Segmented preservation processing technology of low-oxidized yak meat and Tibetan sheep meat

Abstract

The present application relates to meat preservation processing technology field, specifically low oxidation yak meat and Tibetan sheep section preservation processing technology, including precooling bacteria reduction, segmentation coating, storage preservation three link stages: precooling bacteria reduction stage adopts direct current high voltage electrostatic field and two-stage gradient pressure difference precooling, cooperate scanning dielectric barrier discharge cold plasma and slightly acidic electrolytic water atomization synergistic bacteria reduction, synchronous realization rapid cooling, enzyme activity inhibition and uniform sterilization;Segmentation coating stage first carries out air plasma jet passivation treatment to segmentation section, then adopts ultrasonic atomization coating with the Pickering composite emulsion of ferulic acid modified chitosan, forms water-resistant slow-release preservation barrier;Storage preservation stage adopts gradient oxygen reduction gas conditioning package with initial mixed gas and slow-release oxygen removal sheet, built-in shaped phase change cold storage gasket buffers temperature fluctuation, cooperate pulse high voltage electrostatic field assisted refrigeration.The present application can significantly reduce the degree of meat oxidation, resist cold chain temperature fluctuation.

Description

Technical Field

[0001] This invention relates to the field of meat preservation and processing technology, specifically a segmented preservation and processing technology for low-oxidation yak beef and Tibetan mutton. Background Technology

[0002] Yak meat and Tibetan mutton are distinctive high-quality livestock products from the Qinghai-Tibet Plateau region, characterized by high protein, low fat, and rich in unsaturated fatty acids and natural active nutrients, possessing enormous market value and industrial development potential. However, slaughterhouses in the plateau pastoral areas are scattered, processing conditions are limited, and the core consumer market is concentrated in the central and eastern regions, with cold chain transportation cycles lasting several days to tens of days. In addition, yak meat and Tibetan mutton have high myoglobin content, thick muscle fibers, and a high proportion of unsaturated fatty acids, making them highly susceptible to fat oxidation, protein oxidation, and myoglobin browning during processing, storage, and transportation. This is accompanied by microbial proliferation, resulting in a dull color, deteriorated flavor, severe juice loss, and an extremely short shelf life, seriously hindering the export expansion and branding development of the plateau's distinctive meat industry.

[0003] Existing meat preservation technologies mainly include low-temperature refrigeration, modified atmosphere packaging, coating preservation, irradiation sterilization, and chemical preservative preservation. Low-temperature refrigeration alone can only slow down the reaction rate but cannot block the oxidation process; under ordinary refrigeration, the shelf life of fresh beef and mutton is only about 7 days. Modified atmosphere packaging inhibits microorganisms by adjusting the gas ratio; high-oxygen modified atmosphere packaging can maintain the bright red color but accelerates fat oxidation, while low-oxygen modified atmosphere packaging can alleviate oxidation but easily leads to browning of the meat, thus failing to meet the dual requirements of color preservation and anti-oxidation. Coating preservation forms a barrier layer on the surface of the meat to isolate oxygen and microorganisms, but traditional polysaccharide-based coatings are prone to water absorption and swelling in the high-humidity environment of refrigeration, resulting in a rapid decline in barrier performance. The release rate of antioxidant components is uncontrollable, with excessive release in the early stages and insufficient release in the later stages, resulting in poor long-term preservation ability. Furthermore, the compatibility of fat-soluble and water-soluble active ingredients is poor, and the coating liquid is prone to separation after prolonged storage, leading to insufficient stability in industrial batches.

[0004] There is a lack of a comprehensive, segmented control system for the preservation of yak and Tibetan mutton. Some studies use natural extracts combined with modified atmosphere packaging to treat yak meat, but they fail to control the oxidation initiation and microbial proliferation during the pre-cooling stage after slaughter. During the pre-cooling period, preliminary enzymatic oxidation and bacterial growth occur inside the meat, significantly reducing the subsequent preservation effect. Some patents disclose methods for preserving mutton with composite coatings, but these often use soaking or spraying methods, resulting in poor coating uniformity and a lack of specific treatment for mechanical damage to the cut surfaces. After cell damage on the cut surfaces, oxidases directly come into contact with oxygen, becoming the starting point for quality deterioration and limiting the preservation effect. Other technologies use physical fields to assist in meat refrigeration, but these are mostly combined with low temperature alone, failing to consider the temperature fluctuations commonly present in cold chain transportation. When the temperature rises, oxidase activity rebounds rapidly, resulting in poor preservation stability.

[0005] In addition, the existing segmented preservation process still has many shortcomings: Firstly, surface sterilization during the pre-cooling stage is mostly a fixed-point static treatment, resulting in uneven treatment of dead corners such as carcass folds and cavities, which limits the control of the initial bacterial count. Some cold plasma sterilization processes are prone to causing mild oxidation of surface proteins, which in turn accelerates subsequent color deterioration. Secondly, the storage stage mostly adopts a fixed ratio of static controlled atmosphere, which cannot meet the dynamic needs of color protection in the early stage of storage and long-term anti-oxidation. Third, the various preservation methods lack a synergistic design, and the overall effect does not exceed the range of linear superposition of the various technologies, making it difficult to meet the high-quality preservation requirements of long-distance cold chain transportation of meat from high-altitude areas.

