about the potential of biomass resources as renewable fuels and chemicals. As a renewable raw material, lignocellulose has the characteristics of large reserves, abundant sources, renewability and biodegradability, and is considered as an ideal substitute for fossil fuels, with wide application prospects. Lignocellulose is mainly composed of cellulose (glucan), hemicellulose (xylan, etc.) and lignin, which are interconnected and interwoven through hydrogen bonds, chemical bonds and other interactions to form a complex and tight barrier structure, giving lignocellulose certain mechanical strength and stubbornness, affecting the accessibility of cellulase, and making it difficult to be efficiently utilized in the process of bio-refining. Therefore, the original structure needs to be destroyed by pretreatment to increase the accessibility of cellulase. The common pretreatment technologies include mechanical grinding, extrusion, chemical pretreatment under catalytic conditions of alkali / acid / organic solvent, high-temperature steam explosion and combined pretreatment of two or more methods. In chemical treatment, alkali pretreatment shows high efficiency in removing lignin, while reducing the degree of polymerization and crystallinity, which increases the surface area of cellulose inside the raw material and improves the efficiency of enzymatic hydrolysis. Compared with acid treatment, alkali treatment has the advantage of retaining more hemicellulose components, improving the utilization rate of raw materials and the yield of products in the overall bio-refining process. Therefore, it is of great significance to develop efficient alkali treatment methods for the high-value utilization of bamboo shoot shell. Enzymatic hydrolysis is an important step in the conversion of lignocellulosic biomass. Although pretreatment technology can break the physical barrier of lignocellulose and improve the efficiency of enzymatic hydrolysis, the pretreated raw material cannot be completely hydrolyzed, and the residual lignin reduces the accessibility of cellulase to cellulose and the inhibition of sugar products are possible factors. At the same time, the conventional enzymatic hydrolysis process usually uses low solid content (2-5%) to pursue higher sugar conversion rate, which leads to low product concentration and low equipment utilization, seriously restricting the economic feasibility of the process. Generally, more than 20% solid content in the enzymatic hydrolysis system is beneficial to reduce the size of the equipment and energy consumption, so as to achieve effective economic benefits. However, the increase of sugar concentration easily combines with cellulase, which reduces the efficiency of enzymatic hydrolysis. At the same time, the lack of free water in the enzymatic hydrolysis system leads to the increase of system viscosity and the difficulty of mass transfer, which also hinders the effective contact between cellulase and substrate, which is one of the main factors affecting the efficiency of high solid content enzymatic hydrolysis. In order to solve this problem, without affecting the efficiency of enzymatic hydrolysis, high solid content and efficient enzymatic hydrolysis can be achieved by batch feeding. This method can maintain the efficiency of enzymatic hydrolysis while obtaining higher sugar concentration by adding fresh substrate in stages. This reduces the viscosity of the system and enhances the mass transfer efficiency of the system, promoting the progress of enzymatic hydrolysis. Therefore, it is crucial to develop pretreatment methods and feeding methods that can improve the efficiency of lignocellulose enzymatic hydrolysis under high solid content conditions. SUMMARY
[0003] The application aims to provide a pretreatment and feeding method for promoting the enzymolysis of bamboo shoot shell, under the condition of 2% w / v solid content, the glucose yield is 98.10%, and the xylose enzymolysis yield is 93.64%. Under the condition of 45% w / v high solid content, the glucose yield is 95.32%, the xylose enzymolysis yield is 57.54%, and the total sugar concentration reaches 268.7 g / L.
