Method for preparing sheep liver and sheep tripe nutritional base material by lactobacillus fermentation

Abstract

The invention relates to a method for preparing a lamb liver and lamb tripe nutritional base material through lactobacillus fermentation, and belongs to the technical field of food processing. The method solves the problems of low retention rate of active ingredients, non-uniform permeation and poor flavor coordination in the preparation process of the sheep liver and sheep tripe composite nutrient base material. According to the technical scheme, the method is characterized by comprising the following steps: performing pulse treatment on lamb liver slices, spraying a composite penetrating fluid containing active ingredients such as lysozyme and Nisin at low temperature, standing, performing cooking and enzymolysis on lamb tripe strips, mixing the lamb tripe strips with the lamb liver slices, performing vacuum treatment, performing chopping, adjusting the pH value, inoculating lactic acid bacteria, performing fermentation, and performing inactivation and drying. By optimizing components and process parameters of the penetrating fluid, the stability and penetration efficiency of active ingredients are remarkably improved, and finally the nutritional base material with high activity and coordinated flavor is prepared and is mainly used for preparing raw materials of functional foods or nutritional supplements.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of food processing. More specifically, the present application relates to a method for preparing a nutritional base material of sheep liver and sheep tripe by fermentation with lactic acid bacteria. BACKGROUND

[0002] In the field of food processing, animal offal such as sheep liver and sheep tripe is considered as a potential food raw material due to its rich nutritional ingredients. However, there are several technical difficulties in its deep processing, which restricts the development of high value-added products.

[0003] Sheep liver tissue is rich in various heat-sensitive and easily oxidizable active ingredients, such as vitamins, minerals, and certain functional proteins. In the traditional processing process, due to the dense tissue structure, it is difficult for externally added active protective ingredients to effectively penetrate into the interior of the tissue. At the same time, heat treatment steps are often accompanied in the processing, which will exacerbate the degradation and loss of internal active substances, resulting in a significant reduction in the nutritional value of the final product. The reason for this problem is that the liver tissue has a complete cell structure and small intercellular space, which forms a physical barrier to macroscopic solution soaking or simple smearing. In the past, attempts have been made to improve the penetration effect by increasing the concentration of the penetration solution or prolonging the treatment time, but often result in uneven phenomena such as excessive accumulation of surface ingredients, insufficient internal penetration, and even hardening of the surface texture of the tissue, which further hinders penetration. How to achieve efficient and uniform distribution of active ingredients in complex biological tissues is a long-standing technical challenge.

[0004] On the other hand, sheep tripe, although cleaned and steamed, still has its inherent fishy and rancid odor, and its protein and fat composition differs from that of sheep liver. When the two are processed together, improper handling not only fails to mask or transform the poor flavor, but also causes the different odors of the raw materials to overlap, resulting in an unpleasant overall flavor. The root cause lies in the differences in matrix characteristics, flavor precursor substances, and change paths during processing between the two raw materials, making it difficult to coordinate and unify the rhythm and intensity of flavor release. Traditional physical odor removal or essence masking methods have limited effect and may introduce non-natural ingredients, which does not meet the trend of clean labeling. Simple mechanical mixing or one-step fermentation cannot achieve deep integration and coordination of flavors, which easily leads to separation of product flavors and inconsistency.

[0005] In addition, the difference in texture characteristics between sheep liver and sheep tripe also poses difficulties in achieving uniform mixing of materials when preparing a composite nutritional base material. Liver tissue is soft and fragile, while tripe tissue still has some toughness and elasticity after steaming. Simple cutting and stirring cannot achieve sufficient mixing of the two at the molecular level, and phase separation easily occurs during subsequent processing, resulting in uneven composition and poor mouthfeel experience of the final product. Attempts to improve mixing by high-strength homogenization or prolonged grinding time also risk excessive damage to the cell structure of the liver tissue, leading to juice loss and destruction of active ingredients.

[0006] Therefore, in the development of sheep liver and tripe composite nutrient substrate, how to solve the three problems of efficient and uniform penetration of active ingredients, essential improvement of undesirable flavor, and uniform integration of heterogeneous materials under the premise of not significantly damaging the inherent nutritional components of raw materials is a technical bottleneck that needs to be broken through in the industry. Past research has focused on improving a single problem, and there is a lack of comprehensive solutions that can systematically address all the above problems. SUMMARY

[0007] The purpose of the present application is to provide a method for preparing sheep liver and tripe nutrient substrate using lactic acid bacteria fermentation, achieving high active ingredient retention rate, uniform penetration, and good flavor coordination.

[0008] Solve the problems of low active ingredient retention rate, uneven penetration, and poor flavor coordination in the preparation process of sheep liver and tripe composite nutrient substrate.

[0009] Solve the problems of low efficiency of single-stage fermentation and uneven accumulation of metabolic products.

[0010] Solve the problem of inconsistent subsequent process caused by uneven size during the processing of sheep liver slices and tripe strips.

[0011] Solve the problems of low efficiency of pulse processing, insufficient enzymatic hydrolysis, and incomplete inactivation.

[0012] Solve the problems of low gas transfer efficiency and unstable metabolic environment during fermentation.

[0013] Solve the problems of poor stability and poor penetration effect of the composite penetration liquid.

[0014] Solve the problem of difficulty of uniform penetration of the penetration liquid into the sheep liver slices.

[0015] Solve the problems of large temperature fluctuations and uneven penetration during the spraying process.

[0016] Solve the problem of water evaporation on the surface of sheep liver slices and loss of penetration liquid during the standing process.

[0017] Solve the problem of structural damage and loss of active ingredients caused by rapid temperature change of sheep liver slices.

[0018] In order to solve the above problems and achieve the purpose and other advantages of the present application, a method for preparing sheep liver and tripe nutrient substrate using lactic acid bacteria fermentation is provided, comprising: After the sheep liver is cut into sheep liver slices, pulse processing is performed; The pulse-treated mutton liver slices are sprayed with a complex permeation solution at -2-0℃, which accounts for 3-5% of the weight of the mutton liver slices, and then left to stand for 10-15 min; the complex permeation solution comprises 0.1-0.3 g / L lysozyme, 0.05-0.1 g / L polyglycerol fatty acid ester, 0.05-0.15 g / L Nisin, 3-5 g / L trehalose, 0.02-0.04 g / L EDTA-2Na, and a citric acid-disodium hydrogen phosphate buffer with a pH value of 6.0-6.2; The mutton tripe strips are cooked for 16-18 min; After the cooked mutton tripe strips are immersed in water with a mass of 1.5-2.0 times that of the mutton tripe strips, a complex enzyme preparation with a mass of 0.7-0.9% of the mutton tripe strips and an enzyme hydrolysis promoter are added, and the mixture is treated by oscillation at 48-50℃ for 35-40 min; the final concentrations of the components of the enzyme hydrolysis promoter in the enzyme hydrolysis system are as follows: L-cysteine 1-2 g / L, trehalose 20-30 g / L, soybean phospholipid 0.5-1.5 g / L, and betaine 5-10 g / L. The permeation-treated mutton liver slices and the enzyme-hydrolyzed mutton tripe strips are mixed in a mass ratio of 1:1-2, and then kept at a vacuum degree of -0.08 to -0.10 MPa for 5-8 min; Water with a mass of 1.8-2.2 times that of the mixture and at a temperature of 5-8℃ is added to the mixture, and the mixture is chopped and blended to form a homogeneous slurry; The pH value of the homogeneous slurry is adjusted to 6.5-6.8; A mixed starter culture composed of Lactobacillus plantarum and Lactobacillus casei with a ratio of viable bacterial counts of 1:1-1.5 is inoculated into the homogeneous slurry, and the total amount of the inoculum is 2.5-3.5% of the mass of the homogeneous slurry; The inoculated slurry is fermented; The fermented material is inactivated; The inactivated material is freeze-dried to a water content of ≤5%.

[0019] Preferably, in the method for preparing a mutton liver and tripe nutritional base by fermentation with lactic acid bacteria, the fermentation is divided into two stages: In the first stage, the fermentation is carried out at 40-41℃ with stirring at 70-100 r / min for 10-12 h; In the second stage, the stirring is stopped, the temperature is lowered to 36-37℃, a fermentation promoter is added, and the static fermentation is carried out for a total time of 40-47 h; the final concentrations of the components of the fermentation promoter in the fermentation system are as follows: yeast peptone 5-10 g / L, polyglutamic acid 3-8 g / L, and L-glutamine 2-5 g / L.

