A method and apparatus for reducing the viscosity of distiller's grains based on enzymatic treatment

Abstract

The present application belongs to the technical field of processing of by-products of brewing, and specifically discloses a method and device for reducing viscosity of distiller's grains based on enzyme treatment, which comprises the following steps: S1, dispersing the distiller's grains of liquor and mixing the auxiliary materials by means of a stirrer; S2, adjusting the pH of the uniformly dispersed and mixed distiller's grains by means of ammonia water, and then adding enzyme hydrolysate, and performing enzymolysis for 24 hours; and S3, further adding decomposition enzyme to perform enzymolysis into sugar. The method and device for reducing viscosity of distiller's grains based on enzyme treatment are used to disperse the distiller's grains and mix the auxiliary materials by means of the inner rotation and outer rotation modes of the stirrer, and to reduce the viscosity of the distiller's grains by means of a two-step enzyme hydrolysis method, so that the viscosity of the distiller's grains is reduced and the saccharification rate of the distiller's grains is improved, thereby laying a foundation for further fermentation of the distiller's grains to produce protein.

Description

Technical Field

[0001] This invention relates to the field of brewing by-product treatment technology, and in particular to a method and apparatus for reducing the viscosity of brewing lees based on enzyme treatment. Background Technology

[0002] Solid waste from the baijiu (Chinese liquor) industry, also known as lees or discarded lees, is the solid material remaining after the brewing process. As a solid byproduct of baijiu production, the physicochemical properties and composition of baijiu lees are closely related to the type of grain used, the brewing process, and the storage time. Fresh and dried lees have significantly different moisture contents. The dry matter components of lees, including cellulose, hemicellulose, crude protein, starch, and colloids, form a dense, spherical structure. This is due to several factors: First, the raw materials used in brewing vary; different brands of baijiu use different raw materials such as sorghum, rice, millet, and wheat, which contain varying amounts of starch, protein, fat, cellulose, and lignin. Second, the brewing process, with different conditions such as the number of fermentations, turning times, and types of microorganisms, leads to variations in the decomposition, transformation, and utilization rates of the grain components. Third, storage time is crucial; as storage time increases, moisture in the lees diffuses into the environment, and microorganisms continue to decompose residual organic matter. This results in the presence of a large amount of residual starch, hemicellulose, and colloids in the lees, with a viscosity as high as 1000-5000 mPa·s. This severely hinders oxygen diffusion during fermentation, making it impossible to achieve the expected fermentation effect.

[0003] Generally, producing 1 ton of baijiu (Chinese liquor) generates about 3-4 tons of fresh distiller's grains. These grains retain organic components such as protein, starch, cellulose, and fat from the brewing raw materials, making them valuable for resource utilization. On the other hand, distiller's grains have high moisture and microbial content, making them prone to spoilage during storage. They can also produce harmful gases and high concentrations of organic leachate during storage, posing a risk of environmental pollution if not properly handled in a timely manner.

[0004] With reduced viscosity, the starch and protein released from distillers' grains are more easily digested and absorbed by animals, making them a suitable high-protein feed ingredient to replace traditional feeds like soybean meal and reduce farming costs. Lower viscosity distillers' grains exhibit improved flowability during feed pelleting, reducing mechanical blockage and increasing production efficiency. The reduced viscosity also significantly improves mass transfer efficiency, allowing oxygen and nutrients to diffuse more easily, making it suitable for solid-state fermentation by microorganisms such as yeast and Schizophyllum commune to produce single-cell protein (SCP) or high-value-added enzyme preparations. The increased content of true protein in fermentation products lays the foundation for the development of functional protein feeds. In anaerobic fermentation for biogas production, the enhanced flowability of low-viscosity distillers' grains prevents material clumping within the reactor, increasing methane yield. The reducing sugars (such as glucose and maltose) generated by enzymatic hydrolysis can be directly used for ethanol fermentation, achieving cascaded energy utilization.