[0004] The technical scheme of the application is as follows:
[0005] A pretreatment and feeding method for promoting the enzymolysis of bamboo shoot shell, comprising the following steps:
[0006] (1) under the condition of 100℃, the bamboo shoot shell is pretreated by using 1% w / v NaOH, KOH, Ca(OH)2, NaHCO3, CH3COONa and Na2SO3 respectively for 60 min, and then filtered and washed in sequence, and the solid product rich in glucan and xylan is subjected to enzymolysis at 2% w / v, and the glucose concentration in the enzymolysis liquid is determined to screen the superior alkali;
[0007] (2) the bamboo shoot shell is pretreated by using the aqueous solution of NaOH, and the optimal pretreatment condition is obtained, and then filtered and washed in sequence to obtain the solid product rich in glucan and xylan, the concentration of NaOH is 0.5-5% w / v, the pretreatment temperature is 80-150℃, and the pretreatment time is 20-160 min, and the solid product rich in glucan and xylan is subjected to enzymolysis at 2% w / v;
[0008] (3) the solid product obtained by pretreating the bamboo shoot shell by using 3% w / v NaOH at 110℃ for 60 min is subjected to enzymolysis at different solid contents of 0.25-20% w / v, the glucose concentration in the enzymolysis liquid is determined under different enzymolysis times, the rate coefficient k and the fractal dimension h of enzymolysis are calculated, and the optimal initial solid content is determined;
[0009] (4) taking the initial solid content determined in step (3) as the starting point of enzymolysis, setting the final solid content and the feeding time point, and performing batch feeding by using the simplex centroid design model, and taking the group with the highest total sugar concentration as the optimal feeding method.
[0010] (5) taking the initial solid content determined in step (3) as the starting point of enzymolysis, and taking the optimal feeding method determined in step (4), the final solid content is 45% w / v for enzymolysis. In some possible implementation manners, the pretreatment superior alkali obtained in step (1) is NaOH.
[0011] In some possible implementation manners, the pretreated optimal condition obtained in step (2) is that the bamboo shoot shell is treated with a 3% w / v aqueous solution of NaOH at 110 DEG C for 60 min.
[0012] In some possible implementation manners, the calculation formula of the enzyme hydrolysis rate coefficient k and the fractal dimension h in step (3) is as follows:
[0013] G(t) = G0[1-exp(-k*t 1-h )]
[0014] G(t) is the glucose concentration (g / L) at t time; G0 is the theoretical maximum glucose concentration (g / L) of the current solid content; k is the rate coefficient; h is the fractal dimension; and t is the enzyme hydrolysis time.
[0015] In some possible implementation manners, the enzyme hydrolysis condition in step (3) is 50 DEG C and 150 rpm, and the enzyme hydrolysis time is 72 h, and the glucose concentration in the enzyme hydrolysis liquid is detected every 6 h.
[0016] In some possible implementation manners, the initial solid content determined in step (3) is 20% w / v.
[0017] In some possible implementation manners, the final solid content set in step (4) is 40% w / v, the enzyme hydrolysis condition is 50 DEG C and 150 rpm, the enzyme hydrolysis time is 72 h, and the feeding time points are 6 h, 12 h, 24 h and 36 h.
[0018] In some possible implementation manners, the optimal feeding method determined in step (4) is that 12.5%, 62.5%, 12.5% and 12.5% are fed at 6 h, 12 h, 24 h and 36 h respectively, and the total feeding weight is 6 g.
[0019] In some possible implementation manners, the final solid content set in step (5) is 45% w / v, the total feeding weight is 7.5 g by using the optimal feeding method in step (4), the enzyme hydrolysis condition is 50 DEG C and 150 rpm, and the enzyme hydrolysis time is 72 h.
[0020] In some possible implementation manners, the enzyme hydrolysis liquid in steps (1-5) comprises 30 mL of a citric acid-sodium citrate buffer (pH = 4.8) and 15 FPU / g 葡聚糖 of cellulase.
[0021] The present application has at least the following beneficial effects:
[0022] The present invention discloses a pretreatment and feeding method for promoting the enzymatic hydrolysis of bamboo shoot shells. The method pretreats the bamboo shoot shells with hot alkali and then feeds the enzymatic hydrolysis in batches to achieve a glucose yield of 95.32%, a xylose yield of 57.54%, and a total sugar concentration of 268.7 g / L under a high solid content of 45% w / v. The method improves the enzymatic hydrolysis efficiency of bamboo shoot shells, reduces the inhibitory effect of high solid content on the enzymatic hydrolysis process, and reduces the difficulty of mass transfer and effective mixing. The operating method of the present application is simple, low-cost, highly practical, and easy to scale production. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 The figures are the trends of the 72-h enzymatic hydrolysis efficiency, rate coefficient k, and fractal dimension h of bamboo shoot shells with different solid contents measured in Example 5, wherein (a) is the change in glucose concentration obtained during the 72-h enzymatic hydrolysis of bamboo shoot shells with different solid contents, (b) is the glucose yield after 72 h, (c) is the relationship between solid content and rate coefficient k, and (d) is the relationship between solid content and fractal dimension h. DETAILED DESCRIPTION
[0024] The technical solution of the present invention is further illustrated and described below through specific implementation methods.