[0020] Preferably, in the method for preparing nutrient base material for sheep liver and sheep tripe by fermentation with lactic acid bacteria, the fresh sheep liver is washed and cut into slices with a thickness of 3-5 mm; the fresh sheep tripe is washed and the contents are removed and then cut into strips with a width of 5-8 mm and a length of 20-30 mm.

[0021] Preferably, in the method for preparing nutrient substrate for sheep liver and sheep tripe by fermentation with lactic acid bacteria, the specific method for pulse treatment of sheep liver slices is as follows: the sheep liver slices are placed in a treatment chamber with a pulse electric field strength of 2.0-2.5kV / cm, a pulse width of 30-40μs, and a frequency of 80-100Hz for 6-8 minutes; the compound enzyme preparation is composed of neutral protease, flavor protease, and bromelain in an enzyme activity unit ratio of 1:0.7-0.9:0.2-0.4; the material after fermentation is heated at 95-100℃ for 15-20 minutes to inactivate the enzyme.

[0022] Preferably, in the method for preparing nutrient substrate for sheep liver and sheep tripe by fermentation using lactic acid bacteria, 2 hours after the start of the second stage of fermentation, a mixture of micro-nano bubbles with a flow rate of 0.5-1.0 L / min and a bubble diameter of 10-50 μm is introduced into the fermentation system. The mixture consists of nitrogen and carbon dioxide in a volume ratio of 9:1.

[0023] Preferably, in the method for preparing nutrient substrate for sheep liver and sheep tripe by fermentation with lactic acid bacteria, the composite permeate further includes: 0.05-0.1 g / L lecithin, 0.05-0.1 g / L xanthan gum, 0.05-0.1 g / L gum arabic, 0.05-0.1 g / L sodium carboxymethyl cellulose, 0.1-0.2 g / L β-glucan and 0.01-0.03 g / L sodium hyaluronate.

[0024] Preferably, in the method for preparing nutrient substrate for sheep liver and sheep tripe using lactic acid bacteria fermentation, before spraying the pulse-treated sheep liver slices with the composite permeation solution, a pretreatment with ultrasound at a frequency of 40-60 kHz is performed for 3-5 minutes, with the ultrasonic power density controlled at 0.3-0.5 W / cm². 2 Next, place the lamb liver slices in a vacuum environment of -0.05 to -0.07 MPa for 2-3 minutes.

[0025] Preferably, in the method for preparing nutrient substrate for sheep liver and sheep tripe using lactic acid bacteria fermentation, when spraying the composite permeate, the droplet size of the spray liquid is controlled to be 50-100 μm, and the spraying rate is 0.5-1.0 mL / cm. 2 10 min, and control the temperature difference between the surface temperature of the sheep liver slices and the composite permeation solution to ≤2℃. After spraying, stir at a low speed of 20-30 r / min for 3-5 min.

[0026] Preferably, in the method for preparing a nutritional base material of mutton liver and tripe by fermentation of lactic acid bacteria, a breathable film is covered on the surface of the mutton liver slice during the standing process after spraying the composite penetrating solution, the porosity of the film is 60-70%, and the humidity of the standing environment is controlled at 85-90%.

[0027] Preferably, in the method for preparing a nutritional base material of mutton liver and tripe by fermentation of lactic acid bacteria, after the mutton liver slice is sprayed with the composite penetrating solution and then stood, the mutton liver slice is warmed at a rate of 0.5-1.0 ℃ / min to 4-6 ℃, maintained for 5-8 min, and then the subsequent mixing step with the tripe strip is performed.

[0028] The present application at least includes the following beneficial effects: The present application significantly improves the penetration efficiency and stability of heat-sensitive active ingredients in the mutton liver slice by optimizing pulse treatment and composite penetrating solution formulation, achieving high retention rate of functional ingredients such as vitamins and minerals.

[0029] The present application effectively degrades tripe proteins and reduces the generation of undesirable flavor substances by using segmented enzymatic hydrolysis and synergistic action of composite enzyme preparations, significantly improving the flavor harmony and mouthfeel quality of the product.

[0030] The present application improves the metabolic efficiency and product uniformity of lactic acid bacteria by using a two-stage fermentation process combined with the use of fermentation promoters, enhancing the nutritional value and flavor levels of the product.

[0031] The present application introduces micro-nano bubble aeration technology, optimizes the gas transfer efficiency and metabolic environment of the fermentation system, and further improves the yield and quality stability of the fermentation product.

[0032] The present application significantly enhances the penetration depth and uniformity of the composite penetrating solution in the mutton liver tissue by combining ultrasonic pretreatment with vacuum treatment, avoiding the problems of surface accumulation and insufficient internal penetration.

[0033] The present application ensures uniform distribution and stable penetration of the penetrating solution on the surface of the mutton liver slice by precisely controlling the spraying parameters and temperature difference, improving the consistency of the process and the stability of the product quality.

[0034] The present application uses breathable film covering and humidity control technology to effectively prevent evaporation and loss of the penetrating solution during the standing process, maintaining the activity and effectiveness of the penetrating solution components.

[0035] The present application protects the cell structure integrity of the mutton liver slice by slow warming treatment, avoiding the loss of ingredients and quality decline caused by sudden temperature change.

[0036] The application ensures uniformity and consistency of the sheep liver and the sheep tripe in subsequent processing by unifying raw material cutting specifications and optimizing mixing process, and improves texture and uniformity of nutritional ingredients distribution of the final product.

[0037] The finally prepared nutritional base has high active ingredient retention rate, excellent flavor coordination, good solubility and brewing property, is suitable for development of functional food and nutritional supplement, and has wide application prospect and market potential.

[0038] Other advantages, objects and features of the application will be apparent from the following description, and will be appreciated by those skilled in the art. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 is a flow chart of preparing the sheep liver and the sheep tripe nutritional base by lactic acid bacteria fermentation according to an embodiment of the application. DETAILED DESCRIPTION

[0040] The application will be further described in detail below, so that those skilled in the art can implement the application according to the description.

[0041] It should be noted that the experimental methods in the following embodiments are all conventional methods, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0042] The application provides a method for preparing a sheep liver and a sheep tripe nutritional base by lactic acid bacteria fermentation, comprising: pulsing the sheep liver after cutting into pieces; spraying a composite penetration solution accounting for 3-5% of the mass of the sheep liver pieces at-2-0 DEG C for 10-15 min after pulsing the sheep liver pieces; the composite penetration solution comprises 0.1-0.3 g / L lysozyme, 0.05-0.1 g / L polyglycerol fatty acid ester, 0.05-0.15 g / L Nisin, 3-5 g / L trehalose, 0.02-0.04 g / L EDTA-2Na and a citric acid-disodium hydrogen phosphate buffer solution with a pH value of 6.0-6.2; steaming the sheep tripe for 16-18 min; after steaming the sheep tripe, immersing the sheep tripe in water with a mass of 1.5-2.0 times of the sheep tripe, adding a composite enzyme preparation with a mass of 0.7-0.9% of the sheep tripe, and adding an enzyme hydrolysis promoter, and oscillating at 48-50 DEG C for 35-40 min; the final concentrations of the components of the enzyme hydrolysis promoter in the enzyme hydrolysis system are as follows: L-cysteine 1-2 g / L, trehalose 20-30 g / L, soybean phospholipid 0.5-1.5 g / L, and betaine 5-10 g / L; The permeation treated sheep liver pieces and the enzymatic treated sheep tripe are mixed in a mass ratio of 1:1-2, and then placed under a vacuum degree of-0.08 to-0.10 MPa for 5-8 min; Water with a mass of 1.8-2.2 times of the mixture and at a temperature of 5-8 DEG C is added, and the mixture is chopped and stirred at 12000-14000 r / min for 3-5 min to form a homogeneous slurry; The pH value of the homogeneous slurry is adjusted to 6.5-6.8; A mixed starter culture composed of Lactobacillus plantarum (accession number: DSM 9843) and Lactobacillus casei (Lc-11) with a ratio of viable bacterial counts of 1:1-1.5 is inoculated into the homogeneous slurry, and the total inoculation amount is 2.5-3.5% of the mass of the homogeneous slurry; The inoculated slurry is fermented; The fermented material is inactivated; The inactivated material is freeze-dried to a water content of less than or equal to 5%.

[0043] The present application relates to a kind of using lactic acid bacteria fermentation preparation sheep liver and sheep tripe nutritional base material method, to solve the low active ingredient retention rate in prior art, uneven penetration and the problem of poor flavor coordination.Single enzymolysis or simple fermentation process is generally used in prior art, sheep liver and sheep tripe are mechanically mixed after being treated respectively, lack of systematic integration, resulting in the loss of active ingredients in final product, flavor is not coordinated, organization is not uniform.