[0006] Therefore, developing a low-oxidation segmented preservation process that covers the entire processing flow, integrates multiple technologies, and is tailored to the characteristics of meat from high-altitude areas is of great practical significance for extending product shelf life, maintaining product quality, and promoting the upgrading of the high-altitude livestock industry. Summary of the Invention

[0007] To address the problems in existing technologies, this invention provides a segmented preservation and processing technology for low-oxidation yak meat and Tibetan mutton, mainly solving the following technical problems: The long pre-cooling period after slaughter means that the meat is kept in a high-temperature range for a long time, resulting in high activity of endogenous oxidases and early oxidation. In addition, uneven surface sterilization methods and incomplete sterilization of dead corners lead to high initial bacterial counts. Some sterilization methods can even cause surface protein oxidation, which can accelerate subsequent quality deterioration. The segmentation process only controls the cleanliness of the environment, but does not address the damage to muscle cells caused by the cutting tool. Oxidases at the segmentation cut surface come into direct contact with oxygen, and the oxidation reaction starts rapidly, becoming the starting point for quality deterioration. Traditional aqueous coatings have poor water resistance, are prone to swelling and failure under high humidity and refrigeration, have uncontrollable release of active ingredients, insufficient long-term effectiveness, and poor stability of multi-component coating solutions, resulting in poor consistency between industrial batches. During storage, static controlled atmosphere cannot meet the needs of initial color protection and long-term antioxidant; during cold chain transportation, temperature fluctuations are frequent, and each temperature rise will cause oxidase activity to rebound, accelerating quality deterioration. Single low-temperature storage cannot withstand the impact of temperature fluctuations. Existing preservation technologies have poor integration between different stages, failing to form a closed-loop control of oxidation from source to end. The overall preservation effect is merely a linear summation of the various technologies, which cannot meet the high-quality preservation requirements for long-distance transportation of meat from high-altitude areas.

[0008] The technical solution adopted by this invention to solve its technical problem is: a segmented preservation and processing technology for low-oxidation yak meat and Tibetan mutton, including a pre-cooling and sterilization stage, a segmentation and coating stage, and a storage and preservation stage, the specific steps of which are as follows: (1) Pre-cooling and sterilization stage: The slaughtered and trimmed yak meat or Tibetan sheep meat half carcass is sent into the pressure difference pre-cooling room and pre-cooled in a two-stage gradient cooling environment with a relative humidity of 85%-95% and a DC high voltage electrostatic field. During the pre-cooling process, a scanning dielectric barrier discharge cold plasma device is used to scan back and forth along the surface of the carcass, while ultrasonic atomized slightly acidic electrolyzed water works synergistically on the surface of the carcass. When the temperature of the center of the carcass drops to 0-4℃, the pre-cooling and sterilization is completed. (2) Cutting and coating stage: The pre-cooled carcass is transferred to a clean cutting workshop at 0-8℃ and cut into target meat pieces. Within 30 seconds after cutting, a low-temperature plasma jet with compressed air as the working gas is used to passivate all the cut surfaces of the meat pieces. Then the meat pieces are sent into an ultrasonic atomization coating chamber, and a ferulic acid modified chitosan-based Pickering composite preservation emulsion is used to atomize and coat the meat pieces. After draining, a uniform and dense preservation liquid film is formed on the surface. (3) Storage and preservation stage: The coated meat pieces are packed into a packaging box with a built-in fixed phase change cold storage liner, filled with an initial proportion of mixed protective gas and a built-in slow-release deoxygenating tablet for gradient oxygen reduction conditioning packaging, sealed and sent to a 0-4℃ cold storage, and a pulsed high voltage electrostatic field is applied for auxiliary storage to complete the segmented preservation processing.

[0009] Specifically, in step (1), the electric field strength of the DC high-voltage electrostatic field is 80-150kV / m, and it is continuously applied throughout the process; the two-stage gradient cooling is as follows: the first stage reduces the core temperature of the carcass from 38-42℃ to 12-15℃ in 4-6 hours, and the second stage reduces it to 0-4℃ in 8-12 hours; the discharge voltage of the scanning cold plasma is 16-24kV, the discharge frequency is 8-12kHz, the distance between the electrode and the surface of the carcass is 15-30mm, the scanning rate is 0.1-0.3m / s, and the scanning process is performed once every 2-3 hours; each scan is synchronized with the atomization of slightly acidic electrolyzed water, the effective chlorine concentration of the electrolyzed water is 50-80mg / L, and the pH value is 5.0-6.5.

[0010] Specifically, in step (2), the gas flow rate of the low-temperature plasma jet is 8-15 L / min, the processing distance is 1-3 cm, the scanning rate is 0.2-0.5 m / s, and each cut surface is processed 1-2 times; the atomization frequency of the ultrasonic atomization coating is 1.5-2.5 MHz, the droplet size is 10-50 μm, the meat pieces stay in the atomization zone for 2-5 minutes, and the emulsion loading per kilogram of meat pieces is 0.9-1.6 g.

[0011] Specifically, the preparation method of the ferulic acid modified chitosan-based Pickering composite preservative emulsion is as follows: chitosan is dissolved in acetate buffer, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is added for activation, ferulic acid is added for light-protected grafting reaction, and the reaction solution is dialyzed and freeze-dried to obtain ferulic acid modified chitosan; the modified chitosan is dispersed in acetate buffer as an aqueous phase, rosemary essential oil is added as an oil phase, and Pickering promulgation is prepared by high-speed shearing; ferulic yl oligosaccharide and ε-polylysine hydrochloride are then added to the promulgation, and the mixture is stirred evenly to obtain the finished emulsion.

[0012] Specifically, by mass fraction, the finished emulsion contains: 1.2%-2.0% ferulic acid-modified chitosan, 0.3%-0.8% rosemary essential oil, 0.2%-0.6% feruloyl oligosaccharide, 0.1%-0.3% ε-polylysine hydrochloride, and the balance being acetate buffer solution with pH 4.5-5.5; the grafting degree of the ferulic acid-modified chitosan is 12%-25%; the feruloyl oligosaccharide is obtained from barley bran through alkaline hydrolysis, enzymatic hydrolysis, and purification, with an average degree of polymerization of 2-5.

[0013] Specifically, the initial mixed gas volume composition of the gradient oxygen-adjustable packaging in step (3) is: oxygen 10%-12%, carbon dioxide 25%-35%, and nitrogen 53%-65%; the slow-release oxygen removal tablet is an iron-based slow-release oxygen removal tablet, and the oxygen removal capacity of a single tablet matches the volume of the packaging box, which can gradually reduce the oxygen concentration in the packaging to 5%-6% and maintain stability within 7 days of storage.

