Processing method for cooked mutton

Abstract

The invention relates to the technical field of food processing, in particular to a processing method for cooked mutton, which comprises the following steps: obtaining a fresh mutton raw material; performing pretreatment before fermentation on the fresh mutton raw material; adding a compound bacteria solution into the pretreated fresh mutton raw material, and fermenting to hydrolyze goaty-flavor substances in the mutton to obtain fermented mutton; immersing the fermented mutton into a composite gel solution and carrying out vacuum impregnation so as to selectively remove fermented free mutton smell substances, so as to obtain mutton smell removed mutton; and pickling the mutton with the removed mutton smell with ingredients, and cooking the mutton at 80-85 DEG C for 10-15 minutes to obtain a cooked mutton finished product, wherein the compound bacteria liquid consists of staphylococcus carnosus, pediococcus pentosaceus, lactococcus lactis and a calcium chloride solution. According to the invention, mutton-smell-causing short-chain branched fatty acid in mutton is degraded by a microbial mutton-smell-reducing method, and long-chain branched fatty acid with physiological activity is retained at the same time.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, in particular to a processing method for cooked mutton. Background Art

[0002] Branched-chain fatty acids (BCFAs) are a class of saturated fatty acids containing methyl or other alkyl side chains within their carbon backbone. They are widely present in natural lipids, particularly in ruminant adipose tissue and dairy products. Most of these fatty acids originate from bacteria in the animal digestive system. Compared to straight-chain fatty acids, BCFAs exhibit superior physicochemical properties due to their unique molecular structure, including lower melting and freezing points, and enhanced oxidative and thermal stability. Furthermore, studies have demonstrated that these substances possess physiological activities such as anti-cancer and anti-inflammatory properties, as well as regulating lipid metabolism, demonstrating their potential for application in functional foods and pharmaceuticals. Ruminant products (such as beef, lamb, and milk) are the primary dietary source of BCFAs for humans. However, dairy consumption in my country is significantly lower than in Europe and the United States, creating an increasingly urgent need to develop functional foods rich in BCFAs to supplement these nutrients. Against this backdrop, lamb, as a key ruminant meat resource, deserves special attention for its nutritional value and development potential.

[0003] Lamb is rich in high-quality protein, B vitamins, and essential trace elements such as iron, zinc, and selenium. It also boasts low fat and cholesterol levels, and is tender and easily digestible. In 2022, my country's total pork, beef, mutton, and poultry production reached 96.63 million tons, of which mutton accounted for 5.18 million tons, ranking first globally. However, mutton accounts for only 5.3% of total meat production, far lower than other livestock meats. This production bottleneck is directly related to insufficient consumption, and one of the core factors restricting consumption is the characteristic flavor of lamb—often described as "animal-like," "corrupted," or "metallic" in international studies, but widely referred to by Chinese consumers as "mutton." This flavor has become a key limiting factor in consumer acceptance and industry development. Studies have shown that the mutton taint flavor is primarily derived from 4-alkyl branched-chain fatty acids deposited in adipose tissue, including 4-methyloctanoic acid (MOA), 4-ethyloctanoic acid (EOA), and 4-methylnonanoic acid (MNA). Although the absolute concentrations of these compounds in tissues are low, their high volatility significantly influences flavor perception. MOA, with its highest concentration and lowest sensory threshold, contributes most significantly to taint, followed by EOA. MNA, due to its large concentration fluctuations, has a relatively small impact. Microbial taint reduction has become a research hotspot in recent years due to its safety, mild action, and significant effectiveness. This technology involves inoculating a starter culture with a specific bacterial strain, which secretes lipases that selectively degrade taint-causing fatty acids, altering their conformation and form. Furthermore, peptides, amino acids, and fatty acid degradation products generated by protease hydrolysis can form flavor compounds through Maillard reactions and oxidation, reducing taint intensity while maintaining the edible quality of mutton.

[0004] It is noteworthy that a class of branched-chain fatty acids possesses significant biological activity: 13-Methyltetradecanoic acid (13-MTD). This substance is a long-chain saturated branched fatty acid (15 carbon atoms, with a parent structure of tetradecanoic acid and a methyl branch at the 13th carbon position). Multiple studies have confirmed that it can effectively induce apoptosis in various types of human cancer cells, demonstrating potent anti-cancer activity. However, existing microbial methods for reducing mutton odor focus on degrading short-chain BCFAs that cause mutton odor, but this also simultaneously destroys other physiologically active long-chain BCFAs (such as 13-MTD), leading to a loss of nutritional benefits in mutton. While reducing mutton odor, mechanisms for retaining or enriching functional BCFAs have not been established, limiting the development of high-value-added mutton products.

[0005] Chinese Patent Publication No. CN107801926A discloses a method for removing the smell of mutton and cooking the same, comprising the following steps: (1) cutting the mutton into small pieces, soaking the mutton in light salt water for 8-12 minutes, removing the mutton and rinsing with water; (2) applying a mutton shavings remover to the rinsed mutton, allowing it to stand for 5-10 minutes, soaking it in water for 20-30 minutes, removing the mutton and rinsing it with water again; the mutton shavings remover comprises the following components in parts by weight: 3 parts of alfalfa, 3 parts of protease, 4 parts of sodium bicarbonate, 2 parts of soybean flavonoids, and 1 part of vitamin B12; (3) boiling the mutton in water at 80-95°C for 4-8 minutes, removing the mutton and draining the mutton; (4) steaming the drained mutton, adding a seasoning and stir-frying the mutton after it is cooked. To verify the effect of the present invention, the fatty acid content of fresh mutton and mutton treated by the present invention was measured. The results showed that the present invention can reduce the fatty acid content in fresh mutton by 88%-92%, demonstrating a significant deacidification effect.

[0006] It can be seen that the above-mentioned mutton de-smell and cooking method has the following problems: the enzymatic mutton de-smell method focuses on degrading the short-chain BCFAs that cause mutton smell, but will simultaneously destroy other physiologically active long-chain BCFAs (such as 13-MTD), resulting in the loss of nutritional functions of mutton. Summary of the Invention

[0007] To this end, the present invention provides a processing method for cooked mutton, which is used to overcome the problem in the prior art that the microbial mutton reduction method degrades the mutton's mutton-causing short-chain branched fatty acids, while simultaneously destroying other physiologically active long-chain branched fatty acids, resulting in the loss of mutton's nutritional functions.

