Immune-enhanced milk-based kitten food and preparation method thereof

Abstract

The invention provides an immune-enhanced milk-based kitten food and a preparation method thereof, the core of the kitten food is that three-layer microcapsule powder is extruded into main food particles, the outer layer of a microcapsule is composed of whey protein powder, octenyl succinic acid modified starch, chicken liver powder and a sericin-lysozyme / nano-zinc compound, the hydrophobicity is remarkably improved, and the stability of the kitten food is improved. Moisture permeation is effectively blocked, and the moisture absorption softening problem is solved; the interlayer is composed of bovine colostrum powder, casein hydrolysate, zein and whole goat milk powder, and the bioavailability of IgG is improved; the core layer consists of bifidobacteria, galactooligosaccharide and trehalose, so that the bifidobacteria is promoted to colonize and proliferate in a colon hypoxia environment, and the intestinal flora and immunity are synergistically regulated. High-temperature processing protection, gastric acid targeted release and shelf life stability of immune active components are achieved through a microencapsulation technology, and the immunity of kittens in the stress period is effectively improved.

Description

Technical Field

[0001] The present invention belongs to the field of pet food, and in particular relates to an immune-enhanced milk-based kitten food and a preparation method thereof. Background Art

[0002] During critical stages of kitten development, particularly during stressful times like weaning, vaccinations, and environmental changes, their immune systems are immature and their resistance is weak, making them highly susceptible to various pathogens and potentially causing health problems. To protect kittens' health, nutritional interventions to enhance their immunity are crucial. Currently, commercially available kitten foods commonly incorporate active ingredients with immunomodulatory properties, such as lactoferrin, bovine colostrum powder (rich in immunoglobulins IgG), and probiotics. However, these approaches present significant limitations in practical application.

[0003] First, the stability and bioavailability of these active ingredients during processing and digestion are insufficient, significantly compromising their immune-protective effects. For one thing, the mainstream cat food puffing process requires high temperatures (typically exceeding 120°C), making it extremely susceptible to irreversible denaturation and inactivation of heat-sensitive immunoreactive substances (such as IgG) in ingredients like bovine colostrum powder and goat milk powder. Furthermore, even if some of these ingredients are retained after processing, they face significant challenges during subsequent feeding. For example, the IgG in bovine colostrum is highly inactivated in the highly acidic environment of a kitten's stomach, making it difficult for it to effectively reach the intestines and exert its beneficial effects. Furthermore, directly added probiotics (such as Bifidobacterium) have a low survival rate in the acidic environment of the stomach, making it difficult to ensure that a sufficient number of live bacteria can reach the intestines to colonize and exert their beneficial effects.

[0004] Secondly, in the existing technology, raw materials rich in active ingredients (such as goat milk powder and colostrum powder) are often directly mixed with the staple food in powder form or simply sprayed on the surface of particles. This method not only fails to solve the above-mentioned problems of inactivation due to high-temperature processing and degradation by gastric acid, but also fails to effectively block the influence of environmental moisture on the active ingredients. It is also difficult to achieve the sustained release of flavor substances to lastingly improve palatability.

[0005] Therefore, there is an urgent need to develop a new type of milk-based kitten food that can overcome the above-mentioned defects and provide stable and efficient immune nutritional support for kittens during their critical growth period. Summary of the Invention

[0006] Technical problems to be solved: In view of the deficiencies of the above-mentioned technologies, the purpose of the present invention is to provide an immune-enhanced milk-based kitten food and a preparation method thereof. The core of the kitten food is to extrude a special three-layer microcapsule powder into the main food particles, wherein the outer layer of the microcapsule is composed of whey protein powder, octenyl succinate starch ester (OSA), chicken liver powder, and sericin-lysozyme / nano-zinc complex, which significantly improves the hydrophobicity, effectively blocks water penetration, and solves the problem of moisture absorption and softening; the interlayer is composed of bovine colostrum powder, hydrolyzed casein, zein, and whole-fat goat milk powder. Zein self-assembles into a gel to protect immunoglobulin (IgG) in the gastric acid environment, and disintegrates and releases in the alkaline environment of the small intestine, thereby improving the bioavailability of IgG; the core layer is composed of bifidobacteria, oligogalactose, and trehalose. Oligogalactose promotes the colonization and proliferation of bifidobacteria in the hypoxic environment of the colon, The invention uses microencapsulation technology to achieve high-temperature processing protection, targeted release of gastric acid, and shelf-life stability of immune active ingredients, effectively improving the immunity of kittens during stress periods.

[0007] Technical solution: An immune-enhancing milk-based kitten food, the milk-based kitten food comprising a main grain mixture and a sandwich component; The mass ratio of the staple food mixture to the sandwich component is (90-95): (5-10); The sandwich component is composed of microcapsule powder and freeze-dried chicken mince, with a mass ratio of (1-4):1; The microcapsule powder has a three-layer structure, with a core layer comprising freeze-dried bifidobacterium powder, galacto-oligosaccharides and trehalose; an interlayer comprising milk powder, hydrolyzed casein, zein and whole goat milk powder; and an outer layer comprising whey protein powder, octenyl succinate starch ester, chicken liver powder and sericin-lysozyme / nano-zinc complex.

[0008] Furthermore, the staple food mixture comprises 30-32 parts of fresh chicken, 20-22 parts of fresh pigeon meat, 10-11 parts of fish meal, 8-9 parts of chicken meal, 4-5 parts of chicken oil, 4-6 parts of fresh sweet potatoes, 3-4 parts of cassava starch, 3-4 parts of eggs, 1-3 parts of fish oil, 1-2 parts of fresh tomatoes, 1-2 parts of fresh broccoli, 1-1.5 parts of fresh parsley, 1-1.5 parts of butter, 1-1.2 parts of fresh pumpkin, 0.8-1 part of brewer's yeast powder, 1-1.2 parts of alfalfa powder, 0.3-0.5 parts of cranberry powder, 0.1-0.2 parts of spirulina powder, 0.1-0.15 parts of psyllium, 0.8-1 parts of glucosamine hydrochloride, 0.8-1 parts of vitamin premix and 0.5-0.8 parts of mineral premix.

[0009] Furthermore, the preparation steps of the microcapsule powder are as follows: S1. Dissolve galacto-oligosaccharide and trehalose in water at 30-40°C, stir evenly, cool to 20-25°C, add freeze-dried bifidobacterium powder, homogenize at 2000-3000 rpm for 3-5 minutes, and vacuum dry to obtain the core layer powder; S2. Dissolve milk powder, whole goat milk powder and hydrolyzed casein in 50-60 ° C water, add 0.1-0.15% xanthan gum, stir evenly, then add zein ethanol solution, emulsify at 6000-8000 rpm for 5-10min to obtain an interlayer emulsion; S3. Add octenyl succinate starch ester to water, gelatinize at 80°C, cool to 30-40°C, add whey protein powder and chicken liver powder, homogenize at 8000-10000 rpm for 5-8 minutes, then add sericin-lysozyme / nano-zinc complex and stir to obtain the outer layer solution; S4. Spray the interlayer emulsion and outer layer solution onto the core layer powder in sequence with a volume-to-mass ratio of (1.5-2.0) mL: (0.8-1.2) mL: 1 g. Vacuum dry to obtain microcapsule powder.

