Fermented edible sheepskin processing method based on plant lactobacillus

Abstract

The invention relates to a processing method of fermented edible sheepskin based on plant lactobacillus, and belongs to the technical field of food processing. Aiming at the problems of fiber damage, high microbial pollution risk, texture hardening after marinating and the like caused by chemical treatment in the traditional sheepskin processing, the invention provides a solution of combining biological fermentation with gradient temperature control. The method is characterized by comprising the following steps: soaking sheepskin (subjected to unhairing treatment) in a 4-6% sodium carbonate solution (40 DEG C, 2 hours) for pretreatment; activating the plant lactobacillus until the viable bacterium concentration is 8 * 8 * 10 < 8 >-1.2 * 10 < 9 > CFU / mL; performing staged fermentation on the sheepskin and the bacterial suspension according to a ratio of 1: 3 at 30-35 DEG C for 18 hours, and supplementing a 0.1% glucose solution of less than or equal to 5% during the fermentation; washing with distilled water and draining; the marinating liquid contains 8% of table salt, 2% of anise, 1% of cinnamon and 0.5% of clove. The method is used for producing edible sheepskin products with flexible texture and up-to-standard microbiological indexes.

Description

Technical Field

[0001] The present invention relates to the technical field of food processing. More specifically, the present invention relates to a method for processing edible sheepskin by fermentation based on Lactiplantibacillus plantarum. Background Art

[0002] Traditional processing of edible sheepskin mainly relies on treatment with strong alkali (such as sodium hydroxide) for degreasing and softening. The concentration of the alkali solution usually needs to reach 8%-12% to effectively degrade subcutaneous fat. The high-concentration alkali solution easily causes excessive hydrolysis of collagen in the sheepskin, manifested as erosion holes in local areas of the finished product, while other areas have undegraded fat layers remaining due to uneven penetration. This treatment method requires repeated adjustment of the pH value to neutralize the alkali solution, and multiple water washes result in a water consumption of 15-20 times the mass of the raw material, and the COD value of the wastewater exceeds 5000 mg / L.

[0003] Although the natural fermentation process can avoid chemical pollution, due to the uncontrollability of environmental bacteria, the fermentation process is often accompanied by the proliferation of pathogenic bacteria such as Escherichia coli and Salmonella. Existing statistics show that the microbial over-standard rate of natural fermented sheepskin products can reach 23%-35%, and it is necessary to rely on high-temperature sterilization at 121°C to make up for it, but the high temperature causes the collagen fibers to shrink and harden, and the hardness of the product reaches 15-18 kg·f, and the chewing resilience is lower than 0.7.

[0004] In the brining process, in order to cover up the peculiar smell, the brining time is usually extended to more than 40 minutes. The high-temperature and long-time treatment exacerbates the thermal denaturation of collagen fibers, resulting in the formation of an irreversible hardened film layer on the surface of the sheepskin, which affects the penetration of flavor substances. At the same time, the traditional process does not establish a standard for brine circulation. After repeated use, the salinity fluctuation of the brine reaches ±25%, and the loss rate of spice components due to volatilization and thermal decomposition exceeds 60%, resulting in significant flavor differences between batches.

[0005] The prior art has tried to use enzymatic hydrolysis to replace alkali treatment, but the cost of protease (such as trypsin) is as high as 200-300 yuan / kg, and it is difficult to control the enzymatic hydrolysis end point. The products of over-enzymatic hydrolysis are prone to produce bitter peptides. And the research on artificial inoculation fermentation mostly focuses on single strains of lactic acid bacteria, and the problems of staged nutrient supply and temperature adaptation have not been solved, and it is difficult to form an effective biofilm layer. These factors restrict the quality stability and large-scale production of edible sheepskin products. Summary of the Invention

[0006] An object of the present invention is to solve at least the above problems and provide at least the advantages described hereinafter.

[0007] To achieve these and other advantages in accordance with the present invention, there is provided a method for processing edible sheepskin by fermentation based on Lactiplantibacillus plantarum, comprising: Soak the freshly dehaired sheepskin in a sodium carbonate solution with a mass concentration of 4%-6% at an immersion temperature of 38-42°C for 1.5-2.5 h. After immersion, rinse with distilled water until the pH value reaches 6.5-7.0; Inoculate Lactobacillus plantarum into MRS liquid medium for activation culture. The culture conditions are static culture at 37°C for 16-20 h to obtain a bacterial suspension with a viable bacteria concentration of 8×10 8 -1.2×10 9 CFU / mL; Cut the sheepskin into strips, then immerse it in the bacterial suspension at a mass-to-volume ratio of 1:3, keep it immersed, and statically ferment at 30-35°C for 15-18 h. During the fermentation process, supplement and add a glucose solution with a mass fraction of 0.1%, and the addition amount does not exceed 5% of the total volume of the bacterial suspension; Take out the fermented sheepskin and rinse it 2-4 times with distilled water. The interval time between each rinse is 3-7 minutes. After rinsing, place it in a clean environment to drain the surface moisture. The amount of distilled water used for each rinse is 1.5-2.5 times the mass of the sheepskin; Put the air-dried sheepskin directly into the braising liquid. The braising liquid consists of 8% table salt, 2% star anise, 1% cinnamon, and 0.5% cloves by mass fraction. The braising temperature is 85-90°C, and the braising time is 15-20 minutes. The mass-to-volume ratio of the sheepskin to the braising liquid is 1:4, and the finished product is obtained after completion.

[0008] Preferably, the fermentation step specifically includes: In the initial stage of fermentation, after mixing the sheepskin and the bacterial suspension at a mass-to-volume ratio of 1:3, first statically ferment at 30-32°C for 6 h to form an initial bacterial colonization layer. Among them, the viable bacteria concentration of the bacterial suspension in this stage is controlled at 8×10 8 -1.2×10 9 CFU / mL; In the middle stage of fermentation, raise the temperature to 33-34°C and continue to ferment for 6 h. During this period, stir and turn the sheepskin intermittently once every 3 h; In the final stage of fermentation, maintain the temperature at 35°C and ferment for 6 h, and supplement and add a 0.1% glucose solution with a volume of 2% of the total volume of the bacterial suspension at the beginning of this stage; Among them, supplement and add a 0.1% glucose solution with a volume of 3% of the total volume of the bacterial suspension at the 6th h of fermentation.

[0009] Preferably, the braising step specifically includes: Put the air-dried sheepskin into the braising liquid in two batches. The mass ratio of the first batch to the second batch is 2:1. First put in the first batch of sheepskin and braise it at 85-87°C for 8-10 minutes. The mass-to-volume ratio of the first batch of sheepskin to the braising liquid is 1:6; Keep the marinating temperature constant, add the second batch of lambskins, and continue marinating for 7 - 10 minutes. After adding the second batch of lambskins, adjust the overall mass - volume ratio of the lambskins to 1:4. After marinating, leave all the lambskins in the marinating liquid and let them cool naturally to 50 - 55°C at a cooling rate of 2 - 3°C per minute. Among them, before adding the first batch of lambskins, add yeast extract with a mass fraction of 0.8% to the marinating liquid according to the initial total mass of the marinating liquid, and when the temperature of the marinating liquid drops to 60°C after marinating is completed, add clove powder with a mass fraction of 0.2% according to the total mass of the marinating liquid at this time. The total addition amount of yeast extract and clove powder does not exceed 1% of the initial total mass of the marinating liquid.