[0008] To achieve the above object, the present invention provides a method for processing cooked mutton, comprising: Step S1, obtaining a fresh mutton raw material and pre-treating the fresh mutton raw material before fermentation to obtain a pre-treated mutton raw material; Step S2, detecting the initial concentration of mutton smell substances in the pretreated mutton raw material and cutting the pretreated mutton into pieces to obtain pretreated mutton blocks, wherein the cutting size and fermentation time of the pretreated mutton raw material are determined based on the initial concentration of mutton smell substances; Step S3, adding the composite bacterial liquid to the pretreated mutton block and fermenting to hydrolyze the mutton odor substances to obtain fermented mutton; Step S4, immersing the fermented mutton in a composite gel solution and vacuum impregnating the solution to selectively remove free mutton odor substances after fermentation to obtain mutton without odor, wherein the pressure breathing interval during the gel mutton removal process is determined based on the meat looseness of the pretreated mutton block and the fermented mutton; Step S5, marinating the deodorized mutton with ingredients, and then steaming at 80° C. to 85° C. for 10 min to 15 min to obtain a cooked mutton product; The composite bacterial solution consists of Staphylococcus carnosus, Pediococcus pentosaceus, Lactococcus lactis and calcium chloride solution.

[0009] Furthermore, the mass ratio of Staphylococcus carnosus, Pediococcus pentosaceus and Lactococcus lactis in the composite bacterial liquid is 6:3:1, and the total mass of the composite bacterial liquid is 0.1% to 1% of the mass of the fresh mutton raw material.

[0010] Furthermore, the composite gel solution is a citrus pectin-cellulose composite gel solution, wherein the mass ratio of citrus pectin to nanocellulose crystals is 3:1 to 5:1.

[0011] Furthermore, in step S2, the confidence level of the initial mutton smell substance concentration is verified, and the cutting size and fermentation time of the pretreated mutton raw material are determined based on the verified initial mutton smell substance concentration, wherein the initial mutton smell substance concentration is the total concentration of 4-methyloctanoic acid and 4-ethyloctanoic acid.

[0012] Furthermore, step S3 includes: Step S31, re-dissolving the freeze-dried bacterial powder consisting of Staphylococcus carnosus, Pediococcus pentosaceus and Lactococcus lactis in a mass ratio of 6:3:1 with a 0.1 mmol / L CaCl2 solution, and activating the mixture at 32°C for 30 minutes to obtain the composite bacterial solution; Step S32, injecting the composite bacterial solution into the fresh mutton raw material, and leaving it at 4° C. for 20 minutes to allow the composite bacterial solution to diffuse naturally in the fresh mutton raw material; Step S33, placing the fresh mutton raw material injected with the composite bacterial liquid into a tumbling machine, adding 2% salt, and intermittently tumbling at a vacuum degree of -0.09 MPa and 4° C. to promote the penetration of the composite bacterial liquid; Step S34: placing the tumbled fresh mutton raw material in a fermentation chamber for fermentation to obtain the fermented mutton.

[0013] Furthermore, the step S34 includes: Step S341: maintaining an environment at a temperature of 30°C and a relative humidity of 85% for 1 to 2 hours to promote bacterial growth; Step S342, based on the fermentation time, fermenting in an environment of 25° C. and 90% relative humidity to hydrolyze the mutton-flavoring substances through the specific lipase secreted by the bacteria; Step S343 , maintaining the temperature at 50° C. and the relative humidity at 75% for 20 to 30 minutes to inactivate non-specific enzymes, thereby obtaining the fermented mutton.

[0014] Furthermore, the step S342 further includes spraying an atomized citric acid solution onto the fresh mutton raw material to increase the diacetyl production of the Lactococcus lactis; Wherein, the added amount of the citric acid solution is 0.2% of the total mass of the fresh mutton raw material.

[0015] Furthermore, the step S4 includes: Step S41, respectively obtaining the meat looseness of the pre-treated mutton block and the meat looseness of the fermented mutton; Step S42, determining a modified pressure breathing interval during the gel-based meat smell removal process based on the rate of change of the meat loosening degree and the basic pressure breathing interval; Step S43, immersing the fermented mutton in the citrus pectin-cellulose composite gel solution for vacuum impregnation according to the corrected pressure breathing interval; Step S44, real-time monitoring of the turbidity of the citrus pectin-cellulose composite gel solution; Step S45: when the increase in turbidity exceeds the turbidity growth threshold, the soaking is terminated to obtain the deodorized mutton.

[0016] Furthermore, the change rate of the meat looseness is determined according to the ratio of the meat looseness of the pretreated mutton block to the meat looseness of the fermented mutton.

[0017] Furthermore, the step S45 further includes: After the soaking is terminated, the surface and internal concentrations of the mutton are detected, and the mutton smell ratio is determined based on the surface and internal concentrations of the mutton smell, and the basic pressure breathing interval in the next gel deodorization process is adjusted; The turbidity growth threshold is set based on the verified initial odor substance concentration.

[0018] Compared with the existing technology, the beneficial effect of the present invention is that while efficiently degrading the short-chain branched fatty acids that cause mutton taint, it selectively retains and enriches the long-chain branched fatty acids (13-MTD) with anti-cancer activity, thereby achieving a synergistic improvement in mutton taint suppression and functional ingredient enhancement, breaking through the bottleneck of existing mutton taint reduction technology that destroys nutritional active ingredients.

[0019] Furthermore, the present invention uses the short-chain specific lipase secreted by Staphylococcus carnosus to hydrolyze 4-methyloctanoic acid (MOA), 4-ethyloctanoic acid (EOA) and other tainting substances, combined with the acid production of Pediococcus pentosaceus to inhibit the synthesis of tainting precursors, thereby achieving deep degradation of tainting substances. At the same time, the esters and ketone compounds produced by bacterial metabolism synergistically enhance the richness of meat flavor and eliminate the chemical residual odor of traditional processes.

[0020] Furthermore, the present invention ensures the thoroughness of removing the mutton smell and the universality of retaining the nutritional activity by regulating the fermentation time and the turbidity threshold in real time according to the initial mutton smell concentration.

[0021] Furthermore, in the present invention, diacetyl produced by Lactococcus lactis metabolism forms a heat-stable adduct with 13-MTD. The adduct maintains structural integrity during subsequent cooking and gel treatment, avoiding hydrolysis by miscellaneous enzymes. After entering the human intestine, the adduct is specifically recognized by β-oxidation enzyme and releases free 13-MTD, ensuring the bioavailability of its anti-cancer activity.

[0022] Furthermore, the present invention utilizes a calcium ion-activated citrus pectin-cellulose composite gel network to selectively capture free mutton-smelling substances through the dual effects of pore size screening and chemical bonding, while physically blocking the loss of functional ingredients.