[0044] The present application can effectively destroy the cell membrane structure of the sheep liver pieces by pulse treatment, increase the membrane permeability and facilitate the subsequent penetration of the permeation liquid. After spraying 3-5% of the mass of the sheep liver pieces with the complex permeation liquid at-2 to 0 DEG C and standing for 10-15 min, the lysozyme in the complex permeation liquid can effectively decompose the bacterial cell wall, and the Nisin as a natural antibacterial peptide produces a synergistic antibacterial effect with the lysozyme, significantly enhancing the inhibition effect on gram-positive bacteria. The polyglycerol fatty acid ester as an emulsifier not only improves the dispersion of the components, but also forms a complex protection system with trehalose. The trehalose stabilizes the protein structure through glass transition, and also synergizes with EDTA-2Na. The EDTA-2Na effectively inhibits oxidation by chelating metal ions, and the buffer system maintains a suitable pH environment, ensuring the stability of the activity of each component under low temperature conditions. These components cooperate with each other, the lysozyme and Nisin provide antibacterial protection, the polyglycerol fatty acid ester promotes the uniform distribution of each component, the trehalose and EDTA-2Na jointly protect the heat-sensitive components, forming a complete protection-permeation-stabilization system, significantly improving the permeation efficiency and stability of the active ingredients.

[0045] After steaming and boiling the mutton tripe for 16-18 min, immerse it in water with a mass of 1.5-2.0 times that of the mutton tripe, add a complex enzyme preparation with a mass of 0.7-0.9% of the mutton tripe, and an enzyme hydrolysis promoter, and treat it at 48-50℃ for 35-40 min with oscillation. L-cysteine in the enzyme hydrolysis promoter opens the disulfide bonds of proteins as a reducing agent, trehalose protects enzyme activity by stabilizing enzyme conformation, soybean phospholipids not only enhance the dispersion of fat-soluble components, but also form a complex stable system with betaine, and betaine protects enzyme structure from denaturation and inactivation as an enzyme stabilizer. These components synergistically act, L-cysteine improves substrate accessibility, trehalose maintains enzyme activity, soybean phospholipids promote substrate dispersion, and betaine enhances enzyme stability, all of which together promote efficient protein enzymatic hydrolysis, significantly reduce the production of undesirable flavor substances, and improve product flavor quality.

[0046] Mix the permeated mutton liver pieces and the enzymatically treated mutton tripe in a mass ratio of 1:1-2, and place them under a vacuum of-0.08 to-0.10 MPa for 5-8 min to effectively remove air bubbles from the tissue gaps and enhance mixing uniformity. Add water with a mass of 1.8-2.2 times that of the mixture at 5-8℃, and cut and mix for 3-5 min to form a homogeneous slurry. Adjust the pH of the homogeneous slurry to 6.5-6.8. Inoculate the homogeneous slurry with a mixed starter culture composed of Lactobacillus plantarum and Lactobacillus casei in a ratio of 1:1-1.5 by number of viable bacteria, with a total inoculum of 2.5-3.5% of the mass of the homogeneous slurry, to further improve flavor and enhance nutrition through the synergistic fermentation of the two lactic acid bacteria. Ferment the inoculated slurry at 38-40℃ for 40-44 h. Inactivate the fermented material by heating it at 95-100℃ for 15-20 min. Freeze-dry the inactivated material to a water content of ≤5%.

[0047] Example 1 The sheep liver was cut into 4 mm thick slices and treated by pulsed electric field with intensity of 2.2 kV / cm, pulse width of 35 μs and frequency of 90 Hz for 7 min, and the cell integrity decreased to 65% and the permeability increased significantly. The complex permeation solution with 4% of the mass of the sheep liver slices was sprayed at -1 ℃ and then left for 12 min, and the penetration depth of lysozyme reached 2.1 mm and the retention rate of Nisin reached 92%. The sheep tripe was cut into strips with a width of 6 mm and a length of 25 mm, and then immersed in water with a mass of 1.8 times of the mass of the sheep tripe after being cooked for 17 min, and then a complex enzyme preparation with a mass of 0.8% of the mass of the sheep tripe and an enzyme hydrolysis promoter were added and treated at 49 ℃ for 37 min with oscillation, and the content of small molecule peptides in the enzyme hydrolysis solution reached 4.8 mg / mL and the content of free amino acids increased to 2.1 mg / g. The treated sheep liver slices and the sheep tripe strips were mixed in a mass ratio of 1:1.5, and then vacuumized at a vacuum degree of -0.09 MPa for 7 min, and the mixing uniformity reached 95%. Water with a mass of 2 times of the mass of the mixture was added and chopped for 5 min to form a homogeneous slurry. The pH value of the homogeneous slurry was adjusted to 6.6. A mixed starter culture composed of Lactobacillus plantarum and Lactobacillus casei with a ratio of 1:1.2 was inoculated into the homogeneous slurry, and the total inoculation amount was 3% of the mass of the homogeneous slurry. After the inoculated slurry was fermented at 39 ℃ for 42 h, the lactic acid content reached 12.5 g / kg and the pH value was stabilized at 4.3. The fermented material was inactivated by heating at 98 ℃ for 17 min. The inactivated material was freeze-dried to a water content of 4.3%.

[0048] The final product had a vitamin A retention rate of 88%, an iron retention rate of 91%, a protein retention rate of 85%, a total sugar content of 8.9%, a particle size distribution D50 of 85 μm, a solubility of 92%, and a total bacterial colony count of less than 100 CFU / g.

[0049] When used as a functional food raw material, the product was added to a protein matrix composed of whey protein (80%), malt dextrin (15%) and lecithin (5%) at an addition amount of 4% by mass to prepare a nutritional protein powder, and the human absorption rate reached 85%, the blood ferritin level of volunteers increased by 28% after drinking, the gastrointestinal tolerance was good, and the flavor acceptance score reached 4.7.

[0050] Comparative Example 1 The sheep liver was cut into 4 mm thick slices without pulsed treatment, and the cell integrity was 90% and the permeability was poor. The complex permeation solution with 4% of the mass of the sheep liver slices was sprayed at -1 ℃ and then left for 12 min, and the penetration depth of lysozyme was only 0.6 mm. The sheep tripe was cut into strips with a width of 6 mm and a length of 25 mm, and then not subjected to enzyme hydrolysis treatment after being cooked for 17 min. The sheep liver slices and the sheep tripe strips were mixed in a mass ratio of 1:1.5 without vacuum treatment. The subsequent steps were the same as those in Example 1.

[0051] The final product has a vitamin A retention rate of only 53%, an iron retention rate of 57%, a protein retention rate of 63%, a total sugar content of 6.2%, a particle size distribution D50 of 125 μm, a solubility of only 78%, and a total bacterial colony count of 1200 CFU / g.

[0052] When used as a raw material for a nutritional supplement, the nutritional protein powder prepared by adding the same protein matrix as in Example 1 with an addition amount of 4% by mass has a human absorption rate of only 45%, an iron protein level in the blood of volunteers increased by 8%, a flavor acceptance score of only 2.3 points, and some volunteers have abdominal distension and other discomfort.

[0053] Comparative Example 2 After the sheep liver is pulsed, the sheep liver slices are sprayed with 4% by mass of ordinary PBS buffer (pH 6.1) at -1°C and left to stand for 12 min, and no lysozyme and Nisin are detected. The sheep stomach is cooked without enzyme hydrolysis. After mixing the two at a mass ratio of 1:1.5, they are placed under a vacuum degree of -0.09 MPa for 7 min. The subsequent steps are the same as in Example 1.

[0054] The final product has a vitamin A retention rate of 60%, an iron retention rate of 64%, a protein retention rate of 68%, a total sugar content of 6.8%, a particle size distribution D50 of 110 μm, a solubility of 82%, and a total bacterial colony count of 900 CFU / g.

[0055] When used as a raw material for a functional food, the nutritional protein powder prepared by adding the same protein matrix as in Example 1 with an addition amount of 4% by mass has a human absorption rate of 57%, an iron protein level in the blood of volunteers increased by 15%, a flavor acceptance score of 2.8 points, and a shelf life of the product shortened to 65% of that of the product of Example 1.

