A sterilization method applied to dairy products
By using composite microparticles consisting of an outer layer of Fe2+-amino acids, an intermediate layer of chitosan, and a sterilization core, along with magnetic induction electric field sterilization technology, the problems of easy destruction of nutrients and low sterilization efficiency in dairy product sterilization have been solved. This achieves efficient and stable sterilization and nutritional fortification, making it suitable for industrial production of dairy products.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HENAN UNIV OF ANIMAL HUSBANDRY & ECONOMY
- Filing Date
- 2026-03-03
- Publication Date
- 2026-06-09
AI Technical Summary
Existing dairy product sterilization technologies suffer from several drawbacks: nutrients are easily destroyed, sterilization efficiency is low, natural preservatives have poor stability, the sterilization spectrum is narrow, and chemical sterilizers are prone to residues that affect product taste, making it difficult to meet the needs of large-scale industrial production.
It employs multi-layered composite microparticles with an outer layer of Fe2+-amino acids, an intermediate layer of chitosan, and a bactericidal core. Combined with magnetic induction electric field sterilization, it achieves a progressive effect of inducing, anchoring, and killing bacteria through chemotaxis, targeted localization, alternating magnetic field and weak current to generate ROS. It also utilizes the synergistic effect of core components to achieve efficient sterilization.
It achieves efficient killing of microorganisms without damaging the nutritional components and taste of dairy products, preventing their regeneration and reproduction, improving sterilization efficiency and stability, adapting to the dairy product environment, and possessing sterilization, preservation, and nutritional fortification functions, making it suitable for large-scale industrial production.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of food processing, and specifically relates to a sterilization method for dairy products. Background Technology
[0002] Dairy products are rich in nutrients such as protein, lactose, and minerals, making them an excellent substrate for the growth and reproduction of microorganisms. During their production, processing, storage, and transportation, they are highly susceptible to contamination by microorganisms such as bacteria, molds, and yeasts. This can not only lead to spoilage and shorten the shelf life of dairy products, but also cause food safety issues and endanger consumers' health.
[0003] Currently, dairy product sterilization technologies mainly fall into two categories: thermal sterilization and non-thermal sterilization. While thermal sterilization (such as pasteurization and ultra-high temperature sterilization) can effectively kill microorganisms, high temperatures can destroy heat-sensitive nutrients in dairy products (such as vitamins and active proteins), leading to a deterioration in product flavor and a reduction in nutritional value. Non-thermal sterilization technologies (such as high-pressure sterilization, pulsed electric field sterilization, and ultrasonic sterilization) can preserve the nutrients in dairy products to some extent, but they suffer from limited sterilization efficiency, lack of specificity for different types of microorganisms, high equipment costs, and complex operation. Chemical sterilizing agents (such as hydrogen peroxide and hypochlorite) are prone to residues, affecting product taste and potentially reacting with dairy product components to produce harmful substances; these technologies are difficult to meet the needs of large-scale industrial production.
[0004] To address the aforementioned issues, natural preservatives have been widely researched and applied due to their high safety profile. However, single natural preservatives suffer from drawbacks such as poor bactericidal effect and instability. Furthermore, natural preservatives are prone to migration and leakage in dairy product systems, or to interact with proteins, minerals, and other components in dairy products, further reducing their bactericidal efficacy and making it difficult to achieve the desired preservative and bactericidal effect. Summary of the Invention
[0005] Technical Problem to be Solved: This invention aims to solve the technical problems in existing dairy product sterilization technologies, such as easy destruction of nutrients, low sterilization efficiency, poor stability of natural preservatives, and narrow sterilization spectrum. This is addressed by constructing Fe... 2+ - The multi-layered composite microparticles, consisting of an amino acid outer layer, chitosan, and a sterilization core, achieve a progressive effect of inducing, anchoring, and sterilizing bacteria. At the same time, it solves the problems of premature leakage of sterilization components, easy reaction with substances in dairy products, and poor stability. It is compatible with the dairy product environment, natural and healthy, and will not have any negative impact on the flavor or other aspects of dairy products.
[0006] Technical solution: A sterilization method for dairy products, comprising the following steps: Step 1: Add composite microparticles to the liquid dairy product and mix evenly to obtain the liquid dairy product to be sterilized; Step 2: Place the liquid dairy product to be sterilized in a magnetic induction electric field device, turn on the magnetic induction electric field for sterilization, and turn off the magnetic induction electric field after completion to obtain the sterilized liquid dairy product.
[0007] Furthermore, the amount of composite microparticles added in step 1 is 0.05-0.2 wt.%.
[0008] Furthermore, in step 2, the magnetic induction intensity of the magnetic induction electric field sterilization is 30-50 mT, and the electric field intensity is 200-350 V / cm.
[0009] Furthermore, the method for preparing the composite microparticles in step 1 is as follows: S1.Fe 2+ Preparation of -aspartic acid complex: Fe²⁺ solution was slowly added to L-aspartic acid solution, chelated in a constant-temperature water bath with continuous stirring, and then refrigerated to obtain Fe²⁺ complex. 2+ - Aspartic acid complex solution; S2. Preparation of colostrum: Melt butter in a water bath, add lecithin solution and stir to mix, then add theaflavins and chickpea defensins and stir to mix, then sonicate in a water bath to obtain colostrum; S3. Obtaining okra mucilage: Cut okra into pieces, remove seeds, soak in warm water, then blend into a homogeneous paste, squeeze and filter through a sieve, collect the okra mucilage and refrigerate for later use. S4. Preparation of composite particle core: Okra mucilage is added to the primary emulsion, and the emulsion is sheared to obtain a gel emulsion. The gel emulsion is slowly added dropwise to the chitosan acetic acid solution in an ice bath while stirring continuously. The chitosan acetic acid solution is removed, and the core is washed with water to obtain the composite particle core. S5. Preparation of composite microparticles: Fe 2+ Citric acid was added to the aspartic acid complex solution to adjust the pH, and then the composite microparticle core was added and mixed. The mixture was stirred at a constant temperature and spray-dried to obtain the composite microparticles.