[0023] Furthermore, the present invention dynamically sets the fermentation time and turbidity growth threshold by adjusting the initial mutton smell concentration, thereby achieving a precise balance between the degree of mutton removal and nutrient retention. At the same time, the secondary utilization of calcium ions in bacterial enzyme activation and gel cross-linking significantly reduces the cost of auxiliary materials while avoiding the problem of texture hardening caused by excessive addition.

[0024] Furthermore, the present invention softens muscle fiber bundles through the protease secreted by Pediococcus pentosaceus, thereby improving the tenderness and juiciness of cooked mutton. The acidic environment formed simultaneously inhibits the proliferation of spoilage bacteria, extends the shelf life of the product, and reduces dependence on preservatives. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flow chart of the method for processing cooked mutton according to the present invention; Figure 2 This is a flow chart of step S3 of the method for processing cooked mutton of the present invention; Figure 3 Flowchart of step S34 of the method for processing cooked mutton according to the present invention; Figure 4 The figure is a flow chart of step S5 of the method for processing cooked mutton according to the present invention. DETAILED DESCRIPTION

[0026] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0027] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0028] See also Figures 1 to 4 As shown, they are respectively a flow chart of the method for processing cooked mutton of the present invention, a flow chart of step S3 of the method for processing cooked mutton of the present invention, a flow chart of step S34 of the method for processing cooked mutton of the present invention, and a flow chart of step S5 of the method for processing cooked mutton of the present invention. The method for processing cooked mutton of an embodiment of the present invention includes: Step S1, obtaining a fresh mutton raw material and pre-treating the fresh mutton raw material before fermentation to obtain a pre-treated mutton raw material; In a specific embodiment, 6-month-old Albas cashmere goats were selected, and the pretreatment before fermentation was specifically as follows: after slaughter, the carcass was acid-drained at 0°C to 4°C for 24 hours, the hind leg meat or tenderloin was taken, the visible fat and fascia were removed, and the meat was immersed in 4°C water containing 1% sodium bicarbonate, and treated with a vacuum curing machine (-0.05MPa, pressure breathing interval 1min) for 10min to 15min to remove blood and some precursors of mutton odor substances.

[0029] It is understandable that the vacuum negative pressure created by the vacuum curing machine during pre-fermentation pretreatment causes the air in the gaps between the mutton tissues to expand and escape, while destroying some cell structures and increasing the porosity of the tissues; periodic pressure changes accelerate the penetration of the solution and squeeze out the blood inside; at the same time, sodium bicarbonate becomes weakly alkaline after dissolution, and the alkaline environment will change the muscle protein structure, causing the myofibrils to swell and the structure to become loose, which increases the water holding space and permeability of the muscle tissue; more importantly, the alkaline environment can slightly hydrolyze fat (produce free fatty acids) and has a neutralizing effect on some free acidic mutton substances, which helps to convert some fat-soluble mutton precursors into more water-soluble forms (such as fatty acid salts).

[0030] Step S2, detecting the initial concentration of mutton smell substances in the pretreated mutton raw material and cutting the pretreated mutton into pieces to obtain pretreated mutton blocks, wherein the cutting size and fermentation time of the pretreated mutton raw material are determined based on the initial concentration of mutton smell substances; Specifically, in step S2, the confidence level of the initial mutton smell substance concentration is verified, and the cutting size and fermentation time of the pretreated mutton raw material are determined based on the verified initial mutton smell substance concentration, wherein the initial mutton smell substance concentration is the total concentration of 4-methyloctanoic acid and 4-ethyloctanoic acid.

[0031] In a specific embodiment, 100 g of mutton subcutaneous tissue fat sample is taken, and the concentration of short-chain mutton odor substances in the sample is detected by gas chromatography-mass spectrometry (GC-MS) as the initial mutton odor substance concentration of the pretreated mutton raw material.

[0032] Preferably, the detection process of the concentration of short-chain odor substances is as follows: mince the sample, homogenize it at 5000r / min for 5min, wrap it with filter paper and put it into a Soxhlet extractor, use petroleum ether as solvent, and continuously extract for 6h at a constant temperature of 60°C. Use a rotary evaporator to remove the organic solvent in the extract to obtain a transparent and thick crude fatty oil.

[0033] The initial concentration of mutton smell substances in the pretreated fresh mutton raw material is obtained by gas chromatography-mass spectrometry. Preferably, the chromatographic column: ; Heating program: initial temperature 100℃, hold for 2 min, increase to 220℃ at 6.0℃ / min, hold for 10 min; carrier gas (He) flow rate 1.0 mL / min, inlet temperature 270℃; split ratio 10:1; sample injection volume 1.0 μL; transfer line temperature 230℃; ion source temperature 220℃; electron impact (EI) ion source; electron energy 70 eV; selective ion scan mode (SIM); The data were processed and statistically analyzed using a gas chromatography-mass spectrometry workstation to obtain the total concentration of 4-methyloctanoic acid (MOA) and 4-ethyloctanoic acid (EOA), which was recorded as the initial mutton concentration.

[0034] Preferably, the confidence verification is a Grubbs test, α=0.05, and after removing outliers, the mean is taken as the initial concentration of mutton odor substances after verification, recorded as C0, and the unit is mg / kg.

[0035] It is understandable that the above implementation is prior art, and those skilled in the art can adaptively adjust the methods and parameters of the above implementation according to actual conditions, which will not be elaborated here.

[0036] In a specific embodiment, when cutting the mutton raw material into pieces, it is preferred to cut along the direction perpendicular to the muscle texture to avoid damaging the integrity of the muscle fibers; after cutting, it is quickly placed in a 4°C environment to prevent oxidation of mutton odor precursors.

[0037] The calculation formula for the size of the pieces of pre-treated mutton raw material is specifically: ; Among them, L max It is the maximum size of the cut pieces of mutton raw material, that is, the maximum value of any dimension of the length, width or height of the cut pieces of mutton raw material, in centimeters (cm).

[0038] It is understandable that at low concentrations, the larger cut size of meat chunks (8cm) preserves the integrity of the muscle structure, avoids juice loss due to over-cutting, and meets the basic penetration requirements of the bacterial solution. At high concentrations, the smaller cut size of meat chunks (5cm) exposes more fat interfaces, allowing the meat Staphylococcus aureus lipase in the composite bacterial solution to fully contact the mutton odor precursors, solving the problem of incomplete deep fat degradation. Traditional fixed-size cutting is prone to "surface mutton removal and core residue" in high-mutton odor raw materials, while dynamic size adjustment greatly improves the uniformity of mutton removal. At the same time, the size of the chunks is a prerequisite for the subsequent "meat looseness" test. Under a unified size benchmark, the degree of muscle fiber relaxation caused by tumbling and fermentation is comparable. When the size is too large, the looseness test is easily interfered by edge effects, resulting in distortion in the calculation of the breathing interval of vacuum impregnation. This provides accurate input for the subsequent "correction of pressure breathing interval based on meat looseness" to avoid a decrease in gel adsorption efficiency.