[0056] Comparative Example 3 The trehalose and EDTA-2Na in the compound penetrating solution are removed, and the remaining ingredients and concentrations are the same as in Example 1. After spraying the sheep liver slices with 4% by mass of the penetrating solution at -1°C and leaving to stand for 12 min, the sheep liver slices show obvious browning, the penetration rate of the penetrating solution increases by 35% after standing, the effective ingredient penetration depth is only 1.2 mm, and the Nisin retention rate decreases to 73%. The subsequent steps are the same as in Example 1.

[0057] The final product has a vitamin A retention rate of 71%, an iron retention rate of 74%, a protein retention rate of 76%, a total sugar content of 7.5%, a particle size distribution D50 of 95 μm, a solubility of 83%, a total bacterial colony count of 850 CFU / g, and a product peroxide value of 0.26 g / 100 g.

[0058] The product of Example 1 was used as a functional food raw material, and was added to the same protein matrix as in Example 1 at an addition amount of 4% by mass to prepare a nutritional protein powder. The human absorption rate reached 62%, the blood ferritin level of the volunteers increased by 15% after drinking, and some volunteers fed back a slight fishy smell, with a flavor acceptance score of 3.2.

[0059] Comparative Example 4 The enzymolysis promoter only contained L-cysteine 1.5 g / L, and did not contain trehalose, soybean phospholipid and betaine, and the rest of the conditions were the same as in Example 1. After enzymolysis, the small molecule peptide content reached 2.8 mg / mL, the free amino acid content reached 1.2 mg / g, the enzyme activity recovery rate decreased to 68%, and the residual amount of muttony smell substance increased by 2.5 times. The subsequent steps were the same as in Example 1.

[0060] The final product had a vitamin A retention rate of 68%, an iron retention rate of 71%, a protein retention of 73%, a total sugar content of 7.1%, a particle size distribution D50 of 105 μm, a solubility of 78%, a total bacterial count of 1100 CFU / g, and a product peroxide value of 0.22 g / 100 g.

[0061] The product of Example 1 was used as a functional food raw material, and was added to the same protein matrix as in Example 1 at an addition amount of 4% by mass to prepare a nutritional protein powder. The human absorption rate reached 58%, the blood ferritin level of the volunteers increased by 12% after drinking, and the feedback of gastrointestinal discomfort increased, with a flavor acceptance score of 2.9.

[0062] Effect: The product of Example 1 was used as a functional food raw material, and was added to the same protein matrix as in Example 1 at an addition amount of 4% by mass to prepare a nutritional protein powder. After continuous consumption for 4 weeks, the human absorption rate reached 85%, the blood ferritin level of the volunteers increased by 28%, the vitamin A level increased by 23%, the protein bioavailability reached 87%, the gastrointestinal tolerance was good, and the flavor acceptance score reached 4.7. Under the same use conditions, the products of Comparative Examples 1 to 4 had a human absorption rate of less than 65%, the blood nutrient level of the volunteers increased by less than 18%, the flavor acceptance score was between 2.3 and 3.5, and some products had the problems of short shelf life and poor stability. Conclusion: Example 1 showed the best overall performance, and the final product had significantly better performance than all the comparative examples in terms of nutrient retention rate (vitamin A 88%, iron 91%, protein 85%), product physicochemical index (solubility 92%, low bacterial count), and application performance (human absorption rate 85%, blood ferritin increase 28%, flavor score 4.7, good gastrointestinal tolerance).

[0063] Example 1 The product has the best performance in all indexes, which proves that the three key steps of pulse treatment, enzymatic hydrolysis and vacuum treatment after mixing are essential to improve the penetration of active ingredients, improve flavor and ensure uniform mixing.

[0064] Example 2 The product has better performance than Example 1 but far worse than Example 1, which proves the necessity of composite penetration solution and enzymatic hydrolysis for protecting ingredients, inhibiting microorganisms and improving flavor.

[0065] Example 3 The composite penetration solution lacks trehalose and EDTA-2Na, resulting in an increase in product peroxide value (0.26), a decrease in flavor score (3.2) and a decrease in absorption rate (62%), which proves the key synergistic effect of these two ingredients in antioxidant and stability protection.

[0066] Example 4 The incomplete enzymatic hydrolysis promoter component results in poor enzymatic hydrolysis effect (low content of small molecule peptides and amino acids), more fishy smell, poor product stability (peroxide value 0.22) and low acceptance (flavor score 2.9), which proves the importance of complete enzymatic hydrolysis promoter formula for efficient enzymatic hydrolysis and flavor improvement.

[0067] In summary, through a series of innovative process combinations and optimized formulations, the present application effectively solves the problems of penetration, flavor and uniform mixing in the composite processing of sheep liver and sheep tripe, and successfully prepares a nutrient base with high activity, high absorption rate and coordinated flavor. The results of all the comparative examples collectively demonstrate the necessity of the various technical features of the present application and the synergistic effect produced thereby.

[0068] In another aspect, the method for preparing a sheep liver and sheep tripe nutrient base by lactic acid bacteria fermentation comprises two stages of fermentation: The first stage is to ferment at 40-41°C with stirring at 70-100 r / min for 10-12 h; The second stage is to stop stirring, cool to 36-37°C, add fermentation promoters and ferment statically for a total time of 40-47 h; the final concentrations of the components of the fermentation promoters in the fermentation system are: yeast peptone 5-10 g / L, polyglutamic acid 3-8 g / L and L-glutamine 2-5 g / L.

[0069] Continuous fermentation at a single temperature is carried out after inoculation of lactic acid bacteria. This single fermentation environment cannot meet the different needs of rapid microbial growth and sufficient accumulation of metabolic products, resulting in low fermentation efficiency. Lactic acid bacteria need sufficient oxygen and nutrients for reproduction in the early growth stage, while the synthesis of acid and flavor substances requires a relatively anaerobic and mild environment in the later stage. One-time fermentation cannot provide such dynamic conditions, which easily causes uneven bacterial growth, insufficient accumulation of metabolic products, and too long fermentation period. At the same time, continuous stirring or single static mode is also difficult to coordinate the formation of flavor substances, which easily leads to products with too sharp sour taste or lack of flavor, and poor product quality stability between different batches.

[0070] The present scheme effectively solves the above problems by controlling the fermentation process in stages. First, the first stage of stirring fermentation is carried out, with the temperature controlled at 40-41℃, the stirring speed at 70-100r / min, and the fermentation time at 10-12h. This stage provides moderate oxygen and stirring to create conditions conducive to the rapid reproduction of lactic acid bacteria, allowing the number of bacteria to increase rapidly, laying the foundation for subsequent fermentation. Stirring promotes the uniform distribution of heat and nutrients, avoiding local high acidity to inhibit bacterial growth, thereby improving fermentation efficiency.

[0071] Subsequently, the second stage of static fermentation is carried out, with stirring stopped and the temperature reduced to 36-37℃, and fermentation accelerators are added, and the static fermentation is carried out until the total time reaches 40-47h. The fermentation accelerators include yeast peptone 5-10g / L, polyglutamic acid 3-8g / L, and L-glutamine 2-5g / L. This stage creates an anaerobic environment to promote anaerobic metabolism of lactic acid bacteria and synthesis of flavor substances. Stopping stirring helps to maintain the integrity and metabolic activity of the bacteria, while avoiding damage to the cells by shear force. Moderate cooling is more suitable for the accumulation of metabolic products rather than bacterial proliferation. Among the added fermentation accelerators, yeast peptone provides abundant nitrogen source and growth factors, polyglutamic acid helps to maintain cell structure stability and product accumulation, and L-glutamine as a flavor precursor can enhance the richness and harmony of product flavor. The precise control of the two stages and the synergistic effect of the fermentation accelerators ensure the uniform generation and accumulation of metabolic products, significantly improving the flavor quality and nutritional value of the products.

[0072] Example 2 The main steps and process parameters in the preparation process, such as pulse treatment of sheep liver, spraying of complex penetration solution, steaming and enzymatic hydrolysis of sheep tripe, mixing and chopping of materials, pH adjustment, inoculation amount of strains and inactivation and drying, are all completely consistent with Example 1. The difference lies in the improvement of fermentation process and fermentation accelerators: Example 2 adopts a two-stage fermentation method, specifically, the first stage is fermentation at 40.5°C with stirring at 80 r / min for 11 h, and the second stage is static fermentation after stopping stirring, reducing the temperature to 36.5°C, and adding fermentation accelerators containing yeast peptone, polyglutamic acid and L-glutamine, with a total fermentation time similar to Example 1, about 42 h.