[0010] Preferably, the activation and cultivation step specifically includes: Inoculate Lactiplantibacillus plantarum into MRS liquid medium at an inoculation amount of 1% - 3%, and culture it by shaking at 60 - 80 rpm at 34 - 35°C for 6 - 8 h. Among them, adjust the initial pH value of the MRS liquid medium to 6.2 - 6.4. Stop shaking, raise the culture temperature to 37°C and let it stand for 10 - 12 h. At the 2nd h and 8th h after the start of the static culture, add L - cysteine hydrochloride with a mass fraction of 0.05% and vitamin B with a mass fraction of 0.02% to the MRS liquid medium respectively. 12 Each addition volume does not exceed 1% of the total volume of the MRS liquid medium.

[0011] Preferably, in the soaking step, the mass - volume ratio of the sodium carbonate solution to the lambskins is 1:5 - 1:7, and after the soaking is completed, perform centrifugal dehydration treatment. The centrifugation conditions are 2000 - 2500 rpm for 5 - 8 minutes.

[0012] Preferably, in the rinsing step, after each rinsing, blow the surface of the lambskins with sterile compressed air. The pressure of the sterile compressed air is 0.2 - 0.3 MPa, and the blowing time is 30 - 60 seconds.

[0013] Preferably, after the cooling step, the marinating liquid is recycled. When recycling, the mass of the added salt is 10% - 15% of the salt mass during the first marinating, the mass of the added star anise is 5% - 8% of the star anise mass during the first marinating, and the mass of the added clove is 3% - 5% of the clove mass during the first marinating.

[0014] Preferably, before packaging, the finished product is subjected to ultraviolet sterilization treatment. The ultraviolet wavelength is 253.7 nm, the irradiation dose is 8 - 10 mJ / cm², and the irradiation distance is 10 - 15 cm.

[0015] Preferably, the moisture content of the finished sheepskin is detected by interval sampling using an infrared moisture meter. Among them, the sampling ratio for interval sampling detection is 5%-8% of the mass of each batch of finished sheepskin, and the sampling points include both ends and the middle part of the sheepskin. When the detected moisture content is higher than 60%, the finished sheepskin is dried in a hot air environment at 45-50°C for 5-8 minutes, and the hot air velocity is 2-3 m / s.

[0016] Preferably, the Lactiplantibacillus plantarum is Lactiplantibacillus plantarum XAR-10, and the taxonomic name is Lactiplantibacillus plantarum XAR-10, which is deposited in the China Center for Type Culture Collection, with the deposit number CCTCC NO: M 2024143, the deposit date is January 19, 2024, and the deposit address: Wuhan University, Wuhan, China.

[0017] The present invention has at least the following beneficial effects: First, through gentle soaking with a sodium carbonate solution (4%-6%) and selectively removing the fat layer at 38-42°C, the risk of collagen fiber breakage caused by traditional strong alkalis is reduced. Fermentation with Lactiplantibacillus plantarum (30-35°C, 15-18 h) forms a dense biofilm, and its metabolites decompose connective tissues, improving the extensibility of sheepskin and inhibiting the reproduction of miscellaneous bacteria at the same time. Batchwise marinating (85-90°C, 15-20 min) combined with the strategy of gradient feeding of the marinating liquid enables the spice components to gradually penetrate, avoiding surface hardening caused by high-temperature long-term treatment. Multi-stage rinsing with distilled water (1.5-2.5 times the amount of water each time) and blowing with compressed air (0.2-0.3 MPa) synergistically reduce the microbial load, and the total number of colonies of the final product is controlled below 50 CFU / g, and the texture elasticity reaches above 0.85.

[0018] Second, temperature-controlled fermentation in stages (initial 30-32°C → middle 33-34°C → final 35°C) adapts to the metabolic cycle of the strain: the initial low temperature promotes the colonization of the bacterial cells, the temperature increase in the middle stage accelerates the secretion of proteolytic enzymes, and the final stage maintains the activity to complete collagen degradation. Regular turning (once every 3 h) eliminates temperature stratification and ensures the uniformity of fermentation. Timely supplementation of glucose (3% at the 6th h and 2% at the 12th h) avoids excessive accumulation of organic acids caused by excessive carbon sources and maintains the appropriate range of pH 5.8-6.2. This operation increases the tensile strength of the sheepskin to 12.5 kg·f, and there are no local softening defects.

[0019] Third, batch marinating of sheepskin (1:6 liquor ratio for the first batch → adjusted to 1:4 for the second batch) to reduce the heat load: The large liquor ratio in the first batch ensures the heat conduction efficiency, and the second batch utilizes the waste heat for penetration, shortening the total marinating time to within 18 minutes. Pre-adding yeast extract (0.8%) enhances the adsorption of umami substances, and adding clove powder (0.2%) at 60°C retains volatile aroma components, increasing the retention rate of flavor substances by 40%. When the marinating liquid circulates, quantitative feeding (10%-15% salt supplementation / 5%-8% star anise supplementation) is carried out to maintain the Baume degree at 18 ± 0.5°Bé, making the finished products of the fifth cycle of marinating indistinguishable from the first in terms of flavor.

[0020] Fourth, two-stage activation of strains (oscillation + static) to improve the viable cell yield: Oscillatory culture (34 - 35°C, 70 rpm) increases the cell concentration to 5×10 8 CFU / mL, and static culture (37°C) promotes the synthesis of extracellular polysaccharides by the bacteria. Eventually, the viable cell concentration exceeds 1×10 9 CFU / mL. Regularly adding L-cysteine hydrochloride (0.05%) and vitamin B 12 (0.02%) maintains the coenzyme activity, and the survival rate of the bacteria is > 95%. This scheme makes the fluctuation range of the viable cell concentration between fermentation batches ≤ ±5%, ensuring the fermentation stability.

[0021] Using the preserved strain XAR-10 (CCTCC NO: M 2024143) ensures the consistency of fermentation activity, and its acid resistance (pH 5.0) inhibits the growth of miscellaneous bacteria. Subculturing no more than five generations and storing at -80°C makes the decline rate of viable bacteria < 0.1% / generation, and the fluctuation range of the texture hardness of sheepskin between fermentation batches ≤ ±0.5 kg·f.

[0022] Other advantages, objectives, and features of the present invention will be partially reflected by the following description and partially understood by those skilled in the art through the research and practice of the present invention. Detailed Description of the Invention

[0023] The following further elaborates on the present invention in conjunction with embodiments, enabling those skilled in the art to implement it with reference to the text of the specification.

[0024] It should be noted that the experimental methods described in the following implementation examples are all conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial sources unless otherwise specified.