[0039] In a specific embodiment, the calculation formula for the fermentation time is: , Wherein, T is the fermentation time in hours (h).

[0040] It is understandable that based on public data, consumers can accept a concentration of mutton odor ≤ 6 mg / kg, and during processing it must be reduced to at least 10% below this value, i.e. ≤ 0.6 mg / kg; In the formula, based on several historical experimental data, when the initial concentration C0≤20mg / kg, 2h fermentation can reduce the concentration of mutton odor substances to 0.6±0.08mg / kg (meeting the standard); 0.04 is the overall enzymatic hydrolysis rate of MOA and EOA measured based on several historical experimental data. When the initial concentration C0>20mg / kg, the fermentation time needs to be extended; 100mg / kg is the metabolic saturation point of the bacterial flora measured based on historical experimental data. When C0=100mg / kg, the longest allowable fermentation time is 6.2h.

[0041] It is understandable that the concentration of mutton odor substances (the total concentration of MOA and EOA) can vary by 10mg / kg to 200mg / kg depending on the breed, age of the sheep, feed and part of the body. If a uniform fermentation time is used, when the concentration of mutton odor substances is low, excessive fermentation will cause 13-MTD to be hydrolyzed by miscellaneous enzymes. When the concentration of mutton odor substances is high, insufficient enzymatic hydrolysis will cause the mutton odor residue to exceed the standard.

[0042] Step S3, adding the composite bacterial liquid to the pretreated mutton block and fermenting to hydrolyze the mutton odor substances to obtain fermented mutton; The composite bacterial solution consists of Staphylococcus carnosus, Pediococcus pentosaceus, Lactococcus lactis and calcium chloride solution.

[0043] Specifically, the mass ratio of Staphylococcus carnosus, Pediococcus pentosaceus and Lactococcus lactis in the composite bacterial liquid is 6:3:1, and the total mass of the composite bacterial liquid is 0.1% to 1% of the mass of the fresh mutton raw material.

[0044] Specifically, step S3 includes: Step S31, re-dissolving the freeze-dried bacterial powder consisting of Staphylococcus carnosus, Pediococcus pentosaceus and Lactococcus lactis in a mass ratio of 6:3:1 with a 0.1 mmol / L CaCl2 solution, and activating the mixture at 32°C for 30 minutes to obtain the composite bacterial solution; In a specific embodiment, the Staphylococcus carnosus, the Pediococcus pentosaceus and the Lactococcus lactis are derived from the China Industrial Culture Collection Center (CICC), the culture collection number of Staphylococcus carnosus is CICC25173, the culture collection number of Pediococcus pentosaceus is CICC 22227, and the culture collection number of Lactococcus lactis is CICC25270.

[0045] Step S32, injecting the composite bacterial solution into the fresh mutton raw material, and leaving it at 4° C. for 20 minutes to allow the composite bacterial solution to diffuse naturally in the fresh mutton raw material; In a specific embodiment, the composite bacterial solution is evenly injected into the mutton tissue through a multi-needle syringe. After injection, the meat is placed in a 4°C environment for 20 minutes. The temporary expansion of the muscle fiber gap under low temperature conditions (expansion rate of 18% to 22%) is used to promote the natural penetration of the bacterial solution along the perimysium. Preferably, the injection depth is 2 cm to 3 cm, and the number of injection points is 10.

[0046] Step S33, placing the fresh mutton raw material injected with the composite bacterial liquid into a tumbling machine, adding 2% salt, and intermittently tumbling at a vacuum degree of -0.09 MPa and 4° C. to promote the penetration of the composite bacterial liquid; In a specific embodiment, the mutton injected with the bacterial liquid is placed in a tumbling machine, edible salt is added at 2% of the weight of the fresh mutton, and intermittent tumbling is performed under a vacuum degree of -0.09 MPa and 4°C. Preferably, the tumbling is performed for 5 minutes after every 10 minutes of operation, for a total of 40 minutes.

[0047] It can be understood that the vacuum environment creates a negative pressure gradient between myofibrils, which increases the penetration rate of the bacterial solution and ensures that the bacteria are evenly distributed deep in the muscle.

[0048] Step S34: placing the tumbled fresh mutton raw material in a fermentation chamber for fermentation to obtain the fermented mutton.

[0049] Specifically, the step S34 includes: Step S341: maintaining an environment at a temperature of 30°C and a relative humidity of 85% for 1 to 2 hours to promote bacterial growth; It can be understood that step S341 is the activation period of enzymatic hydrolysis, which is used to promote bacterial growth and secrete the basic enzyme system.

[0050] Step S342, based on the fermentation time, fermenting in an environment of 25° C. and 90% relative humidity to hydrolyze the mutton-flavoring substances through the specific lipase secreted by the bacteria; Specifically, the step S342 further includes spraying an atomized citric acid solution onto the fresh mutton raw material to increase the diacetyl production of the Lactococcus lactis; Wherein, the added amount of the citric acid solution is 0.2% of the total mass of the fresh mutton raw material.

[0051] It is understandable that the citric acid solution provides Lactococcus lactis with a carbon source other than glucose, which produces additional pyruvate through decomposition, artificially increasing the supply of pyruvate in the cell, thereby "forcing" the metabolic flow of Lactococcus lactis to shift more to the branch of α-acetolactate synthesis, ultimately leading to a significant increase in diacetyl production.

[0052] It can be understood that step S342 is a targeted enzymatic hydrolysis phase for inducing specific lipase to hydrolyze muttony substances, while simultaneously protecting 13-MTD by forming a heat-stable adduct between the diacetyl produced by Lactococcus lactis and the carboxyl group of 13-MTD.

[0053] Step S343 , maintaining the temperature at 42° C. and the relative humidity at 75% for 20 to 30 minutes to inactivate non-specific enzymes, thereby obtaining the fermented mutton.

[0054] It can be understood that step S343 is the pause period of enzymatic hydrolysis, which is used to inactivate non-specific enzymes.

[0055] It is understandable that Staphylococcus carnosus secretes short-chain specific lipases that preferentially degrade MOA / EOA (chain length C8, C10). At the same time, Staphylococcus carnosus is placed at 0.1mmol / LCa 2+ solution, induced expression of Ca 2+ Dependent lipase, improving its selectivity for MOA / EOA (Ca 2+ Chelated with branched carboxyl groups) to achieve efficient degradation of short-chain odor substances.