[0010] Furthermore, Fe in S1 2+ The solution is ferrous gluconate or ferrous fumarate solution, Fe 2+ The concentrations of the solution and the L-aspartic acid solution were 0.1-0.3 wt.%; Fe 2+ The mass ratio of the solution to the L-aspartic acid solution is (1-3):2; the stirring speed is 100-200 rpm and the time is 30-45 min; the temperature of the constant temperature water bath is 35-45℃; and the solution is refrigerated for 8-12 h.
[0011] Furthermore, in S2, the water bath melting temperature is 35-45℃; the concentration of the lecithin solution is 5-8 wt.%; the mass ratio of butter to lecithin solution is 1:(8-10); the addition amounts of theaflavins and chickpea defensins are 0.1-0.4 wt.% respectively; the water bath ultrasonic temperature is 35-45℃, the power is 100-300W, and the time is 10-20min.
[0012] Furthermore, in S3, the ratio of okra to warm water is 1:(5-8); the soaking time in warm water is 2-3 hours.
[0013] Furthermore, in step S4, the mass ratio of the primary emulsion to the okra mucilage is (10-20):1; the emulsification shearing speed is 3000-5000 rpm; the time is 10-15 min; the acetic acid concentration of the chitosan acetic acid solution is 50-70 wt.%; the chitosan content is 3-5 wt.%; the stirring speed is 100-200 rpm; and the number of times water is added for washing is 3-5 times.
[0014] Furthermore, in S5, the amount of citric acid added is 0.05-0.1 wt.%, and the pH is adjusted to 5.0-6.0; the composite microparticle core and Fe 2+ The mass ratio of the aspartic acid complex solution is (1-2):(1-3); the constant temperature stirring temperature is 30-35℃, the stirring speed is 200-300rpm, and the stirring time is 20-30min. Beneficial effects
[0015] This invention Fe 2+ -Fe in the outer layer of amino acids 2+ It is a trace element essential for microbial growth. Through chemotaxis, it attracts contaminating microorganisms in dairy products to aggregate towards the microparticles. L-Aspartic acid is a potent attractant, actively attracting bacteria to approach and anchor on the microparticle surface to achieve targeted localization, thus improving the contact efficiency between bactericidal ingredients and microorganisms. The magnetic induction electric field can generate an alternating magnetic field and a weak current, acting on the Fe of the composite microparticles. 2+ - Amino acid outer layer, making Fe 2+ Electron transitions occur, generating ROS, which can indiscriminately attack bacteria; at the same time, it disrupts the electrostatic bonding between the outer and middle layers, and induces a conformational change in the chitosan middle layer, leading to the dissociation of the entire nuclear membrane structure and the release of the bactericidal core.
[0016] In the core of this invention, theaflavins and chickpea defensins work synergistically to cover various microorganisms and achieve highly efficient killing. On this basis, relying on the unique physical barrier, anti-adhesion effect, and potential chemical inhibition effect of okra mucus, it blocks bacterial adhesion and biofilm formation, preventing residual bacteria from re-invading after sterilization, forming a dual protection of "killing + preventing recurrence", and completely solving the problem of microbial contamination in dairy products. Compared with traditional gel matrices, the unique advantage of okra mucus lies in "functional diversification and natural compatibility", breaking the limitation of traditional matrices that can only achieve the single function of "encapsulation", and superimposing functions to enhance the bactericidal and bacteriostatic effects.
[0017] This invention utilizes butter and lecithin, both inherent components of dairy products. As the core oil phase matrix, their core functions are reflected in two aspects: improved compatibility and enhanced stability. First, they are naturally compatible with dairy product systems, and their addition will not damage the original flavor, texture, or nutritional structure of dairy products. This avoids problems such as reactions and off-flavors between traditional foreign matrices and dairy product components, significantly improving the compatibility of the composite microparticles with dairy products. Second, they can optimize the structural stability of the dual emulsion gel particles, enhance the core encapsulation, and assist okra mucus in forming a more uniform and dense gel system. At the same time, they can improve the stability of the core bactericidal components during storage and the slow-release effect during sterilization, making the bactericidal effect more lasting, further reducing the loss of bactericidal components, and improving sterilization efficiency.
[0018] The magnetic induction electric field of this invention can destroy the permeability of microbial cell membranes through electroporation, creating tiny pores in the cell membranes. At this time, bactericidal components are rapidly released under the action of the electric field and quickly enter the microbial cells through the pores, exerting effects such as cell membrane destruction and protein synthesis inhibition, forming a synergistic effect of "electric field perforation + biological sterilization". Compared with a single electric field or a single bactericidal component, the sterilization efficiency is improved.