[0014] Specifically, the shaped phase change cold storage liner described in step (3) uses high-density polyethylene as the shaped carrier, composite paraffin-based phase change material, phase change temperature of 0-2℃, latent heat of phase change ≥180J / g, liner thickness of 2-4mm, and is placed in a 0℃ environment for cold storage for more than 12 hours before use.

[0015] Specifically, the electric field strength of the pulsed high-voltage electrostatic field in step (3) is 100-200kV / m, the pulse frequency is 0.5-2Hz, and it is applied intermittently for 3-5 hours every 12 hours.

[0016] Specifically, in step (2), the weight of each cut meat piece is 0.2-1.0 kg, and the total number of airborne bacteria in the cutting workshop is ≤100 CFU / m³. 3 .

[0017] Specifically, the yak meat is the longissimus dorsi muscle of the yak, and the Tibetan mutton is the leg meat of the Tibetan mutton.

[0018] The beneficial effects of this invention are: 1. Full-process segmented control to block oxidation and microbial proliferation at the source: From pre-cooling and cutting to storage, a complete preservation chain is formed. Technical measures are matched to the core deterioration mechanisms of each stage. Enzyme inhibition and bacteria reduction during pre-cooling, surface passivation during cutting, and temperature control and slow release during storage block the path of oxidation and microbial proliferation throughout the process, ensuring no blind spots in preservation.

[0019] 2. Synergistic effects of multiple technologies significantly improve preservation: In the pre-cooling stage, the combination of electrostatic field enzyme inhibition and plasma-electrolysis sterilization reduces initial oxidation while ensuring uniform sterilization; passivation of the cut surface during the segmentation stage blocks the initiation of deterioration, and the Pickering emulsion coating provides long-lasting water resistance; during storage, phase change liner temperature control, gradient modified atmosphere dynamic adaptation, and pulsed electric field-assisted enzyme inhibition work synergistically to achieve stable and long-lasting preservation. The synergistic effect of each stage's technologies far exceeds the linear summation of individual technologies, extending the shelf life compared to conventional processes.

[0020] 3. Stable and safe system with strong industrial adaptability: The Pickering emulsion system has high stability and good batch consistency. All preservative ingredients are of natural origin and contain no chemically synthesized preservatives, meeting food safety requirements. The equipment used is all conventional food industry equipment with parameters within the normal adjustable range. It is simple and controllable to operate and suitable for large-scale application in meat processing enterprises in plateau areas.

[0021] 4. Resisting temperature fluctuations and adapting to long-distance cold chain: Phase change cold storage pads can effectively buffer temperature fluctuations during cold chain transportation, solving the industry pain points of long distances and unstable temperature control conditions in high-altitude transportation, greatly improving product quality stability, and adapting to the needs of long-distance cross-regional transportation. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Figure 1 A flowchart of the segmented preservation and processing technology for low-oxidation yak meat and Tibetan mutton provided by the present invention; Figure 2 The logic diagram of the synergistic preservation effect of the segmented preservation processing technology for low-oxidation yak meat and Tibetan mutton provided by the present invention. Detailed Implementation

[0024] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0025] like Figure 1-2 As shown, the segmented preservation and processing technology for low-oxidation yak meat and Tibetan mutton of the present invention includes the following steps: Step 1, Pre-cooling and sterilization stage: DC high voltage electrostatic field combined with gradient pressure difference pre-cooling plus scanning cold plasma-slightly acidic electrolyzed water atomization for synergistic sterilization.

[0026] A two-stage gradient pressure differential precooling process is employed. The first stage involves rapid cooling that bypasses the optimal growth temperature range of 20-38℃ for microorganisms, while the second stage involves slow cooling to prevent muscle contraction and ensure tenderness. A DC high-voltage electrostatic field is applied throughout the precooling process. This field polarizes water molecules, lowering the freezing point of muscle juices and delaying ice crystal formation. Simultaneously, by altering the spatial conformation of oxidase proteins, the activity of lipoxygenase and polyphenol oxidase is inhibited, effectively blocking the initiation of oxidation during precooling at the enzymatic level and significantly reducing the initial degree of oxidation.

[0027] During the pre-cooling process, a scanning dielectric barrier discharge cold plasma device is used to uniformly scan the carcass surface, combined with synchronously ultrasonically atomized slightly acidic electrolyzed water, to achieve uniform sterilization of the entire surface. The high-energy active particles generated by the plasma can rapidly kill the dominant putrefactive bacteria such as Pseudomonas, lactic acid bacteria, and Enterobacteriaceae on the carcass surface. The atomized slightly acidic electrolyzed water can form a thin liquid film on the carcass surface, prolonging the action time of the active particles. At the same time, the active chlorine in the electrolyzed water and the active oxygen in the plasma produce a synergistic sterilization effect, significantly improving the sterilization effect in dead corners such as folds and cavities. In addition, the slightly acidic electrolyzed water can neutralize the excess oxides generated by the plasma, avoiding excessive oxidation of surface proteins, while moderately activating the functional groups of meat surface proteins, increasing surface polarity, and significantly enhancing the adhesion and uniformity of subsequent coatings on the meat surface, providing an excellent interface foundation for the next stage of coating and preservation.

[0028] Step 2, Segmentation Coating Stage: Plasma jet passivation of the segmentation surface followed by ultrasonic atomization coating with ferulic acid-modified chitosan-based Pickering emulsion.

[0029] After the meat is cut in a low-temperature, clean environment, a low-temperature plasma jet using compressed air as the working gas rapidly scans all cut surfaces within 30 seconds. The plasma's active particles instantly inactivate exposed oxidases and surface microorganisms, preventing oxidation and microbial invasion caused by mechanical damage during cutting from the source, without raising the meat temperature. This fills a gap in traditional processes for preserving the cut surfaces. Using compressed air as the working gas eliminates the need for an additional gas source, resulting in low cost and suitability for large-scale industrial production.