[0005] Traditional physical pulverization or single enzymatic hydrolysis methods can temporarily reduce viscosity, but they suffer from high energy consumption, protein damage, or viscosity rebound, failing to meet the requirements of material stability and nutrient retention in the aforementioned application scenarios. This invention provides a method and apparatus for reducing the viscosity of distiller's grains based on enzyme treatment, fundamentally solving this problem. Summary of the Invention

[0006] The purpose of this invention is to provide a method and apparatus for reducing the viscosity of distiller's grains based on enzyme treatment. The method utilizes the internal and external rotation modes of a mixer to disperse the distiller's grains and mix the auxiliary materials. It employs a two-step enzymatic hydrolysis method to reduce the viscosity of the distiller's grains. The dispersing of the distiller's grains and the two-step enzymatic hydrolysis method reduce the viscosity of the distiller's grains and increase the saccharification rate of the distiller's grains, laying the foundation for further fermentation and protein production from the distiller's grains.

[0007] To achieve the above objectives, the present invention provides a method for reducing the viscosity of distiller's grains based on enzyme treatment, comprising the following steps:

[0008] S1. The lees of the liquor are broken up and the auxiliary materials are mixed using a mixer;

[0009] S2. The mixed lees are broken up and the pH is adjusted with ammonia water, then the enzymatic hydrolysate is added and enzymatically hydrolyzed for 24 hours.

[0010] S3. Add a decomposing enzyme for further enzymatic hydrolysis, which is then converted into sugar. After 12 hours, the physicochemical indicators are measured.

[0011] Preferably, in step S2, the pH is adjusted to 5.8 ± 0.2 using ammonia.

[0012] Preferably, in step S2, the enzymatic hydrolysate is mesophilic α-amylase, and the enzymatic hydrolysis temperature is 70°C.

[0013] Preferably, in step S2, after 24 hours of enzymatic hydrolysis, the pH decreases and stabilizes at 5.0 ± 0.5.

[0014] Preferably, in step S3, the decomposing enzymes are pullulanase and glucoamylase, with pullulanase having an enzyme activity of 5 U / g and glucoamylase having an enzyme activity of 150 U / g.

[0015] The present invention also provides an apparatus for reducing the viscosity of distiller's grains based on enzyme treatment, including the mixer in the above method. The mixer includes a feed inlet, a discharge outlet, a rotating shaft, a motor, and a housing. The top of one end of the housing is provided with a feed inlet, and the bottom of the other end is provided with a discharge outlet. The rotating shaft is located inside the housing. One end of the rotating shaft is rotatably connected to the inner wall of the housing, and the other end of the rotating shaft penetrates through the inner wall of the housing. One end of the rotating shaft penetrating the inner wall of the housing is provided with a pulley, and the pulley is connected to the output end of the motor by a belt.

[0016] Preferably, the rotating shaft is provided with an inner spiral ribbon and an outer spiral ribbon along the axis, and the inner spiral ribbon and the outer spiral ribbon are respectively spirally wound on the rotating shaft.

[0017] The advantages and beneficial effects of the above-mentioned method and apparatus for reducing the viscosity of distiller's grains based on enzyme treatment are as follows:

[0018] 1. Compared to traditional methods of processing distiller's grains, such as physical pulverization, the resulting fine particles are detrimental to subsequent fermentation. This invention uses the inner and outer rotation of a mixer to tear and break up clumps of distiller's grains, which is beneficial for fermentation.

[0019] 2. This invention reduces the viscosity of distiller's grains through a two-step enzymatic hydrolysis method. Compared to traditional distiller's grains processing methods: extrusion puffing is energy-intensive and severely damages nutrients; simple enzymatic hydrolysis with α-amylase only works on α-1-4 glycosidic bonds and has no effect on α-1-6 glycosidic bonds, resulting in minimal viscosity reduction; chemical treatment methods such as soaking cause contamination and protein damage. This invention, through two-step enzymatic hydrolysis and dynamic stirring equipment, stabilizes the viscosity of the treated distiller's grains at 200 mPa·s; the protein retention rate is >17.5%, and maltose and maltotriose are produced.

