A lactic acid bacteria microencapsulated feed and its preparation method

Abstract

This invention belongs to the field of feed technology, specifically relating to a lactic acid bacteria microencapsulated feed and its preparation method. The feed comprises basic feed components, freeze-dried lactic acid bacteria powder, composite wall material, calcium salt solidifying agent, oil coating components, succinyl fructooligosaccharide-quercetin loading material, and chitosan-oligosaccharide-lecithin-curcumin loading material. In preparation, a composite wall material liquid is first prepared and mixed with the freeze-dried lactic acid bacteria powder. This mixture is then solidified with calcium chloride and coated with chitosan to form lactic acid bacteria composite microcapsules. The basic feed is then granulated and coated with the microcapsule coating mixture to obtain the lactic acid bacteria microencapsulated feed. This invention can improve the stability and survival rate of lactic acid bacteria during feed processing, storage, and the gastrointestinal environment, and also improve feed palatability and intestinal delivery.

Description

Technical Field

[0001] This invention belongs to the field of feed technology, specifically relating to a lactic acid bacteria microencapsulated feed and its preparation method. Background Technology

[0002] Lactic acid bacteria, a commonly used microecological functional component in animal feed, can participate in regulating the balance of intestinal flora, improving feed digestibility and utilization, and alleviating intestinal stress caused by factors such as weaning, regrouping, transportation, feed changes, and high-density feeding. Therefore, it has high application value in livestock, poultry, aquaculture, and special breeding feeds. Currently, lactic acid bacteria freeze-dried powder is usually mixed directly with the basal feed or added using a simple oil coating method. However, lactic acid bacteria are live microorganisms and are sensitive to moisture, oxygen, heat, mechanical shear, acidic environments, and bile salt environments. During feed mixing, pelleting, transportation, storage, and gastrointestinal transit after animal consumption, the bacterial cell membrane and cell wall are easily damaged, leading to a decrease in the number of live bacteria. Ultimately, the effective number of bacteria reaching the intestine to exert their effects is insufficient, affecting product stability and actual performance.

[0003] To improve the stability of lactic acid bacteria in feed systems, existing technologies include encapsulation with alginate, chitosan, starch, protein, colloids, or oils. Sodium alginate can form a gel network with calcium ions, chitosan can dissolve under acidic conditions and form a composite film with alginate, and materials such as whey protein, maltodextrin, resistant starch, and inulin can also provide some protection for the bacteria during drying and storage. However, single or simple compound wall materials still have problems such as insufficient wall layer density, inadequate antioxidant capacity, limited gastric acid shielding effect, unstable intestinal release, easy moisture absorption and adhesion of microcapsules, and poor adhesion to pelleted feed. Especially in complex feed environments containing oils, proteins, mineral salts, and polysaccharides, uneven dispersion, coating layer detachment, or rapid decline in viable bacteria during storage are common issues with microcapsule wall materials and base feed.

[0004] Furthermore, existing lactic acid bacteria coated feeds often focus on physical isolation and protection, neglecting the synergistic utilization of natural functional components such as plant polyphenols, oligosaccharides, and lecithin within the microcapsule walls of lactic acid bacteria. While natural polyphenols like quercetin and curcumin possess strong antioxidant properties, their poor water dispersibility makes them difficult to distribute evenly when directly added to feed systems. Fructooligosaccharides, inulin, and chitosan oligosaccharides exhibit good animal suitability and intestinal regulation potential, but their individual use has limited effect on loading hydrophobic active substances and strengthening the microcapsule structure. Therefore, how to rationally combine natural oligosaccharides, polyphenols, lecithin, alginate, chitosan, and basic feed components to construct lactic acid bacteria microcapsule-coated feeds with good resistance to processing damage, storage degradation, gastric acid and bile salts, and intestinal delivery, while ensuring the safety, availability, and suitability of raw materials for animal use, remains a technical problem that needs to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a lactic acid bacteria microencapsulated feed and its preparation method.