[0019] This invention is entirely green and safe, with no harmful residues. All components of the composite microparticles are of natural origin (okra mucilage, theaflavins, chickpea defensins) or inherent components of dairy products (butter, lecithin); Fe 2+ L-aspartic acid, mucopolysaccharides and polyphenols in okra mucilage are all nutrients needed by the human body. Even if a small amount remains, it will not affect the product quality and can even enhance nutrition. The complex microparticles have multiple functions, including sterilization, preservation, and nutritional fortification. Theaflavins have antioxidant and lipid-lowering effects, chickpea defensins have immune-regulating effects, and okra mucilage supplements mucopolysaccharides and has antioxidant effects, meeting consumers' demand for healthy dairy products. Detailed Implementation
[0020] The present invention will be further described below with reference to embodiments. These embodiments are illustrative of the present invention, but the present invention is not limited to these embodiments: Example 1
[0021] The preparation of composite microparticles includes the following steps: S1. Fe 2+ Preparation of aspartic acid complex: A 0.2 wt.% L-aspartic acid solution and a 0.2 wt.% ferrous gluconate solution were prepared separately. 15 g of ferrous gluconate solution was slowly added dropwise to 10 g of L-aspartic acid solution while stirring at 150 rpm. Chelation was carried out in a 40°C constant temperature water bath for 40 min with continuous stirring. After chelation, the mixture was refrigerated at 4°C for 10 h to obtain stable Fe. 2+ - Aspartic acid complex solution; S2. Preparation of colostrum: Melt butter in a 40℃ water bath, prepare a 5wt.% lecithin solution, mix 5g butter with 45g lecithin solution, stir for 15min until uniform, add 0.1g theaflavins and 0.1g chickpea defensin, stir to disperse the theaflavins and chickpea defensin evenly, sonicate at 200W power for 15min in a 40℃ water bath, cool to room temperature to obtain colostrum; S3. Obtaining okra mucilage: Cut immature okra pods into pieces, remove seeds, soak 100g of okra in 500g of 35℃ warm water for 2 hours, then stir into a homogenous paste, squeeze and filter through a sieve, collect the okra mucilage and refrigerate for later use. S4. Preparation of composite particle core: Add 4g of okra mucilage to 40g of primary emulsion, emulsify and shear at 4000rpm for 12min to obtain gel emulsion. Mix acetic acid and deionized water to prepare an acetic acid solution with a concentration of 60wt.%. Add 4wt.% chitosan to the acetic acid solution and stir until the chitosan is completely dissolved to obtain a chitosan-acetic acid solution. Cool the solution to 0-4℃ in an ice bath. Slowly add the gel emulsion to the chitosan-acetic acid solution in the ice bath while stirring continuously at 100rpm. After the addition is complete, continue stirring for 30min. Then, remove the chitosan-acetic acid solution by centrifugation (4℃, 5000rpm, 10min), collect the precipitate, and wash it with water 4 times to obtain the composite particle core. S5. Preparation of composite microparticles: 20g of Fe 2+ Add 0.01g of citric acid to the aspartic acid complex solution to adjust the pH to 5.5, then add 10g of the composite microparticle core and mix. Stir at 200rpm for 30 minutes at 30℃ and spray dry to obtain composite microparticles. Example 2
[0022] The preparation of composite microparticles includes the following steps: S1. Fe 2+Preparation of aspartic acid complex: A 0.2 wt.% L-aspartic acid solution and a 0.2 wt.% ferrous gluconate solution were prepared separately. 10 g of ferrous fumarate solution was slowly added dropwise to 20 g of L-aspartic acid solution while stirring at 150 rpm. Chelation was carried out in a 40°C constant temperature water bath for 40 min with continuous stirring. After chelation, the mixture was refrigerated at 4°C for 10 h to obtain stable Fe. 2+ - Aspartic acid complex solution; S2. Preparation of colostrum: Melt butter in a 40℃ water bath, prepare a 5wt.% lecithin solution, mix 5g butter with 45g lecithin solution, stir for 15min until uniform, add 0.1g theaflavins and 0.1g chickpea defensin, stir to disperse the theaflavins and chickpea defensin evenly, sonicate at 200W power for 15min in a 40℃ water bath, cool to room temperature to obtain colostrum; S3. Obtaining okra mucilage: Cut immature okra pods into pieces, remove seeds, soak 100g of okra in 500g of 35℃ warm water for 2 hours, then stir into a homogenous paste, squeeze and filter through a sieve, collect the okra mucilage and refrigerate for later use. S4. Preparation of composite particle core: Add 4g of okra mucilage to 40g of primary emulsion, emulsify and shear at 4000rpm for 12min to obtain gel emulsion. Mix acetic acid and deionized water to prepare an acetic acid solution with a concentration of 60wt.%. Add 4wt.% chitosan to the acetic acid solution and stir until the chitosan is completely dissolved to obtain a chitosan-acetic acid solution. Cool the solution to 0-4℃ in an ice bath. Slowly add the gel emulsion to the chitosan-acetic acid solution in the ice bath while stirring continuously at 100rpm. After the addition is complete, continue stirring for 30min. Then, remove the chitosan-acetic acid solution by centrifugation (4℃, 5000rpm, 10min), collect the precipitate, and wash it with water 4 times to obtain the composite particle core. S5. Preparation of composite microparticles: 20g of Fe 2+ Add 0.01g of citric acid to the aspartic acid complex solution to adjust the pH to 5.5, then add 10g of the composite microparticle core and mix. Stir at 200rpm for 30 minutes at 30℃ and spray dry to obtain composite microparticles. Example 3