[0020] 3. This invention solves the problems of low efficiency, rapid rebound and high pollution of traditional methods by using precise bio-enzyme degradation and equipment mass transfer optimization, and has both high efficiency and sustainability.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] Figure 1 This is an overall schematic diagram of the mixer equipment of the present invention;

[0023] Figure 2 This is a schematic diagram of the internal structure of the mixer equipment of the present invention;

[0024] Figure 3 This is a schematic diagram of the rotating shaft in the mixer equipment of the present invention;

[0025] Figure 4 This is a schematic diagram of the cross-section of the rotating shaft in the mixer equipment of the present invention;

[0026] Figure 5 This is a graph showing the viscosity results before and after enzymatic hydrolysis in this invention;

[0027] Figure 6 These are electron microscope images of the present invention before and after enzymatic hydrolysis;

[0028] Figure 7 These are XRD patterns before and after enzymatic hydrolysis in this invention;

[0029] Figure 8 The sugar content before and after enzymatic hydrolysis in this invention;

[0030] Figure 9These are electron micrographs of fermentation before and after enzymatic hydrolysis of the present invention, where A is the inoculation of different yeasts before enzymatic hydrolysis and B is the inoculation of different yeasts after multi-enzyme hydrolysis.

[0031] Figure 10 The two samples are CLSM fermentation before and after enzymatic hydrolysis according to the present invention, where A is the un-enzymatic hydrolysis group and B is the multi-enzyme hydrolysis group.

[0032] Figure Labels

[0033] 1. Outer shell; 2. Feed inlet; 3. Shaft; 4. Outer threaded ribbon; 5. Inner threaded ribbon; 6. Discharge outlet; 7. Pulley; 8. Belt; 9. Motor. Detailed Implementation

[0034] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0036] Example 1

[0037] like Figure 1 and Figure 2 As shown, an apparatus for reducing the viscosity of distiller's grains based on enzyme treatment includes a mixer, which includes an inlet 2, an outlet 6, a rotating shaft 2, a motor 9, and a housing 1. The inlet 2 is located at the top of one end of the housing 1, and the outlet 6 is located at the bottom of the other end. The rotating shaft 2 is located inside the housing 1. One end of the rotating shaft 2 is rotatably connected to the inner wall of the housing 1, and the other end penetrates through the inner wall of the housing 1. The end of the rotating shaft 2 penetrating the inner wall of the housing 1 is provided with a belt pulley 7. The belt pulley 7 is connected to the output end of the motor 9 through a belt 8.

[0038] like Figure 3 and Figure 4 As shown, the rotating shaft 2 is provided with an inner spiral ribbon 5 and an outer spiral ribbon 4 along the axis, and the inner spiral ribbon 5 and the outer spiral ribbon 4 are respectively spirally wound on the rotating shaft 2.

[0039] The lees enter the outer casing 1 through the feed inlet 2. The motor 9 drives the belt 8 and pulley 7 to rotate, which in turn drives the rotating shaft 2 to rotate. The rotating shaft 2 tears and breaks up the clumps of lees through the inner and outer spiral belts 5 and 4. Compared with the traditional method of crushing the lees, the lees that are torn and broken up have a larger particle size than those that are crushed, which is beneficial to fermentation. The torn and broken lees are removed from the mixer through the discharge outlet 6.

[0040] Clumped, sticky distiller's grains enter the mixer through inlet 2. The inner and outer spirals, with their toothed interlocking and mirror-image motion, effectively break down and disperse the sticky, high-moisture clumps and spherical materials. The dispersed material exits through the end of the outer spiral belt 4, which rotates in the same direction as the outlet 6. The spherical materials undergo a long-distance mirror-image pulling process within the mixer.

[0041] Inside the crusher, the rotating shaft 3 adopts a coaxial nested design, with an inner helical ribbon 5 and an outer helical ribbon 4 installed respectively. The two work together through mirror motion.

[0042] The inner spiral band 5 is directly fixed on the central rotating shaft 3, and the spiral blades are in the form of a continuous strip, tightly wound along the length of the rotating shaft 3.

[0043] The spiral direction is unidirectional (e.g., right-handed), and the blade edges are designed with a serrated or toothed structure for preliminary cutting and tearing of materials.