[0030] The coating uses a ferulic acid-modified chitosan-based Pickering composite preservative emulsion, which is uniformly applied to the surface of meat pieces via ultrasonic atomization. First, through a carbodiimide-mediated grafting reaction, ferulic acid, which has strong antioxidant properties, is covalently grafted onto the chitosan molecular chain to obtain a modified chitosan that combines film-forming properties and antioxidant properties. Using this modified chitosan as a solid particle emulsifier, rosemary essential oil is encapsulated to form a stable Pickering emulsion. In the aqueous phase, ferulic yl oligosaccharides derived from barley and ε-polylysine hydrochloride are compounded. In this system, modified chitosan particles adsorb onto the oil-water interface to form a dense interfacial film, significantly improving emulsion stability and preventing delamination even after prolonged storage. After film formation, the three-dimensional network structure formed by the modified chitosan exhibits significantly better water resistance than ordinary chitosan films, resisting swelling under high humidity and refrigeration conditions and maintaining barrier properties for an extended period. The encapsulated rosemary essential oil is slowly released, providing long-lasting antioxidant effects and forming a synergistic antioxidant system with the ferulic oligosaccharides in the aqueous phase. ε-polylysine provides broad-spectrum antibacterial effects. Ultrasonic atomization disperses the emulsion into micron-sized droplets, uniformly covering all surfaces and crevices of the meat, resulting in a low emulsion dosage, uniform film formation, and no dripping or sagging issues.

[0031] Step 3, Storage and Preservation Stage: Gradient oxygen descent packaging with shape-stabilizing phase change cold storage pads and pulsed high-voltage electrostatic field assisted refrigeration.

[0032] This product employs a gradient oxygen-degrading modified atmosphere packaging method. The initial oxygen concentration is set at a slightly higher level, which, combined with the color-protecting components in the coating, maintains the bright red color of the meat during the initial storage period. An iron-based slow-release oxygen-absorbing tablet is placed inside the packaging box, gradually reducing the oxygen concentration to a low level over the course of one week. This inhibits fat oxidation during long-term storage, resolving the inherent contradiction between color protection and antioxidant effects that static modified atmosphere packaging cannot simultaneously address. The high concentration of carbon dioxide continuously inhibits the growth of aerobic spoilage bacteria. The dosage of the oxygen-absorbing tablet is precisely matched to the volume of the packaging box, ensuring a stable oxygen reduction rate and preventing sudden drops in oxygen concentration from affecting the meat's color.

[0033] The packaging box features a built-in shaped phase change cooling liner. Utilizing the property of phase change materials to absorb and release a large amount of latent heat during the solid-liquid phase transition, this liner maintains a stable internal temperature, resisting temperature fluctuations of 3-5°C during cold chain transportation. It prevents rebound of oxidase activity and microbial proliferation caused by temperature rise, significantly improving the stability of the preservation process. The phase change material is encapsulated in high-density polyethylene, eliminating leakage risk, meeting food contact safety requirements, and is reusable for cooling.

[0034] A pulsed high-voltage electrostatic field is applied to the storage environment in an intermittent manner. The pulsed electric field can continuously inhibit oxidase activity by affecting the charged groups and spatial conformation of enzyme proteins, while maintaining the integrity of muscle cell membranes, reducing cell fluid leakage, and lowering juice loss. Furthermore, the electric field promotes the slow penetration of antioxidant components in the coating into the superficial layers of muscle, prolonging the depth and duration of antioxidant effects, thus creating a triple synergistic preservation effect with the coating and modified atmosphere packaging. The intermittent application mode reduces energy consumption while ensuring preservation effects, making it suitable for large-scale industrial production.

[0035] Experimental materials and equipment: Yak meat was taken from the longissimus dorsi muscle of 3-year-old healthy yaks in Yushu, Qinghai; Tibetan mutton was taken from the leg meat of 2-year-old healthy Tibetan sheep in Nagqu, Tibet, and was delivered to the experimental workshop within 1 hour after slaughter; chitosan (degree of deacetylation ≥90%), ferulic acid, rosemary essential oil, ε-polylysine hydrochloride, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) were all food grade; highland barley bran was obtained from a local highland barley processing plant; slightly acidic electrolyzed water was generated from commercially available slightly acidic electrolyzed water. The equipment is manufactured on-site; the iron-based slow-release deoxygenating tablets are food-contact grade commercial products with a single tablet deoxygenating capacity of 500mL; the shaped phase change cold storage liner is made of high-density polyethylene shaped paraffin-based phase change material; the differential pressure precooling room, DC high-voltage electrostatic field generator, scanning dielectric barrier discharge cold plasma equipment, low-temperature plasma jet device, ultrasonic atomization coating equipment, modified atmosphere packaging machine, and pulsed high-voltage electrostatic field cold storage are all conventional equipment in the food industry; the dialysis bags have a molecular weight cutoff of 8000-14000Da.

[0036] Detection methods: Total bacterial count was determined using the plate count method according to GB 4789.2-2022; the degree of lipid oxidation was expressed as thiobarbituric acid value (TBARS), with units of mg MDA / kg; color was determined using a colorimeter to measure the a* value (redness value), with a higher value indicating a brighter red; juice loss rate was determined by gravimetric method; the grafting degree of ferulic acid-modified chitosan was determined by ultraviolet spectrophotometry, using ferulic acid as a standard, with a detection wavelength of 280 nm; the average degree of polymerization of feruloyl oligosaccharides was determined by high performance liquid chromatography; temperature fluctuation simulation adopted an intermittent heating mode, with the temperature rising to 8℃ every 12 hours and maintained for 2 hours before recovery; sensory evaluation was conducted by 5 professional tasters, who scored the color, odor, and texture comprehensively, with a maximum score of 10 points and a lower acceptable limit of 6 points.