[0056] Lactococcus lactis synthesizes diacetyl in large quantities through a citric acid enhancement pathway. This substance forms a heat-stable adduct with the carboxyl group of 13-MTD. The keto group of diacetyl wraps around the carboxyl group of 13-MTD, blocking the lipase catalytic site. At the same time, the resulting adduct has a melting point of 85°C to 90°C and can withstand subsequent cooking processes. After ingestion by the human body, in the small intestine, the intestinal β-oxidation enzyme specifically recognizes the keto-enol structure of the adduct and hydrolyzes it to release free 13-MTD. The diacetyl protection mechanism only changes the physical form of 13-MTD (anti-digestion and degradation) without destroying its chemical structure and biological function. It is ultimately released and absorbed efficiently in the intestine, and its nutritional value is completely retained.

[0057] Pediococcus pentosaceus lowers the pH to 5.4-5.6 by producing acid, inhibiting the synthesis of branched-chain aldehydes, the precursor of mutton taste. At the same time, the protease it secretes breaks down myofibril protein, improving the tenderness of the meat.

[0058] Step S4, immersing the fermented mutton in a composite gel solution and vacuum impregnating the solution to selectively remove free mutton odor substances after fermentation to obtain mutton without odor, wherein the pressure breathing interval during the gel mutton removal process is determined based on the meat looseness of the pretreated mutton block and the fermented mutton; Specifically, the composite gel solution is a citrus pectin-cellulose composite gel solution, wherein the mass ratio of citrus pectin to nanocellulose crystals is 3:1 to 5:1.

[0059] Specifically, step S4 includes: Step S41, respectively obtaining the meat looseness of the pre-treated mutton block and the meat looseness of the fermented mutton; In a specific embodiment, a texture analyzer puncture probe (3 mm in diameter) is used to vertically puncture the center of the pretreated mutton block at a rate of 1 mm / s, avoiding puncturing fat or fascia, and recording the peak puncture force (unit: N). The average value is repeated three times and recorded as the loosening degree D1 of the pretreated mutton block (this implementation is completed before the mutton is fermented to remove the smell of mutton); the same method is used to determine the central puncture force of the fermented mutton block after fermentation, which is recorded as the loosening degree D2 of the fermented mutton.

[0060] It can be understood that the peak puncture force directly represents the degree of looseness, and the smaller the force value, the softer the meat.

[0061] Step S42, determining a modified pressure breathing interval during the gel-based meat smell removal process based on the rate of change of the meat loosening degree and the basic pressure breathing interval; Specifically, the change rate of the meat looseness is determined according to the ratio of the meat looseness of the pretreated mutton block to the meat looseness of the fermented mutton.

[0062] In a specific embodiment, the calculation formula for the change rate of the meat looseness is: , Where R is the rate of change of meat looseness, which is dimensionless.

[0063] It can be understood that the R value represents the degree of meat loosening caused by fermentation. The farther R is from 1, the greater the degree of meat loosening caused by fermentation.

[0064] In a specific embodiment, the calculation formula of the corrected pressure breathing interval is specifically: , Wherein, t1 is the corrected pressure breathing interval, in minutes (min); t0 is the basic pressure breathing interval, in minutes (min), preferably, for the preparation of the first de-stinky mutton, it is 5 minutes; f is the looseness response coefficient, in minutes (min), with a value range of 0.5min to 2min, preferably, f is 1.5min.

[0065] Step S43, immersing the fermented mutton in the citrus pectin-cellulose composite gel solution for vacuum impregnation according to the corrected pressure breathing interval; In a specific embodiment, a vacuum pickling machine is used with a vacuum pressure of -0.05 MPa; the vacuum is evacuated to the target pressure, maintained for t1, and then released to normal pressure and maintained for 10 seconds; the vacuum impregnation is terminated when the increase in turbidity exceeds a turbidity growth threshold.

[0066] It can be understood that the rate of change in meat looseness (R) is a direct quantitative indicator of changes in the muscle fiber network structure. During the fermentation process, the protease secreted by Pediococcus pentosaceus hydrolyzes myofibrillar proteins (such as myosin cross-links), resulting in an expansion of the intermuscular gaps (manifested as a decrease in the puncture force D2, R < 1). This structural change directly affects the penetration efficiency of the gel solution under vacuum conditions. An R value close to 1 indicates that the meat is still very firm after enzymatic hydrolysis, the intermuscular gaps change very little, and the diffusion resistance of gel molecules into the interior of the meat block is large. A smaller pressure breathing interval is required to enhance the frequency of external gel renewal and prevent surface adsorption saturation. The smaller the R value, the longer the single vacuum action time needs to be extended to ensure sufficient infiltration. The setting of the coefficient f is based on a mathematical model constructed based on the gel diffusion rate, diffusion coefficient and muscle fiber porosity. Its value range and preferred value are calibrated based on several historical experimental data, which will not be repeated here.

[0067] In a specific embodiment, the composite gel solution is prepared as follows: Citrus pectin (esterification degree ≤ 50%) and nanocellulose crystals (diameter 50±10 nm) are mixed in a mass ratio of 3:1 to 5:1; deionized water is added to prepare a 5% (w / v) gel solution, and the pH is adjusted to 5.5±0.1 (citric acid-sodium citrate buffer system); 0.05 mol / L CaCl2 is added to initiate cross-linking to obtain the citrus pectin-cellulose composite gel solution.

[0068] The fermented mutton is immersed in the composite gel solution and vacuum impregnated according to the modified pressure breathing interval; preferably, the meat-liquid ratio is 1:2, that is, 2 L of the composite gel solution is used for every 1 kg of fermented mutton.

[0069] It is understandable that citrus pectin is rich in galacturonic acid, the free carboxyl group (-COOH) of which is ionized to -COO at pH 5.5. - , forming ionic bonds with the free short-chain odor substances (MOA / EOA, containing carbonyl groups) after enzymatic hydrolysis.

[0070] Nanocellulose crystals can construct a 5nm to 10nm porous network, and the MOA / EOA molecules (≈1.2nm) can easily enter the pores, while 13-MTD (≈1.8nm) can be partially blocked. 2+ It cross-links with the carboxyl groups of pectin to form an "egg-box structure", shrinking the gel pore size from 5nm to 10nm to 2nm to 3nm, completely blocking the entry of 13-MTD (molecular size ≈ 1.8nm).