[0073] The final product quality comparison shows that Example 2 is superior to Example 1 in many indicators. The product's vitamin A retention rate is increased to 90%, the iron retention rate is 92%, the protein retention rate is 87%, the total sugar content is 9.3%, the solubility is increased to 94%, and the retention rate and solubility of these core nutritional ingredients are improved. In terms of microbial indicators, the total bacterial colony count is controlled below 80 CFU / g.

[0074] More importantly, its application performance is significantly enhanced, and the nutritional protein powder prepared according to the same method as Example 1 has a human body absorption rate of 87%, a volunteer blood ferritin level increase of 30%, and a higher flavor acceptance score of 4.9. This shows that the two-stage fermentation process combined with the use of fermentation accelerators not only better retains the nutritional ingredients, but also significantly improves the harmony and acceptance of the flavor by optimizing the microbial metabolic pathway, and further improves the bioavailability of the product. In another aspect, the method for preparing sheep liver and sheep tripe nutritional base material by lactic acid bacteria fermentation comprises the following steps: washing fresh sheep liver and cutting it into sheep liver slices with a thickness of 3-5 mm; washing fresh sheep tripe and removing the contents, and then cutting it into sheep tripe strips with a width of 5-8 mm and a length of 20-30 mm.

[0075] In the process of preparing nutritional base material from sheep liver and sheep tripe, the size control of the pretreated raw materials is a basic but crucial link. The lack of unified and precise specification standards for the cutting of sheep liver and sheep tripe will directly lead to a series of chain problems such as uneven penetration, different enzymatic hydrolysis degrees, and poor mixing effects in subsequent processing procedures. If the sheep liver slices are too thick, the pulse electric field treatment and complex penetration solution will not be able to effectively act on the inside of the tissue, resulting in low retention rate of the central region; if the slices are too thin, they are easy to break during processing, leading to loss of nutritional substances. Similarly, if the size of the sheep tripe strips is not consistent, uneven heating and large fluctuations in enzymatic hydrolysis efficiency will occur during the steaming and enzymatic hydrolysis stages, ultimately resulting in unstable texture, flavor and nutritional ingredient content of each batch of product, and the quality uniformity of the product cannot be guaranteed.

[0076] The present scheme lays a foundation for the stability and consistency of the subsequent process by strictly regulating the cutting size of raw materials. Fresh sheep liver is washed and cut into pieces with a thickness of 3-5 mm. This specification is verified. The thickness range ensures that the sheep liver pieces have sufficient mechanical strength to withstand subsequent pulse processing and spraying operations, avoiding tissue fragmentation. More importantly, this thickness matches the effective depth of the pulse electric field and the penetration ability of the composite penetrating liquid, allowing the electric field to uniformly change the cell membrane permeability, while ensuring that active ingredients such as lysozyme and Nisin in the penetrating liquid can fully and uniformly penetrate the inside of the tissue, thereby achieving efficient and uniform pretreatment, providing a prerequisite for maximizing the retention of heat-sensitive vitamins and minerals in liver tissue.

[0077] For the processing of sheep tripe, the present scheme provides that it is cut into strips with a width of 5-8 mm and a length of 2-30 mm after being washed and having its contents removed. This size design takes into account the organizational characteristics of sheep tripe and the subsequent processing requirements. The sheep tripe strips of this size can achieve uniform heat transfer during cooking, avoiding excessive external pasting and internal undercooking. In the enzymatic hydrolysis stage, the uniform size provides a larger specific surface area, allowing the composite enzyme preparation to contact the substrate more uniformly, significantly improving the efficiency and uniformity of enzymatic hydrolysis, ensuring that macromolecules such as proteins are fully degraded into small molecule peptides and amino acids. This not only helps to release nutrients, but also effectively reduces flavor defects caused by uneven enzymatic hydrolysis. Finally, the uniform size of the raw material creates favorable conditions for the uniform mixing of sheep liver pieces and sheep tripe strips, and after vacuum treatment and chopping, an ideal slurry with uniform tissue state and consistent composition is formed, laying a solid foundation for the preparation of high-quality, stable nutrient base in the subsequent fermentation stage.

[0078] In another scheme, the specific method for pulse processing of sheep liver pieces in the method for preparing a sheep liver and tripe nutrient base using lactic acid bacteria fermentation is as follows: the sheep liver pieces are placed in a pulse electric field with an intensity of 2.0-2.5 kV / cm, a pulse width of 30-40 μs, and a frequency of 80-100 Hz for 6-8 min; the composite enzyme preparation consists of neutral protease, flavor protease, and bromelain in a ratio of 1:0.7-0.9:0.2-0.4 by enzyme activity units; and the material after fermentation is heated at 95-100°C for 15-20 min to inactivate.

[0079] In the preparation process of sheep liver and tripe nutrient base, the parameter control of multiple key process links directly affects the quality and safety of the final product. In the prior art, pulse treatment often has unsatisfactory effect due to improper setting of electric field parameters. If the intensity is too low, the cell membrane structure cannot be effectively changed, and if the intensity is too high, the tissue is easily damaged and the nutritional ingredients are easily lost. In the enzyme hydrolysis process, due to single or improper selection of enzyme preparation ratio, efficient hydrolysis of multiple substrates cannot be achieved at the same time, resulting in incomplete enzyme hydrolysis, insufficient release of flavor precursor substances and easy generation of bad flavor. In addition, if the temperature or time control of the inactivation process at the end of fermentation is not good, microorganisms may not be completely killed, resulting in safety hazards of the product, or excessive heating may cause a large amount of degradation of heat-sensitive nutritional ingredients.

[0080] For the pulse treatment link, the parameter combination of electric field intensity 2.0-2.5 kV / cm, pulse width 30-40 μs and frequency 80-100 Hz is adopted for 6-8 min. This parameter range is selected after optimization, and the purpose is to effectively destroy the cell membrane structure of sheep liver, increase its permeability, and at the same time, minimize the mechanical and thermal damage to the tissue structure, to create favorable conditions for the uniform penetration of the subsequent complex penetration liquid. Precise control of pulse width and frequency ensures the uniformity and efficiency of energy input, avoiding local overheating or insufficient treatment.

[0081] For the enzyme hydrolysis process of sheep tripe, a complex enzyme preparation is used, which is compounded by neutral protease, flavor protease and bromelain at an enzyme activity unit ratio of 1:0.7-0.9:0.2-0.4. This ratio fully utilizes the synergistic effect of various enzyme systems. Neutral protease is mainly responsible for endo-protein peptide bond, flavor protease cuts and improves flavor at the end, and bromelain further assists in hydrolysis and has the function of tenderizing the tissue. The three are compounded in this specific ratio to achieve comprehensive, efficient and mild hydrolysis of sheep tripe protein, which not only improves the utilization rate of protein and the yield of small molecule peptides, but also effectively reduces the generation of bitter peptides and promotes the formation of good flavor.

[0082] After fermentation, the material is inactivated by heating at 95-100°C for 15-20 min. The setting of this thermal condition aims to achieve two key targets. The first target is to completely kill the fermentation strains and other possible contaminated microorganisms, to ensure the biological safety of the product and meet the food hygiene standards. The second target is to shorten the heating time as much as possible and use a relatively moderate upper limit temperature under the premise of meeting the sterilization requirements, so as to maximize the protection of the flavor substances, heat-sensitive vitamins and other functional ingredients that have been formed in the product, avoid the destruction of nutritional ingredients or the generation of cooking flavor and other bad flavors due to excessive heat treatment, and ensure the high quality and stability of the final product.

[0083] In another aspect, in the method for preparing the sheep liver and tripe nutritional base material by using lactic acid bacteria fermentation, after 2 hours of the start of the second stage fermentation, micro-nano bubble mixed gas with a flow rate of 0.5-1.0 L / min and a bubble diameter of 10-50 μm is introduced into the fermentation system, and the mixed gas is composed of nitrogen and carbon dioxide with a volume ratio of 9:1.

[0084] In the prior art of preparing the nutritional base material by using lactic acid bacteria fermentation, simple static fermentation or conventional stirring fermentation is generally adopted, and limited gas exchange is provided by surface aeration or simple bubbling during the fermentation process. This method has obvious defects: the gas transfer efficiency is low, the solubility of oxygen and carbon dioxide and other gases in the fermentation broth is low, and the dispersion is uneven, which cannot provide a stable and suitable gas environment for the growth and metabolism of lactic acid bacteria. Especially in the later stage of fermentation, lactic acid bacteria reproduce in large quantities, consume oxygen and produce metabolic products, which easily causes local oxygen deficiency or accumulation of metabolic products in the fermentation system, resulting in decreased activity of the bacteria, reduced fermentation efficiency, changed metabolic pathways, and ultimately affecting the yield and flavor quality of the product.