[0044] The inner spiral band 5 has a smaller diameter and typically covers the middle section of the shaft to the discharge end, forming the core crushing zone.

[0045] External threaded ribbon configuration: The external threaded ribbon 4 is coaxially installed with the rotating shaft 3 via a support frame or auxiliary shaft, and wraps around the outside of the internal threaded ribbon 5, with a gap of 10-30cm between them (adjusted according to the material characteristics).

[0046] The spiral direction is opposite to that of the inner spiral (e.g., left-handed), the blade width is larger, and the end extends to the discharge port 6, forming a conveying and guiding function.

[0047] The outer spiral 4 blades also adopt a toothed design, but they are misaligned with the inner spiral 5 teeth, forming shear force through mirror rotation.

[0048] Positional relationship and motion, coaxial but different speeds: the inner and outer spiral ribbons 4 are controlled by independent drive systems, and the speed difference can be adjusted (e.g., the inner spiral ribbon 5 rotates at high speed to crush, while the outer spiral ribbon 4 pushes in the opposite direction at low speed).

[0049] Biting effect: After the material enters, it is first cut by the 5 teeth of the inner spiral band, and then pulled in the opposite direction by the 4 teeth of the outer spiral band in the gap, forming a mirror tearing effect, especially for spherical lumps.

[0050] Example 2

[0051] A method for reducing the viscosity of distiller's grains based on enzyme treatment includes the following steps:

[0052] S1. The lees of the liquor are broken up and the auxiliary materials are mixed using a mixer.

[0053] Add 30% straw and 70% distiller's grains to the mixer. Use the inner and outer spiral belts of the mixer to tear and break up any clumps of distiller's grains. Add straw to prevent the broken-up distiller's grains from clumping together again.

[0054] S2. The mixed lees are broken up and the pH is adjusted with ammonia water. Then, the enzymatic hydrolysate, which is medium-temperature α-amylase, is added and enzymatically hydrolyzed for 24 hours.

[0055] The initial pH of the distiller's grains was 3.85. The pH was adjusted to 5.8±0.2 using 3% ammonia water. 0.021% calcium oxide was added. Calcium ions have an activating effect on α-amylase. Without calcium ions, the enzyme is completely inactivated because the optimal pH for α-amylase hydrolysis is 5.5. The moisture content was controlled at 55%. Enzymatic hydrolysis was carried out at 70℃ for 24 hours. 70℃ not only enables enzymatic hydrolysis but also serves as a sterilization process, reducing the time required for secondary sterilization and lowering energy consumption.

[0056] The pH slowly decreased during this process because the pH of the distiller's grains was 3.85. When ammonia was added, the pH seemed to be neutralized. However, as time went on, the unneutralized acids were released, causing the pH to drop and eventually stabilize at 5.0 ± 0.5.

[0057] S3. Add a decomposing enzyme for further enzymatic hydrolysis, which is then converted into sugar. After 12 hours, the physicochemical indicators are measured.

[0058] After 24 hours of enzymatic hydrolysis, pullulanase (5 U / g) and glucoamylase (150 U / g) were added. The optimal pH for enzymatic hydrolysis of pullulanase and glucoamylase is 5.0. After exactly 24 hours, the pH dropped to 5.0 ± 0.3. Considering this, no additional ammonia was added to adjust the pH. The moisture content was 55%. After enzymatic hydrolysis at 60℃ for 12 hours, the reducing sugar, starch content, viscosity and other indicators were measured.

[0059] The remaining portion was used for inoculation and fermentation to produce protein. Schizophyllum commune and Candida utilis were added for 5 days of fermentation. The fermentation medium consisted of 0.5% potassium chloride and 0.5% magnesium sulfate heptahydrate added to the enzymatically hydrolyzed distiller's grains, dissolved in sterile water.

[0060] Schizophyllum commune culture medium: 100% wheat bran, 0.01% Tween-80, 0.5% magnesium sulfate heptahydrate, 0.5% potassium chloride, 0.01% manganese sulfate heptahydrate, pH adjusted to 6.0±0.2, solid-liquid ratio 1:0.8, 40g wet material in a 250ml Erlenmeyer flask, sterilized at 121℃ for 30min, Schizophyllum commune spore suspension (10 7Inoculate with 10% of the amount of mycelium and incubate at 32.5℃ for 4 days until the white mycelium has covered the triangular flask and completely wrapped the bran.