[0071] The present invention uses citrus pectin-cellulose composite gel to selectively adsorb free short-chain mutton odor substances after enzymatic hydrolysis, thereby achieving a complete mutton removal effect. 2+ Cross-linking pectin-cellulose and physical barrier method of shrinking gel pore size retain 13-MTD in the flesh.

[0072] Step S44, real-time monitoring of the turbidity of the citrus pectin-cellulose composite gel solution; In a specific embodiment, an online turbidity meter (such as HACH 2100N) is used to detect the turbidity of the solution in real time, with the unit being NTU; data is recorded every 2 minutes, and a turbidity-time curve is plotted.

[0073] Step S45: when the increase in turbidity exceeds the turbidity growth threshold, the soaking is terminated to obtain the deodorized mutton.

[0074] Specifically, the step S45 further includes: After the soaking is terminated, the surface and internal concentrations of the mutton are detected, and the uniformity of the mutton removal is determined based on the surface and internal concentrations of the mutton, and the basic pressure breathing interval in the next gel deodorization process is adjusted; The turbidity growth threshold is set based on the verified initial odor substance concentration.

[0075] In a specific embodiment, the calculation formula of the turbidity growth threshold is specifically: , Wherein, Z is the turbidity growth threshold, the unit is NTU; k is the turbidity linear coefficient, the unit is NTU·kg / mg, and the value range is 0.7NTU·kg / mg to 0.9NTU·kg / mg. Preferably, k is 0.8NTU·kg / mg; a is the background calibration constant, the unit is NTU. Preferably, a is 6NTU.

[0076] It can be understood that the turbidity linear coefficient k is calibrated based on some historical experimental data. When turbidity is about Gel; the background calibration constant a is calibrated based on several historical experimental data, which is the extreme value of the turbidity fluctuation of the blank gel solution to avoid false triggering and termination.

[0077] It can be understood that the turbidity increment directly reflects the amount of mutton-smelling substances adsorbed by the gel. When the turbidity increase exceeds the turbidity growth threshold, it indicates that the gel adsorption is close to saturation. Continuing to soak will easily lead to the dissociation of the adsorbed MOA and the physical retention of 13-MTD due to long-term contact.

[0078] In a specific embodiment, 50 g of the mutton block with the mutton smell removed was taken from the surface of the mutton block within 2 mm, and the surface mutton smell concentration was measured by the same method as in step S2, and recorded as C1; the center of the mutton block with the mutton smell removed was taken from the mutton block (avoiding the injection path), and the internal mutton smell concentration was measured by the same method as in step S2, and recorded as C 2， , in, is the basic pressure breathing interval in the next gel deodorization process, in minutes (min); b is the uniformity adjustment coefficient, ranging from 0.05 to 0.15. Preferably, the uniformity adjustment coefficient b is 0.1.

[0079] It is understandable that the ratio of the surface concentration of mutton to the internal concentration of mutton, that is, the deodorization uniformity, is the core indicator of the gel deodorization uniformity. When the deodorization uniformity is greater than 1, it indicates that the surface odor residue is higher than the internal one, reflecting that the vacuum breathing interval is too short, resulting in the gel only being updated on the surface, and the deep-layer odor substances are not fully adsorbed; when the deodorization uniformity is less than 1, it indicates that the internal deodorization is insufficient, reflecting that the single vacuum action time is too long, causing the gel to be saturated prematurely on the surface. The introduction of the logarithmic function correction model stems from the nonlinear relationship between the gel adsorption efficiency and the odor concentration gradient. When the surface odor concentration of the deodorized mutton is the same as the internal odor concentration (that is, the deodorization uniformity is equal to 1), it indicates that the basic pressure breathing interval is already optimal and no further adjustment is required. The preferred value of b, 0.10, was calibrated through several deodorization uniformity tests, which will not be repeated here.

[0080] Step S5: marinate the deodorized mutton with ingredients, and then steam it at 80°C to 85°C for 10min to 15min to obtain a cooked mutton product. Example 1

[0081] Six-month-old Albas cashmere goats from the same batch were slaughtered and allowed to drain acid at 4°C for 24 hours. The hind legs were then removed, their visible fat and fascia removed, and then immersed in 4°C water containing 1% sodium bicarbonate for 10 minutes using a vacuum curing machine (-0.05 MPa, pressure-respiration interval 1 minute). The initial odor concentration (MOA + EOA) was determined to be 23.6 mg / kg, and the data were validated by the Grubbs test. Based on the initial concentration of 23.6 mg / kg, the cut size was calculated to be 8 cm according to the formula and cut into pieces; Based on the initial concentration of 23.6 mg / kg, the fermentation time was calculated to be 2.144 h; Based on the initial concentration of 23.6 mg / kg, the turbidity growth threshold is calculated to be 24.88 NTU according to the formula; The looseness D1 of the pretreated mutton blocks was measured using a texture analyzer puncture probe and was 41N.

[0082] Weigh 0.6% of the mutton weight of the freeze-dried bacterial powder (Staphylococcus carnosus: Pediococcus pentosaceus: Lactococcus lactis in a mass ratio of 6:3:1). Reconstitute with 0.1 mmol / L CaCl₂ solution and activate in a 32°C water bath for 30 minutes. The bacterial solution was injected using a multi-needle syringe (depth 2.5 cm, number of injection points 10) and allowed to stand at 4°C for 20 min; Add 2% edible salt by weight of the mutton, and tumble and knead intermittently under -0.09 MPa vacuum and 4°C conditions (work for 10 minutes and pause for 5 minutes, for a total of 40 minutes); Temperature 30℃, relative humidity 85% maintained for 1.5h; Temperature 25°C, relative humidity 90% for 2.144 hours, during which time 0.2% citric acid solution was sprayed; Temperature 42°C, relative humidity 75% for 25 minutes; The looseness degree D2 of fermented mutton was measured by the puncture probe of the texture analyzer and was 34N; Based on D1 and D2, the corrected pressure breathing interval is calculated as 5.26 minutes according to the formula; Citrus pectin (45% esterification) and nanocellulose crystals were mixed in a 4:1 mass ratio to prepare a 5% aqueous solution, and 5 mmol / L calcium chloride was added to adjust the pH to 5.5. The fermented mutton and gel solution were placed in a vacuum curing machine at a mass-to-volume ratio of 1:2 and immersed at a vacuum pressure of -0.05 MPa. The vacuum was evacuated to the target pressure, maintained for 5.26 minutes, and then released to atmospheric pressure and maintained for 10 seconds. The turbidity was monitored in real time, and the immersion was terminated when the threshold of 24.88 NTU was reached (the actual turbidity at the time of termination was 25.1 NTU). The surface and internal concentrations of mutton odor substances were tested to determine the odor removal uniformity of 1.12. According to the deodorization uniformity of 1.12, the basic pressure breathing interval in the next gel deodorization process is calculated to be 5.06 minutes according to the formula.