[0006] A first aspect of the present invention provides a lactic acid bacteria microencapsulated feed, comprising the following components in parts by weight: Corn flour 35-55 parts, soybean meal 15-25 parts, fermented soybean meal 5-12 parts, wheat bran 4-10 parts, fish meal 2-6 parts, rice bran meal 3-8 parts, soybean oil 1-3 parts, dicalcium phosphate 0.8-1.6 parts, calcium carbonate 0.5-1.2 parts, sodium chloride 0.2-0.5 parts, L-lysine hydrochloride 0.2-0.6 parts, DL-methionine 0.1-0.3 parts, DL-α-tocopherol acetate powder 0.02-0.08 parts, zinc sulfate monohydrate 0.03-0.10 parts, feed-grade Lactobacillus plantarum freeze-dried powder 2-6 parts, feed-grade Lactobacillus acidophilus 1-4 parts freeze-dried bacterial powder, 1-3 parts feed-grade Pediococcus lactis freeze-dried bacterial powder, 1.5-3.5 parts sodium alginate, 0.3-1.2 parts chitosan, 2-5 parts whey protein powder, 3-8 parts maltodextrin, 4-10 parts resistant starch, 2-6 parts inulin, 0.5-1.5 parts glycerol, 0.8-2.0 parts anhydrous calcium chloride, 0.2-0.8 parts locust bean gum, 0.3-1.0 parts soybean lecithin, 1.5-5.0 parts palm fat powder, 0.5-1.5 parts succinyl fructooligosaccharide quercetin loading, and 0.3-1.2 parts chitosan oligosaccharide lecithin curcumin loading.

[0007] This invention also provides a method for preparing the aforementioned lactic acid bacteria microencapsulated feed, comprising the following steps: S1. Under stirring, sodium alginate, whey protein powder, maltodextrin, resistant starch, inulin, locust bean gum, glycerol, succinyl fructooligosaccharide-quercetin loading material, and chitosan oligosaccharide-lecithin-curcumin loading material are dispersed in deionized water to obtain a composite wall material solution; the composite wall material solution is heat-treated at 80-90℃, then cooled to 32-38℃, and feed-grade Lactobacillus plantarum freeze-dried powder, feed-grade Lactobacillus acidophilus freeze-dried powder, and feed-grade Pediococcus lactis freeze-dried powder are added to adjust the pH. A lactic acid bacteria composite wall material suspension was obtained by mixing anhydrous calcium chloride with deionized water to obtain a calcium chloride curing solution. The lactic acid bacteria composite wall material suspension was added dropwise to the calcium chloride curing solution and cured at 8-15℃. After filtration, primary lactic acid bacteria microcapsules were obtained. Chitosan was dispersed in an aqueous solution of glacial acetic acid to obtain a chitosan coating solution. The primary lactic acid bacteria microcapsules were added to the chitosan coating solution and coated at 20-30℃. After filtration and washing, the lactic acid bacteria composite microcapsules were obtained. S2. Mix corn flour, soybean meal, fermented soybean meal, wheat bran, fish meal, rice bran meal, dicalcium phosphate, calcium carbonate, sodium chloride, L-lysine hydrochloride, DL-methionine, DL-α-tocopherol acetate powder, and zinc sulfate monohydrate to obtain a basic feed mixture; granulate the basic feed mixture at 70-78℃ and cool it to 25-35℃ to obtain basic pelleted feed; mix lactic acid bacteria complex microcapsules, soybean lecithin, soybean oil, and molten palm fat powder to obtain a microcapsule coating mixture; coat the surface of the basic pelleted feed with the microcapsule coating mixture, dry it at 25-35℃, and sieve it.