[0010] Furthermore, the mass volume ratio of oligosaccharides, trehalose and water in step S1 is (30-35) g: (50-60) g: 100 mL; the concentration of the freeze-dried bifidobacterium powder is 10 9 -10 10 CFU / g, and the mass volume ratio of the freeze-dried Bifidobacterium powder to water is (10-15) g:100 mL.

[0011] Furthermore, in step S2, the mass volume ratio of cow milk powder, whole goat milk powder, hydrolyzed casein and water is (25-30) g: (20-25) g: (15-20) g: 100 mL; the volume ratio of the zein ethanol solution to water is (10-15): 100; and the zein ethanol solution is 12% zein dissolved in 70% ethanol solution.

[0012] Furthermore, in step S3, octenyl succinate starch ester, whey protein powder, chicken liver powder, sericin-lysozyme / nanoprotein The mass volume ratio of zinc complex and water is (20-25) g: (35-40) g: (20-25) g: (12-15) g: 100 mL.

[0013] Furthermore, the preparation steps of the sericin-lysozyme / nano-zinc complex are as follows: Step 1. Dissolve zinc acetate in 50 mM Tris-HCl buffer at pH 8, stir in a water bath at 50-55°C, add sodium ascorbate, continuously introduce nitrogen, then add lysozyme, stir at a constant temperature of 40-45°C for 1-2 hours, centrifuge at 4°C, collect the precipitate, wash, resuspend, sonicate, and filter to obtain a lysozyme / nano-zinc complex colloidal solution; Step 2. Add sericin and genipin to the lysozyme / nano-zinc complex colloidal solution, react at 40-50° C. for 30 min, dialysis purification, and freeze-drying to obtain the sericin-lysozyme / nano-zinc complex.

[0014] Furthermore, in step 1, the mass volume ratio of zinc acetate, sodium ascorbate, lysozyme and Tris-HCl buffer is (2-2.5) g: (1-1.5) g: (5-8) g: 500 mL.

[0015] Furthermore, in step 2, the mass volume ratio of the sericin, genipin and lysozyme / nano-zinc complex colloidal solution is (15-20) g: (0.2-0.3) g: 100 mL.

[0016] The preparation method of the above-mentioned immune-enhanced milk-based kitten food comprises the following steps: (1) Fresh meat processing: mince fresh chicken and fresh pigeon meat, pasteurize them, mix them with eggs, chicken fat, butter, and fish oil, then add fish meal and chicken meal, and emulsify them in a chopper to obtain a mixed meat paste; (2) Fruit and vegetable processing: Steam fresh sweet potatoes and fresh pumpkins, then crush and pulp fresh broccoli, fresh tomatoes, and fresh parsley to prepare mixed fruit and vegetable juice; (3) Dry material mixing: mixing cassava starch, brewer's yeast powder, alfalfa powder, cranberry powder, spirulina powder, psyllium, glucosamine hydrochloride, vitamin premix and mineral premix to obtain a mixed dry material; (4) The mixed meat paste, mixed fruit and vegetable juice and mixed dry materials are further mixed and extruded from the outer channel of a coaxial twin-screw extruder as the main food mixture. The microcapsule powder and freeze-dried chicken mince are extruded from the inner channel and granulated to obtain immune-enhanced milk-based kitten food.

[0017] Furthermore, the vitamin premix in step (3) includes any one or more of vitamin A, vitamin E, vitamin D3, vitamin K, vitamin B1, vitamin B2, vitamin B3, vitamin B5 and vitamin B6; and the mineral premix includes any one or more of light calcium carbonate, potassium chloride, ferrous sulfate, copper sulfate, manganese sulfate, zinc sulfate, calcium iodate and citric acid.

[0018] Furthermore, the parameters of the coaxial twin-screw extruder in step (4) are as follows: the screw aspect ratio is (15-18):1; the inner channel temperature is 80-100°C, the screw speed is 140-160 rpm; the outer channel temperature is 140-160°C, the screw speed is 200-250 rpm, and the die pressure is 4-5 MPa.

[0019] Beneficial effects: 1. The present invention adopts a coaxial double-channel extrusion process to prepare an immune-enhanced milk-based kitten food. The outer channel is the main food mixture, and the inner channel is the microcapsule powder. The microcapsule consists of a three-layer structure, wherein the outer layer is composed of whey protein powder, octenyl succinate starch ester (OSA), chicken liver powder, and sericin-lysozyme / nano-zinc complex. First, OSA can significantly improve hydrophobicity and improve moisture absorption and softening. The long octenyl chain of OSA is hydrophobic and can form a molecular layer on the surface of the whey protein network, reducing the surface energy and effectively blocking the penetration of water molecules. OSA can also fill the whey protein during the drying process. The micropores formed reduce the water adsorption sites, lower the porosity and moisture absorption weight gain rate; secondly, the molecular chaperone activity of sericin can maintain the conformation of bovine colostrum IgG, and protect the protein from environmental stress by interacting with the protein to form a barrier; the carboxyl group of sericin condenses with the amino group on the lysozyme / nano-zinc complex to form an amide bond to achieve grafting, and the β-folded structure of sericin provides spatial support for the grafting, forming a physical barrier, reducing water penetration and improving moisture resistance; saliva dissolution triggers the release of lysozyme, and the lysozyme in the lysozyme / nano-zinc complex destroys the cell wall of Gram-positive bacteria, and Zn 2+ Inhibit the metabolism of Gram-negative bacteria, and the two work together to destroy oral pathogens and enhance antibacterial activity; finally, chicken liver powder acts as a natural attractant, allowing flavor substances to be slowly released, effectively increasing the intake rate and palatability of cat food.

[0020] 2. The interlayer of the microcapsule powder prepared by the present invention is bovine colostrum powder, hydrolyzed casein, zein, and whole goat milk powder. Ordinary bovine colostrum powder has a high inactivation rate of immunoglobulin IgG after being exposed to gastric acid, while zein can self-assemble into a nanostructure through hydrophobic interactions in a gastric fluid environment. Its hydrophobicity and dense structure can effectively block the degradation of IgG by gastric acid and pepsin. When it reaches the alkaline environment of the small intestine, the structure disintegrates, IgG is released in large quantities, and the immune efficacy is enhanced; in addition, hydrolyzed casein is decomposed into small molecular peptides and then penetrates into the core layer, which can serve as a nitrogen source for probiotics, promote the proliferation of bifidobacteria, and regulate intestinal health.

[0021] 3. The core layer of the microcapsule powder prepared by the present invention is bifidobacterium, oligogalactose and trehalose. Trehalose protects bifidobacteria, and oligogalactose promotes the colonization and proliferation of bifidobacteria in the hypoxic environment of the colon. At the same time, oligogalactose acts as a prebiotic. The two synergistically regulate the intestinal flora of kittens and enhance immunity.