[0083] Rinse with purified water, drain, marinate the ingredients, steam at 85℃ for 10 minutes, cool to room temperature and then package. Example 2

[0084] The initial concentration of mutton odor substances was 25.2 mg / kg; the mass ratio of Staphylococcus carnosus: Pediococcus pentosaceus: Lactococcus lactis was 7:2:1, and the rest was the same as in Example 1. Example 3

[0085] The initial concentration of mutton odor substances was 26.1 mg / kg; the mass ratio of Staphylococcus carnosus: Pediococcus pentosaceus: Lactococcus lactis was 5:4:1, and the rest was the same as in Example 1. Example 4

[0086] The initial concentration of mutton odor substances was 22.2 mg / kg; the mass ratio of Staphylococcus carnosus: Pediococcus pentosaceus: Lactococcus lactis was 6.5:3:0.5, and the rest was the same as in Example 1. Example 5

[0087] The initial concentration of mutton odor substances was 30.1 mg / kg; the mass ratio of Staphylococcus carnosus: Pediococcus pentosaceus: Lactococcus lactis was 5.5:4:0.5, and the rest was the same as in Example 1. Example 6

[0088] The initial concentration of mutton odor substances was 28.8 mg / kg; the freeze-dried bacterial powder was dissolved in pure water instead of calcium chloride solution, and the rest was the same as in Example 1. Example 7

[0089] The initial concentration of mutton odor substances was 20.5 mg / kg; the gel deodorization step was omitted, and the rest was the same as in Example 1. Example 8

[0090] The initial concentration of mutton odor substances was 29.5 mg / kg; the fermentation time was fixed at 2 hours, and the rest was the same as in Example 1. Example 9

[0091] The initial concentration of mutton odor substances was 16.2 mg / kg; the turbidity threshold was fixed at 20 turbidity units, and the rest was the same as in Example 1. Example 10

[0092] The initial concentration of the mutton odor substance was 25.5 mg / kg; the pressure interval time during the mutton removal of the fixed gel was 5 min, and the rest was the same as in Example 1.

[0093] Detection method: Detection of residual odor substances: Method: GB5009.168-2016 gas chromatography-mass spectrometry method; Conditions: Column: DB-WAX (60 m × 0.25 mm × 0.25 μm); Temperature program: 50°C (2 min) to 10°C / min to 240°C (10 min); Quantitative ions: MOAm / z74, EOAm / z117.

[0094] 13-MTD retention rate detection: Methods: UPLC-MS / MS was used to detect the adduct (m / z 241.216 to 152.104); Conditions: Column: ACQUITY UPLC BEH C18 (2.1×100 mm, 1.7 μm); Mobile phase: A: 0.1% formic acid in water; B: acetonitrile; Ion source: Electrospray negative ionization (ESI - ).

[0095] Hardness testing: Instrument: Texture Analyzer TA.XT Plus; Parameters: Probe: P / 5 cylinder (diameter 5 mm), test rate: 1 mm / s, compression ratio: 50%; Metric: First compression peak force.

[0096] Sensory evaluation: Standard: GB / T 22210-2008 Specification for sensory evaluation of meat and meat products; Indicators: mutton smell intensity (0-5 points), meat tenderness (0-5 points), total score (0-10 points); Evaluation group: 10 qualified personnel (double-blind test).

[0097] The experimental results are shown in Table 1.

[0098] Table 1 Test results of Examples 1 to 10 ; As shown, when the bacterial species ratio of 6:3:1 for Staphylococcus carnosaceus: Pediococcus pentosaceus: Lactococcus lactis is strictly adhered to (Example 1), both the degradation rate of taint substances and the retention rate of 13-MTD are optimal. The dominant presence of Staphylococcus carnosaceus ensures efficient hydrolysis of short-chain taint acids; the appropriate proportion of Pediococcus pentosaceus maintains an acidic environment, inhibiting the synthesis of taint precursors without affecting bacterial symbiosis; and the precise proportion of Lactococcus lactis ensures saturated diacetyl production and complete protection of 13-MTD. Disruption of this ratio (as in Examples 2-5) triggers a cascading imbalance: an excess of Staphylococcus carnosaceus leads to excessive meat hydrolysis (abnormally increased firmness); an insufficient amount of Lactococcus lactis leads to a sharp decrease in diacetyl synthesis and significant 13-MTD loss during subsequent processing; and an excess of Pediococcus pentosaceus results in an excessively low pH, inhibiting core lipase activity. This demonstrates that this ratio represents the optimal balance for synergistic bacterial function.

[0099] In Example 6, where calcium ions were omitted, the residual amount of mutton smell increased several times, and the retention rate of 13-MTD plummeted. This is due to the lack of the two-way action of calcium ions: in the fermentation stage, the lack of calcium-activated Staphylococcus carnosus lipase cannot accurately identify short-chain mutton-smelling acids, resulting in a significant reduction in degradation efficiency; in the gel de-stinking stage, the lack of calcium cross-linking causes the pectin-cellulose network pore size to expand, losing size screening ability, and short-chain mutton-smelling acids and 13-MTD adducts are adsorbed simultaneously. What's more serious is that diacetyl is insufficiently synthesized due to the lack of calcium signals, and 13-MTD loses its protective barrier. This shows that calcium ions are the key medium throughout the entire chain of "targeted de-stinking-ingredient protection."

[0100] While the control groups with fixed fermentation times (Example 8) or fixed turbidity thresholds (Example 9) could handle ingredients with specific mutton odor concentrations, they were vulnerable to concentration fluctuations. The fixed fermentation time group incompletely degraded high-mutton mutton and caused over-fermentation and hardening of low-mutton mutton. The fixed turbidity threshold group prematurely terminated mutton removal in low-mutton mutton, leaving odorous substances. In high-mutton mutton, the gel saturated and ruptured, leading to loss of functional ingredients. Only by dynamically adjusting parameters based on initial concentration, as in Example 1, can we precisely match the mutton removal requirements of different ingredients and achieve consistent quality.

[0101] In Example 7, in which gel removal was omitted, although the degradation of mutton smell met the standard during the fermentation stage, the intensity of mutton smell rebounded after cooking, and the sensory score deteriorated significantly. This is because the free mutton smell substances remaining from fermentation evaporated and escaped during the heat treatment process. The composite gel completely captures free mutton smell molecules through the dual mechanism of "pore size screening + chemical bonding", while its food-grade raw material characteristics avoid the risk of chemical solvent residues. More importantly, the gel treatment significantly improves the tenderness of the meat, because the microporous structure it forms promotes moisture retention, partially offsetting the muscle fiber contraction effect caused by fermentation.