[0025] In the following examples, the water used can be one or more of distilled water, purified water, and drinking water. Unless otherwise specified, the detection methods in the following examples are all conventional detection methods. The reagents in the following examples were all purchased from commercial sources unless otherwise specified. Unless otherwise specified, % refers to mass ratio; %w / v refers to mass / volume ratio, and the unit of volume v is mL.
[0026] Example 1 Screening of predominant alkali from bamboo shoot shells
[0027] The bamboo shoot shells were ground through a 60-mesh sieve and dried at 105°C to constant weight. The components were 34.80% cellulose, 18.69% hemicellulose, and 17.92% lignin. Six grams of bamboo shoot shells were weighed and added to 60 mL of water at a 1:10 w / v solid-to-liquid ratio. 1% w / v of NaOH, KOH, Ca(OH)2, NaHCO3, CH3COONa, and Na2SO3 were added. The mixture was reacted at 100°C for 60 minutes. After the reaction, the mixture was filtered through a 400-mesh filter, and the residue was washed with deionized water and dried to obtain the processed bamboo shoot shell solid product.
[0028] The bamboo shoot shell solid product and untreated bamboo shoot shell were added to 30 mL of 0.05 M citric acid-sodium citrate buffer (pH = 4.8) at a solid content of 2% w / v, and 15 FPU / g 葡聚糖hydrolysis for 72h at 50°C, 150rpm, glucose and xylose were obtained.
[0029] The 72h enzymatic hydrolysis efficiency of bamboo shoot shell after different alkali pretreatment was detected and shown in Table 1.
[0030] Example 2 Pretreatment NaOH concentration optimization
[0031] 6g of bamboo shoot shell raw material was weighed and added to 60mL water according to 1:10 w / v solid-liquid ratio, and 3% w / v concentration of NaOH was added, and the reaction was carried out at 80-150°C for 60min. After the reaction was completed, it was poured into a 400 mesh filter screen for filtration, and the filter residue was washed with deionized water, and the treated bamboo shoot shell solid product was obtained after drying.
[0032] The bamboo shoot shell solid product and untreated bamboo shoot shell were respectively added to 30mL 0.05M citric acid-sodium citrate buffer (pH=4.8) at a solid content of 2% w / v, and 15FPU / g 葡聚糖 of cellulase (Cellic@CTec3) was added, and the enzymatic hydrolysis was carried out at 50°C, 150rpm for 72h, and glucose and xylose were obtained.
[0033] The 72h enzymatic hydrolysis efficiency of bamboo shoot shell after different alkali pretreatment was detected and shown in Table 2.
[0034] Example 3 Pretreatment temperature optimization
[0035] According to the method of Example 2, the difference is that the pretreatment temperature is different.
[0036] 6g of bamboo shoot shell raw material was weighed and added to 60mL water according to 1:10 w / v solid-liquid ratio, and 3% w / v concentration of NaOH was added, and the reaction was carried out at 80-150°C for 60min. After the reaction was completed, it was poured into a 400 mesh filter screen for filtration, and the filter residue was washed with deionized water, and the treated bamboo shoot shell solid product was obtained after drying.
[0037] The bamboo shoot shell solid product was added to 30mL 0.05M citric acid-sodium citrate buffer (pH=4.8) at a solid content of 2% w / v, and 15FPU / g 葡聚糖 of cellulase (Cellic@CTec3) was added, and the enzymatic hydrolysis was carried out at 50°C, 150rpm for 72h, and glucose and xylose were obtained.
[0038] The 72h enzymatic hydrolysis efficiency of bamboo shoot shell after different pretreatment temperatures was detected and shown in Table 2.
[0039] Example 4 Pretreatment time optimization
[0040] The method according to Example 3 was followed, except that the pretreatment time was varied.
[0041] 6 g of bamboo shoot shell raw material was weighed out according to a solid-liquid ratio of 1 : 10 w / v, added to 60 mL of water, and treated with 3% w / v NaOH at 110°C for different times of 20-160 min. After the reaction was completed, the mixture was filtered through a 400-mesh filter screen, the filter residue was washed with deionized water, and the treated bamboo shoot shell solid product was obtained after drying.