[0022] 4. This invention uses microcapsule powder and freeze-dried chicken mince as the "sandwich" of the staple food granules. During the puffing and granulation process, the staple food shell is formed under high temperature and high pressure, forming a dense physical barrier. The microcapsule powder encapsulated inside avoids direct contact with the high-temperature puffing cavity, significantly reducing the damage caused by heat conduction and shear forces to the heat-sensitive active ingredients (such as bovine colostrum IgG and probiotics) inside, and solving the key problem of inactivation during high-temperature processing. This "sandwich" structure also blocks water penetration, effectively reducing the problem of cat food products being easily softened and clumped, and significantly extending the product's stability and shelf life. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 This is a picture showing the appearance of immune-enhanced milk-based kitten food. DETAILED DESCRIPTION

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments. The following embodiments are intended to explain the present invention, but the present invention is not limited to the following embodiments: Example 1 The preparation steps of microcapsule powder are as follows: S1. Dissolve 30g of oligogalactose and 55g of trehalose in 100mL of water at 35℃, stir evenly, and add 10g of 10% trehalose after cooling to 25℃. 10 CFU / g of Bifidobacterium freeze-dried powder, homogenized at 3000 rpm for 3 min, and vacuum dried to obtain the core layer powder; S2. 30 g of milk powder, 25 g of whole goat milk powder and 15 g of hydrolyzed casein were dissolved in 100 mL of water at 50 ° C, 0.1% xanthan gum was added, stirred, and then 10 mL of zein ethanol solution was added. Emulsification was carried out at 7000 rpm for 6 min to obtain an interlayer emulsion. S3. Dissolve 2 g of zinc acetate in 500 mL of 50 mM Tris-HCl buffer, pH 8, and stir in a 50°C water bath. Then, add 1 g of sodium ascorbate while continuously purging with nitrogen. Add 6 g of lysozyme and stir at 40°C for 1.5 h. Centrifuge at 4°C, collect the precipitate, wash, resuspend, sonicate, and filter to obtain a lysozyme / nano-zinc complex colloidal solution. S4. 15 g of sericin and 0.2 g of genipin were added to 100 mL of lysozyme / nano-zinc complex colloidal solution, reacted at 45°C for 30 min, purified by dialysis, and freeze-dried to obtain sericin-lysozyme / nano-zinc complex; S5. 20 g of octenyl succinate starch ester was added to 100 mL of water, gelatinized at 80°C, cooled to 35°C, and 35 g of whey protein powder and 20 g of chicken liver powder were added. Homogenization was performed at 8000 rpm for 6 min, and then 12 g of sericin-lysozyme / nano-zinc complex was added and stirred to obtain the outer layer solution. S6. Spray the interlayer emulsion and outer layer solution onto the core layer powder in sequence with a volume-to-mass ratio of 1.5 mL:0.8 mL:1 g, and vacuum dry to obtain microcapsule powder.

[0024] Example 2 The preparation steps of microcapsule powder are as follows: S1. Dissolve 30g of oligogalactose and 55g of trehalose in 100mL of water at 35℃, stir evenly, and add 12g of 10% trehalose after cooling to 25℃. 10 CFU / g of Bifidobacterium freeze-dried powder, homogenized at 3000 rpm for 3 min, and vacuum dried to obtain the core layer powder; S2. 30 g of milk powder, 25 g of whole goat milk powder and 15 g of hydrolyzed casein were dissolved in 100 mL of water at 50 ° C, 0.1% xanthan gum was added, stirred, and then 10 mL of zein ethanol solution was added. Emulsification was carried out at 7000 rpm for 6 min to obtain an interlayer emulsion. S3. Dissolve 2 g of zinc acetate in 500 mL of 50 mM Tris-HCl buffer, pH 8, and stir in a 50°C water bath. Then, add 1 g of sodium ascorbate while continuously purging with nitrogen. Add 6 g of lysozyme and stir at 40°C for 1.5 h. Centrifuge at 4°C, collect the precipitate, wash, resuspend, sonicate, and filter to obtain a lysozyme / nano-zinc complex colloidal solution. S4. 15 g of sericin and 0.2 g of genipin were added to 100 mL of lysozyme / nano-zinc complex colloidal solution, reacted at 45°C for 30 min, purified by dialysis, and freeze-dried to obtain sericin-lysozyme / nano-zinc complex; S5. 20 g of octenyl succinate starch ester was added to 100 mL of water, gelatinized at 80°C, cooled to 35°C, and 35 g of whey protein powder and 20 g of chicken liver powder were added. Homogenization was performed at 8000 rpm for 6 min, and then 12 g of sericin-lysozyme / nano-zinc complex was added and stirred to obtain the outer layer solution. S6. Spray the interlayer emulsion and outer layer solution onto the core layer powder in sequence with a volume-to-mass ratio of 1.5 mL:0.8 mL:1 g, and vacuum dry to obtain microcapsule powder.

[0025] Example 3 The preparation steps of microcapsule powder are as follows: S1. Dissolve 30g of oligogalactose and 55g of trehalose in 100mL of water at 35℃, stir evenly, cool to 25℃ and add 14g of 10% 10 CFU / g of Bifidobacterium freeze-dried powder, homogenized at 3000 rpm for 3 min, and vacuum dried to obtain the core layer powder; S2. 30 g of milk powder, 25 g of whole goat milk powder and 15 g of hydrolyzed casein were dissolved in 100 mL of water at 50 ° C, 0.1% xanthan gum was added, stirred, and then 10 mL of zein ethanol solution was added. Emulsification was carried out at 7000 rpm for 6 min to obtain an interlayer emulsion. S3. Dissolve 2 g of zinc acetate in 500 mL of 50 mM Tris-HCl buffer, pH 8, and stir in a 50°C water bath. Then, add 1 g of sodium ascorbate while continuously purging with nitrogen. Add 6 g of lysozyme and stir at 40°C for 1.5 h. Centrifuge at 4°C, collect the precipitate, wash, resuspend, sonicate, and filter to obtain a lysozyme / nano-zinc complex colloidal solution. S4. 15 g of sericin and 0.2 g of genipin were added to 100 mL of lysozyme / nano-zinc complex colloidal solution, reacted at 45°C for 30 min, purified by dialysis, and freeze-dried to obtain sericin-lysozyme / nano-zinc complex; S5. 20 g of octenyl succinate starch ester was added to 100 mL of water, gelatinized at 80°C, cooled to 35°C, and 35 g of whey protein powder and 20 g of chicken liver powder were added. Homogenization was performed at 8000 rpm for 6 min, and then 12 g of sericin-lysozyme / nano-zinc complex was added and stirred to obtain the outer layer solution. S6. Spray the interlayer emulsion and outer layer solution onto the core layer powder in sequence with a volume-to-mass ratio of 1.5 mL:0.8 mL:1 g, and vacuum dry to obtain microcapsule powder.