[0025] An embodiment of the present invention provides a method for processing fermentable edible sheepskin based on Lactiplantibacillus plantarum, including: Soaking the freshly dehaired sheepskin in a sodium carbonate solution with a mass concentration of 4% - 6%, at an immersion temperature of 38 - 42°C for 1.5 - 2.5 h, and after immersion, rinsing with distilled water until the pH value reaches 6.5 - 7.0; Inoculate Lactobacillus plantarum into MRS liquid medium for activation culture. The culture conditions are static culture at 37°C for 16 - 20 h to obtain a bacterial suspension with a viable bacteria concentration of 8×10 8 -1.2×10 9 CFU / mL; Cut the sheepskin into strips, and then immerse it in the bacterial suspension according to the mass - volume ratio of 1:3, keep it immersed, and carry out static fermentation at 30 - 35°C for 15 - 18 h. During the fermentation process, supplement and add a glucose solution with a mass fraction of 0.1%, and the addition amount does not exceed 5% of the total volume of the bacterial suspension; Take out the fermented sheepskin and rinse it with distilled water 2 - 4 times. The interval time between each rinse is 3 - 7 minutes. After rinsing, place it in a clean environment to drain the surface moisture. The amount of distilled water used for each rinse is 1.5 - 2.5 times the mass of the sheepskin; Put the air - dried sheepskin directly into the braising liquid. The braising liquid consists of 8% (mass fraction) of table salt, 2% (mass fraction) of star anise, 1% (mass fraction) of Chinese cinnamon, and 0.5% (mass fraction) of cloves. The braising temperature is 85 - 90°C, the braising time is 15 - 20 minutes, and the mass - volume ratio of the sheepskin to the braising liquid is 1:4. After completion, the finished product is obtained.

[0026] In the above - mentioned embodiment, in the soaking step, the mass concentration of the sodium carbonate solution can be selected as 4.0%, 4.5%, 5.0%, 5.5%, or 6.0%; the temperature can be selected as 38°C, 39°C, 40°C, 41°C, or 42°C; the time can be selected as 1.5 h, 1.8 h, 2.0 h, 2.2 h, or 2.5 h. The target pH value range after rinsing is 6.5 - 7.0, which can be monitored by pH test paper or digital pH meter. The equipment can use a constant - temperature water bath to maintain the temperature, and use a stainless - steel soaking tank to hold the solution. The sodium carbonate is food - grade, and the mass - volume ratio of the sheepskin to the solution of 1:5 - 1:7 can be controlled by weighing. After soaking, a horizontal centrifuge can be used for centrifugal dehydration, with a rotation speed of 2000 - 2500 rpm (such as 2200 rpm, 2400 rpm) and a time of 5 - 8 minutes (such as 6 minutes, 7 minutes). This step can remove impurities on the surface of the sheepskin and adjust the pH, creating conditions for subsequent fermentation.

[0027] The size of sheepskin has a significant impact on the technological effect and eating experience. The optimal cutting time is preferably after soaking in sodium carbonate and before fermentation. Since the sheepskin softens after soaking, cutting is less likely to strain the fibers, and cutting after fermentation is avoided to prevent damage to the formed bacterial colonization layer. The length is 5 - 8 cm and the width is 1.5 - 2.0 cm, ensuring the penetration efficiency of the bacterial suspension and adapting to the heat convection space of the marinating container. A food-grade stainless steel reciprocating cutter can be used, with a tool inclination angle of 30° (to reduce the fiber cutting rate), and the ambient temperature during cutting is controlled at 10 - 15 °C (to inhibit microbial proliferation). A width of 1.5 cm shows the best performance in terms of fermentation uniformity, marinating efficiency, and palatability. A width less than 2 cm ensures that the bacterial suspension completely penetrates to the center of the sheepskin within 6 h, and a width of 1.5 cm shortens the time for the central temperature to reach 85 °C during marinating to 8.5 min. The tensile strength is good when the aspect ratio is 3:1 - 5:1.

[0028] Lactiplantibacillus plantarum (such as strain XAR - 10 with the preservation number CCTCC NO: M 2024143) is inoculated into MRS liquid medium, and the inoculation amount can be selected as 1.0%, 2.0%, or 3.0%. The activation is carried out in two stages: first, shake-culture at 34–35 °C (such as 34.5 °C) at 60–80 rpm (such as 70 rpm) for 6–8 h (such as 7 h), and the initial pH of the medium is adjusted to 6.2–6.4 (such as 6.3); then statically culture for 10–12 h (such as 11 h) at 37 °C. During this period, L-cysteine hydrochloride (food grade) and vitamin B 12 (medical grade) are added, and the addition amount each time is ≤ 1% of the medium volume. During fermentation, the sheepskin and the bacterial suspension are mixed at a mass-volume ratio of 1:3, and the viable cell concentration is 8×10 8 –1.2×10 9 CFU / mL (such as 1.0×10 9 CFU / mL). A constant-temperature shaker and a sterile fermenter can be selected as the equipment. The addition amount of glucose solution (0.1%) is ≤ 5% (such as 3%, 4%) of the total volume of the bacterial suspension and is supplemented in stages. A uniform bacterial film is formed during this process, promoting the degradation of sheepskin.

[0029] After fermentation, the sheepskin is rinsed with distilled water 2–4 times (such as 3 times), and the water consumption each time is 1.5–2.5 times (such as 2.0 times) the mass of the sheepskin, with an interval of 3–7 minutes (such as 5 minutes). A spray cleaning machine can be used as the equipment. After rinsing, it is blown with sterile compressed air (pressure 0.2–0.3 MPa such as 0.25 MPa, time 30–60 s such as 45 s). Drainage is carried out on a clean workbench, and the ambient humidity ≤ 50%. This step removes residual bacteria and metabolites, avoiding cross-contamination.

[0030] The brine contains 8% salt, 2% star anise, 1% cinnamon, and 0.5% cloves. The lamb skins are put in in two batches: the first batch accounts for 2 / 3 of the total amount, and the mass - to - volume ratio of lamb skins to brine is 1:6 (e.g., 100g:600mL), and it is brined at 85 - 87°C (e.g., 86°C) for 8 - 10 minutes (e.g., 9 minutes); the second batch accounts for 1 / 3, and the overall ratio is adjusted to 1:4 (e.g., 300g:1200mL), and it is brined for 7 - 10 minutes (e.g., 8 minutes). A jacketed brine - cooking pot can be selected as the equipment. Before brining, 0.8% yeast extract (food - grade) is added according to the mass of the initial brine, and 0.2% clove powder is added when the temperature drops to 60°C (total addition amount ≤ 1%). The finished product is sterilized by ultraviolet light (wavelength 253.7nm, dose 8 - 10mJ / cm², e.g., 9mJ / cm², distance 10 - 15cm, e.g., 12cm). The moisture is detected by an infrared moisture meter (sampling ratio 5% - 8%). When it exceeds the standard, it is dried with hot air at 45 - 50°C (e.g., 48°C) for 5 - 8 minutes (wind speed 2 - 3m / s, e.g., 2.5m / s). This process endows flavor and ensures product safety.

[0031] In this example, the microbial activity is optimized by controlling the fermentation parameters in stages, and the thermal damage is reduced by combined gradient brining, and finally an edible lamb skin product with uniform texture is obtained. Ultraviolet sterilization and moisture control extend the shelf life, and centrifugal dehydration and compressed - air purging improve the processing efficiency.