[0037] Example 1: Segmented preservation processing of the longissimus dorsi muscle of yak: This embodiment describes a segmented preservation process for the longissimus dorsi muscle of yaks, with the following specific steps: (1) Pre-cooling and sterilization stage: Select yak half carcasses that have been trimmed and had their skin, excess fat and lymph nodes removed after slaughter, and immediately send them to the differential pressure pre-cooling room. Set the relative humidity of the pre-cooling room to 90% and apply a DC high voltage electrostatic field with an electric field strength of 120kV / m throughout the process. A two-stage gradient cooling is adopted: the first stage of pre-cooling lasts for 5 hours, rapidly reducing the carcass center temperature from the initial 40℃ to 14℃, quickly passing through the optimal growth temperature range for microorganisms; the second stage of pre-cooling lasts for 10 hours, slowly reducing the center temperature to 2℃ to avoid muscle contraction. During the pre-cooling process, a scanning dielectric barrier discharge cold plasma device was simultaneously activated, with a discharge voltage of 20kV, a discharge frequency of 10kHz, an electrode-carcass surface distance of 20mm, and a scanning rate of 0.2m / s. The device scanned the carcass surface cyclically every 2.5 hours. Simultaneously, an ultrasonic atomizer was activated for each scan, atomizing slightly acidic electrolyzed water with an effective chlorine concentration of 60mg / L and a pH of 5.8. The droplets settled uniformly on the carcass surface. After pre-cooling, samples were taken for testing. The total bacterial count on the carcass surface decreased from an initial 5.3log CFU / g to 1.8log CFU / g, indicating uniform sterilization and no excessive oxidation of surface proteins.

[0038] (2) Splitting and coating stage: The pre-cooled carcasses are transferred to a clean splitting workshop, where the temperature is controlled at 4℃ and the total number of airborne bacteria is controlled at 80 CFU / m³. 3 The following steps were performed: After disinfection, the operators divided and trimmed the carcass into individual pieces of the longest back muscle, each weighing approximately 500g, removing surface fascia and bone fragments. Within 30 seconds of division, all sections were scanned using a low-temperature plasma jet with compressed air as the working gas. The gas flow rate was 10L / min, the processing distance was 2cm, and the scanning rate was 0.3m / s. Each section was treated once, instantly inactivating surface oxidases and microorganisms.

[0039] The meat pieces were then evenly placed on a food-grade conveyor belt and fed into an ultrasonic atomization coating chamber at a uniform speed for coating. The ferulic acid-modified chitosan-based Pickering composite preservative emulsion used in this embodiment was prepared as follows: First, ferulic acid-modified chitosan was prepared. 1g of chitosan was weighed and dissolved in 100mL of 0.1mol / L, pH 5.0 acetate buffer solution, stirred until completely dissolved, 0.3g of EDC was added and stirred for 15 minutes for activation, followed by the addition of 0.4g of ferulic acid. The mixture was stirred and reacted at room temperature in the dark for 12 hours. The reaction solution was transferred to a dialysis bag with a molecular weight cutoff of 8000-14000 Da and dialyzed with deionized water for 72 hours, with the dialysis medium replaced every 12 hours. After dialysis, the solution was freeze-dried at -50℃ for 24 hours to obtain ferulic acid-modified chitosan with a grafting degree of 18%. 1.5g of modified chitosan was weighed and dispersed in 100mL of pH 5.0 acetate buffer as the aqueous phase, and 0.5g of rosemary essential oil was added as the oil phase. The mixture was sheared at 10000rpm for 5 minutes to obtain Pickering colostrum. Then, 0.4g of feruloyl oligosaccharide and 0.2g of ε-polylysine hydrochloride were added to the colostrum and stirred at low speed until homogeneous to obtain the finished emulsion.

[0040] The feruloyl oligosaccharide was prepared as follows: after defatting barley bran with petroleum ether, 0.5 mol / L NaOH solution was added at a material-to-liquid ratio of 1:10, and alkaline hydrolysis was carried out at 40°C for 2 hours. The solution was neutralized with hydrochloric acid to pH 6.0, and xylanase was added at 0.5% of the substrate mass. The solution was enzymatically hydrolyzed at 50°C for 3 hours, and the enzyme was inactivated at 95°C for 10 minutes. The supernatant was collected by centrifugation and purified by ultrafiltration membrane with a molecular weight cutoff of 1000 Da. After freeze-drying, feruloyl oligosaccharide with an average degree of polymerization of 3 was obtained.

[0041] The ultrasonic atomization frequency was set to 2.0 MHz, the average droplet size was 30 μm, the total residence time of the meat piece in the atomization zone was 3 minutes, and the emulsion loading per kilogram of meat piece was controlled at 1.2 g. After coating, the meat piece was transferred to a clean environment at 4°C and allowed to drain for 5 minutes until a uniform, transparent, and dense liquid film formed on the surface of the meat piece, without liquid accumulation or dripping.

[0042] (3) Storage and preservation stage: Select a 1000mL PP material preservation packaging box with a 3mm thick shaped phase change cold storage liner at the bottom. The liner is pre-cooled at 0℃ for 12 hours. Place the drained meat pieces into the packaging box, with a 500mL iron-based slow-release deoxygenating tablet inside. Send it into a modified atmosphere packaging machine to fill with an initial mixed protective gas. The gas volume composition is 11% oxygen, 30% carbon dioxide, and 59% nitrogen. After sealing, immediately send it into a 0-2℃ pulsed high-voltage electrostatic field cold storage. Set the pulsed electrostatic field strength to 150kV / m and the pulse frequency to 1Hz. Use an intermittent application mode, applying the electric field for 4 hours every 12 hours and turning it off for the rest of the time.

[0043] Samples were taken at 0, 7, 14, 21, and 30 days of storage to test various quality indicators, with parallel groups tested under temperature fluctuation conditions. Results showed that after 30 days of constant temperature storage, the total bacterial count of the meat was 4.7 log CFU / g, below the spoilage threshold of 6 log CFU / g; the TBARS value was 0.30 mg MDA / kg, still within the quality range of fresh meat; the meat color a* value was 16.5, maintaining a good bright red color; the juice loss rate was 1.9%; the sensory score was 7.9 points, with no off-odors, no stickiness, and normal texture. Under temperature fluctuation conditions, the differences in all indicators compared to constant temperature conditions were less than 10%, demonstrating excellent resistance to temperature fluctuations.