[0042] The bamboo shoot shell solid product was added to 30 mL of 0.05 M citric acid-sodium citrate buffer (pH = 4.8) at a solid content of 2% w / v, and 15 FPU / g 葡聚糖 of cellulase (Cellic® CTec3) was added, and the mixture was reacted at 50°C and 150 rpm for 72 h to obtain glucose and xylose.
[0043] It was found that the 72 h enzymolysis efficiency of bamboo shoot shell pretreated for different times was as shown in Table 2.
[0044] The optimal pretreatment conditions for bamboo shoot shell were as follows: NaOH concentration of 3% w / v, pretreatment temperature of 110°C, and pretreatment time of 60 min.
[0045] Table 1 Enzymolysis yield of glucose and xylose (%) of bamboo shoot shell treated with different alkalis
[0046]
[0047] Table 2 Enzymolysis yield of glucose and xylose (%) of bamboo shoot shell pretreated for different times
[0048]
[0049]
[0050] Example 5
[0051] The method according to Example 4 was followed, except that the solid content of the enzymolysis was varied.
[0052] The pretreated bamboo shoot shell solid product was added to 30 mL of 0.05 M citric acid-sodium citrate buffer (pH = 4.8) at different solid contents (0.25-20% w / v), and 15 FPU / g 葡聚糖 of cellulase (Cellic® CTec3) was added, and the mixture was reacted at 50°C and 150 rpm for 72 h to obtain glucose and xylose. The glucose content was detected at different time points (6 h, 12 h, 24 h, 36 h, 48 h, and 72 h), and the rate coefficient k and fractal dimension h were calculated.
[0053] The rate coefficient k and the fractal dimension h are calculated according to the following formula:
[0054] G(t) = G0[1 - exp(-k*t 1-h )]
[0055] G(t) is the glucose concentration (g / L) at time t; G0is the theoretical maximum glucose concentration (g / L) for the current solid content; k is the rate coefficient; h is the fractal dimension; t is the enzymatic hydrolysis time.
[0056] Figure 1 The trends of the 72h enzymatic hydrolysis efficiency, rate coefficient k and fractal dimension h of the bamboo shoot shell with different solid contents after pretreatment are shown, and the optimal initial solid content is finally determined to be 20% w / v.
[0057] Example 6
[0058] According to the method of Example 4, the difference is that different enzyme hydrolysis feeding methods are used.
[0059] The pretreated bamboo shoot shell solid product is added to 30 mL of 0.05M citric acid-sodium citrate buffer (pH = 4.8) with an initial solid content of 20% w / v, and 15 FPU / g 葡聚糖 of cellulase (Cellic@CTec3) is added, and the enzymatic hydrolysis is carried out at 50°C and 150 rpm. The simplex centroid design is used as a model, and different weights of bamboo shoot shell solid product and corresponding amount of cellulase are added at 6h, 12h, 24h and 36h of enzymatic hydrolysis, and the final solid content is 40% w / v. The reaction is carried out for 72h to obtain glucose and xylose. The initial bamboo shoot shell solid product of the control group is 40% w / v solid content.
[0060] It is detected that the 72h enzymatic hydrolysis efficiency and sugar concentration of different feeding methods shown in Table 3.
[0061] Example 7
[0062] According to the method of Example 6, the difference is that different final solid contents are used.
[0063] The pretreated bamboo shoot shell solid product is added to 30 mL of 0.05M citric acid-sodium citrate buffer (pH = 4.8) with an initial solid content of 20% w / v, and 15 FPU / g 葡聚糖The cellulase (Cellic CTec3) was used to hydrolyze the bamboo shoot shell at 50℃ and 150rpm. The different weights of bamboo shoot shell solid product and corresponding amount of cellulase were added at 6h, 12h, 24h and 36h of the hydrolysis according to the simplex centroid design model. The final solid content was 45% w / v. The reaction was carried out for 72h to obtain glucose and xylose. The initial bamboo shoot shell solid product of the control group was 45% w / v solid content.
[0064] The 72h hydrolysis efficiency and sugar concentration shown in Table 4 were detected.