[0008] In this invention, the formation of lactic acid bacteria microencapsulated feed includes composite wall material construction, lactic acid bacteria encapsulation, calcium chloride solidification, chitosan coating, and surface coating of granular feed. Sodium alginate, whey protein powder, maltodextrin, resistant starch, inulin, locust bean gum, glycerol, succinyl fructooligosaccharide-quercetin loading material, and chitosan oligosaccharide-lecithin-curcumin loading material form a composite wall material solution in deionized water. Sodium alginate provides the subsequent ionic cross-linking framework. Whey protein powder undergoes heat treatment to expand its structure and improve film-forming and encapsulation capabilities. Maltodextrin, resistant starch, inulin, and locust bean gum enhance the adhesiveness, filling capacity, and drying protection of the wall material system. Glycerol improves the flexibility of the wall layer. The succinyl fructooligosaccharide-quercetin loading material and the chitosan oligosaccharide-lecithin-curcumin loading material improve the interfacial stability and antioxidant protection of the wall material system. After the composite wall material liquid is cooled, feed-grade freeze-dried Lactobacillus plantarum powder, feed-grade freeze-dried Lactobacillus acidophilus powder, and feed-grade freeze-dried Pediococcus lactis powder are added, so that the lactic acid bacteria cells are surrounded and dispersed in the lactic acid bacteria composite wall material suspension. After the lactic acid bacteria composite wall material suspension is added dropwise to the calcium chloride curing solution, anhydrous calcium chloride releases calcium ions in the aqueous phase. These calcium ions undergo ionic cross-linking with the carboxylate groups in the sodium alginate molecular chain, forming primary microcapsules of lactic acid bacteria encapsulating the bacteria. Chitosan, after dissolving in glacial acetic acid aqueous solution, carries a positive charge and electrostatically binds to the negatively charged groups of sodium alginate on the surface of the primary lactic acid bacteria microcapsules, forming a denser outer composite membrane, thus obtaining the lactic acid bacteria composite microcapsules. Corn flour, soybean meal, fermented soybean meal, wheat bran, fish meal, rice bran meal, dicalcium phosphate, calcium carbonate, sodium chloride, L-lysine hydrochloride, DL-methionine, DL-α-tocopherol acetate powder, and zinc sulfate monohydrate are mixed and granulated to form a basic pelleted feed. A microcapsule coating mixture consisting of lactic acid bacteria microcapsules, soybean lecithin, soybean oil, and molten palm fat powder is then applied to the surface of the basic pelleted feed. Soybean oil and palm fat powder form an outer hydrophobic barrier, while soybean lecithin improves the interfacial bonding between the lactic acid bacteria microcapsules and the oil phase, ensuring stable adhesion of the microcapsules to the surface of the basic pelleted feed. This reduces the impact of post-granulation processing, storage, and the gastric acid and bile salt environment on lactic acid bacteria activity and enhances the effective delivery capacity of lactic acid bacteria after entering the intestines.

[0009] According to a preferred embodiment of the present invention, in step S1, the heat treatment time at 80-90°C is 15-25 minutes.

[0010] According to a preferred embodiment of the present invention, in step S1, the curing time at 8-15°C is 20-40 min.

[0011] According to a preferred embodiment of the present invention, the method for preparing the succinyl fructooligosaccharide quercetin loading includes: A1. By weight, mix 20-35 parts of fructooligosaccharide, 4-7 parts of succinic anhydride and 180-260 parts of deionized water, adjust the pH to 8.0-9.0 with sodium hydroxide aqueous solution, react at 45-55℃, after the reaction is completed, adjust the pH to 4.0-5.0 with hydrochloric acid, and ultrafilter to obtain succinyl fructooligosaccharide intermediate solution; A2. Dissolve 8-12 parts of quercetin in 120-180 parts of anhydrous ethanol to obtain quercetin ethanol solution; add the quercetin ethanol solution to the succinyl fructooligosaccharide intermediate solution with stirring, adjust the pH to 7.0-7.5, and react at 45-50℃; after the reaction is completed, reduce the pressure, ultrafilter, wash, freeze dry, pulverize, and sieve.