[0023] The preparation of composite microparticles includes the following steps: S1. Fe 2+Preparation of aspartic acid complex: A 0.2 wt.% L-aspartic acid solution and a 0.2 wt.% ferrous gluconate solution were prepared separately. 15 g of ferrous gluconate solution was slowly added dropwise to 10 g of L-aspartic acid solution while stirring at 150 rpm. Chelation was carried out in a 40°C constant temperature water bath for 40 min with continuous stirring. After chelation, the mixture was refrigerated at 4°C for 10 h to obtain stable Fe. 2+ - Aspartic acid complex solution; S2. Preparation of colostrum: Melt butter in a 40℃ water bath, prepare a 5wt.% lecithin solution, mix 5g butter with 45g lecithin solution, stir for 15min until uniform, add 0.2g theaflavins and 0.2g chickpea defensin, stir to disperse the theaflavins and chickpea defensin evenly, sonicate at 200W power for 15min in a 40℃ water bath, cool to room temperature to obtain colostrum; S3. Obtaining okra mucilage: Cut immature okra pods into pieces, remove seeds, soak 100g of okra in 500g of 35℃ warm water for 2 hours, then stir into a homogenous paste, squeeze and filter through a sieve, collect the okra mucilage and refrigerate for later use. S4. Preparation of composite particle core: Add 4g of okra mucilage to 40g of primary emulsion, emulsify and shear at 4000rpm for 12min to obtain gel emulsion. Mix acetic acid and deionized water to prepare an acetic acid solution with a concentration of 60wt.%. Add 4wt.% chitosan to the acetic acid solution and stir until the chitosan is completely dissolved to obtain a chitosan-acetic acid solution. Cool the solution to 0-4℃ in an ice bath. Slowly add the gel emulsion to the chitosan-acetic acid solution in the ice bath while stirring continuously at 100rpm. After the addition is complete, continue stirring for 30min. Then, remove the chitosan-acetic acid solution by centrifugation (4℃, 5000rpm, 10min), collect the precipitate, and wash it with water 4 times to obtain the composite particle core. S5. Preparation of composite microparticles: 20g of Fe 2+ Add 0.01g of citric acid to the aspartic acid complex solution to adjust the pH to 5.5, then add 10g of the composite microparticle core and mix. Stir at 200rpm for 30 minutes at 30℃ and spray dry to obtain composite microparticles. Example 4
[0024] The preparation of composite microparticles includes the following steps: S1. Fe 2+Preparation of aspartic acid complex: A 0.2 wt.% L-aspartic acid solution and a 0.2 wt.% ferrous gluconate solution were prepared separately. 15 g of ferrous gluconate solution was slowly added dropwise to 10 g of L-aspartic acid solution while stirring at 150 rpm. Chelation was carried out in a 40°C constant temperature water bath for 40 min with continuous stirring. After chelation, the mixture was refrigerated at 4°C for 10 h to obtain stable Fe. 2+ - Aspartic acid complex solution; S2. Preparation of colostrum: Melt butter in a 40℃ water bath, prepare a 5wt.% lecithin solution, mix 5g butter with 45g lecithin solution, stir for 15min until uniform, add 0.1g theaflavins and 0.1g chickpea defensin, stir to disperse the theaflavins and chickpea defensin evenly, sonicate at 200W power for 15min in a 40℃ water bath, cool to room temperature to obtain colostrum; S3. Obtaining okra mucilage: Cut immature okra pods into pieces, remove seeds, soak 100g of okra in 800g of 35℃ warm water for 2 hours, then stir into a homogenous paste, squeeze and filter through a sieve, collect the okra mucilage and refrigerate for later use. S4. Preparation of composite particle core: Add 4g of okra mucilage to 40g of primary emulsion, emulsify and shear at 4000rpm for 12min to obtain gel emulsion. Mix acetic acid and deionized water to prepare an acetic acid solution with a concentration of 60wt.%. Add 4wt.% chitosan to the acetic acid solution and stir until the chitosan is completely dissolved to obtain a chitosan-acetic acid solution. Cool the solution to 0-4℃ in an ice bath. Slowly add the gel emulsion to the chitosan-acetic acid solution in the ice bath while stirring continuously at 100rpm. After the addition is complete, continue stirring for 30min. Then, remove the chitosan-acetic acid solution by centrifugation (4℃, 5000rpm, 10min), collect the precipitate, and wash it with water 4 times to obtain the composite particle core. S5. Preparation of composite microparticles: 20g of Fe 2+ Add 0.01g of citric acid to the aspartic acid complex solution to adjust the pH to 5.5, then add 10g of the composite microparticle core and mix. Stir at 200rpm for 30 minutes at 30℃ and spray dry to obtain composite microparticles. Example 5
[0025] The preparation of composite microparticles includes the following steps: S1. Fe 2+Preparation of aspartic acid complex: A 0.2 wt.% L-aspartic acid solution and a 0.2 wt.% ferrous gluconate solution were prepared separately. 15 g of ferrous gluconate solution was slowly added dropwise to 10 g of L-aspartic acid solution while stirring at 150 rpm. Chelation was carried out in a 40°C constant temperature water bath for 40 min with continuous stirring. After chelation, the mixture was refrigerated at 4°C for 10 h to obtain stable Fe. 2+ - Aspartic acid complex solution; S2. Preparation of colostrum: Melt butter in a 40℃ water bath, prepare a 5wt.% lecithin solution, mix 5g butter with 45g lecithin solution, stir for 15min until uniform, add 0.1g theaflavins and 0.1g chickpea defensin, stir to disperse the theaflavins and chickpea defensin evenly, sonicate at 200W power for 15min in a 40℃ water bath, cool to room temperature to obtain colostrum; S3. Obtaining okra mucilage: Cut immature okra pods into pieces, remove seeds, soak 100g of okra in 500g of 35℃ warm water for 2 hours, then stir into a homogenous paste, squeeze and filter through a sieve, collect the okra mucilage and refrigerate for later use. S4. Preparation of composite particle core: Add 4g of okra mucilage to 40g of primary emulsion, emulsify and shear at 4000rpm for 12min to obtain gel emulsion. Mix acetic acid and deionized water to prepare an acetic acid solution with a concentration of 60wt.%. Add 3wt.% chitosan to the acetic acid solution and stir until the chitosan is completely dissolved to obtain a chitosan-acetic acid solution. Place it in an ice bath to cool to 0-4℃. Slowly add the gel emulsion dropwise to the chitosan-acetic acid solution in the ice bath while stirring continuously at 100rpm. After the dropwise addition is complete, continue stirring for 30min. Then, remove the chitosan-acetic acid solution by centrifugation (4℃, 5000rpm, 10min), collect the precipitate, and wash it with water 4 times to obtain the composite particle core. S5. Preparation of composite microparticles: 20g of Fe 2+ Add 0.01g of citric acid to the aspartic acid complex solution to adjust the pH to 5.5, then add 10g of the composite microparticle core and mix. Stir at 200rpm for 30 minutes at 30℃ and spray dry to obtain composite microparticles. Example 6