[0065] Table 3 Simplex Centroid Design
[0066]
[0067] Table 4 Difference between feeding and not feeding under the optimal feeding method
[0068]
[0069] As shown in Table 1, in Example 1, the enzymatic hydrolysis efficiency of glucose and xylose of untreated bamboo shoot shell was 60.10% and 27.54%, respectively. After 60min of different alkali treatment at 100℃, the enzymatic hydrolysis efficiency of bamboo shoot shell was significantly improved. The enzymatic hydrolysis efficiency of glucose and xylose of NaOH was 96.55% and 86.56%, respectively, and the pretreatment effect was the best.
[0070] As shown in Table 2, in Example 2, after 60min of treatment with different concentrations of NaOH, the enzymatic hydrolysis efficiency of bamboo shoot shell was significantly improved. When the concentration of NaOH was 3%, the enzymatic hydrolysis efficiency of glucose and xylose reached the maximum value, which was 96.71% and 83.31%, respectively. Based on Example 2, Example 3 was carried out. The results showed that 110℃ was the most suitable treatment temperature for NaOH, and the enzymatic hydrolysis efficiency of glucose and xylose was 98.10% and 93.64%, respectively. Based on Example 3, Example 4 was carried out. The results showed that the conditions of Example 3 were the optimal conditions for NaOH treatment of bamboo shoot shell.
[0071] As shown in Table 4, the glucose and xylose concentrations of the control group were 0.45g / L and 0.22g / L, respectively. The glucose and xylose concentrations of the bamboo shoot shell treated with 3% NaOH at 110℃ were 1.05g / L and 0.95g / L, respectively, which were significantly higher than those of the control group. Figure 1As can be seen, in Example 5, with the increase of solid content, the glucose enzymatic hydrolysis efficiency of bamboo shoot shell gradually decreases, and when the solid content is 20% w / v, the glucose efficiency decreases to 94.26%, the rate coefficient k decreases with the increase of solid content, and the fractal dimension h first decreases and then increases. The fractal dimension h is a key parameter in the fractal kinetics model, which usually reflects the heterogeneity of the substrate. When the solid content is lower than 12.5%, it enables the enzyme to interact with the substrate more uniformly, promotes hydrolysis, and leads to the decrease of the fractal dimension h. However, when the solid content is higher than 12.5%, mass transfer becomes more difficult, and substrate aggregation limits enzyme accessibility, leading to the increase of the fractal dimension h, which indicates that in the enzymatic hydrolysis system of the present application, the greater the solid content, the less the free water visible to the naked eye, resulting in high viscosity of the hydrolysate, which greatly reduces the mass transfer efficiency. The increase of substrate concentration also leads to the increase of sugar concentration in the hydrolysate, and the feedback inhibition caused by it is stronger. In Example 6, as can be seen from Table 3, when the initial solid content is 40% w / v, the glucose yield is 89.36% after 72h. When the initial solid content is 20% w / v, the model fed-batch to 40% w / v solid content designed by simplex centroid, can improve the enzymatic hydrolysis efficiency of bamboo shoot shell, and the glucose enzymatic hydrolysis efficiency is as high as 98.92%, the xylose enzymatic hydrolysis efficiency is as high as 60.90%, and the total sugar concentration is 248.9g / L.
[0072] In Example 7, as can be seen from Table 4, when the initial solid content is 45% w / v, the glucose yield is 88.71% after 72h. When the initial solid content is 20% w / v, the model fed-batch to 45% w / v solid content by the best feeding method, can improve the enzymatic hydrolysis efficiency of bamboo shoot shell, and the glucose enzymatic hydrolysis efficiency is 95.32%, the xylose enzymatic hydrolysis efficiency is 57.54%, and the total sugar concentration is 268.7g / L. As can be seen, the method according to the present application can effectively improve the enzymatic hydrolysis efficiency and increase the yield of glucose and xylose.
[0073] The above is only a preferred embodiment of the present application, and therefore cannot limit the scope of the present application, i.e. equivalent changes and modifications made according to the scope and content of the present patent should still be within the scope of the present application.