[0061] YPD (Candida utilis) culture medium: 2% tryptone, 1% yeast extract, 2% glucose, 2% agar powder added to solids, natural pH 5.8, sterilized at 115℃ for 15 min. First, take the glycerol tube out of the -80℃ freezer, add a small amount and use the three-point streak method to incubate at 900 mm. Note that a different pipette tip should be used for each streak. Streak the plate and incubate upside down at 30℃ for 24 h. Take a large and plump single colony and inoculate it into YPD liquid medium, and incubate at 30℃ and 220 rpm for 18 h for later use.

[0062] Viscosity test: The mixture of α-amylase and pullulanase showed a significant effect on the enzymatic hydrolysis of amylopectin. The viscosity change after enzymatic hydrolysis with α-amylase and pullulanase was measured under the following conditions: a constant temperature of 70℃, a rotation speed of 20 rpm / min, and a solid-liquid ratio of 1:3.25 (w / v). The results are as follows: Figure 5 As shown.

[0063] X-ray diffraction (XRD): The test target was a copper target, the scanning range was 5 to 45°, the scanning speed was 10° / min, the diffraction angle was 2θ, and the tube voltage and current were 45 kV and 40 mA, respectively. Results are as follows... Figure 7 As shown.

[0064] Sugar content determination method: Dry at 65°C for 72 hours, grind and pass through a 60-mesh sieve for later use. Accurately weigh 10g of sample, add 80ml of water, stir slowly at 60°C for 2 hours, centrifuge (4000g, 10min), and collect the supernatant. Results are as follows: Figure 8 As shown.

[0065] The supernatant was mixed with anhydrous ethanol (1:3), precipitated at 4°C for 16-24 hours, centrifuged (4000g, 10min), the supernatant was discarded, and dried at 65°C for later use.

[0066] First, the content of reducing sugar in the sample was detected by spectrophotometry. Then, the sample was diluted to below 1 g / L and then analyzed by liquid chromatography.

[0067] CLSM (Confocal Laser Scanning Microscopy) before and after enzymatic digestion:

[0068] The sample (1 g) was soaked in deionized water (5 mL) for 4 h, and then 30 mg of wet sample was stained with a mixed solution of fluorescein isothiocyanate (FITC Fourier transform infrared spectroscopy, 0.2 mg / mL) and rhodamine B (0.02 mg / mL). All samples were retained under light-protected conditions for a short period of time to avoid fluorescence quenching. All images were analyzed using ZEN imaging software. Several parameter settings were used: FITC fluorescence excitation wavelength was 488 nm, fluorescence emission wavelength was 450–540 nm; Rhodamine B fluorescence excitation wavelength was 543 nm, fluorescence emission wavelength was 545–660 nm.

[0069] Fermentation sample testing:

[0070] Neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein, and true protein were air-dried at 65°C, pulverized, and sieved through a 60-mesh sieve. 0.5g ± 0.001g of sample was accurately weighed, with three samples per treatment. For specific determination methods, refer to the Feed Analysis and Feed Quality Testing Technical Manual.

[0071] Figure 6 The images are electron micrographs before and after enzymatic hydrolysis. The combined treatment, namely the combined hydrolysis of α-amylase and pullulanase, can hydrolyze both α-1,4-glycosidic bonds and α-1,6-glycosidic bonds, resulting in more thorough degradation.

[0072] Figure 7 The images show the XRD patterns before and after enzymatic hydrolysis. With the dual-enzyme synergistic treatment: 0h: strong A-type peak. 72h: almost all characteristic peaks disappeared, and crystallinity decreased significantly (<10%), indicating that the dual enzymes completely degraded the starch crystal structure, releasing more fermentable sugars.

[0073] Figure 8 This represents the sugar content before and after enzymatic hydrolysis.