[0026] The preparation of composite microparticles includes the following steps: S1. Fe 2+Preparation of aspartic acid complex: A 0.2 wt.% L-aspartic acid solution and a 0.2 wt.% ferrous gluconate solution were prepared separately. 15 g of ferrous gluconate solution was slowly added dropwise to 10 g of L-aspartic acid solution while stirring at 150 rpm. Chelation was carried out in a 40°C constant temperature water bath for 40 min with continuous stirring. After chelation, the mixture was refrigerated at 4°C for 10 h to obtain stable Fe. 2+ - Aspartic acid complex solution; S2. Preparation of colostrum: Melt butter in a 40℃ water bath, prepare a 5wt.% lecithin solution, mix 5g butter with 45g lecithin solution, stir for 15min until uniform, add 0.1g theaflavins and 0.1g chickpea defensin, stir to disperse the theaflavins and chickpea defensin evenly, sonicate at 200W power for 15min in a 40℃ water bath, cool to room temperature to obtain colostrum; S3. Obtaining okra mucilage: Cut immature okra pods into pieces, remove seeds, soak 100g of okra in 500g of 35℃ warm water for 2 hours, then stir into a homogenous paste, squeeze and filter through a sieve, collect the okra mucilage and refrigerate for later use. S4. Preparation of composite particle core: Add 4g of okra mucilage to 40g of primary emulsion, emulsify and shear at 4000rpm for 12min to obtain gel emulsion. Mix acetic acid and deionized water to prepare an acetic acid solution with a concentration of 60wt.%. Add 4wt.% chitosan to the acetic acid solution and stir until the chitosan is completely dissolved to obtain a chitosan-acetic acid solution. Cool the solution to 0-4℃ in an ice bath. Slowly add the gel emulsion to the chitosan-acetic acid solution in the ice bath while stirring continuously at 100rpm. After the addition is complete, continue stirring for 30min. Then, remove the chitosan-acetic acid solution by centrifugation (4℃, 5000rpm, 10min), collect the precipitate, and wash it with water 4 times to obtain the composite particle core. S5. Preparation of composite microparticles: 20g of Fe 2+ Add 0.01g of citric acid to the aspartic acid complex solution to adjust the pH to 5.5, then add 20g of composite microparticle core and mix. Stir at 200rpm for 30 minutes at 30℃ and spray dry to obtain composite microparticles. Comparative Example 1
[0027] The difference between this comparative example and Example 1 is that Fe is not added. 2+ -Aspartic acid complex, as detailed below: S1. Preparation of colostrum: Melt butter in a 40℃ water bath, prepare a 5wt.% lecithin solution, mix 5g butter with 45g lecithin solution, stir for 15min until uniform, add 0.1g theaflavins and 0.1g chickpea defensin, stir to disperse the theaflavins and chickpea defensin evenly, sonicate at 200W power for 15min in a 40℃ water bath, cool to room temperature to obtain colostrum; S2. Obtaining okra mucilage: Cut immature okra pods into pieces, remove seeds, soak 100g of okra in 500g of 35℃ warm water for 2 hours, then stir into a homogenous paste, squeeze and filter through a sieve, collect the okra mucilage and refrigerate for later use. S3. Preparation of composite particles: Add 4g of okra mucilage to 40g of primary emulsion, emulsify and shear at 4000rpm for 12min to obtain a gel emulsion. Mix acetic acid and deionized water to prepare an acetic acid solution with a concentration of 60wt.%. Add 4wt.% chitosan to the acetic acid solution and stir until the chitosan is completely dissolved to obtain a chitosan-acetic acid solution. Place the solution in an ice bath to cool to 0-4℃. Slowly add the gel emulsion dropwise to the chitosan-acetic acid solution in the ice bath while stirring continuously at 100rpm. After the addition is complete, continue stirring for 30min. Then, remove the chitosan-acetic acid solution by centrifugation (4℃, 5000rpm, 10min), collect the precipitate, and wash it with water 4 times to obtain composite particles. Comparative Example 2
[0028] The difference between this comparative example and Example 1 is that the colostrum was prepared without the addition of butter and lecithin, as detailed below: S1. Fe 2+ Preparation of aspartic acid complex: A 0.2 wt.% L-aspartic acid solution and a 0.2 wt.% ferrous gluconate solution were prepared separately. 15 g of ferrous gluconate solution was slowly added dropwise to 10 g of L-aspartic acid solution while stirring at 150 rpm. Chelation was carried out in a 40°C constant temperature water bath for 40 min with continuous stirring. After chelation, the mixture was refrigerated at 4°C for 10 h to obtain stable Fe. 2+ - Aspartic acid complex solution; S2. Preparation of sterilization mixture: Add 0.1g of theaflavins and 0.1g of chickpea defensin to 50g of water, stir to disperse the theaflavins and chickpea defensin evenly, sonicate at 200W power for 15min in a 40℃ water bath, and cool to room temperature to obtain sterilization mixture. S3. Obtaining okra mucilage: Cut immature okra pods into pieces, remove seeds, soak 100g of okra in 500g of 35℃ warm water for 2 hours, then stir into a homogenous paste, squeeze and filter through a sieve, collect the okra mucilage and refrigerate for later use. S4. Preparation of composite particle core: Add 4g of okra mucilage to 40g of sterilization mixture, emulsify and shear at 4000rpm for 12min to obtain gel emulsion. Mix acetic acid and deionized water to prepare acetic acid solution with a concentration of 60wt.%. Add 4wt.% chitosan to the acetic acid solution and stir until the chitosan is completely dissolved to obtain chitosan acetic acid solution. Place it in an ice bath to cool to 0-4℃. Slowly add the gel emulsion to the chitosan acetic acid solution in the ice bath while stirring continuously at 100rpm. After the addition is complete, continue stirring for 30min. Then, remove the chitosan acetic acid solution by centrifugation (4℃, 5000rpm, 10min), collect the precipitate, and wash with water 4 times to obtain composite particle core. S5. Preparation of composite microparticles: 20g of Fe 2+ Add 0.01g of citric acid to the aspartic acid complex solution to adjust the pH to 5.5, then add 10g of the composite microparticle core and mix. Stir at 200rpm for 30 minutes at 30℃ and spray dry to obtain composite microparticles. Comparative Example 3