Claims
1. A pretreatment and feeding method for promoting enzymatic hydrolysis of bamboo shoot shells, characterized in that: The steps include: (1) Bamboo shoot shells were pretreated with 1% w / v NaOH, KOH, Ca(OH)2, NaHCO3, CH3COONa, and Na2SO3 at 100°C for 60 min, followed by filtration and washing. The resulting solid product rich in glucan and xylan was enzymatically hydrolyzed at 2% w / v, and the glucose concentration in the hydrolyzate was determined to screen for a dominant base. (2) A pretreatment test was conducted on bamboo shoot shells using an aqueous solution of NaOH to obtain the optimal pretreatment conditions, followed by filtration and washing to obtain a solid product rich in glucan and xylan, wherein the concentration of NaOH was 0.5-5% w / v, the pretreatment temperature was 80-150°C, and the pretreatment time was 20-160 min. The solid product rich in glucan and xylan was enzymatically hydrolyzed at 2% w / v; (3) The solid product of the bamboo shoot shell treated with 3% w / v NaOH at 110° C. for 60 min was enzymatically hydrolyzed at different solid contents ranging from 0.25% to 20% w / v, and the glucose concentration in the enzymatic hydrolyzate at different enzymatic hydrolysis times was measured. The enzymatic hydrolysis rate coefficient k and fractal dimension h were calculated to determine the optimal initial solid content; (4) Taking the initial solid content determined in step (3) as the starting point of enzymatic hydrolysis, the final solid content and feeding time point are set, and batch feeding is performed using a simplex centroid design model, and the group with the highest total sugar concentration is selected as the optimal feeding method. (5) Taking the initial solid content determined in step (3) as the starting point of enzymatic hydrolysis, and using the optimal feeding method determined in step (4), enzymatic hydrolysis is performed with a final solid content of 45% w / v.
2. The pretreatment and feeding method according to claim 1, wherein The enzymatic hydrolysis conditions obtained in step (1) are 50° C. and 150 rpm, the enzymatic hydrolysis solid content is 2% w / v, the enzymatic hydrolysis time is 72 h, and the dominant alkali for pre-treating bamboo shoot shells is NaOH.
3. The pretreatment and feeding method according to claim 1, wherein The optimal conditions for the pretreatment obtained in step (2) are to treat the bamboo shoot shells with a 3% w / v NaOH aqueous solution at 110°C for 60 minutes, the enzymatic hydrolysis conditions are 50°C and 150rpm, the enzymatic hydrolysis solid content is 2% w / v, and the enzymatic hydrolysis time is 72 hours.
4. The pretreatment and feeding method according to claim 1, wherein The calculation formulas for the rate coefficient k and fractal dimension h of the enzymatic hydrolysis in step (3) are as follows: G(t)=G0[1-exp(-k*t 1-h )] G(t) is the glucose concentration at time t (g / L); G0 is the theoretical maximum glucose concentration under the current solid content conditions (g / L); k is the rate coefficient; h is the fractal dimension; and t is the enzymatic hydrolysis time.
5. The pretreatment and feeding method according to claim 1, wherein The enzymatic hydrolysis conditions in step (3) are 50° C. and 150 rpm, the enzymatic hydrolysis time is 72 h, and the glucose concentration in the enzymatic hydrolyzate is detected every 6 h.
6. The pretreatment and feeding method according to claim 1, wherein The initial solid content determined in step (3) is 20% w / v.
7. The pretreatment and feeding method according to claim 1, wherein The final solid content set in step (4) was 40% w / v, the enzymatic hydrolysis conditions were 50° C., 150 rpm, the enzymatic hydrolysis time was 72 h, and the feeding time points were 6 h, 12 h, 24 h, and 36 h.
8. The pretreatment and feeding method according to claim 1, wherein The optimal feeding method determined in step (4) is to feed 12.5%, 62.5%, 12.5% and 12.5% at 6h, 12h, 24h and 36h respectively, and the total weight of the feeding is 6g.
9. The pretreatment and feeding method according to claim 1, wherein The final solid content was set to 45% w / v, the optimal feeding method of step (4) was used, the total feeding weight was 7.5 g, the enzymatic hydrolysis conditions were 50° C., 150 rpm, and the enzymatic hydrolysis time was 72 h.
10. The pretreatment and feeding method according to claim 1, wherein The enzymatic hydrolysate in steps (1-5) includes 30 mL of citric acid-sodium citrate buffer (pH = 4.8) and 15 FPU / g 葡聚糖 of cellulase.