[0032] In another example, the fermentation step specifically includes: In the initial fermentation stage, the lamb skins and the bacterial suspension are mixed at a mass - to - volume ratio of 1:3, and then left to ferment statically at 30 - 32°C for 6h to form an initial bacterial colonization layer. Among them, the viable - cell concentration of the bacterial suspension in this stage is controlled at 8×10 8 -1.2×10 9 CFU / mL; In the middle fermentation stage, the temperature is raised to 33 - 34°C and fermentation continues for 6h. During this period, the lamb skins are intermittently stirred and turned over once every 3h; In the final fermentation stage, the temperature is maintained at 35°C and fermentation continues for 6h, and a 0.1% glucose solution accounting for 2% of the total volume of the bacterial suspension is supplemented at the beginning of this stage; Among them, a 0.1% glucose solution accounting for 3% of the total volume of the bacterial suspension is supplemented at the 6th hour of fermentation.

[0033] In the above example, the temperature in the initial fermentation stage can be selected as 30°C, 31°C, or 32°C, and 31°C is typically used in the typical implementation. The viable - cell concentration can be selected as 8×10 8 CFU / mL, 1.0×10 9 CFU / mL, or 1.2×10 9 CFU / mL, and 1.0×10 9CFU / mL is a commonly used value. A constant temperature fermentation tank can be selected for the equipment, and the tank body is equipped with a temperature sensor and a bacterial suspension circulation system. The sheepskin and the bacterial suspension are mixed at a mass-volume ratio of 1:3 (such as 10 kg of sheepskin: 30 L of bacterial suspension) and then left to stand. During this stage, the bacteria are allowed to form a uniform colonization layer on the surface of the sheepskin through constant temperature standing, without mechanical agitation.

[0034] The temperature is raised to 33 °C, 33.5 °C or 34 °C, and 33.5 °C is typically used in the typical implementation. The stirring interval is fixed at once every 3 h (such as at the 9th h and 12th h), and the stirring action can be manual turning or low-speed stirring with a mechanical paddle (rotation speed ≤ 15 rpm). The equipment can be configured with a timing stirring device, and the stirring paddle is located in the middle of the fermentation tank. When turning, the upper and lower positions of the sheepskin are interchanged, and each turning lasts for 30 - 45 seconds. Stirring during this stage promotes nutrient exchange and avoids local overheating.

[0035] The temperature is maintained at a constant 35 °C. The glucose supplement is carried out in two times: at the 12th h (the start of the final stage), a 0.1% glucose solution of 2% of the total volume of the bacterial suspension is added (such as adding 600 mL to 30 L of bacterial suspension); at the 18th h (before the end of fermentation), 3% (900 mL) is supplemented. The glucose solution can be prepared by mixing food-grade glucose powder and distilled water on-site. The adding device can be configured with a metering pump, and the liquid inlet is located at the top of the fermentation tank. Supplementing the carbon source during this stage maintains the activity of the bacterial community and promotes collagen degradation.

[0036] In this embodiment, the temperature control in stages and the timing stirring optimize the microbial metabolism efficiency. The initial standing ensures the uniform formation of the bacterial film, the middle-stage turning prevents temperature stratification, and the accurate glucose supplementation in the final stage avoids resource waste. This control logic helps to obtain a fermented sheepskin product with consistent texture.

[0037] In yet another embodiment, the marinating step specifically includes: The dried sheepskin is put into the marinating liquid in two batches, and the mass ratio of the first batch to the second batch is 2:1. First, the first batch of sheepskin is put in and marinated at 85 - 87 °C for 8 - 10 minutes. The mass-volume ratio of the first batch of sheepskin to the marinating liquid is 1:6; Keeping the marinating temperature unchanged, the second batch of sheepskin is put in and marinated for another 7 - 10 minutes. After the second batch of sheepskin is put in, the overall mass-volume ratio of the sheepskin is adjusted to 1:4; After marinating is completed, all the sheepskin is left in the marinating liquid and naturally cooled to 50 - 55 °C at a cooling rate of 2 - 3 °C per minute; Among them, before adding the first batch of sheepskin, 0.8% of yeast extract by mass fraction is added to the marinating liquid in advance according to the initial total mass of the marinating liquid, and 0.2% of clove powder by mass fraction is added according to the total mass of the marinating liquid when the temperature is cooled to 60 °C after marinating is completed. The total addition amount of the yeast extract and the clove powder does not exceed 1% of the initial total mass of the marinating liquid.

[0038] In the above embodiments, for the technical content of claim 3, the input amount of the first batch of sheepskins accounts for 2 / 3 of the total amount (e.g., 6 kg), and the mass-volume ratio of the brine to the sheepskins can be selected as 1:6 (e.g., 6 kg of sheepskins: 36 L of brine). The brining temperature can be selected as 85 °C, 86 °C or 87 °C, and the time is 8 - 10 minutes (e.g., 9 minutes). A stainless steel jacketed brining pot can be selected as the equipment, and the pot body is equipped with a thermometer and a timer. The second batch of sheepskins accounts for 1 / 3 (e.g., 3 kg). After being put in, the overall mass-volume ratio is adjusted to 1:4 (e.g., 9 kg of sheepskins: 36 L of brine), and brining continues for 7 - 10 minutes (e.g., 8.5 minutes). The interval time between the two batches does not exceed 2 minutes.

[0039] Yeast extract is added before the first batch of feeding, and the addition amount is 0.8% of the initial total mass of the brine (e.g., 288 g is added to 36 L of brine). Commercially available food-grade yeast extract powder can be selected. Cloves powder is added when the temperature is lowered to 60 °C, and the addition amount is calculated according to the total mass of the brine at this time (e.g., when the mass of the brine after cooling is 34 kg, 68 g is added), and the concentration is 0.2%. The adding device can be configured with an automatic powder feeder, and the feeding port is located on the side wall of the brining pot. The total addition amount of yeast extract and cloves powder does not exceed 1.0% of the initial mass of the brine (e.g., the upper limit for 36 kg of brine is 360 g).

[0040] After brining is completed, it is naturally cooled, and the cooling rate is controlled at 2.0 °C / min, 2.5 °C / min or 3.0 °C / min (e.g., 2.5 °C / min). The target cooling end point is 50 - 55 °C (e.g., 52 °C), which can be achieved through the cooling water system in the pot body jacket. When the brine is recycled, the supplementary amount of salt is 10% - 15% of the first time (e.g., the first time the salt is 2.88 kg, and 0.29 - 0.43 kg is supplemented), the supplementary amount of star anise is 5% - 8% (e.g., the first time the star anise is 0.72 kg, and 0.036 - 0.058 kg is supplemented), and the supplementary amount of cloves is 3% - 5% (e.g., the first time the cloves is 0.18 kg, and 0.0054 - 0.009 kg is supplemented). The supplementary materials are added when the brine is heated to 80 °C.

[0041] In this embodiment, batch brining reduces the damage of the heat load to the texture of the sheepskins. Yeast extract enhances flavor penetration, and the strategy of adding cloves later avoids the high-temperature volatilization of aroma components. Temperature control cooling and quantitative supplementary feeding maintain the stability of the brine, and recycling reduces the production cost.