[0029] The difference between this comparative example and Example 1 is that pectin is used instead of okra mucilage, as detailed below: S1. Fe 2+ Preparation of aspartic acid complex: A 0.2 wt.% L-aspartic acid solution and a 0.2 wt.% ferrous gluconate solution were prepared separately. 15 g of ferrous gluconate solution was slowly added dropwise to 10 g of L-aspartic acid solution while stirring at 150 rpm. Chelation was carried out in a 40°C constant temperature water bath for 40 min with continuous stirring. After chelation, the mixture was refrigerated at 4°C for 10 h to obtain stable Fe. 2+ - Aspartic acid complex solution; S2. Preparation of colostrum: Melt butter in a 40℃ water bath, prepare a 5wt.% lecithin solution, mix 5g butter with 45g lecithin solution, stir for 15min until uniform, add 0.1g theaflavins and 0.1g chickpea defensin, stir to disperse the theaflavins and chickpea defensin evenly, sonicate at 200W power for 15min in a 40℃ water bath, cool to room temperature to obtain colostrum; S3. Preparation of composite particle core: Add 4g of pectin solution to 40g of primary emulsion, emulsify and shear at 4000rpm for 12min to obtain gel emulsion. Mix acetic acid and deionized water to prepare an acetic acid solution with a concentration of 60wt.%. Add 4wt.% chitosan to the acetic acid solution and stir until the chitosan is completely dissolved to obtain a chitosan-acetic acid solution. Place it in an ice bath to cool to 0-4℃. Slowly add the gel emulsion dropwise to the chitosan-acetic acid solution in the ice bath while stirring continuously at 100rpm. After the dropwise addition is complete, continue stirring for 30min. Then, remove the chitosan-acetic acid solution by centrifugation (4℃, 5000rpm, 10min), collect the precipitate, and wash it with water 4 times to obtain the composite particle core. S4. Preparation of composite microparticles: 20g of Fe 2+ Add 0.01g of citric acid to the aspartic acid complex solution to adjust the pH to 5.5, then add 10g of the composite microparticle core and mix. Stir at 200rpm for 30 minutes at 30℃ and spray dry to obtain composite microparticles. Comparative Example 4
[0030] The difference between this comparative example and Example 1 is that ethanol is used instead of chitosan acetic acid solution, as detailed below: S1. Fe 2+ Preparation of aspartic acid complex: A 0.2 wt.% L-aspartic acid solution and a 0.2 wt.% ferrous gluconate solution were prepared separately. 15 g of ferrous gluconate solution was slowly added dropwise to 10 g of L-aspartic acid solution while stirring at 150 rpm. Chelation was carried out in a 40°C constant temperature water bath for 40 min with continuous stirring. After chelation, the mixture was refrigerated at 4°C for 10 h to obtain stable Fe. 2+ - Aspartic acid complex solution; S2. Preparation of colostrum: Melt butter in a 40℃ water bath, prepare a 5wt.% lecithin solution, mix 5g butter with 45g lecithin solution, stir for 15min until uniform, add 0.1g theaflavins and 0.1g chickpea defensin, stir to disperse the theaflavins and chickpea defensin evenly, sonicate at 200W power for 15min in a 40℃ water bath, cool to room temperature to obtain colostrum; S3. Obtaining okra mucilage: Cut immature okra pods into pieces, remove seeds, soak 100g of okra in 500g of 35℃ warm water for 2 hours, then stir into a homogenous paste, squeeze and filter through a sieve, collect the okra mucilage and refrigerate for later use. S4. Preparation of composite particle core: Add 4g of okra mucilage to 40g of primary emulsion, emulsify and shear at 4000rpm for 12min to obtain gel emulsion, place 60wt.% ethanol solution in an ice bath to cool to 0-4℃, slowly add the gel emulsion dropwise to the ethanol solution in the ice bath while stirring continuously at 100rpm, after the dropwise addition is complete, continue stirring for 30min, then centrifuge (4℃, 5000rpm, 10min) to remove ethanol, collect the precipitate, wash with water 4 times to obtain composite particle core; S5. Preparation of composite microparticles: 20g of Fe 2+ Add 0.01g of citric acid to the aspartic acid complex solution to adjust the pH to 5.5, then add 10g of the composite microparticle core and mix. Stir at 200rpm for 30 minutes at 30℃ and spray dry to obtain composite microparticles. Performance testing
[0031] inhibition zone assay Staphylococcus aureus and Escherichia coli are the main pathogenic bacteria in dairy products. 200 μL of the test bacterial solution (bacterial content 1 × 10⁻⁶) was transferred in a sterile environment. 8 Add CFU / mL to a petri dish containing culture medium, then add the reconstituted sample of the composite microparticles to the center of the petri dish, and incubate in a constant temperature incubator at 37℃ for 24 hours to test the inhibition zone.
[0032] A larger inhibition zone indicates a better antibacterial effect. Specific results are shown in Table 1. All examples maintained excellent and stable antibacterial effects. In Example 3, the dosage of theaflavins and chickpea defensins was doubled, resulting in the largest inhibition zone and enhanced antibacterial effect. In Comparative Example 3, pectin was used instead of okra mucilage. Since pectin lacks the natural antibacterial components found in okra mucilage, its antibacterial effect was significantly weakened.
[0033] Table 1. Diameter of the inhibition zone of the composite microparticles
[0034] 2. Stability Test After storing the composite microparticles at 50°C for 12 hours, the above-mentioned inhibition zone experiment was performed.
[0035] The percentage decreases in all Examples 1-6 were relatively low, with a 4-7% decrease in inhibition zones against Staphylococcus aureus and Escherichia coli; while the percentage decreases in Comparative Examples 1-4 were significantly higher, ranging from 9-15%; particularly in Comparative Examples 2 and 4, the emulsion system and chitosan played a crucial role in system stability. This indicates that the complete composite microparticle encapsulation system can effectively protect the active ingredients, maintaining good antibacterial activity and high stability after high-temperature storage.
[0036] Table 2. Diameter of the inhibition zone of the composite microparticles after high-temperature storage.