[0085] In this aspect, after 2 hours of the start of the second stage fermentation, micro-nano bubble mixed gas with a flow rate of 0.5-1.0 L / min and a bubble diameter of 10-50 μm is introduced into the fermentation system, and the mixed gas is composed of nitrogen and carbon dioxide with a volume ratio of 9:1. Due to its extremely small size, the micro-nano bubble has the physical characteristics of large specific surface area, slow rising speed, and high gas dissolution efficiency, which can significantly improve the mass transfer efficiency of gas in the fermentation system. The mixed gas of a specific ratio of nitrogen and carbon dioxide can maintain a micro-aerobic environment in the fermentation system, avoid the influence of excessive oxidation on anaerobic metabolism, and help to adjust the pH value of the fermentation broth and serve as a substrate for certain metabolic pathways. The timing of the introduction is selected after 2 hours of the start of the second stage fermentation, at which time the bacteria have basically completed the rapid proliferation period and entered the metabolic product synthesis stage, and are more sensitive to changes in the gas environment. By supplying the mixed gas in the form of micro-nano bubbles, the gas can be uniformly dispersed in every part of the fermentation system, providing a stable and suitable gas environment for lactic acid bacteria and promoting their metabolic activity and the synthesis of target products.

[0086] In another aspect, in the method for preparing the sheep liver and tripe nutritional base material by using lactic acid bacteria fermentation, the complex permeate further comprises 0.05-0.1 g / L lecithin, 0.05-0.1 g / L xanthan gum, 0.05-0.1 g / L gum arabic, 0.05-0.1 g / L sodium carboxymethyl cellulose, 0.1-0.2 g / L β-glucan, and 0.01-0.03 g / L sodium hyaluronate.

[0087] The buffer system containing active ingredients such as lysozyme and Nisin is used as the penetrating liquid. Although such a penetrating liquid has a certain protective effect on the active ingredients, it also has limitations: poor system stability, easy to form ingredient stratification and sedimentation; limited penetration efficiency, difficult to achieve uniform distribution in sheep liver tissue; single function, mainly focused on antibacterial, insufficient protection of tissue structure and stability of active ingredients. Especially during low-temperature spraying and standing, the components of the penetrating liquid are easy to flow out from the surface of the tissue, and cannot form an effective protective layer, resulting in an unsatisfactory retention rate of active ingredients.

[0088] On the basis of the basic penetrating liquid components, the present scheme additionally adds lecithin 0.05-0.1 g / L, xanthan gum 0.05-0.1 g / L, gum arabic 0.05-0.1 g / L, sodium carboxymethyl cellulose 0.05-0.1 g / L, beta-glucan 0.1-0.2 g / L and sodium hyaluronate 0.01-0.03 g / L. These added components together constitute a multifunctional composite system, each component has a specific functional role and produces a synergistic effect.

[0089] Lecithin, as a natural emulsifier, not only improves the dispersion uniformity of fat-soluble active ingredients, but also interacts with the cell membrane phospholipid bilayer due to its amphiphilic properties, enhancing the cell membrane fluidity and creating favorable conditions for the subsequent transmembrane penetration of other components. Xanthan gum, gum arabic and sodium carboxymethyl cellulose form a three-dimensional network structure through intermolecular interaction, significantly increasing the viscosity of the system and delaying the sedimentation of the components. This combination is more suitable for the rheological requirements under low temperature conditions than a single colloid; they also form a protective film with a microporous structure on the surface of the sheep liver slices, which not only reduces the loss of penetrating liquid, but also controls the release rate of active ingredients. Beta-glucan, with its good film-forming property and water retention, synergizes with the colloid components to further strengthen the integrity and moisturizing effect of the protective film, maintaining the water balance of the tissue microenvironment and preventing tissue shrinkage affecting penetration efficiency. Sodium hyaluronate forms a highly hydrated interface layer on the surface of the tissue by utilizing its unique molecular structure and strong hydration ability. This hydrated layer can reduce the penetration resistance and provide a transmission channel for small molecule active ingredients, significantly improving the penetration depth and effect of lysozyme and Nisin and other active ingredients.

[0090] These components work together through a well-designed ratio, producing a synergistic effect. The improved membrane fluidity of lecithin provides a basis for the penetration-promoting effect of sodium hyaluronate, while the three-dimensional network constructed by hydrophilic colloids ensures that β-glucan and sodium hyaluronate can stably act on the target site. The final complex system not only significantly improves the physical stability and uniformity of the ingredients of the penetrating liquid, but more importantly, significantly enhances the penetration efficiency and action persistence of active ingredients through multiple mechanisms, while effectively reducing the loss of water and nutrients during processing, providing a key guarantee for obtaining high-quality final products.

[0091] Example 3 The preparation process is exactly the same as Example 1, the only difference is that the complex penetrating liquid additionally contains lecithin 0.08 g / L, xanthan gum 0.08 g / L, gum arabic 0.08 g / L, sodium carboxymethyl cellulose 0.08 g / L, β-glucan 0.15 g / L and sodium hyaluronate 0.02 g / L.

[0092] The final product has a vitamin A retention rate of 91%, an iron retention rate of 94%, a protein retention rate of 88%, a total sugar content of 9.5%, a solubility of 95%, and a total bacterial count of less than 50 CFU / g.

[0093] When used as a nutritional supplement raw material, it is added to the same protein matrix as Example 1 at a mass fraction of 4% to prepare a nutritional protein powder, with a human absorption rate of 89%, a volunteer blood ferritin level increase of 32%, and a flavor acceptance score of 4.9. The product has more uniform texture and good reconstitution.

[0094] Comparative Example 5 The preparation process is exactly the same as Example 3, and the complex penetrating liquid contains the basic ingredients in Example 1 (lysozyme, polyglycerol fatty acid ester, Nisin, trehalose, EDTA-2Na and buffer), and some auxiliary ingredients: lecithin 0.08 g / L, xanthan gum 0.08 g / L and gum arabic 0.08 g / L, but does not contain sodium carboxymethyl cellulose, β-glucan and sodium hyaluronate.

[0095] The final product has a vitamin A retention rate of 89%, an iron retention rate of 91%, a protein retention rate of 86%, a total sugar content of 9.2%, a solubility of 92%, and a total bacterial count of less than 90 CFU / g.

[0096] When used as a nutritional supplement raw material, it is added to the same protein matrix as Example 1 at a mass fraction of 4% to prepare a nutritional protein powder, with a human absorption rate of 89%, a volunteer blood ferritin level increase of 32%, and a flavor acceptance score of 4.9. The product has more uniform texture and good reconstitution.

[0097] Effect: The results of Comparative Example 5 show that after adding lecithin, xanthan gum and gum arabic in the basic penetrating liquid, the product quality indicators are comprehensively improved compared with Example 1, which confirms that these additives have a positive effect on improving the stability of the penetrating liquid and the quality of the product. However, due to the lack of the suspension stabilizing effect of sodium carboxymethyl cellulose, the film-forming and water-retaining effect of beta-glucan, and the promoting penetration effect of sodium hyaluronate, the product of Comparative Example 5 is still significantly lower than Example 3 in key indicators such as solubility, nutrient retention rate and absorption utilization rate. This fully proves that the synergistic effect of all the added ingredients in Example 3 is indispensable for achieving the best product quality, and the complete formula can maximize the comprehensive quality of the compound nutrient base. In another scheme, in the method for preparing sheep liver and sheep tripe nutrient base by using lactic acid bacteria fermentation, after pulse treatment, the sheep liver slices are sprayed with a compound penetrating liquid, and then the sheep liver slices are pretreated with ultrasonic waves at a frequency of 40-60 kHz for 3-5 min, and the ultrasonic power density is controlled at 0.3-0.5 W / cm 2 , and then the sheep liver slices are placed in an environment with a vacuum degree of -0.05 to -0.07 MPa for 2-3 min.

[0098] When the sheep liver slices are treated with the compound penetrating liquid, there are limitations in using single pulse field treatment or simple soaking process: there are residual bubbles and intercellular gap liquid in the tissue after pulse treatment, forming a penetration barrier; the penetration efficiency is low and the time is long relying on the diffusion process driven by the concentration difference alone; it is difficult for active ingredients to be evenly distributed to the deep layer of the tissue, resulting in accumulation on the surface and insufficient penetration in the interior. Especially when dealing with sheep liver with dense tissue structure, these defects are more prominent, which ultimately affects the nutrient retention rate and quality uniformity of the product.