[0044] Example 2: Segmented Preservation Processing of Tibetan Lamb Leg Meat: This embodiment focuses on the segmented preservation processing of Tibetan lamb leg meat. Some process parameters are adjusted to take advantage of the finer muscle fibers and lower fat content of Tibetan lamb. The specific steps are as follows: (1) Pre-cooling and sterilization stage: Selected Tibetan sheep half-carcasses that had been trimmed after slaughter were sent to the differential pressure pre-cooling room, with a relative humidity of 88%. A DC high-voltage electrostatic field with an electric field strength of 100kV / m was applied throughout the process. Two-stage gradient cooling: The first stage of pre-cooling lasted 4 hours, during which the carcass center temperature dropped from 41℃ to 13℃; the second stage of pre-cooling lasted 9 hours, during which the center temperature dropped to 1℃. During the pre-cooling process, the scanning cold plasma device was intermittently turned on, with a discharge voltage of 18kV, a discharge frequency of 9kHz, an electrode-carcass surface distance of 18mm, a scanning rate of 0.25m / s, and scanning every 2 hours. Each time, slightly acidic electrolyzed water was atomized simultaneously, with an effective chlorine concentration of 55mg / L and a pH of 5.5. After the pre-cooling was completed, the total number of colonies on the carcass surface dropped from the initial 5.1log CFU / g to 1.7log CFU / g.

[0045] (2) Splitting and coating stage: The temperature in the splitting workshop is controlled at 3℃, and the total number of airborne bacteria is 70 CFU / m³. 3 The carcass was then divided into boneless leg meat pieces weighing approximately 300g each. Within 20 seconds of division, all cut surfaces were treated with compressed air plasma jet at a gas flow rate of 9L / min, a treatment distance of 1.5cm, and a scanning rate of 0.4m / s, with each cut surface treated once.

[0046] Subsequently, ultrasonic atomization coating was performed. The composite preservative emulsion in this embodiment was prepared as follows: Ferulic acid-modified chitosan was prepared with a feed ratio of 1g chitosan, 0.25g EDC, and 0.35g ferulic acid, under the same reaction conditions as in Example 1, yielding modified chitosan with a grafting degree of 15%. The finished emulsion was prepared by mass fraction as follows: 1.3% ferulic acid-modified chitosan, 0.4% rosemary essential oil, 0.3% feruloyl oligosaccharide, 0.15% ε-polylysine hydrochloride, and the balance being acetate buffer at pH 4.8. The average degree of polymerization of the feruloyl oligosaccharide was 2, and the preparation method was the same as in Example 1. The atomization frequency was set to 1.8MHz, the meat block residence time to 2.5 minutes, and the emulsion loading per kilogram of meat block to 1.0g. After coating, the emulsion was drained at 3°C ​​for 4 minutes, forming a uniform liquid film on the surface.

[0047] (3) Storage and preservation stage: Select a packaging box with a volume of 800mL, with a 2mm thick shape-fixed phase change cold storage liner inside. The liner is pre-cooled at 0℃ for 12 hours. Place one iron-based slow-release deoxygenating tablet with a deoxygenation capacity of 400mL inside. The initial gas volume composition of the controlled atmosphere is 10% oxygen, 32% carbon dioxide, and 58% nitrogen. After sealing, it is sent to a cold storage at 0-2℃. The electric field strength of the pulsed high-voltage electrostatic field is 120kV / m, the pulse frequency is 0.8Hz, and it is applied for 3.5 hours every 12 hours.

[0048] Results of sampling and testing after 30 days of storage: total bacterial count was 4.4 log CFU / g, TBARS value was 0.26 mg MDA / kg, meat color a* value was 16.1, juice loss rate was 1.7%, sensory score was 8.1 points, overall quality was excellent, and it met the preservation requirements of Tibetan mutton; the quality retention rate was higher than 92% under temperature fluctuation conditions, and the stability was good.

[0049] Example 3: Long-cycle transportation-adapted yak meat preservation processing: This embodiment aims to enhance preservation strength in long-distance cold chain transportation scenarios and verifies the preservation effect at the upper limit of the parameter range. The specific steps are as follows: (1) Pre-cooling and sterilization stage: Yak half-carcasses were placed in a differential pressure pre-cooling room with a relative humidity of 95%. A DC high-voltage electrostatic field with an electric field strength of 140kV / m was applied throughout the process. Two-stage gradient cooling was used: the first stage reduced the temperature from 39℃ to 15℃ in 6 hours, and the second stage reduced it to 4℃ in 12 hours. The scanning cold plasma discharge voltage was 24kV, the frequency was 12kHz, the electrode spacing was 28mm, the scanning rate was 0.15m / s, and scanning was performed every 3 hours. Slightly acidic electrolyzed water was atomized simultaneously each time, with an effective chlorine concentration of 75mg / L and a pH of 6.2. After pre-cooling, the total bacterial count dropped to 1.5log CFU / g.

[0050] (2) Splitting and coating stage: The temperature in the splitting workshop is 6℃, and the total number of airborne bacteria is 90 CFU / m³. 3The meat was then cut into 1000g pieces. Within 30 seconds of cutting, it underwent plasma jet slicing treatment at a gas flow rate of 12L / min, a processing distance of 2.5cm, and a scanning rate of 0.25m / s, with each slice being processed twice.

[0051] Preparation of composite preservative emulsion: The feed ratio of ferulic acid-modified chitosan was 1g chitosan, 0.35g EDC, and 0.5g ferulic acid. The reaction conditions were the same as in Example 1, yielding modified chitosan with a grafting degree of 23%. The mass fraction of the finished emulsion was: 2.0% ferulic acid-modified chitosan, 0.7% rosemary essential oil, 0.6% feruloyl oligosaccharide, 0.3% ε-polylysine hydrochloride, and the balance being acetate buffer at pH 5.5. The average degree of polymerization of feruloyl oligosaccharide was 5. Ultrasonic atomization frequency was 2.5MHz, meat block residence time was 5 minutes, and emulsion loading was 1.5g per kilogram of meat block. After coating, the emulsion was drained for 7 minutes.