[0037] A sterilization method for dairy products includes the following steps: Step 1: Add 0.05 wt.% of the composite microparticles prepared in Example 1 to the liquid dairy product and mix evenly to obtain the liquid dairy product to be sterilized; Step 2: Place the liquid dairy product to be sterilized in a magnetic induction electric field device with a magnetic induction intensity of 30mT and an electric field intensity of 300V / cm. Turn on the magnetic induction electric field for sterilization, and turn off the magnetic induction electric field after completion to obtain the sterilized liquid dairy product. Example 8
[0038] A sterilization method for dairy products includes the following steps: Step 1: Add 0.05 wt.% of the composite microparticles prepared in Example 1 to the liquid dairy product and mix evenly to obtain the liquid dairy product to be sterilized; Step 2: Place the liquid dairy product to be sterilized in a magnetic induction electric field device with a magnetic induction intensity of 30mT and an electric field intensity of 200V / cm. Turn on the magnetic induction electric field for sterilization, and turn off the magnetic induction electric field after completion to obtain the sterilized liquid dairy product. Comparative Example 5
[0039] The difference between this comparative example and Example 7 is that only a magnetic induction electric field is used for sterilization, as detailed below: Step 1: Place the liquid dairy product to be sterilized in a magnetic induction electric field device with a magnetic induction intensity of 30mT and an electric field intensity of 300V / cm. Turn on the magnetic induction electric field for sterilization, and turn off the magnetic induction electric field after completion to obtain the sterilized liquid dairy product. Comparative Example 6
[0040] The difference between this comparative example and Example 7 is that Comparative Example 1 replaces Example 1, as detailed below: Step 1: Add 0.05 wt.% of the composite microparticles prepared in Example 1 to the liquid dairy product and mix evenly to obtain the liquid dairy product to be sterilized; Step 2: Place the liquid dairy product to be sterilized in a magnetic induction electric field device with a magnetic induction intensity of 30mT and an electric field intensity of 300V / cm. Turn on the magnetic induction electric field for sterilization, and turn off the magnetic induction electric field after completion to obtain the sterilized liquid dairy product. Comparative Example 7
[0041] The difference between this comparative example and Example 7 is that Comparative Example 2 replaces Example 1, as detailed below: Step 1: Add 0.05 wt.% of the composite microparticles prepared in Example 1 to the liquid dairy product and mix evenly to obtain the liquid dairy product to be sterilized; Step 2: Place the liquid dairy product to be sterilized in a magnetic induction electric field device with a magnetic induction intensity of 30mT and an electric field intensity of 300V / cm. Turn on the magnetic induction electric field for sterilization, and turn off the magnetic induction electric field after completion to obtain the sterilized liquid dairy product. Comparative Example 8
[0042] The difference between this comparative example and Example 7 is that Comparative Example 3 replaces Example 1, as detailed below: Step 1: Add 0.05 wt.% of the composite microparticles prepared in Example 1 to the liquid dairy product and mix evenly to obtain the liquid dairy product to be sterilized; Step 2: Place the liquid dairy product to be sterilized in a magnetic induction electric field device with a magnetic induction intensity of 30mT and an electric field intensity of 300V / cm. Turn on the magnetic induction electric field for sterilization, and turn off the magnetic induction electric field after completion to obtain the sterilized liquid dairy product. Comparative Example 9
[0043] The difference between this comparative example and Example 7 is that Comparative Example 4 replaces Example 1, as detailed below: Step 1: Add 0.05 wt.% of the composite microparticles prepared in Example 1 to the liquid dairy product and mix evenly to obtain the liquid dairy product to be sterilized; Step 2: Place the liquid dairy product to be sterilized in a magnetic induction electric field device with a magnetic induction intensity of 30mT and an electric field intensity of 300V / cm. Turn on the magnetic induction electric field for sterilization, and turn off the magnetic induction electric field after completion to obtain the sterilized liquid dairy product. Performance testing
[0044] 1. Sterilization rate Refer to the national standard GB 4789.2-2022, "National Food Safety Standard - Microbiological Examination of Food - Determination of Total Colony Count".
[0045] Take dairy product samples before and after sterilization, perform appropriate serial dilutions, spread them on plate counting agar, incubate at 37℃ for 48 hours, and count the samples. Calculate the sterilization rate using the following formula: Sterilization rate (%) = (1-N / N0) × 100% In the formula: N0 and N are the total number of colonies before and after treatment, respectively.
[0046] Table 3 shows that the sterilization rates of Examples 7 and 8 are as high as 96% or more, while the sterilization rates of the comparative examples are all below 90%. Compared with Example 7, the electric field strength in Example 8 decreased from 300V / cm to 200V / cm, the synergistic effect of the magnetic induction electric field weakened, and the sterilization rate decreased slightly. Comparative Example 5 only used a magnetic induction electric field, without the synergistic effect of composite particles, and the sterilization rate was significantly reduced to only 60%, which is difficult to meet the sterilization requirements. Comparative Example 6 used the composite particles of Comparative Example 1 (lacking Fe). 2+-Aspartic acid complex) cannot cooperate efficiently with magnetic fields, resulting in a significant reduction in synergistic effect and a decrease in sterilization rate.
[0047] Table 3. Sterilization rate of dairy products in Examples 7-8 and Comparative Examples 5-9
[0048] 2. Verification of various indicators after sterilization Microbiological indicators were tested on the dairy products obtained from sterilization in Examples 7-8 and Comparative Examples 5-9. The results are shown in Table 4 below. The results show that the final products from the comparative examples and Comparative Example 6 had unsatisfactory microbiological performance. The dairy products treated in Examples 7 and 8 exhibited excellent sterilization effects across all microbiological indicators. The coliform count was <1 CFU / g, indicating almost complete elimination of pathogenic bacteria; the mold and yeast counts were <10 CFU / g, inhibiting fungal growth; Staphylococcus aureus and Salmonella were not detected, demonstrating complete eradication of common pathogens; and the total aerobic spore count was <10 CFU / g, indicating significant spore removal. In contrast, most indicators in the comparative examples, except for Staphylococcus aureus, were above the detection limit and showed significant fluctuations, especially with Salmonella being detected in Comparative Example 5. The technology of this invention (Examples 7-8) demonstrates extremely high effectiveness in the field of dairy product sterilization, reducing key pathogens and spoilage bacteria to extremely low levels, significantly superior to the comparative examples. This not only improves the safety of dairy products, but may also extend their shelf life.