[0042] In another embodiment, the activation culture step specifically includes: Lactiplantibacillus plantarum is inoculated into the MRS liquid medium at an inoculation amount of 1% - 3%, and cultured with shaking at 60 - 80 rpm at 34 - 35 °C for 6 - 8 h. Among them, the initial pH value of the MRS liquid medium is adjusted to 6.2 - 6.4. Stop shaking, raise the culture temperature to 37 °C and statically culture for 10 - 12 h; At the 2nd hour and the 8th hour after the start of static culture, 0.05% (mass fraction) of L-cysteine hydrochloride and 0.02% of vitamin B were respectively added to the MRS liquid medium. 12 The volume added each time did not exceed 1% of the total volume of the MRS liquid medium.

[0043] In the above-mentioned embodiment, the inoculation amount can be selected as 1.0%, 1.5%, 2.0%, 2.5% or 3.0% (such as 2.0%). The temperature range is 34 - 35 °C (such as 34.5 °C), the oscillation speed is 60 - 80 rpm (such as 70 rpm), and the culture time is 6 - 8 hours (such as 7 hours). A constant temperature shaker can be selected as the equipment, and a sterile Erlenmeyer flask is placed in the shaker to contain the MRS medium. The initial pH value of the medium is calibrated to 6.2 - 6.4 (such as 6.3) by a pH meter, and food-grade hydrochloric acid or sodium hydroxide solution can be used for adjustment. During the oscillation culture process, the bacterial liquid remains in a uniformly suspended state.

[0044] After stopping the oscillation, the temperature rises to 37 °C (±0.5 °C) for static culture for 10 - 12 hours (such as 11 hours). The equipment can be transferred to a constant temperature incubator, and the culture container remains in a static state. The temperature switching time is controlled to be completed within 20 minutes to avoid affecting the bacterial activity due to sudden temperature changes. During the static period, the bacteria gradually settle to form a layered metabolic environment.

[0045] L-cysteine hydrochloride (food grade) was added at the 2nd hour of static culture, with a concentration of 0.05% (such as adding 50 mg to 100 mL of medium); vitamin B 12 (medical grade) was added at the 8th hour, with a concentration of 0.02% (such as adding 20 mg to 100 mL of medium). The volume of the added solution did not exceed 1.0% of the total volume of the medium (such as adding ≤10 mL to 1 L of medium). A micro-injection pump can be configured as the feeding device, and the liquid inlet is located at the upper part of the culture container. After adding, the container was gently shaken to mix the solution evenly.

[0046] The staged culture strategy in this embodiment adapts to the metabolic requirements of the strain at different growth stages. The oscillation stage promotes the proliferation of bacteria, and the static stage accumulates metabolites. Precise addition of L-cysteine hydrochloride and vitamin B 12 maintains the coenzyme activity and ensures that the viable cell concentration of the final bacterial suspension stably reaches 8×10 8 –1.2×10 9 CFU / mL technical requirements.

[0047] In another embodiment, in the soaking step, the mass-volume ratio of the sodium carbonate solution to the sheepskin is 1:5 - 1:7, and after the soaking ends, centrifugal dehydration treatment is carried out, and the centrifugation conditions are 2000 - 2500 rpm for 5 - 8 minutes.

[0048] In the above embodiments, the mass concentration of the sodium carbonate solution can be selected from 4.0%, 4.5%, 5.0%, 5.5% or 6.0% (such as 5.0%). The mass-to-volume ratio of the solution to the sheepskin can be selected from 1:5, 1:6 or 1:7 (such as 1:6), that is, 5 - 7 liters of the solution are used per kilogram of sheepskin. The equipment can be a stainless-steel soaking tank with scale markings, and a drain valve is provided at the bottom of the tank body. Temperature control is achieved through an external constant-temperature water circulation system, and the temperature sensor probe is located in the middle of the tank body. After the soaking is completed, the pH value is detected using a digital pH meter, and the probe is immersed in the liquid layer on the surface of the sheepskin.

[0049] The centrifugation speed can be selected from 2000 rpm, 2200 rpm, 2400 rpm or 2500 rpm (such as 2300 rpm). The centrifugation time can be selected from 5 minutes, 6 minutes, 7 minutes or 8 minutes (such as 6.5 minutes). The equipment can be a horizontal centrifuge, and the drum capacity is matched according to the batch of sheepskin (such as a 50L drum for a 10kg batch). After centrifugation, the water content of the sheepskin is controlled at 45% - 50%, and the dehydration rate is calculated by the weighing method. The drum lining can be configured with a food-grade polyethylene filter screen with a pore size of ≤2mm to prevent damage to the sheepskin fibers.

[0050] Immediately take out the sheepskin after centrifugation to avoid the temperature rising due to long-term retention. The transfer equipment can be a stainless-steel conveyor belt with a conveying speed of 0.5m / s. The sheepskin is laid flat in a single layer on a sterile tray, and the tray is placed on a ventilation rack, with the ambient temperature of 25 ± 2°C and the relative humidity ≤60%. The standing time is 10 - 15 minutes (such as 12 minutes) to allow the surface moisture to volatilize evenly.

[0051] The precise solution ratio in this embodiment ensures the consistency of the alkali treatment effect, and centrifugal dehydration significantly shortens the time of the subsequent draining process. The filter screen configuration reduces the physical damage to the sheepskin, and ventilation and standing avoid local moisture residue. This combination of measures provides pre-treated sheepskin raw materials with stable water content for the fermentation process.

[0052] In another embodiment, in the rinsing step, after each rinsing, the surface of the sheepskin is purged with sterile compressed air. The pressure of the sterile compressed air is 0.2 - 0.3MPa, and the purging time is 30 - 60 seconds.

[0053] In the above embodiments, the number of times of rinsing with distilled water can be selected from 2 times, 3 times or 4 times (such as 3 times). The water consumption per time is 1.5 times, 2.0 times or 2.5 times the mass of the sheepskin (such as 2.0 times). The rinsing interval time can be selected from 3 minutes, 5 minutes or 7 minutes (such as 5 minutes). The equipment can be a food-grade stainless-steel spray cleaning machine, and the spray nozzles are evenly distributed 20 centimeters above the conveyor belt. The rinsing water temperature is maintained at 25 ± 3°C and is adjusted through an internal heat exchanger. After each rinsing, the residual liquid on the surface of the sheepskin naturally drains into the wastewater tank through the inclined conveyor belt.

[0054] The pressure of sterile compressed air can be selected as 0.20 MPa, 0.25 MPa or 0.30 MPa (such as 0.25 MPa). The purging time can be selected as 30 seconds, 45 seconds or 60 seconds (such as 45 seconds). An oil-free screw air compressor can be selected for the equipment, equipped with a 0.22-micron air filter. A fan-shaped stainless steel nozzle can be selected, installed 30 cm above the conveyor belt, with a spacing of 50 cm. The air flow direction forms a 45-degree angle with the surface of the sheepskin, and the coverage width is the same as the width of the conveyor belt. The air temperature is controlled at 40 ± 5°C to avoid shrinkage of the sheepskin caused by low temperature.

[0055] Immediately transfer to the draining area after purging. A multi-layer stainless steel mesh rack can be selected for the draining rack, with a layer spacing of 15 cm. The environmental cleanliness reaches the ten-thousand-class standard, and the temperature and humidity are respectively controlled at 25 ± 2°C and 50% ± 5%. The draining time is fixed at 10 minutes, during which the sheepskins are laid flat in a single layer without overlap. After each batch of sheepskins is drained, the mesh rack is sterilized by ultraviolet irradiation, and the irradiation dose is 5 mJ / cm 2 .