[0052] (3) Storage and preservation stage: Select a 1500mL packaging box, with a 4mm thick shape-fixed phase change cold storage liner inside, and pre-store cold at 0℃ for 12 hours; add one iron-based slow-release deoxygenating tablet with a deoxygenation capacity of 750mL. The initial gas volume composition of the controlled atmosphere is 12% oxygen, 35% carbon dioxide, and 53% nitrogen. After sealing, it is sent to a 0-4℃ cold storage. The pulsed high-voltage electrostatic field has an electric field strength of 180kV / m and a pulse frequency of 1.5Hz, and is applied for 5 hours every 12 hours.

[0053] Results of sampling and testing after 30 days of storage: total bacterial count was 4.1 log CFU / g, TBARS value was 0.27 mg MDA / kg, flesh color a* value was 16.8, juice loss rate was 1.6%, sensory score was 8.2 points, indicating excellent preservation effect; after simulating multiple temperature fluctuations, all indicators remained at a good level, which can meet the needs of long-term cross-regional cold chain transportation.

[0054] Comparison of control case settings and results To verify the synergistic effect of the various technical aspects of this invention, seven control examples were set up. Except for the specified variables, all other conditions were kept consistent with those in Example 1. The quality indicators after 30 days of storage (temperature fluctuation conditions) were compared, and the results are as follows: Control Example 1 (Conventional Traditional Process): The product underwent conventional air-cooling pre-cooling for 24 hours to reach 4°C, without any sterilization treatment. It was then soaked in a common chitosan solution for coating, packaged in ordinary air, and refrigerated at 0-2°C. Results: On the 9th day of storage, the total bacterial count reached 6.4 logCFU / g, exceeding the spoilage threshold; the TBARS value reached 0.65 mg MDA / kg, indicating severe oxidation; the a* value dropped to 10.2, and the color became dull, rendering it completely unmarketable.

[0055] Control Example 2 (using only the pre-cooling and sterilization technology of this scheme): The pre-cooling stage was the same as in Example 1, with no passivation of the cut surfaces after segmentation. The cells were soaked in ordinary chitosan solution for coating, packaged in ordinary air, and refrigerated as usual. Results: On the 18th day of storage, the total bacterial count reached 6.1 logCFU / g, reaching the spoilage threshold; the TBARS value was 0.48 mg MDA / kg, the a* value was 12.5, and obvious oxidative browning was observed at the segmented surfaces.

[0056] Control Example 3 (Pre-cooling and sterilization + cut surface passivation + ordinary coating): Pre-cooling and cut surface passivation were the same as in Example 1. The coating was applied using a common chitosan composite coating solution (composition same as in Example 1, but without Pickering emulsion, only simple blending). Ordinary static low-oxygen modified packaging was used, without a cooling pad or electrostatic field, and conventional refrigeration was performed. Results: On day 22 of storage, the total bacterial count reached 6.0 logCFU / g, reaching the spoilage threshold; the TBARS value was 0.41 mg MDA / kg, and the a* value was 13.6. Significant film swelling and accelerated oxidation rate were observed in the later stages of storage, and the indicators decreased significantly after temperature fluctuations.

[0057] Control Example 4 (Pre-cooling and sterilization + cut surface passivation + Pickering coating + static low-oxygen conditioning): Pre-cooling, cut surface passivation, and coating were the same as in Example 1, using a fixed ratio of low-oxygen conditioning (oxygen concentration 6%), without a cooling pad or electrostatic field, and conventional refrigeration. Results: On day 26 of storage, the total bacterial count reached 5.9 log CFU / g, close to the spoilage threshold; TBARS value was 0.36 mg MDA / kg, a* value was 14.2, the meat color was darker in the early stage of storage, and the oxidation rate rebounded after temperature fluctuations.

[0058] Comparative Example 5 (passivation treatment of the dividing surface removed, otherwise the same as Example 1): Except for not performing plasma jet treatment on the dividing surface, the other processes were the same as in Example 1. Results: After 30 days of storage, the total bacterial count was 5.3 log CFU / g, the TBARS value was 0.39 mg MDA / kg, and the a* value was 14.8. Browning and stickiness first appeared at the dividing surface, and the overall quality declined significantly.

[0059] Control Example 6 (static high-oxygen conditioning instead of gradient deoxygenation, otherwise the same as Example 1): Static high-oxygen conditioning with 80% oxygen + 20% carbon dioxide was used, without deoxygenating tablets, otherwise the same as Example 1. Results: After 30 days of storage, the total bacterial count was 5.1 log CFU / g, the TBARS value was 0.52 mg MDA / kg, severe lipid oxidation was observed, the a* value was high in the early stage but rapidly decreased to 13.5 in the later stage, and the flavor deterioration was obvious.

[0060] Control Example 7 (without the phase change cooling liner, otherwise the same as Example 1): Except for the absence of the phase change cooling liner, everything else was the same as Example 1, with simultaneous temperature fluctuation treatment. Results: After 30 days of storage, the total bacterial count was 5.5 log CFU / g, the TBARS value was 0.42 mg MDA / kg, and the a* value was 14.0. The rate of quality degradation significantly accelerated after temperature fluctuation, and the juice loss rate increased to 3.2%.

[0061] The comparison shows that each technical point of the present invention makes a significant contribution to the final preservation effect. After the multi-stage technologies of pre-cooling and sterilization, segmentation and passivation, water-resistant coating and temperature-controlled storage are connected and coordinated, the preservation period, antioxidant capacity and resistance to temperature fluctuations have all been improved beyond linear superposition. This proves that the overall technical solution has produced a significant synergistic effect and has outstanding substantive features and significant progress.