[0049] Table 4. Microbiological indicators in sterilized dairy products of Examples 7-8 and Comparative Examples 5-9.
[0050] 3. Sensory evaluation Sensory evaluation was conducted on the pasteurized liquid milk. A panel of 10 members was invited to evaluate the milk based on its appearance, taste, and texture. The evaluation process followed a standardized sensory evaluation procedure, scoring the milk on appearance, taste, and texture, with a maximum score of 100 points. After scoring, the data from all members was statistically analyzed to calculate the average score for each sample under each indicator and the overall average score.
[0051] The results are shown in Table 5. Intact composite microparticles (Example 7) combined with an appropriate electric field strength (300 V / cm) maintained good sensory quality in dairy products; reducing the electric field strength (Example 8, 200 V / cm) further optimized sensory performance; the absence of key components or the use of defective microparticles led to a decline in sensory quality, with Comparative Example 7 showing the most significant decrease, indicating that the emulsion system significantly affects microparticle dispersibility, flavor buffering, and mouthfeel smoothness. Compared to Comparative Example 8, Okra mucilage in Example 7 had no strong odor, and the mouthfeel and appearance actually decreased after pectin replacement.
[0052] Table 5 Sensory evaluation of pasteurized dairy products from Examples 7-8 and Comparative Examples 5-9
[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the technical solutions of the present invention, shall still fall within the scope of protection of the present invention.
Claims
1. A sterilization method for dairy products, characterized in that, Includes the following steps: Step 1: Add composite microparticles to the liquid dairy product and mix evenly to obtain the liquid dairy product to be sterilized; Step 2: Place the liquid dairy product to be sterilized in a magnetic induction electric field device, turn on the magnetic induction electric field for sterilization, and turn off the magnetic induction electric field after completion to obtain the sterilized liquid dairy product.
2. The sterilization method for dairy products according to claim 1, characterized in that: The amount of composite microparticles added in step 1 is 0.05-0.2 wt.%.
3. The sterilization method for dairy products according to claim 1, characterized in that: In step 2, the magnetic induction intensity of the magnetic induction field for sterilization is 30-50 mT, and the electric field intensity is 200-350 V / cm.
4. The sterilization method for dairy products according to claim 1, characterized in that, The method for preparing the composite microparticles in step 1 is as follows: S1.Fe 2+ Preparation of -aspartic acid complex: Fe was slowly added to the L-aspartic acid solution. 2+ The solution was chelated in a constant-temperature water bath with continuous stirring, and then refrigerated to obtain Fe. 2+ - Aspartic acid complex solution; S2. Preparation of colostrum: Melt butter in a water bath, add lecithin solution and stir to mix, then add theaflavins and chickpea defensins and stir to mix, then sonicate in a water bath to obtain colostrum; S3. Obtaining okra mucilage: Cut okra into pieces, remove seeds, soak in warm water, then blend into a homogeneous paste, squeeze and filter through a sieve, collect the okra mucilage and refrigerate for later use. S4. Preparation of composite particle core: Okra mucilage is added to the primary emulsion, and the emulsion is sheared to obtain a gel emulsion. The gel emulsion is slowly added dropwise to the chitosan acetic acid solution in an ice bath while stirring continuously. The chitosan acetic acid solution is removed, and the core is washed with water to obtain the composite particle core. S5. Preparation of composite microparticles: Fe 2+ Citric acid was added to the aspartic acid complex solution to adjust the pH, and then the composite microparticle core was added and mixed. The mixture was stirred at a constant temperature and spray-dried to obtain the composite microparticles.
5. The sterilization method for dairy products according to claim 4, characterized in that: Fe in S1 2+ The solution is ferrous gluconate or ferrous fumarate solution, Fe 2+ The concentrations of the solution and the L-aspartic acid solution were 0.1-0.3 wt.%; Fe 2+ The mass ratio of the solution to the L-aspartic acid solution is (1-3):2; the stirring speed is 100-200 rpm and the time is 30-45 min; the temperature of the constant temperature water bath is 35-45℃; and the solution is refrigerated for 8-12 h.
6. The sterilization method for dairy products according to claim 4, characterized in that: The water bath melting temperature in S2 is 35-45℃; the concentration of lecithin solution is 5-8 wt.%; the mass ratio of butter to lecithin solution is 1:(8-10); the amount of theaflavins and chickpea defensins added is 0.1-0.4 wt.% respectively; the water bath ultrasonic temperature is 35-45℃, the power is 100-300W, and the time is 10-20min.
7. A sterilization method for dairy products according to claim 4, characterized in that: The ratio of okra to warm water in S3 is 1:(5-8); the soaking time in warm water is 2-3 hours.
8. The sterilization method for dairy products according to claim 4, characterized in that: In S4, the mass ratio of the primary emulsion to the okra mucilage is (10-20):1; the emulsification shearing speed is 3000-5000 rpm; the time is 10-15 min; the acetic acid concentration of the chitosan acetic acid solution is 50-70 wt.%; the chitosan content is 3-5 wt.%; the stirring speed is 100-200 rpm; and the number of times water is added for washing is 3-5 times.
9. A sterilization method for dairy products according to claim 4, characterized in that: The amount of citric acid added in S5 is 0.05-0.1 wt.%, and the pH is adjusted to 5.0-6.0; the composite microparticle core and Fe 2+ The mass ratio of the aspartic acid complex solution is (1-2):(1-3); the constant temperature stirring temperature is 30-35℃, the stirring speed is 200-300rpm, and the stirring time is 20-30min.