[0074] Summary of HPLC (High Performance Liquid Chromatography) Peak Analysis of Enzymatic Hydrolysis Products

[0075] 1. Single enzyme treatment (α-amylase or pullulanase) 11.514 / 12.036 min peaks: maltose (11.560 min) and maltotriose (12.001 min). The peak area increased with the enzymatic hydrolysis time, indicating that starch was gradually hydrolyzed into small molecule sugars.

[0076] Peak at 23.749 min: arabinose (23.263 min), possibly originating from: indirect release of hemicellulose from the distiller's grains (α-amylase destroys the starch encapsulation structure), and the synergistic effect of trace amounts of other enzymes (such as xylanase) in commercial enzyme preparations.

[0077] Pullulanase specificity phenomenon: A glucose peak appeared at 18.627 min after 48 h (18.704 min), and disappeared after 72 h, possibly because the glucose concentration was below the detection limit (due to excessive dilution).

[0078] 2. Synergistic treatment with two enzymes (α-amylase and pullulanase)

[0079] 11.506 / 11.975 min: Maltose and maltotriose showed a significant increase in peak area, indicating that the two enzymes synergistically improved starch degradation efficiency.

[0080] 18.639 min: The glucose peak appeared stably, confirming that pullulanase cleaved the α-1,6 glycosidic bond to release glucose.

[0081] Figure 9 These are electron microscope images of fermentation before and after enzymatic hydrolysis. Figure 9 In section A, different yeasts were inoculated without enzymatic hydrolysis. Figure 9 Figure B shows the results of multi-enzyme hydrolysis followed by inoculation with different yeasts. It can be seen that after multi-enzyme hydrolysis, starch granules become smaller, more porous, and have larger gaps. α-Amylase: randomly hydrolyzes α-1,4 glycosidic bonds in starch, breaking long-chain starch into short-chain dextrins and oligosaccharides (such as maltose and maltotriose), reducing the degree of starch polymerization, but cannot attack the α-1,6 bonds at branching points. Pullulanase: specifically cleaves the α-1,6 glycosidic bonds in amylopectin and glycogen, breaking the branching structure, releasing linear oligosaccharides, and exposing more non-reducing ends for saccharifying enzyme activity.

[0082] Glycoamylase: It hydrolyzes α-1,4 and α-1,6 bonds sequentially from the non-reducing end, completely degrading linear oligosaccharides into glucose.

[0083] Synergistic effect: α-amylase rapidly breaks down the starch skeleton, pullulanase eliminates branching barriers, and saccharifying enzymes ultimately achieve complete saccharification. The three-step combined approach can significantly improve starch conversion rate, which is superior to single enzyme treatment and is suitable for the deep degradation of high-viscosity materials such as distiller's grains.

[0084] Figure 10 In this study, the distribution of starch and protein in distiller's grains inoculated with different yeasts, Rhodamine B and Schizophyllum commune, was compared using fluorescent staining (FITC-labeled starch was green, Rhodamine B-labeled protein was red, and overlapping areas were yellow).

[0085] Undigested group ( Figure 10 (A)

[0086] Starch (green) densely coats protein (red), forming numerous overlapping yellow areas, indicating that the starch-protein complex has a dense structure that hinders microbial utilization. Yeast and Schizophyllum commune growth is restricted (the cell distribution in the image is sparse).

[0087] Multi-enzyme digestion group ( Figure 10 (B)

[0088] The starch signal was significantly weakened (green area decreased) and separated from the protein (yellow area decreased), indicating that enzymatic hydrolysis effectively degraded starch and released protein. The yeast and Schizophyllum commune were more densely distributed, indicating that the substrate availability was improved after enzymatic hydrolysis, which promoted microbial growth.

[0089] Conclusion: Enzymatic hydrolysis disrupts the starch-protein complex structure, releases nutrients, and significantly optimizes the fermentation environment of yeast and Schizophyllum commune.

[0090] Table 1. Fermented protein data before and after enzymatic hydrolysis.