[0056] In this embodiment, the compressed air purging effectively removes the attached water on the surface of the sheepskin and reduces the subsequent draining time. The constant-temperature air flow avoids the influence of temperature fluctuations on the texture of the sheepskin, and the nozzle layout at a specific angle ensures the uniformity of purging. Combined with draining in a clean environment, the risk of secondary microbial contamination is reduced.

[0057] In another embodiment, the brine is recycled after the cooling step. When recycling, the mass of the added salt is 10% - 15% of the salt mass during the first brining, the mass of the added star anise is 5% - 8% of the star anise mass during the first brining, and the mass of the added clove is 3% - 5% of the clove mass during the first brining.

[0058] In the above embodiment, the salt supplement amount can be selected as 10%, 12% or 15% (such as 12%) of the salt mass during the first brining. The star anise supplement amount can be selected as 5%, 6% or 8% (such as 6%). The clove supplement amount can be selected as 3%, 4% or 5% (such as 4%). The supplementary materials are all food-grade raw materials, among which the salt is refined iodized salt, the star anise is whole dried product, and the clove is in powder form. An electronic scale can be selected for the supplementary material equipment to weigh quantitatively, and the feeding port is located above the side wall of the brine pot. When supplementing materials, the temperature of the brine needs to reach 80 ± 2°C and is monitored by a temperature sensor.

[0059] Record the basic usage amount of raw materials (such as 8 kg of salt per 100 L of brine) after the first brining. Heat the brine to 80°C before recycling, and at this time, turn on the stirring paddle (rotation speed 15 - 20 rpm). The supplementary materials weighed in proportion are added batch by batch through the feeding port: first add star anise and clove, and then add salt after stirring for 3 minutes. The total stirring time is 10 minutes until the solids are completely dissolved. The equipment can be configured with an automatic temperature control stirring system, and the stirring paddle is located at the center of the bottom of the brine pot.

[0060] It is recommended that the number of brine circulation times does not exceed 5 times. After each circulation, the brine salinity (Baumé degree ≥ 18°Bé) and pH value (5.0 - 5.5) are detected. Portable salinometers and pH meters can be selected as the detection equipment, and the depth of the probe immersed in the brine is ≥ 10 cm. Stop using when the salinity or pH value exceeds the range. After each use, the brine pot needs to be rinsed with hot water at 80°C, and the rinsing water volume is 30% of the brine pot volume.

[0061] In this embodiment, quantitative feeding maintains the stability of the concentration of flavor substances in the brine, and the feeding temperature of 80°C ensures the effective dissolution of spice components. Monitoring of salinity and pH value avoids the risk of brine deterioration, and hot water rinsing reduces the growth of microorganisms. This circulation scheme reduces raw material consumption on the premise of ensuring product flavor.

[0062] In another embodiment, the finished product is subjected to ultraviolet sterilization treatment before packaging. The ultraviolet wavelength is 253.7 nm, the irradiation dose is 8 - 10 mJ / cm², and the irradiation distance is 10 - 15 cm.

[0063] In the above embodiment, the ultraviolet wavelength is fixed at 253.7 nm (characteristic spectral line of low-pressure mercury lamp). The irradiation dose can be selected as 8.0 mJ / cm², 9.0 mJ / cm² or 10.0 mJ / cm² (such as 9.0 mJ / cm²). The irradiation distance can be selected as 10 cm, 12 cm or 15 cm (such as 12 cm). A conveyor belt type ultraviolet sterilizer can be selected as the equipment, and the lamp tube power is configured at 30W / 100cm². The lamp tube can be encapsulated with a quartz sleeve and installed on an adjustable bracket above the conveyor belt. The irradiation dose is achieved by controlling the conveyor belt speed, and the speed calculation formula is: speed (m / min) = total lamp tube power (W) × 60 / (dose (mJ / cm²) × bandwidth (cm)).

[0064] The arrangement spacing of the lamp tubes is 1.0 - 1.2 times the length of the lamp tube (such as the spacing of 60 cm long lamp tubes is 72 cm). The reflector can be selected as an anodized aluminum plate and installed 5 cm behind the lamp tube. The conveyor belt material is food-grade polytetrafluoroethylene, and the width matches the effective irradiation width of the lamp tube (such as 50 cm). The single-layer paving thickness of the sheepskin is ≤ 1.5 cm, and the paving interval is ≥ 2 cm. The equipment is preheated for 10 minutes before operation, and the ambient humidity is ≤ 65%. After sterilization, the surface temperature of the sheepskin is monitored ≤ 40°C, and the infrared thermometer probe is 10 cm away from the surface.

[0065] Detect the water content of sheepskin before sterilization (≤60%). When it exceeds the standard, pre-treat it with hot air at 45-50°C (wind speed 2-3m / s, time 5-8 minutes). Immediately transfer it to the cooling area after sterilization, with the cooling temperature at 4-8°C and the time being 15 minutes. Replace the lamp tube compulsorily when the cumulative usage reaches 1000 hours, and calibrate the ultraviolet intensity meter monthly. The cleanliness of the packaging environment reaches the ten-thousand-level standard. Select aluminum foil composite film as the packaging material, with an oxygen transmission rate ≤0.5cm³ / m²·24h.

[0066] In this Example 253.7nm ultraviolet rays effectively inactivate surface microorganisms, and precise irradiation dose control ensures the reliability of sterilization. The cooperation between the conveyor belt speed and the lamp tube layout achieves uniform irradiation, and water content control avoids the interference of water layer on ultraviolet absorption. This process meets the food safety requirements on the premise of maintaining the texture integrity of sheepskin.

[0067] In another embodiment, the water content of the finished sheepskin is detected by interval sampling with an infrared moisture analyzer. Among them, the sampling ratio for interval sampling detection is 5%-8% of the mass of each batch of finished sheepskin, and the sampling points include both ends and the middle part of the sheepskin; When the detected water content is higher than 60%, place the finished sheepskin in a hot air environment at 45-50°C for drying treatment for 5-8 minutes, and the hot air speed is 2-3m / s.

[0068] In the above embodiment, the sampling ratio can be selected as 5.0%, 6.5% or 8.0% (such as 6.0%). The detection equipment can choose a non-contact infrared moisture analyzer, and the probe is 5±1 cm away from the sheepskin surface. The sampling points are evenly divided according to the length of each batch of sheepskin: the sampling points at both ends are 10 cm away from the edge, and the middle sampling point is located at the geometric center. Each sampling point is detected 3 times and the average value is taken, and the single detection time ≤3 seconds. The equipment is calibrated using standard water-containing silica gel plates (water content 30%, 50%, 70%), and calibrated before daily use.

[0069] The drying temperature can be selected as 45°C, 47°C or 50°C (such as 48°C). The hot air speed can be selected as 2.0 m / s, 2.5 m / s or 3.0 m / s (such as 2.5m / s). The treatment time can be selected as 5 minutes, 6 minutes or 8 minutes (such as 7 minutes). The equipment can choose a hot air circulation drying oven, and the air ducts are evenly distributed on both sides of the box body. The sheepskin is laid flat in a single layer on a stainless steel mesh belt, and the mesh belt aperture ≤3mm. The temperature uniformity error in the box ≤±1.5°C, and the wind speed fluctuation ≤±0.2 m / s.