[0026] Example 4 The preparation steps of microcapsule powder are as follows: S1. Dissolve 30g of oligogalactose and 55g of trehalose in 100mL of water at 35℃, stir evenly, and add 15g of 10% trehalose after cooling to 25℃. 10 CFU / g of Bifidobacterium freeze-dried powder, homogenized at 3000 rpm for 3 min, and vacuum dried to obtain the core layer powder; S2. 30 g of milk powder, 25 g of whole goat milk powder and 15 g of hydrolyzed casein were dissolved in 100 mL of water at 50 ° C, 0.1% xanthan gum was added, stirred, and then 10 mL of zein ethanol solution was added. Emulsification was carried out at 7000 rpm for 6 min to obtain an interlayer emulsion. S3. Dissolve 2 g of zinc acetate in 500 mL of 50 mM Tris-HCl buffer, pH 8, and stir in a 50°C water bath. Then, add 1 g of sodium ascorbate while continuously purging with nitrogen. Add 6 g of lysozyme and stir at 40°C for 1.5 h. Centrifuge at 4°C, collect the precipitate, wash, resuspend, sonicate, and filter to obtain a lysozyme / nano-zinc complex colloidal solution. S4. 15 g of sericin and 0.2 g of genipin were added to 100 mL of lysozyme / nano-zinc complex colloidal solution, reacted at 45°C for 30 min, purified by dialysis, and freeze-dried to obtain sericin-lysozyme / nano-zinc complex; S5. 20 g of octenyl succinate starch ester was added to 100 mL of water, gelatinized at 80°C, cooled to 35°C, and 35 g of whey protein powder and 20 g of chicken liver powder were added. Homogenization was performed at 8000 rpm for 6 min, and then 12 g of sericin-lysozyme / nano-zinc complex was added and stirred to obtain the outer layer solution. S6. Spray the interlayer emulsion and outer layer solution onto the core layer powder in sequence with a volume-to-mass ratio of 1.5 mL:0.8 mL:1 g, and vacuum dry to obtain microcapsule powder.

[0027] Example 5 The preparation steps of microcapsule powder are as follows: S1. Dissolve 30g of oligogalactose and 55g of trehalose in 100mL of water at 35℃, stir evenly, and add 12g of 10% trehalose after cooling to 25℃. 10 CFU / g of Bifidobacterium freeze-dried powder, homogenized at 3000 rpm for 3 min, and vacuum dried to obtain the core layer powder; S2. 30 g of milk powder, 25 g of whole goat milk powder and 15 g of hydrolyzed casein were dissolved in 100 mL of water at 50 ° C, 0.1% xanthan gum was added, stirred, and then 10 mL of zein ethanol solution was added. Emulsification was carried out at 7000 rpm for 6 min to obtain an interlayer emulsion. S3. Dissolve 2 g of zinc acetate in 500 mL of 50 mM Tris-HCl buffer, pH 8, and stir in a 50°C water bath. Then, add 1 g of sodium ascorbate while continuously purging with nitrogen. Add 6 g of lysozyme and stir at 40°C for 1.5 h. Centrifuge at 4°C, collect the precipitate, wash, resuspend, sonicate, and filter to obtain a lysozyme / nano-zinc complex colloidal solution. S4. 15 g of sericin and 0.2 g of genipin were added to 100 mL of lysozyme / nano-zinc complex colloidal solution, reacted at 45°C for 30 min, purified by dialysis, and freeze-dried to obtain sericin-lysozyme / nano-zinc complex; S5. 25 g of octenyl succinate starch ester was added to 100 mL of water, gelatinized at 80 ° C, cooled to 35 ° C, 40 g of whey protein powder and 20 g of chicken liver powder were added, and homogenized at 8000 rpm for 6 min. Then, 15 g of sericin-lysozyme / nano-zinc complex was added and stirred to obtain the outer layer solution; S6. Spray the interlayer emulsion and outer layer solution onto the core layer powder in sequence with a volume-to-mass ratio of 2 mL:1 mL:1 g. Vacuum dry the mixture to obtain microcapsule powder.

[0028] Example 6 The preparation steps of microcapsule powder are as follows: S1. Dissolve 30g of oligogalactose and 55g of trehalose in 100mL of water at 35℃, stir evenly, and add 12g of 10% trehalose after cooling to 25℃. 10 CFU / g of Bifidobacterium freeze-dried powder, homogenized at 3000 rpm for 3 min, and vacuum dried to obtain the core layer powder; S2. 30 g of milk powder, 25 g of whole goat milk powder and 15 g of hydrolyzed casein were dissolved in 100 mL of water at 50 ° C, 0.1% xanthan gum was added, stirred, and then 10 mL of zein ethanol solution was added. Emulsification was carried out at 7000 rpm for 6 min to obtain an interlayer emulsion. S3. Dissolve 2 g of zinc acetate in 500 mL of 50 mM Tris-HCl buffer, pH 8, and stir in a 50°C water bath. Then, add 1 g of sodium ascorbate while continuously purging with nitrogen. Add 6 g of lysozyme and stir at 40°C for 1.5 h. Centrifuge at 4°C, collect the precipitate, wash, resuspend, sonicate, and filter to obtain a lysozyme / nano-zinc complex colloidal solution. S4. 15 g of sericin and 0.2 g of genipin were added to 100 mL of lysozyme / nano-zinc complex colloidal solution, reacted at 45°C for 30 min, purified by dialysis, and freeze-dried to obtain sericin-lysozyme / nano-zinc complex; S5. 22 g of octenyl succinate starch ester was added to 100 mL of water, gelatinized at 80 ° C, cooled to 35 ° C, 38 g of whey protein powder and 22 g of chicken liver powder were added, and homogenized at 8000 rpm for 6 min. Then, 14 g of sericin-lysozyme / nano-zinc complex was added and stirred to obtain the outer layer solution; S6. Spray the interlayer emulsion and outer layer solution onto the core layer powder in sequence with a volume-to-mass ratio of 2 mL:1 mL:1 g. Vacuum dry the mixture to obtain microcapsule powder.

[0029] Example 7 The preparation steps of microcapsule powder are as follows: S1. Dissolve 30g of oligogalactose and 55g of trehalose in 100mL of water at 35℃, stir evenly, and add 12g of 10% trehalose after cooling to 25℃. 10 CFU / g of Bifidobacterium freeze-dried powder, homogenized at 3000 rpm for 3 min, and vacuum dried to obtain the core layer powder; S2. 30 g of milk powder, 25 g of whole goat milk powder and 15 g of hydrolyzed casein were dissolved in 100 mL of water at 50 ° C, 0.1% xanthan gum was added, stirred, and then 10 mL of zein ethanol solution was added. Emulsification was carried out at 7000 rpm for 6 min to obtain an interlayer emulsion. S3. Dissolve 2 g of zinc acetate in 500 mL of 50 mM Tris-HCl buffer, pH 8, and stir in a 50°C water bath. Then, add 1 g of sodium ascorbate while continuously purging with nitrogen. Add 6 g of lysozyme and stir at 40°C for 1.5 h. Centrifuge at 4°C, collect the precipitate, wash, resuspend, sonicate, and filter to obtain a lysozyme / nano-zinc complex colloidal solution. S4. 15 g of sericin and 0.2 g of genipin were added to 100 mL of lysozyme / nano-zinc complex colloidal solution, reacted at 45°C for 30 min, purified by dialysis, and freeze-dried to obtain sericin-lysozyme / nano-zinc complex; S5. 25 g of octenyl succinate starch ester was added to 100 mL of water, gelatinized at 80 ° C, cooled to 35 ° C, 40 g of whey protein powder and 20 g of chicken liver powder were added, and homogenized at 8000 rpm for 6 min. Then, 15 g of sericin-lysozyme / nano-zinc complex was added and stirred to obtain the outer layer solution; S6. Spray the interlayer emulsion and outer layer solution onto the core layer powder in sequence with a volume-to-mass ratio of 1.6 mL:1.2 mL:1 g, and vacuum dry to obtain microcapsule powder.