[0091]

[0092] Table 2. Fiber data before and after enzymatic hydrolysis

[0093]

[0094]

[0095] Note: L125 represents Schizophyllum commune, TZJM represents Pichia pastoris, MKJM represents Maxella spp., CRJM represents Candida utilis, and BL5 represents Saccharomyces cerevisiae.

[0096] Changes in true protein: The enzymatic hydrolysis group (with added α-amylase, pullulanase, glucoamylase, and neutral protease) increased the true protein content by breaking down large molecules into smaller ones through enzymatic action. This is because proteolysis promotes protein release and the formation of soluble proteins, while the control group (without enzymatic hydrolysis) had lower protein release efficiency due to the lack of enzymatic hydrolysis.

[0097] Crude protein content decreases: The crude protein content decreases after enzymatic hydrolysis because some proteins are further broken down into free amino acids or small peptides during the hydrolysis process, which are then utilized by microorganisms to synthesize substances that can be absorbed and utilized by animals.

[0098] The fiber content increases after enzymatic hydrolysis because:

[0099] ① Enzymatic hydrolysis removes other components (such as starch and protein), increasing the relative proportion of fiber. In addition, microorganisms (such as Schizophyllum commune and yeast) may secrete cellulase during cultivation, partially degrading the fiber, but the remaining fiber becomes more prominent due to the reduction of other components.

[0100] ② During fermentation, the total content of available carbohydrates decreases due to microbial utilization, and fiber concentration leads to an increase in fiber content.

[0101] Therefore, the present invention adopts the above-mentioned method and apparatus for reducing the viscosity of lees based on enzyme treatment. It uses the internal and external rotation modes of the mixer to disperse the lees and mix the auxiliary materials. It uses a two-step enzymatic hydrolysis method to reduce the viscosity of the lees. The lees dispersion and two-step enzymatic hydrolysis method reduce the viscosity of the lees and improve the saccharification rate of the lees, laying the foundation for further fermentation of lees to produce protein.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for reducing the viscosity of distiller's grains based on enzyme treatment, characterized in that, Includes the following steps: S1. The lees of the liquor are broken up and the auxiliary materials are mixed using a mixer; S2. The mixed lees are dispersed and the pH is adjusted with ammonia water. Then, the enzymatic hydrolysate is added and enzymatically hydrolyzed for 24 hours. The enzymatic hydrolysate is mesophilic α-amylase and the enzymatic hydrolysis temperature is 70℃. S3. Add decomposing enzymes for further enzymatic hydrolysis to convert sugars into sugars. Detect physicochemical indicators after 12 hours. The decomposing enzymes are pullulanase and glucoamylase. The mixer includes a feed inlet, a discharge outlet, a rotating shaft, a motor, and a housing. The top of one end of the housing has a feed inlet, and the bottom of the other end has a discharge outlet. The rotating shaft is located inside the housing. One end of the rotating shaft is rotatably connected to the inner wall of the housing, and the other end penetrates through the inner wall of the housing. The end of the rotating shaft that penetrates through the inner wall of the housing has a pulley, and the pulley is connected to the output end of the motor via a belt. The rotating shaft is provided with an inner spiral ribbon and an outer spiral ribbon along the axis. The inner spiral ribbon and the outer spiral ribbon are spirally wound on the rotating shaft. The edge of the inner spiral ribbon blade is designed with a serrated or toothed structure. The outer spiral ribbon blade is also designed with a toothed shape, but it is misaligned with the toothed shape of the inner spiral ribbon. Shear force is generated through mirror rotation. The spiral direction of the outer spiral ribbon is opposite to that of the inner spiral ribbon.

2. The method for reducing the viscosity of distiller's grains based on enzyme treatment according to claim 1, characterized in that: In step S2, the pH is adjusted to 5.8 ± 0.2 using ammonia.

3. The method for reducing the viscosity of distiller's grains based on enzyme treatment according to claim 1, characterized in that: In step S2, after 24 hours of enzymatic hydrolysis, the pH decreased and stabilized at 5.0 ± 0.

5.

4. The method for reducing the viscosity of distiller's grains based on enzyme treatment according to claim 1, characterized in that: In step S3, the pullulanase activity is 5 U / g and the glucoamylase activity is 150 U / g.

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