[0070] The moisture content detection frequency is one batch per 30 minutes. When the single-point detection value > 60% (such as 62%), the drying program is triggered. After drying, the retest sampling point is within 5 cm around the original over-standard point, and the target value of the retest moisture content ≤ 55%. The distance between the drying equipment and the detection station ≤ 5 m, and the transfer time ≤ 1 minute. The running speed of the mesh belt is 0.3 - 0.5 m / min (such as 0.4 m / min) to ensure uniform heating.

[0071] In this embodiment, multi-point sampling detection avoids quality fluctuations caused by uneven local moisture in the sheepskin, and infrared detection realizes non-destructive and rapid monitoring. Precise control of the hot air parameters prevents texture hardening caused by over-drying, and the closed-loop drying trigger mechanism ensures that the moisture content of the finished product meets the standard stably. This solution provides a reliable moisture control means for large-scale production.

[0072] In another embodiment, the Lactiplantibacillus plantarum is Lactiplantibacillus plantarum XAR-10, and the taxonomic name is Lactiplantibacillus plantarum XAR-10, which is deposited in the China Center for Type Culture Collection, with the deposit number CCTCC NO: M 2024143.

[0073] In the above embodiment, the cell morphology of Lactiplantibacillus plantarum XAR-10 is short rod-shaped (0.8 - 1.0 μm × 1.5 - 3.0 μm), and it is Gram-positive. The optimal growth temperature can be selected as 35 °C, 37 °C or 40 °C (such as 37 °C), and the pH tolerance range is 5.0 - 7.0 (such as 6.2). The strain source can be selected from the lyophilized tube provided by the China Center for Type Culture Collection (deposit number CCTCC NO: M 2024143). When activating and culturing, the viable cell concentration threshold of the bacterial suspension is set to 8×10 8 CFU / mL (the lowest value) and 1.2×10 9 CFU / mL (the highest value).

[0074] The production strain is passaged no more than 5 generations, and each generation of the strain is stored in a -80 °C glycerol tube (glycerol concentration 15%). The equipment can be selected from a liquid nitrogen tank or an ultra-low temperature refrigerator, and the storage rack is located in the middle of the freezer. Before use, it is necessary to verify the plate purity (MRS agar medium, cultured at 37 °C for 24 h).

[0075] Before the fermentation process, the activity of the strain is detected: inoculate the stored strain into MRS broth, and after culturing at 37 °C for 12 h, the OD600 value should reach 0.8 - 1.2 (such as 1.0). Unqualified strains are immediately discarded. The inoculation operation of the fermentation tank is carried out in a hundred-class clean bench, and the operation time ≤ 30 minutes. Each batch of production records the strain generation number, activation time and fermentation viable cell concentration, and archives them for future reference.

[0076] The use of the specific strain in this embodiment ensures the stability of fermentation activity, and strict strain management avoids performance degradation during the production process. The standard strain provided by the preservation institution has clear traceability, and combined with the records of the entire production process, it meets the regulatory requirements for microorganisms used in food processing.

[0077] <Example 1> Processing of edible sheepskin by fermentation based on Lactiplantibacillus plantarum: I. Experimental materials: Fresh sheepskin (dehaired): 10 kg (from 6-month-old goats, thickness 1.5 ± 0.2 mm); Lactiplantibacillus plantarum XAR-10: CCTCC NO: M 2024143; food-grade sodium carbonate, MRS medium, glucose, etc. (meeting the GB 31638 standard).

[0078] II. Experimental procedure 1. Pretreatment of sheepskin Soaking: Prepare 60 L of 5.0% sodium carbonate solution (6 times the mass of the sheepskin), heat it to 40°C. Put the sheepskin in and soak for 2.0 h, turning it over every 30 min. After taking it out, rinse it 4 times with distilled water (20 L of water each time) until the pH = 6.8 (detected with a pH meter).

[0079] Centrifugal dehydration: Place it in a horizontal centrifuge (2300 rpm, 6 min), and the water content of the sheepskin after dehydration is 48% ± 2%.

[0080] 2. Strain activation Take the freeze-dried tube of the strain and inoculate it into 100 mL of MRS liquid medium (pH 6.3), and culture it with shaking at 34°C and 70 rpm for 7 h. Transfer it to static culture at 37°C for 11 h, add 0.05% L-cysteine hydrochloride (1 mL) at the 2nd h, and add 0.02% vitamin B 12 (0.4 mL) at the 8th h. The concentration of the bacterial suspension is measured to be 1.0×10 9 CFU / mL (plate counting method).

[0081] 3. Fermentation Mix the sheepskin and the bacterial suspension in a ratio of 1:3 (10 kg of sheepskin + 30 L of bacterial suspension).

[0082] Stage control: 0 - 6 h: Static at 31°C to form a bacterial film; 6 - 12 h: Ferment at 33.5°C, manually turn it over once every 3 h; 12 - 18 h: Ferment at 35°C, add 600 mL of 0.1% glucose at the 12th h.

[0083] 4. Rinsing and draining After the fermentation is completed, rinse with distilled water three times (20 L each time, with a 5-minute interval).

[0084] Blow with sterile compressed air (0.25 MPa, 45 s), and let it stand in the draining room (25°C, RH 50%) for 10 minutes.

[0085] 5. Braising Braising liquid preparation: 36 L of water + 2.88 kg of table salt + 0.72 kg of star anise + 0.36 kg of cinnamon + 0.18 kg of cloves. After boiling, add 0.288 kg of yeast extract.

[0086] Braise in two batches: The first batch is 6 kg of sheepskin (braising liquid ratio 1:6), braise at 86°C for 9 minutes; the second batch is 4 kg of sheepskin. After putting it in, adjust the overall ratio to 1:4 and continue to braise for 8 minutes. Naturally cool down to 52°C (rate 2.5°C / min).

[0087] 6. Sterilization and Packaging Ultraviolet sterilization: wavelength 253.7 nm, dose 9.0 mJ / cm², distance 12 cm. Vacuum package with aluminum foil bags (residual oxygen content ≤ 0.8%).

[0088] III. Detection Process 1. Key Point Monitoring Table 1 Key Point Monitoring 2. Finished Product Detection Microbiological indicators (GB 4789.2): Total number of colonies: < 50 CFU / g (no pathogenic bacteria detected); Coliform bacteria: < 0.3 MPN / g; Texture analysis (Texture Analyzer TA.XT Plus): Hardness: 12.5 ± 0.8 kg·f; Elasticity: 0.85 ± 0.03 Moisture content (GB 5009.3): Multi-point detection with an infrared moisture analyzer: 55.2% ± 1.5% (meeting the requirement of ≤ 60%). Sensory evaluation (10-person group): Color and luster: Uniform light brown (qualified rate 100%); Odor: No rancidity, with a braised aroma (qualified rate 100%).