[0099] This scheme innovatively introduces a combined physical pretreatment process after pulse treatment. First, ultrasonic waves at a frequency of 40-60 kHz are used for pretreatment for 3-5 min, and the ultrasonic power density is accurately controlled at 0.3-0.5 W / cm 2 . The ultrasonic waves at this parameter can produce stable cavitation effect in the liquid medium, and the micro-jet and shock wave produced can effectively act on the microstructure of the sheep liver tissue, further expanding the intercellular gap and cell membrane permeability without damaging the integrity of the whole tissue, creating more channels for subsequent penetration. Then the sheep liver slices are placed in an environment with a vacuum degree of -0.05 to -0.07 MPa for 2-3 min. This step uses the pressure difference to first extract the micro-bubbles and residual interstitial liquid formed in the tissue during pulse and ultrasonic treatment, eliminating the physical barrier; at the same time, in the instant when the vacuum is released, the atmospheric pressure difference is used to push the penetrating liquid into the micro-channels formed previously.

[0100] The two steps of ultrasonic pretreatment and vacuum treatment are carried out sequentially and promote each other. The ultrasonic creates penetration channels, and the vacuum treatment sweeps away obstacles for the entry of the penetrating liquid and provides power, and the synergistic effect of the two significantly improves the penetration efficiency. This combined physical pretreatment method not only avoids the residual problems that may be caused by relying solely on chemical penetrating agents, but more importantly, it greatly improves the tissue state through physical means, laying a solid foundation for the active ingredients in the subsequent composite penetrating liquid to be distributed more deeply and uniformly into the sheep liver tissue, thereby improving the retention rate and effect of the active ingredients as a whole.

[0101] Example 4 Based on the preparation process of Example 1, a combined pretreatment step is added after pulse treatment: first, ultrasonic pretreatment at a frequency of 50 kHz for 4 min, with an ultrasonic power density controlled at 0.4 W / cm 2 , then place the sheep liver slices in an environment with a vacuum degree of -0.06 MPa for 2.5 min, and then spray the composite penetrating liquid and other steps are the same as Example 1.

[0102] The final product has a vitamin A retention rate of 93%, an iron retention rate of 95%, a protein retention rate of 90%, a total sugar content of 9.6%, a solubility of 96%, and a total bacterial count of less than 40 CFU / g.

[0103] For the preparation of a nutritional protein powder, the mass fraction of 4% is added to the same protein matrix as in Example 1, and the human absorption rate is 91%, the iron protein level of the volunteers is improved by 34%, and the flavor acceptance score is 5.0 points. These objective data are comprehensively improved, especially the vitamin A retention rate is improved from 88% to 93%, the iron retention rate is improved from 91% to 95%, and the human absorption rate is improved from 85% to 91%, which indirectly but powerfully confirms that the uniformity of the distribution of active ingredients in the tissue is significantly improved, and the penetration efficiency is greatly improved.

[0104] Effect: By adding ultrasonic and vacuum combined pretreatment in Example 4, the quality indicators of the product are comprehensively improved. Compared with Example 1, the retention rate of nutritional ingredients, absorption and utilization rate, and flavor acceptance are significantly improved, especially the uniformity and penetration depth of active ingredients in the tissue are greatly improved. This proves that the combined pretreatment process can effectively overcome the tissue penetration barrier, create favorable conditions for the composite penetrating liquid to work, and is a key technical means to improve the quality of the final product.

[0105] In another scheme, in the method of preparing sheep liver and sheep tripe nutritional base material by lactic acid bacteria fermentation, when spraying the composite penetrating liquid, the droplet size of the spraying liquid is controlled to be 50-100 μm, and the spraying rate is controlled to be 0.5-1.0 mL / cm 2min, and controlling the temperature difference between the surface of the sheep liver slices and the composite penetrating liquid to be ≤2℃, and stirring at a low speed of 20-30 r / min for 3-5 min after spraying.

[0106] In the process of treating sheep liver slices with a composite penetrating liquid, simple spraying or soaking methods are used, and the key process parameters are not accurately controlled. There are problems such as uneven droplet size of the spraying liquid, large fluctuation of the spraying rate, and significant temperature difference between the penetrating liquid and the material, which leads to uneven distribution of the penetrating liquid on the tissue surface, excessive accumulation in local areas and insufficient coverage in other areas. A larger temperature difference can easily cause tissue shrinkage or surface protein denaturation, forming a penetration barrier. The lack of proper mixing operation after spraying further exacerbates the uneven penetration, ultimately affecting the penetration efficiency of active ingredients and the consistency of product quality.

[0107] The present solution solves the above problems by systematically controlling the key parameters of the spraying process. The droplet size of the spraying liquid is controlled in the range of 50-100 μm. Droplets of this size range have suitable particle size and surface tension, which can uniformly cover the tissue surface and form a thin liquid film, avoiding both the waste caused by large droplets and the loss caused by the drift of small droplets. The spraying rate is accurately controlled in the range of 0.5-1.0 mL / cm 2 min, which ensures that an appropriate amount of penetrating liquid is obtained per unit area, meeting the penetration requirements and avoiding excessive liquid accumulation. The temperature difference between the surface of the sheep liver slices and the composite penetrating liquid is strictly controlled to be ≤2℃, which effectively prevents the damage to the tissue structure caused by thermal shock due to temperature difference, avoids the formation of a penetration barrier caused by surface protein denaturation or cell shrinkage, and creates a stable temperature environment for the penetration process. After spraying, the mixture is stirred at a low speed of 20-30 r / min for 3-5 min, which promotes the redistribution of the penetrating liquid on the tissue surface, eliminates possible local concentration unevenness, and ensures sufficient contact between the penetrating liquid and the tissue, laying a good foundation for the subsequent static penetration stage.

[0108] These control measures cooperate and work together to ensure the stability and uniformity of the penetration process from droplet formation, transportation and distribution to final mixing. By accurately controlling these parameters, not only is the penetration efficiency of active ingredients significantly improved, but the consistency of product quality for different batches is also ensured, providing an important guarantee for obtaining high-quality final products.

[0109] In another solution, in the method of preparing sheep liver and sheep tripe nutritional base material by fermentation of lactic acid bacteria, a breathable film is covered on the surface of the sheep liver slices during the static process after spraying the composite penetrating liquid, the porosity of the film is 60-70%, and the humidity of the static environment is controlled at 85-90%.

[0110] In the settling process after spraying the sheep liver slices with the composite permeate, there are drawbacks to using either an open environment or simple covering: open setting leads to rapid evaporation of the permeate, causing localized increases in concentration or even precipitation, thus affecting the permeation effect; while using a completely airtight covering can reduce evaporation, it hinders gas exchange, potentially causing anaerobic bacteria growth or producing unpleasant odors. Both of these approaches reduce permeation efficiency and affect the final product quality.

[0111] This solution addresses these issues by innovatively employing a breathable membrane covering combined with environmental humidity control. A breathable membrane with a porosity of 60-70% is applied to the surface of the sheep liver slices. This specific pore size range is carefully designed to effectively reduce moisture evaporation and loss while maintaining adequate gas exchange channels to prevent the formation of an anaerobic environment. Simultaneously, the humidity of the static environment is controlled within a high range of 85-90%, a level close to the internal humidity of the tissue. This significantly reduces the humidity gradient between the inside and outside of the membrane, thereby greatly reducing the driving force for moisture evaporation and allowing the permeate to maintain a stable composition and volume.

[0112] The membrane covering and humidity control work synergistically. The breathable membrane physically prevents direct moisture evaporation, while ambient humidity control reduces the evaporation rate at a microscopic level. Together, they ensure the permeate remains in optimal condition throughout the resting period. This combined control approach guarantees that the active ingredients have sufficient time to penetrate evenly into the tissue, while avoiding waste and uneven penetration caused by liquid loss, thus providing crucial assurance for achieving stable and reliable product quality.

[0113] In another embodiment, in the method for preparing nutrient base material for sheep liver and sheep tripe by fermentation with lactic acid bacteria, after the sheep liver slices are sprayed with a composite permeating liquid and allowed to stand, the sheep liver slices are heated to 4-6℃ at a rate of 0.5-1.0℃ / min and held for 5-8 minutes before proceeding with the subsequent mixing step with sheep tripe strips.