[0030] Example 8 The preparation steps of microcapsule powder are as follows: S1. Dissolve 30g of oligogalactose and 55g of trehalose in 100mL of water at 35℃, stir evenly, and add 12g of 10% trehalose after cooling to 25℃. 10 CFU / g of Bifidobacterium freeze-dried powder, homogenized at 3000 rpm for 3 min, and vacuum dried to obtain the core layer powder; S2. 30 g of milk powder, 25 g of whole goat milk powder and 15 g of hydrolyzed casein were dissolved in 100 mL of water at 50 ° C, 0.1% xanthan gum was added, stirred, and then 10 mL of zein ethanol solution was added. Emulsification was carried out at 7000 rpm for 6 min to obtain an interlayer emulsion. S3. Dissolve 2 g of zinc acetate in 500 mL of 50 mM Tris-HCl buffer, pH 8, and stir in a 50°C water bath. Then, add 1 g of sodium ascorbate while continuously purging with nitrogen. Add 6 g of lysozyme and stir at 40°C for 1.5 h. Centrifuge at 4°C, collect the precipitate, wash, resuspend, sonicate, and filter to obtain a lysozyme / nano-zinc complex colloidal solution. S4. 15 g of sericin and 0.2 g of genipin were added to 100 mL of lysozyme / nano-zinc complex colloidal solution, reacted at 45°C for 30 min, purified by dialysis, and freeze-dried to obtain sericin-lysozyme / nano-zinc complex; S5. 25 g of octenyl succinate starch ester was added to 100 mL of water, gelatinized at 80 ° C, cooled to 35 ° C, 40 g of whey protein powder and 20 g of chicken liver powder were added, and homogenized at 8000 rpm for 6 min. Then, 15 g of sericin-lysozyme / nano-zinc complex was added and stirred to obtain the outer layer solution; S6. Spray the interlayer emulsion and outer layer solution onto the core layer powder in sequence with a volume-to-mass ratio of 1.5 mL:1.2 mL:1 g, and vacuum dry to obtain microcapsule powder.

[0031] Comparative Example 1 The difference between this comparative example and Example 5 is that no octenyl succinate starch is added, specifically as follows: The preparation steps of microcapsule powder are as follows: S1. Dissolve 30g of oligogalactose and 55g of trehalose in 100mL of water at 35℃, stir evenly, and add 12g of 10% trehalose after cooling to 25℃. 10 CFU / g of Bifidobacterium freeze-dried powder, homogenized at 3000 rpm for 3 min, and vacuum dried to obtain the core layer powder; S2. 30 g of milk powder, 25 g of whole goat milk powder and 15 g of hydrolyzed casein were dissolved in 100 mL of water at 50 ° C, 0.1% xanthan gum was added, stirred, and then 10 mL of zein ethanol solution was added. Emulsification was carried out at 7000 rpm for 6 min to obtain an interlayer emulsion. S3. Dissolve 2 g of zinc acetate in 500 mL of 50 mM Tris-HCl buffer, pH 8, and stir in a 50°C water bath. Then, add 1 g of sodium ascorbate while continuously purging with nitrogen. Add 6 g of lysozyme and stir at 40°C for 1.5 h. Centrifuge at 4°C, collect the precipitate, wash, resuspend, sonicate, and filter to obtain a lysozyme / nano-zinc complex colloidal solution. S4. 15 g of sericin and 0.2 g of genipin were added to 100 mL of lysozyme / nano-zinc complex colloidal solution, reacted at 45°C for 30 min, purified by dialysis, and freeze-dried to obtain sericin-lysozyme / nano-zinc complex; S5. 40 g of whey protein powder and 20 g of chicken liver powder were added to 100 mL of water and homogenized at 8000 rpm for 6 min. 15 g of sericin-lysozyme / nano-zinc complex was then added and stirred to obtain an outer layer solution. S6. Spray the interlayer emulsion and outer layer solution onto the core layer powder in sequence with a volume-to-mass ratio of 2 mL:1 mL:1 g. Vacuum dry the mixture to obtain microcapsule powder.

[0032] Comparative Example 2 The difference between this comparative example and Example 5 is that no sericin is added, specifically as follows: The preparation steps of microcapsule powder are as follows: S1. Dissolve 30g of oligogalactose and 55g of trehalose in 100mL of water at 35℃, stir evenly, and add 12g of 10% trehalose after cooling to 25℃. 10 CFU / g of Bifidobacterium freeze-dried powder, homogenized at 3000 rpm for 3 min, and vacuum dried to obtain the core layer powder; S2. 30 g of milk powder, 25 g of whole goat milk powder and 15 g of hydrolyzed casein were dissolved in 100 mL of water at 50 ° C, 0.1% xanthan gum was added, stirred, and then 10 mL of zein ethanol solution was added. Emulsification was carried out at 7000 rpm for 6 min to obtain an interlayer emulsion. S3. Dissolve 2 g of zinc acetate in 500 mL of 50 mM Tris-HCl buffer, pH 8, in a 50°C water bath. Add 1 g of sodium ascorbate, continue purging with nitrogen, and then add 6 g of lysozyme. Stir at 40°C for 1.5 h. Centrifuge at 4°C, collect the precipitate, wash, resuspend, sonicate, filter, and dry to obtain the lysozyme / nano-zinc complex. S4. 25g of octenyl succinate starch ester was added to 100mL of water, gelatinized at 80°C, cooled to 35°C, 40g of whey protein powder, 20g of chicken liver powder were added, homogenized at 8000rpm for 6min, and then 15g of lysozyme / nano-zinc complex was added and stirred to obtain the outer layer solution; S5. Spray the interlayer emulsion and outer layer solution onto the core layer powder in sequence with a volume-to-mass ratio of 2 mL:1 mL:1 g, and vacuum dry to obtain microcapsule powder.