[0062] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A segmented preservation and processing technology for low-oxidation yak meat and Tibetan mutton, characterized in that, The process includes a pre-cooling and sterilization stage, a segmentation and coating stage, and a storage and preservation stage, with the specific steps as follows: (1) Pre-cooling and sterilization stage: The slaughtered and trimmed yak meat or Tibetan sheep meat half carcass is sent into the pressure difference pre-cooling room and pre-cooled in a two-stage gradient cooling environment with a relative humidity of 85%-95% and a DC high voltage electrostatic field. During the pre-cooling process, a scanning dielectric barrier discharge cold plasma device is used to scan back and forth along the surface of the carcass, while ultrasonic atomized slightly acidic electrolyzed water works synergistically on the surface of the carcass. When the temperature of the center of the carcass drops to 0-4℃, the pre-cooling and sterilization is completed. (2) Cutting and coating stage: The pre-cooled carcass is transferred to a clean cutting workshop at 0-8℃ and cut into target meat pieces. Within 30 seconds after cutting, a low-temperature plasma jet with compressed air as the working gas is used to passivate all the cut surfaces of the meat pieces. Then the meat pieces are sent into an ultrasonic atomization coating chamber, and a ferulic acid modified chitosan-based Pickering composite preservation emulsion is used to atomize and coat the meat pieces. After draining, a uniform and dense preservation liquid film is formed on the surface. (3) Storage and preservation stage: The coated meat pieces are packed into a packaging box with a built-in fixed phase change cold storage liner, filled with an initial proportion of mixed protective gas and a built-in slow-release deoxygenating tablet for gradient oxygen reduction conditioning packaging, sealed and sent to a 0-4℃ cold storage, and a pulsed high voltage electrostatic field is applied for auxiliary storage to complete the segmented preservation processing.

2. The segmented preservation and processing technology for low-oxidation yak meat and Tibetan mutton according to claim 1, characterized in that: The electric field strength of the DC high voltage electrostatic field mentioned in step (1) is 80-150kV / m, and it is continuously applied throughout the entire process; The two-stage gradient cooling process is as follows: the first stage lasts 4-6 hours to reduce the core temperature of the carcass from 38-42℃ to 12-15℃, and the second stage lasts 8-12 hours to reduce it to 0-4℃. The discharge voltage of the scanning cold plasma is 16-24kV, the discharge frequency is 8-12kHz, the distance between the electrode and the carcass surface is 15-30mm, the scanning rate is 0.1-0.3m / s, and the scanning process is performed once every 2-3 hours. Each scan simultaneously atomizes slightly acidic electrolyzed water, with an effective chlorine concentration of 50-80 mg / L and a pH value of 5.0-6.

5.

3. The segmented preservation and processing technology for low-oxidation yak meat and Tibetan mutton according to claim 1, characterized in that: In step (2), the gas flow rate of the low-temperature plasma jet is 8-15 L / min, the processing distance is 1-3 cm, the scanning rate is 0.2-0.5 m / s, and each cross section is processed 1-2 times. The ultrasonic atomization coating has an atomization frequency of 1.5-2.5MHz, a droplet size of 10-50μm, and the meat pieces remain in the atomization zone for 2-5 minutes. The emulsion loading per kilogram of meat pieces is 0.9-1.6g.

4. The segmented preservation and processing technology for low-oxidation yak meat and Tibetan mutton according to claim 1, characterized in that: The preparation method of the ferulic acid modified chitosan-based Pickering composite preservative emulsion is as follows: Chitosan was dissolved in acetate buffer, activated with 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and then ferulic acid was added for a light-protected grafting reaction. The reaction solution was dialyzed and freeze-dried to obtain ferulic acid-modified chitosan. Modified chitosan was dispersed in acetate buffer as the aqueous phase, and rosemary essential oil was added as the oil phase. Pickering colostrum was prepared by high-speed shearing. Then, feruloyl oligosaccharide and ε-polylysine hydrochloride are added to the colostrum and stirred until homogeneous to obtain the finished emulsion.

5. The segmented preservation and processing technology for low-oxidation yak meat and Tibetan mutton according to claim 4, characterized in that: By mass fraction, the finished emulsion contains: The composition consists of 1.2%-2.0% ferulic acid-modified chitosan, 0.3%-0.8% rosemary essential oil, 0.2%-0.6% ferulic yl oligosaccharide, 0.1%-0.3% ε-polylysine hydrochloride, with the balance being acetate buffer at pH 4.5-5.

5. The grafting degree of the ferulic acid-modified chitosan is 12%-25%; the feruloyl oligosaccharide is obtained from barley bran through alkaline hydrolysis, enzymatic hydrolysis, and purification, with an average degree of polymerization of 2-5.

6. The segmented preservation and processing technology for low-oxidation yak meat and Tibetan mutton according to claim 1, characterized in that: The initial mixed gas volume composition of the gradient oxygen conditioning packaging described in step (3) is: oxygen 10%-12%, carbon dioxide 25%-35%, and nitrogen 53%-65%; The slow-release oxygen removal tablets are iron-based slow-release oxygen removal tablets, with a single tablet's oxygen removal capacity matching the packaging box volume. They can gradually reduce the oxygen concentration inside the packaging to 5%-6% and maintain stability within 7 days of storage.

7. The segmented preservation and processing technology for low-oxidation yak meat and Tibetan mutton according to claim 1, characterized in that: The shaped phase change cold storage liner described in step (3) uses high-density polyethylene as the shaped carrier, composite paraffin-based phase change material, phase change temperature of 0-2℃, latent heat of phase change ≥180J / g, liner thickness of 2-4mm, and is placed in a 0℃ environment for cold storage for more than 12 hours before use.

8. The segmented preservation and processing technology for low-oxidation yak meat and Tibetan mutton according to claim 1, characterized in that: The electric field strength of the pulsed high voltage electrostatic field in step (3) is 100-200kV / m, the pulse frequency is 0.5-2Hz, and it is applied intermittently for 3-5 hours every 12 hours.

9. The segmented preservation and processing technology for low-oxidation yak meat and Tibetan mutton according to claim 1, characterized in that: In step (2), the weight of each cut meat piece is 0.2-1.0 kg, and the total number of bacterial colonies in the air of the cutting workshop is ≤100 CFU / m³. 3 .

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