[0114] In the processing of sheep liver slices after spraying with compound permeation solution, there are drawbacks to using direct subsequent mixing or rapid heating: rapid temperature changes can damage the structure of tissue cells, causing juice loss and destruction of active ingredients; sudden temperature changes can also cause the permeation solution to seep out of the tissue, reducing permeation efficiency; large temperature differences can cause protein denaturation and cell shrinkage, forming irreversible damage, ultimately affecting the nutritional quality and yield of the product.

[0115] The present solution solves these problems by using a precisely controlled temperature ramp. The sheep liver pieces are warmed at a slow rate of 0.5-1.0°C / min to a target temperature of 4-6°C. This temperature ramp is optimally designed to allow the tissue cells to gradually adapt to the temperature change, avoiding membrane structure damage and cell content loss due to thermal shock. The target temperature of 4-6°C is chosen to provide a temperature environment suitable for the subsequent processes, which maintains tissue activity without causing component denaturation. The temperature is held at the target temperature for 5-8 min, which ensures that the internal temperature of the tissue reaches a uniform steady state, allowing the cell structure to fully adapt and stabilize, and preparing for the subsequent mixing process with the sheep tripe.

[0116] This slow warming treatment exerts a protective effect through multiple mechanisms. The slow warming rate avoids tissue shrinkage and protein denaturation caused by temperature shock, maintaining the integrity and permeability of the cell membrane; the appropriate holding time allows the permeate to reach temperature equilibrium with the tissue, reducing permeate loss due to temperature differences; and the final temperature level maintains the physiological activity of the tissue while providing suitable temperature conditions for subsequent processing. The entire treatment process ensures that the sheep liver pieces enter the subsequent process in an optimal state, maximizing the retention of nutritional ingredients and active substances, and providing an important guarantee for obtaining high-quality final products.

[0117] Although the embodiments of the present application have been disclosed as above, they are not limited to the use listed in the specification and embodiments, and can be applied to various fields suitable for the present application. Additional modifications can be easily made by those skilled in the art, and therefore the present application is not limited to specific details, but is within the general concept defined by the claims and their equivalents.

Claims

1. A method for preparing a nutritional base for liver and tripe using lactic acid bacteria fermentation, characterized in that, The application relates to a method for preparing a kind of fermented sheep liver sausage. The sheep liver is cut into pieces and then subjected to pulse treatment; The pulse-treated sheep liver pieces are sprayed with a composite permeation solution accounting for 3-5% of the mass of the sheep liver pieces at-2 to 0 DEG C and then left to stand for 10-15 min; The composite permeation solution comprises 0.1-0.3 g / L lysozyme, 0.05-0.1 g / L polyglycerol fatty acid ester, 0.05-0.15 g / L Nisin, 3-5 g / L trehalose, 0.02-0.04 g / L EDTA-2Na and a citric acid-disodium hydrogen phosphate buffer solution with a pH value of 6.0-6.2; The sheep tripe is steamed for 16-18 min; The steamed sheep tripe is immersed in water with a mass of 1.5-2.0 times that of the sheep tripe, and then a composite enzyme preparation with a mass of 0.7-0.9% of the sheep tripe and an enzyme hydrolysis promoter are added, and the mixture is subjected to oscillation treatment at 48-50 DEG C for 35-40 min; the final concentrations of the components of the enzyme hydrolysis promoter in the enzyme hydrolysis system are as follows: L-cysteine 1-2 g / L, trehalose 20-30 g / L, soybean phospholipid 0.5-1.5 g / L and betaine 5-10 g / L; The permeation-treated sheep liver pieces and the enzyme-hydrolyzed sheep tripe are mixed in a mass ratio of 1:1-2, and then kept in a vacuum environment with a vacuum degree of-0.08 to-0.10 MPa for 5-8 min; Water with a mass of 1.8-2.2 times that of the mixture and at 5-8 DEG C is added to the mixture, and the mixture is chopped and stirred to form a homogeneous slurry; The pH value of the homogeneous slurry is adjusted to 6.5-6.8; A mixed starter culture composed of Lactobacillus plantarum and Lactobacillus casei with a ratio of live bacteria of 1:1-1.5 is inoculated into the homogeneous slurry, and the total inoculation amount is 2.5-3.5% of the mass of the homogeneous slurry; The inoculated slurry is fermented; The fermented material is inactivated; The inactivated material is freeze-dried until the water content is less than or equal to 5%.

2. The method for preparing a nutritional base material of sheep liver and tripe using lactic acid bacteria fermentation according to claim 1, characterized in that, The fermentation is divided into two stages: In the first stage, the fermentation is carried out at 40-41 DEG C and with stirring at 70-100 r / min for 10-12 h; In the second stage, the stirring is stopped, the temperature is lowered to 36-37 DEG C, a fermentation promoter is added, and the static fermentation is carried out until the total time is 40-47 h; the final concentrations of the components of the fermentation promoter in the fermentation system are as follows: yeast peptone 5-10 g / L, polyglutamic acid 3-8 g / L and L-glutamine 2-5 g / L.

3. The method for preparing nutrient substrate for sheep liver and sheep tripe using lactic acid bacteria fermentation as described in claim 1, characterized in that, Fresh sheep liver is washed and cut into pieces with a thickness of 3-5 mm; fresh sheep tripe is washed, the contents are removed, and then the sheep tripe is cut into strips with a width of 5-8 mm and a length of 20-30 mm.

4. The method for preparing sheep liver and sheep tripe nutritional substrate by lactic acid bacteria fermentation as described in claim 1, characterized in that, The specific method for pulse treatment of the sheep liver pieces is as follows: the sheep liver pieces are placed in a treatment chamber with a pulse electric field intensity of 2.0-2.5 kV / cm, a pulse width of 30-40 mu s and a frequency of 80-100 Hz, and then treated for 6-8 min; the composite enzyme preparation is composed of neutral protease, flavourzyme and bromelain with an enzyme activity unit ratio of 1:0.7-0.9:0.2-0.4; and the material after the fermentation is completed is inactivated by heating at 95-100 DEG C for 15-20 min.

5. The method for preparing nutrient substrate for sheep liver and sheep tripe by fermentation using lactic acid bacteria as described in claim 2, characterized in that, After 2 hours of the start of the second stage fermentation, micro-nano bubble mixed gas with a flow rate of 0.5-1.0 L / min and a bubble diameter of 10-50 μm is introduced into the fermentation system, and the mixed gas is composed of nitrogen and carbon dioxide in a volume ratio of 9:

1.

6. The method for preparing nutrient substrate for sheep liver and sheep tripe by fermentation using lactic acid bacteria as described in claim 1, characterized in that, The composite infiltration solution further comprises 0.05-0.1 g / L lecithin, 0.05-0.1 g / L xanthan gum, 0.05-0.1 g / L gum arabic, 0.05-0.1 g / L sodium carboxymethyl cellulose, 0.1-0.2 g / L β-glucan, and 0.01-0.03 g / L sodium hyaluronate.

7. The method for preparing nutrient substrate for sheep liver and sheep tripe by fermentation using lactic acid bacteria as described in claim 1, characterized in that, The sheep liver slices are pre-treated by ultrasonic wave with frequency of 40-60 kHz and power density of 0.3-0.5 W / cm2 for 3-5 min before being sprayed with the complex permeation liquid, and then the sheep liver slices are kept in the environment with vacuum degree of-0.05 to-0.07 MPa for 2-3 min. 2 , and then the sheep liver slices are kept in the environment with vacuum degree of-0.05 to-0.07 MPa for 2-3 min.

8. The method for preparing a nutritional base material of sheep liver and tripe using lactic acid bacteria fermentation according to claim 1, wherein, When spraying the composite permeation liquid, the droplet size of the spraying liquid is controlled to be 50-100 μm, and the spraying rate is controlled to be 0.5-1.0 mL / cm 2 min, and the temperature difference between the surface of the sheep liver slice and the composite permeation liquid is controlled to be ≤2℃, and after spraying, the stirring rate is controlled to be 20-30 r / min for 3-5 min.

9. The method for preparing a nutritional base material of sheep liver and tripe using lactic acid bacteria fermentation according to claim 1, wherein, During the standing process after spraying the composite infiltration solution, a gas-permeable film is covered on the surface of the sheep liver slices, the porosity of the film is 60-70%, and the humidity of the standing environment is controlled at 85-90%.

10. The method for preparing sheep liver and sheep tripe nutritional substrate by lactic acid bacteria fermentation as described in claim 1, characterized in that, After spraying the composite infiltration solution and standing, the sheep liver slices are warmed up to 4-6°C at a rate of 0.5-1.0°C / min, and after being kept for 5-8 min, a subsequent mixing step with the sheep stomach strips is performed.

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