[0033] Comparative Example 3 The difference between this comparative example and Example 5 is that only the interlayer emulsion is sprayed to prepare the microcapsule powder, which is as follows: The preparation steps of microcapsule powder are as follows: S1. Dissolve 30g of oligogalactose and 55g of trehalose in 100mL of water at 35℃, stir evenly, and add 12g of 10% trehalose after cooling to 25℃. 10 CFU / g of Bifidobacterium freeze-dried powder, homogenized at 3000 rpm for 3 min, and vacuum dried to obtain the core layer powder; S2. 30 g of milk powder, 25 g of whole goat milk powder and 15 g of hydrolyzed casein were dissolved in 100 mL of water at 50 ° C, 0.1% xanthan gum was added, stirred, and then 10 mL of zein ethanol solution was added. Emulsification was carried out at 7000 rpm for 6 min to obtain an interlayer emulsion. S3. Spray the interlayer emulsion onto the core layer powder at a volume-to-mass ratio of 2 mL:1 g and vacuum dry to obtain microcapsule powder.

[0034] Comparative Example 4 The difference between this comparative example and Example 5 is that only the outer layer solution is sprayed to prepare the microcapsule powder, which is as follows: The preparation steps of microcapsule powder are as follows: S1. Dissolve 30g of oligogalactose and 55g of trehalose in 100mL of water at 35℃, stir evenly, and add 12g of 10% trehalose after cooling to 25℃. 10 CFU / g of Bifidobacterium freeze-dried powder, homogenized at 3000 rpm for 3 min, and vacuum dried to obtain the core layer powder; S2. Dissolve 2 g of zinc acetate in 500 mL of 50 mM Tris-HCl buffer, pH 8, and stir in a 50°C water bath. Then, add 1 g of sodium ascorbate while continuously purging with nitrogen. Add 6 g of lysozyme and stir at 40°C for 1.5 h. Centrifuge at 4°C, collect the precipitate, wash, resuspend, sonicate, and filter to obtain a lysozyme / nano-zinc complex colloidal solution. S3. 15 g of sericin and 0.2 g of genipin were added to 100 mL of lysozyme / nano-zinc complex colloidal solution, reacted at 45°C for 30 min, purified by dialysis, and freeze-dried to obtain sericin-lysozyme / nano-zinc complex; S4. 25 g of octenyl succinate starch ester was added to 100 mL of water, gelatinized at 80 ° C, cooled to 35 ° C, 40 g of whey protein powder and 20 g of chicken liver powder were added, and homogenized at 8000 rpm for 6 min. Then, 15 g of sericin-lysozyme / nano-zinc complex was added and stirred to obtain the outer layer solution; S5. Spray the outer layer solution onto the core layer powder in sequence with a volume-to-mass ratio of 1 mL:1 g, and vacuum dry to obtain microcapsule powder.

[0035] Performance testing: (1) Particle size The particle sizes of the microcapsules prepared in Examples 1-8 and Comparative Examples 1-4 were measured using a laser particle size analyzer. The results are shown in Table 1. Table 1 Particle size of microcapsules prepared in Examples 1-8 and Comparative Examples 1-4 As shown in Table 1, the particle size of the microcapsules prepared in Examples 1-8 ranged from 93 to 100 µm. In Comparative Example 1, the lack of OSA reduced the viscosity of the outer layer solution, resulting in larger spray droplets and a slight increase in microcapsule particle size. In Comparative Example 2, the lack of sericin reduced the film-forming continuity of the outer layer solution, causing the microcapsules to shrink easily during drying, resulting in a slight decrease in particle size. In Comparative Example 3, only the interlayer was sprayed, without the constraints of outer layer curing. This allowed the microcapsules to shrink freely, resulting in an increase in particle size. In Comparative Example 4, only the outer layer was sprayed, and the core layer was not pre-fixed by the interlayer. The outer layer liquid seeped into the gaps between the core layers, reducing the overall coating volume and correspondingly reducing the particle size.

[0036] (2) Bifidobacterium survival rate Cell wall disruption solution: 0.1% Triton X-100 + 0.85% NaCl Simulated gastric fluid: pH 2.0 HCl solution (containing 0.3% pepsin), 37°C shaking (100 rpm); Take 0.5g of microcapsule powder and add it to 10mL of wall-breaking liquid, ultrasonically disperse and crush, spread on MRS agar after gradient dilution, and culture anaerobically at 37℃ for 48h, and calculate the number of viable bacteria N0; similarly, take 0.5g of microcapsule powder and add it to 10mL of simulated gastric fluid, react for 2h, spread on MRS agar after gradient dilution, and culture anaerobically at 37℃ for 48h, and calculate the number of viable bacteria N t The survival rate of bifidobacteria in simulated gastric fluid was calculated as follows: Survival rate (%) = N t / N0×100 Table 2 Survival rate of Bifidobacterium in microcapsules prepared in Examples 1-8 and Comparative Examples 1-4 in simulated gastric fluid As shown in Table 2, the survival rates of bifidobacteria in the microcapsules prepared in Examples 1-8 and Comparative Examples 1-4 in simulated gastric fluid ranged from 75.2% to 78.2%. Comparative Example 2 lacked sericin, resulting in a damaged outer barrier and exacerbated gastric acid erosion. Comparative Example 3 lacked an outer protective layer, allowing the interlayer to be rapidly penetrated by gastric acid, significantly reducing the survival rate of bifidobacteria. Comparative Example 4 lacked an interlayer to protect bifidobacteria, making the probiotics more susceptible to inactivation by contact with gastric acid.

[0037] (3) Moisture absorption weight gain rate The microcapsules prepared in Examples 1-8 and Comparative Examples 1-4 were placed in a constant temperature and humidity chamber at 25°C and 75% RH for 14 days, and the moisture absorption weight gain was measured: Moisture absorption weight gain rate (%) = [(W t -W0) / W0]×100 Where W0 is the initial mass; W t The quality is after 14 days.

[0038] Table 3 Moisture absorption weight gain of microcapsules prepared in Examples 1-8 and Comparative Examples 1-4 As shown in Table 3, the microcapsules prepared in Examples 1-8 had a moisture absorption weight gain of 4.3-5.0%. The microcapsules prepared in Comparative Example 1, which did not add OSA, failed to effectively block water molecule penetration and had an increased moisture absorption rate. The microcapsules prepared in Comparative Example 2, which did not add sericin, also had an increased moisture absorption rate. The β-pleated structure of sericin can provide spatial support for grafting, forming a physical barrier that reduces water penetration and improves moisture resistance. Without sericin, no physical barrier can be formed. In Comparative Example 3, only the interlayer was sprayed, lacking an outer protective layer, resulting in a significantly increased moisture absorption rate. In Comparative Example 4, only the outer layer was sprayed, and the moisture absorption rate was slightly higher than in the Examples.

[0039] In summary, the microcapsule powder prepared in Example 5 was selected for the subsequent preparation of immune-enhanced milk-based kitten food.