[0089] Through staged fermentation and gradient braising, the microbiological indicators of the finished product are significantly lower than the industry standards (such as the conventional requirement of < 1000 CFU / g for the total number of colonies). The texture parameters indicate an improvement in the flexibility of the sheepskin, and the moisture control avoids the risk of subsequent mildew. No chemical preservatives are used throughout the process, meeting the trend of clean labels.

[0090] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those skilled in the art, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to specific details and the embodiments shown and described herein.

Claims

1. A processing method for fermented edible sheepskin based on Lactiplantibacillus plantarum, characterized in that, Comprising: Soak the fresh sheepskin after hair removal treatment in a sodium carbonate solution with a mass concentration of 4% - 6%, at a soaking temperature of 38 - 42°C, for a soaking time of 1.5 - 2.5 h. After soaking, rinse with distilled water until the pH value reaches 6.5 - 7.0; Inoculate Lactobacillus plantarum in MRS liquid medium for activation culture. The culture conditions are static culture at 37 °C for 16 - 20 h to obtain a bacterial suspension with a viable cell concentration of 8×10 8 - 1.2×10 9 CFU / mL; Cut the sheepskin into strips, then immerse it in the bacterial suspension according to a mass - to - volume ratio of 1:3, keep it submerged, and let it stand and ferment at 30 - 35°C for 15 - 18 h. During the fermentation process, supplement and add a glucose solution with a mass fraction of 0.1%, and the addition amount does not exceed 5% of the total volume of the bacterial suspension; Take out the fermented sheepskin and rinse it with distilled water 2 - 4 times. The interval time between each rinse is 3 - 7 minutes. After rinsing, place it in a clean environment to drain the surface water. The amount of distilled water used for each rinse is 1.5 - 2.5 times the mass of the sheepskin; Put the air - dried sheepskin directly into the braising liquid. The braising liquid consists of 8% by mass of salt, 2% by mass of star anise, 1% by mass of cinnamon, and 0.5% by mass of cloves. The braising temperature is 85 - 90°C, and the braising time is 15 - 20 minutes. The mass - to - volume ratio of the sheepskin to the braising liquid is 1:4, and the finished product is obtained after completion; 2. The processing method of fermented edible sheepskin based on Lactobacillus plantarum according to claim 1, characterized in that, The fermentation step specifically includes: At the initial stage of fermentation, after mixing sheepskin with the bacterial suspension at a mass-volume ratio of 1:3, first let it stand and ferment at 30 - 32 °C for 6 h to form an initial colonization layer of bacteria. Among them, the viable bacteria concentration of the bacterial suspension in this stage is controlled at 8×10 8 -1.2×10 9 CFU / mL; In the middle stage of fermentation, raise the temperature to 33 - 34°C and continue to ferment for 6 h. During this period, stir and turn the sheepskin intermittently once every 3 h; In the final stage of fermentation, maintain the temperature at 35°C and ferment for 6 h, and supplement and add a 0.1% glucose solution with a volume of 2% of the total volume of the bacterial suspension at the beginning of this stage; Among them, supplement a 0.1% glucose solution with a volume of 3% of the total volume of the bacterial suspension at the 6th h of fermentation.

3. The processing method of fermented edible sheepskin based on Lactobacillus plantarum according to claim 1, characterized in that, The braising step specifically includes: Put the air - dried sheepskin into the braising liquid in two batches. The mass ratio of the first batch to the second batch is 2:

1. First, put in the first batch of sheepskin and braise it at 85 - 87°C for 8 - 10 minutes. The mass - to - volume ratio of the first batch of sheepskin to the braising liquid is 1:6; Maintain the braising temperature unchanged, put in the second batch of sheepskin, and continue to braise for 7 - 10 minutes. After the second batch of sheepskin is put in, the overall mass - to - volume ratio of the sheepskin is adjusted to 1:4; After braising is completed, leave all the sheepskin in the braising liquid to cool naturally to 50 - 55°C, and the cooling rate is 2 - 3°C / minute; Among them, before adding the first batch of sheepskin, add yeast extract with a mass fraction of 0.8% according to the initial total mass of the braising liquid, and add clove powder with a mass fraction of 0.2% according to the total mass of the braising liquid when it cools to 60°C after braising. The total addition amount of yeast extract and clove powder does not exceed 1% of the initial total mass of the braising liquid.

4. The processing method of fermented edible sheepskin based on Lactobacillus plantarum according to claim 1, characterized in that, The activation and culture step specifically includes: Inoculate Lactobacillus plantarum into the MRS liquid medium at an inoculation amount of 1% - 3%, and shake - culture at 34 - 35°C at 60 - 80 rpm for 6 - 8 h. Among them, the initial pH value of the MRS liquid medium is adjusted to 6.2 - 6.4, Stop shaking, raise the culture temperature to 37°C, and let it stand and culture for 10 - 12 h; At the 2nd hour and the 8th hour after the start of static culture, add 0.05% (by mass) of L-cysteine hydrochloride and 0.02% of vitamin B to the MRS liquid medium respectively. 12 The volume added each time does not exceed 1% of the total volume of the MRS liquid medium.

5. The processing method of fermented edible sheepskin based on Lactobacillus plantarum according to claim 1, characterized in that In the soaking step, the mass - to - volume ratio of the sodium carbonate solution to the sheepskin is 1:5 - 1:7, and after the soaking ends, perform centrifugal dehydration treatment. The centrifugal conditions are 2000 - 2500 rpm for 5 - 8 minutes.

6. The processing method of fermented edible sheepskin based on Lactobacillus plantarum according to claim 1, characterized in that, In the flushing step, sterile compressed air is used to blow the sheepskin surface after each flushing. The sterile compressed air pressure is 0.2-0.3MPa and the blowing time is 30-60 seconds.

7. The processing method of fermented edible sheepskin based on Lactobacillus plantarum according to claim 1, characterized in that, The marinating liquid is recycled after the cooling step, and the mass of the additional salt added during recycling is 10%-15% of the mass of the salt during the first marinating, the mass of the additional star anise added is 5%-8% of the mass of the star anise added, and the mass of the additional cloves added is 3%-5% of the mass of the cloves added during the first marinating.

8. The processing method of fermented edible sheepskin based on Lactobacillus plantarum according to claim 1, characterized in that, The finished product is sterilized by ultraviolet light before packaging. The ultraviolet wavelength is 253.7nm, the irradiation dose is 8-10mJ / cm², and the irradiation distance is 10-15cm.

9. The processing method of fermented edible sheepskin based on Lactobacillus plantarum according to claim 1, characterized in that The moisture content of the finished sheepskin is tested by interval sampling with an infrared moisture meter. The sampling ratio of the interval sampling test is 5%-8% of the mass of each batch of finished sheepskin, and the sampling points include the two ends and the middle part of the sheepskin. When the moisture content is detected to be higher than 60%, the sheepskin product is placed in a 45-50℃ hot air environment for drying for 5-8 minutes with a hot air speed of 2-3m / s.

10. The processing method of fermented edible sheepskin based on Lactobacillus plantarum according to claim 1, characterized in that, The plant Lactiplantibacillus plantarum is Lactiplantibacillus plantarum XAR-10, and its taxonomic name is Lactiplantibacillus plantarum XAR-10, which is deposited in the China Center for Type Culture Collection under the accession number CCTCC NO: M 2024143.

Images