[0102] In Example 10, in which the calculation of the pressure interval time during gel deodorization was omitted, the residual concentration of mutton smell substances rebounded to a certain extent compared with Example 1, and the 13-MTD retention rate also decreased, indicating that the gel diffusion rate did not match the muscle fiber porosity of the mutton after enzymatic hydrolysis well, resulting in insufficient gel penetration or saturated adsorption of the gel surface, which in turn led to insufficient adsorption of free mutton smell substances and physical retention of some 13-MTD.

[0103] All control groups with modified core processes exhibited excessive total bacterial counts or flavor defects. For example, the calcium-free group, due to insufficient lipase activity, required extended fermentation time, leading to the growth of bacteria. The unbalanced bacterial strain group, however, suffered from inadequate pH control, which weakened its antibacterial capacity. Only by fully implementing this process (Example 1), through temperature and timing control in staged fermentation, citric acid-enhanced diacetyl synthesis, and the physical barrier of the gel, can we achieve both microbial safety and flavor optimization while achieving deep mutton removal.

[0104] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A method for processing cooked mutton, characterized in that: include: Step S1, obtaining a fresh mutton raw material and pre-treating the fresh mutton raw material before fermentation to obtain a pre-treated mutton raw material; Step S2, detecting the initial concentration of mutton smell substances in the pretreated mutton raw material and cutting the pretreated mutton into pieces to obtain pretreated mutton blocks, wherein the cutting size and fermentation time of the pretreated mutton raw material are determined based on the initial concentration of mutton smell substances; Step S3, adding the composite bacterial liquid to the pretreated mutton block and fermenting to hydrolyze the mutton odor substances to obtain fermented mutton; Step S4, immersing the fermented mutton in a composite gel solution and vacuum impregnating the solution to selectively remove free mutton odor substances after fermentation to obtain mutton without odor, wherein the pressure breathing interval during the gel mutton removal process is determined based on the meat looseness of the pretreated mutton block and the fermented mutton; Step S5, marinating the deodorized mutton with ingredients, and then steaming at 80° C. to 85° C. for 10 min to 15 min to obtain a cooked mutton product; The composite bacterial solution consists of Staphylococcus carnosus, Pediococcus pentosaceus, Lactococcus lactis and calcium chloride solution.

2. The method for processing cooked mutton according to claim 1, characterized in that: The mass ratio of Staphylococcus carnosus, Pediococcus pentosaceus and Lactococcus lactis in the composite bacterial liquid is 6:3:1, and the total mass of the composite bacterial liquid is 0.1% to 1% of the mass of the fresh mutton raw material.

3. The method for processing cooked mutton according to claim 1 or 2, characterized in that: The composite gel solution is a citrus pectin-cellulose composite gel solution, wherein the mass ratio of citrus pectin to nanocellulose crystals is 3:1 to 5:

1.

4. The method for processing cooked mutton according to claim 3, characterized in that: In step S2, the confidence level of the initial mutton odor concentration is verified, and the cutting size and fermentation time of the pretreated mutton raw material are determined based on the verified initial mutton odor concentration, wherein the initial mutton odor concentration is the total concentration of 4-methyloctanoic acid and 4-ethyloctanoic acid.

5. The method for processing cooked mutton according to claim 4, characterized in that: The step S3 comprises: Step S31, re-dissolving the freeze-dried bacterial powder consisting of Staphylococcus carnosus, Pediococcus pentosaceus and Lactococcus lactis in a mass ratio of 6:3:1 with a 0.1 mmol / L CaCl2 solution, and activating the mixture at 32°C for 30 minutes to obtain the composite bacterial solution; Step S32, injecting the composite bacterial solution into the fresh mutton raw material, and leaving it at 4° C. for 20 minutes to allow the composite bacterial solution to diffuse naturally in the fresh mutton raw material; Step S33, placing the fresh mutton raw material injected with the composite bacterial liquid into a tumbling machine, adding 2% salt, and intermittently tumbling at a vacuum degree of -0.09 MPa and 4° C. to promote the penetration of the composite bacterial liquid; Step S34: placing the tumbled fresh mutton raw material in a fermentation chamber for fermentation to obtain the fermented mutton.

6. The method for processing cooked mutton according to claim 5, characterized in that: The step S34 includes: Step S341: maintaining an environment at a temperature of 30°C and a relative humidity of 85% for 1 to 2 hours to promote bacterial growth; Step S342, based on the fermentation time, fermenting in an environment of 25° C. and 90% relative humidity to hydrolyze the mutton-flavoring substances through the specific lipase secreted by the bacteria; Step S343 , maintaining the temperature at 50° C. and the relative humidity at 75% for 20 to 30 minutes to inactivate non-specific enzymes, thereby obtaining the fermented mutton.

7. The method for processing cooked mutton according to claim 6, characterized in that: The step S342 further includes spraying an atomized citric acid solution onto the fresh mutton raw material to increase the diacetyl production of the Lactococcus lactis; Wherein, the added amount of the citric acid solution is 0.2% of the total mass of the fresh mutton raw material.

8. The method for processing cooked mutton according to claim 7, characterized in that: The step S4 comprises: Step S41, respectively obtaining the meat looseness of the pre-treated mutton block and the meat looseness of the fermented mutton; Step S42, determining a modified pressure breathing interval during the gel-based meat smell removal process based on the rate of change of the meat loosening degree and the basic pressure breathing interval; Step S43, immersing the fermented mutton in the citrus pectin-cellulose composite gel solution for vacuum impregnation according to the corrected pressure breathing interval; Step S44, real-time monitoring of the turbidity of the citrus pectin-cellulose composite gel solution; Step S45: when the increase in turbidity exceeds the turbidity growth threshold, the soaking is terminated to obtain the deodorized mutton.

9. The method for processing cooked mutton according to claim 8, characterized in that: The change rate of the meat looseness is determined according to the ratio of the meat looseness of the pretreated mutton block to the meat looseness of the fermented mutton.

10. The method for processing cooked mutton according to claim 9, characterized in that: The step S45 further includes: After the soaking is terminated, the surface and internal concentrations of the mutton are detected, and the mutton smell ratio is determined based on the surface and internal concentrations of the mutton smell, and the basic pressure breathing interval in the next gel deodorization process is adjusted; The turbidity growth threshold is set based on the verified initial odor substance concentration.

Images