[0040] Example 9 A method for preparing an immune-enhancing milk-based kitten food comprises the following steps: (1) Fresh meat processing: mince 30g fresh chicken and 22g fresh pigeon meat, pasteurize at 70℃ for 15s, mix with 3g egg, 4g chicken fat, 1.5g butter, 2g fish oil, add 10g fish meal and 8g chicken meal, and emulsify in a chopper to obtain a mixed meat paste; (2) Fruit and vegetable processing: Steam 4 g of fresh sweet potato and 1 g of fresh pumpkin, and crush and pulp 1.5 g of fresh broccoli, 2 g of fresh tomatoes, and 1 g of fresh parsley to prepare a mixed fruit and vegetable juice; (3) Dry material mixing: 3 g of tapioca starch, 1 g of brewer's yeast powder, 1 g of alfalfa powder, 0.4 g of cranberry powder, 0.1 g of spirulina powder, 0.1 g of psyllium, 0.8 g of glucosamine hydrochloride, 0.8 g of vitamin A and 0.5 g of light calcium carbonate were mixed to obtain a mixed dry material; (4) The mixed meat paste, mixed fruit and vegetable juice and mixed dry materials are further mixed and extruded from the outer channel of a coaxial twin-screw extruder as a staple food mixture. The microcapsule powder prepared in Example 5 and freeze-dried chicken mince (mass ratio of 4:1) are extruded from the inner channel as sandwich components. The mass ratio of the staple food mixture to the sandwich components is 95:5. In addition, the screw length-diameter ratio of the coaxial twin-screw extruder is 18:1, the temperature of the inner channel is 100°C, and the screw speed is 150 rpm; the temperature of the outer channel is 160°C, the screw speed is 220 rpm, and the die pressure is 4 MPa. Granulation is performed to obtain immune-enhanced milk-based kitten food.

[0041] Comparative Example 5 The difference between this comparative example and Example 9 is that the microcapsules were not prepared in the form of microcapsules, and the components of the microcapsules were directly mixed as sandwich components, specifically as follows: A method for preparing an immune-enhancing milk-based kitten food comprises the following steps: (1) Fresh meat processing: mince 30g fresh chicken and 22g fresh pigeon meat, pasteurize at 70℃ for 15s, mix with 3g egg, 4g chicken fat, 1.5g butter, 2g fish oil, add 10g fish meal and 8g chicken meal, and emulsify in a chopper to obtain a mixed meat paste; (2) Fruit and vegetable processing: Steam 4 g of fresh sweet potato and 1 g of fresh pumpkin, and crush and pulp 1.5 g of fresh broccoli, 2 g of fresh tomatoes, and 1 g of fresh parsley to prepare a mixed fruit and vegetable juice; (3) Dry material mixing: 3 g of tapioca starch, 1 g of brewer's yeast powder, 1 g of alfalfa powder, 0.4 g of cranberry powder, 0.1 g of spirulina powder, 0.1 g of psyllium, 0.8 g of glucosamine hydrochloride, 0.8 g of vitamin A and 0.5 g of light calcium carbonate were mixed as the mixed dry material; (4) Mix the mixed meat paste, mixed fruit and vegetable juice, and mixed dry materials to prepare the main food mixture; (5) 30g galacto-oligosaccharide, 55g trehalose, 12g 10 10 A sandwich component is prepared by mixing freeze-dried Bifidobacterium powder with a CFU / g content, 30g cow milk powder, 25g whole goat milk powder, 15g hydrolyzed casein, 1g freeze-dried chicken mince, 25g octenylsuccinate starch, 40g whey protein powder, 20g chicken liver powder, 15g sericin-lysozyme / nano-zinc complex, and 10g zein. (6) The main food mixture is extruded from the outer channel of a coaxial twin-screw extruder, and the sandwich component is extruded from the inner channel. The mass ratio of the main food mixture to the sandwich component is 95:5. In addition, the screw length-diameter ratio of the coaxial twin-screw extruder is 18:1, the temperature of the inner channel is 100°C, and the screw speed is 150 rpm; the temperature of the outer channel is 160°C, the screw speed is 220 rpm, and the die pressure is 4 MPa. Granulation is performed to obtain immune-enhanced milk-based kitten food.

[0042] Comparative Example 6 The difference between this comparative example and Example 9 is that the microcapsule powder prepared in Comparative Example 1 was used.

[0043] Comparative Example 7 The difference between this comparative example and Example 9 is that the microcapsule powder prepared in Comparative Example 2 was used.

[0044] Comparative Example 8 The difference between this comparative example and Example 9 is that the microcapsule powder prepared in Comparative Example 3 was used.

[0045] Comparative Example 9 The difference between this comparative example and Example 9 is that the microcapsule powder prepared in Comparative Example 4 was used.

[0046] Study on the effects of immune-enhanced dairy-based kitten food on the immune health of pet kittens: 1. Experimental Design The test period was 33 days. During the test period, 21 healthy kittens were selected. They weighed 1.90 ± 0.33 kg and were randomly divided into 7 groups of 3 cats. Each cat was raised in a single cage in a pet cat cage. 6 groups were fed the milk-based kitten food prepared by Example 9 and Comparative Examples 5-9, and another group (control group) was fed commercially available kitten food. Necessary immunity and anthelmintic treatment were performed before the test. The enclosure was cleaned every day, and hygiene was maintained to keep the pet enclosure clean.

[0047] During the trial period, the animals were fed 80g of cat food and 300mL of water daily, starting at 8:30 AM. All pets were observed for their feeding habits, mental state, and any adverse reactions such as aversion, diarrhea, and vomiting.

[0048] 2. Feeding performance measurement The daily food intake of the experimental cats was continuously recorded, and the average daily food intake was calculated after the experiment.

[0049] 3. Blood index measurement On the 33rd day of the experiment, blood was collected from the forelimb vein of each kitten and injected into a special blood collection tube. The blood antioxidant indicators superoxide dismutase (SOD), total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px), catalase (CAT), malondialdehyde (MDA) were measured, and the blood immunoglobulins IgA, IgM, IgD and IgG were also measured.

[0050] 4. Stool Scoring Before feeding each day, refer to Table 4 to score the appearance of each pet kitten's feces.

[0051] Table 4 Stool scoring criteria Experimental results: 1. Feeding performance Table 5 Average daily food intake of pet kittens As can be seen from Table 5, the kitten food prepared by the present invention (Example 9) had the highest intake rate of 65.23 g / d after feeding pet kittens, while the intake rate of commercially available kitten food (control group) was the lowest. The kitten food prepared by directly mixing the components of the microcapsules without preparing it in the form of microcapsules (Comparative Example 5) had a slightly higher intake rate than the control group.

[0052] 2. Blood indicators Table 6 Effects of milk-based kitten food on blood immune indicators of pet kittens As shown in Table 6, after feeding kittens with the milk-based kitten food prepared in Example 9, the levels of blood immunoglobulins IgA, IgM, IgD, and IgG were the highest, while the levels of IgA, IgM, IgD, and IgG in the control group were the lowest. After feeding kittens with cat food without OSA, without sericin, or with only the interlayer spraying or only the outer layer spraying, the blood immunoglobulin levels were all lower than those in Example 9.

[0053] Table 7 Effects of milk-based kitten food on blood antioxidant indicators of pet kittens As shown in Table 7, kittens fed the milk-based cat food prepared in Example 9 had the highest SOD values ​​in their blood. Bifidobacteria in the microcapsule core layer colonize the intestines and secrete extracellular SOD, and galacto-oligosaccharides promote host SOD synthesis. The probiotic activity of Comparative Examples 5-9 was affected to varying degrees, resulting in decreased SOD values. Example 9 had the lowest MDA value. The outer OSA layer blocked oxygen permeation, reducing the risk of lipid oxidation. Comparative Examples 8 and 9 lacked a coating, significantly increasing oxygen permeation and accelerating lipid oxidation. Example 9 had the highest T-AOC level, while the other comparative examples lacked the corresponding outer layer's physical protection and exhibited decreased antioxidant capacity. Example 9 had the highest GSH-Px level, as the -SH groups of sericin provide reducing power. Comparative Examples 7 and 8, both lacking sericin, had lower GSH-Px levels. Example 9 had an ideal CAT level, while the other comparative examples may have exposed live bear components, leading to elevated CAT levels due to sustained oxidative stress.

[0054] 3. Stool scoring Table 8 Effects of milk-based kitten food on feces of pet kittens As can be seen from Table 8, the feces score of kittens fed with the cat food prepared in Example 9 is 3.07, indicating that the addition of the microcapsules of the present invention is beneficial to improving feces formation, reducing soft stools in kittens, and improving intestinal health.

[0055] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any person skilled in the art can, without departing from the spirit and technical solution of the present invention, use the methods and technical contents disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent embodiment with equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. An immune-enhancing milk-based kitten food, characterized by: The milk-based kitten food is composed of a main grain mixture and a sandwich component; The mass ratio of the staple food mixture to the sandwich component is (90-95): (5-10); The sandwich component is composed of microcapsule powder and freeze-dried chicken mince, with a mass ratio of (1-4):1; The microcapsule powder has a three-layer structure, with a core layer comprising freeze-dried bifidobacterium powder, galacto-oligosaccharides and trehalose; an interlayer comprising milk powder, hydrolyzed casein, zein and whole goat milk powder; and an outer layer comprising whey protein powder, octenyl succinate starch ester, chicken liver powder and sericin-lysozyme / nano-zinc complex.

2. The immune-enhancing milk-based kitten food according to claim 1, characterized in that: The preparation steps of the microcapsule powder are as follows: S1. Dissolve galacto-oligosaccharide and trehalose in water at 30-40°C, stir evenly, cool to 20-25°C, add freeze-dried bifidobacterium powder, homogenize at 2000-3000 rpm for 3-5 minutes, and vacuum dry to obtain the core layer powder; S2. Dissolve milk powder, whole goat milk powder and hydrolyzed casein in 50-60 ° C water, add 0.1-0.15% xanthan gum, stir evenly, then add zein ethanol solution, emulsify at 6000-8000 rpm for 5-10min to obtain an interlayer emulsion; S3. Add octenyl succinate starch ester to water, gelatinize at 80°C, cool to 30-40°C, add whey protein powder and chicken liver powder, homogenize at 8000-10000 rpm for 5-8 minutes, then add sericin-lysozyme / nano-zinc complex and stir to obtain the outer layer solution; S4. Spray the interlayer emulsion and outer layer solution onto the core layer powder in sequence with a volume-to-mass ratio of (1.5-2.0) mL: (0.8-1.2) mL: 1 g. Vacuum dry to obtain microcapsule powder.

3. The immune-enhancing milk-based kitten food according to claim 2, characterized in that: The mass volume ratio of oligosaccharides, trehalose and water in step S1 is (30-35) g: (50-60) g: 100 mL; the concentration of the freeze-dried bifidobacterium powder is 10 9 -10 10 CFU / g, and the mass volume ratio of the freeze-dried Bifidobacterium powder to water is (10-15) g:100 mL.

4. The immune-enhancing milk-based kitten food according to claim 2, characterized in that: In step S2, the mass volume ratio of cow milk powder, whole goat milk powder, hydrolyzed casein and water is (25-30) g: (20-25) g: (15-20) g: 100 mL; and the volume ratio of the zein ethanol solution to water is (10-15):

100.

5. The immune-enhancing milk-based kitten food according to claim 2, characterized in that: In step S3, the mass volume ratio of octenyl succinate starch ester, whey protein powder, chicken liver powder, sericin-lysozyme / nano-zinc complex and water is (20-25) g: (35-40) g: (20-25) g: (12-15) g: 100 mL.

6. The immune-enhancing milk-based kitten food according to claim 5, characterized in that: The steps for preparing the sericin-lysozyme / nano-zinc complex are as follows: Step 1. Dissolve zinc acetate in pH 8 50mM Tris-HCl buffer, stir in a 50-55°C water bath, and then add sodium ascorbate. Continuously introduce nitrogen, then add lysozyme, stir at a constant temperature of 40-45°C for 1-2 hours, centrifuge at 4°C, take the precipitate, wash, resuspend, sonicate, and filter to obtain a lysozyme / nano-zinc complex colloidal solution; Step 2. Add sericin and genipin to the lysozyme / nano-zinc complex colloidal solution, react at 40-50° C. for 30 min, dialysis purification, and freeze-drying to obtain the sericin-lysozyme / nano-zinc complex.

7. The immune-enhancing milk-based kitten food according to claim 6, characterized in that: The mass volume ratio of zinc acetate, sodium ascorbate, lysozyme and Tris-HCl buffer in step 1 is (2-2.5) g: (1-1.5) g: (5-8) g: 500 mL.

8. The immune-enhancing milk-based kitten food according to claim 6, characterized in that: In the step 2, the mass volume ratio of the sericin, genipin and lysozyme / nano-zinc complex colloidal solution is (15-20) g: (0.2-0.3) g: 100 mL.

9. The method for preparing an immune-enhanced milk-based kitten food according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) Fresh meat processing: mince fresh chicken and fresh pigeon meat, pasteurize them, mix them with eggs, chicken fat, butter, and fish oil, then add fish meal and chicken meal, and emulsify them in a chopper to obtain a mixed meat paste; (2) Fruit and vegetable processing: Steam fresh sweet potatoes and fresh pumpkins, then crush and pulp fresh broccoli, fresh tomatoes, and fresh parsley to prepare mixed fruit and vegetable juice; (3) Dry material mixing: mixing cassava starch, brewer's yeast powder, alfalfa powder, cranberry powder, spirulina powder, psyllium, glucosamine hydrochloride, vitamin premix and mineral premix to obtain a mixed dry material; (4) The mixed meat paste, mixed fruit and vegetable juice and mixed dry materials are further mixed and extruded from the outer channel of a coaxial twin-screw extruder as the main food mixture. The microcapsule powder and freeze-dried chicken mince are extruded from the inner channel and granulated to obtain immune-enhanced milk-based kitten food.

10. The method for preparing an immune-enhanced milk-based kitten food according to claim 9, characterized in that: The parameters of the coaxial twin-screw extruder in step (4) are: screw aspect ratio of (15-18):1; inner channel temperature of 80-100°C, screw speed of 140-160rpm; outer channel temperature of 140-160°C, screw speed of 200-250rpm, and die pressure of 4-5MPa.

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