[0012] In this invention, the formation of the succinyl fructooligosaccharide-quercetin-supported compound involves fructooligosaccharides, succinic anhydride, deionized water, sodium hydroxide aqueous solution, hydrochloric acid, quercetin, and anhydrous ethanol as the main reactants. Fructooligosaccharide molecules contain numerous hydroxyl groups. In the weakly alkaline environment created by the sodium hydroxide aqueous solution, the hydroxyl groups on the fructooligosaccharide molecular chains become more active, enabling them to undergo ring-opening acylation with succinic anhydride. This allows succinyl groups to attach to the fructooligosaccharide molecular chains, forming a succinyl fructooligosaccharide intermediate solution containing both carboxyl and hydroxyl groups. Hydrochloric acid is used for system conditioning after the reaction, neutralizing residual alkaline substances and maintaining the succinyl fructooligosaccharide intermediate solution in a relatively stable acidic to weakly acidic dispersion state. After ultrafiltration, unreacted small molecules and generated inorganic salts are removed, retaining the succinyl fructooligosaccharide intermediate solution with its hydrophilic backbone and carboxyl structure. Quercetin is difficult to disperse uniformly in deionized water directly. It is first dissolved in anhydrous ethanol to form a quercetin ethanol solution, which is then added to a succinyl fructooligosaccharide intermediate solution. This allows quercetin to gradually enter the aqueous system containing the succinyl fructooligosaccharide intermediate solution from the ethanol phase. During this process, the phenolic hydroxyl groups in the quercetin molecule form hydrogen bonds with the hydroxyl and carboxyl groups in the succinyl fructooligosaccharide intermediate solution. The aromatic structure in the quercetin molecule undergoes hydrophobic association and van der Waals interactions with the locally hydrophobic regions formed after succinyl modification. Therefore, quercetin is stably loaded onto the succinyl fructooligosaccharide carrier. This process mainly relies on hydrogen bonding, hydrophobic association, and intermolecular interactions to form the loaded structure. After depressurization, ultrafiltration, washing, freeze-drying, pulverizing, and sieving, the succinyl fructooligosaccharide quercetin-loaded product is obtained, which improves the dispersion stability of quercetin in the subsequent composite wall material solution and enhances the compatibility between the fructooligosaccharide carrier and the lactic acid bacteria microcapsule wall material.

[0013] According to a preferred embodiment of the present invention, in step A1, the reaction time at 45-55°C is 4-6 hours.

[0014] According to a preferred embodiment of the present invention, in step A2, the reaction time at 45-50°C is 2-4 hours.

[0015] According to a preferred embodiment of the present invention, the method for preparing the chitosan oligosaccharide lecithin curcumin loading includes: B1. By weight, disperse 25-40 parts of chitosan oligosaccharide in 150-220 parts of deionized water, stir at 45-55℃, add 8-12 parts of food-grade citric acid, and adjust the pH to 4.8-5.5 to obtain the chitosan oligosaccharide aqueous phase; disperse 5-9 parts of curcumin and 2-4 parts of soybean lecithin in 80-120 parts of anhydrous ethanol, stir at 35-45℃ to obtain the curcumin lecithin ethanol phase; B2. Under stirring, add the curcumin lecithin ethanol phase dropwise to the chitosan oligosaccharide aqueous phase, adjust the pH to 5.0-5.5, and react at 45-55℃. After the reaction is complete, reduce the pressure, filter, spray dry, and sieve.

[0016] In this invention, the chitosan oligosaccharide-lecithin-curcumin loading is formed using chitosan oligosaccharide, deionized water, food-grade citric acid, curcumin, soybean lecithin, and anhydrous ethanol as the main components. Chitosan oligosaccharide itself has good water dispersibility, forming a relatively uniform aqueous phase in deionized water. The addition of food-grade citric acid partially protonates the amino groups on the chitosan oligosaccharide molecular chains, enhancing the dispersion stability of the aqueous phase and providing a suitable weakly acidic environment for subsequent binding with the curcumin-lecithin ethanol phase. Curcumin, being a hydrophobic polyphenol, easily aggregates and settles in deionized water, making it difficult to distribute evenly when directly added to the composite wall material system. Soybean lecithin molecules have both hydrophilic and hydrophobic portions, which can assist curcumin in forming the curcumin-lecithin ethanol phase in anhydrous ethanol, ensuring a relatively uniform dispersion of curcumin initially. After the curcumin-lecithin ethanol phase was dropwise added to the chitosan oligosaccharide aqueous phase, the anhydrous ethanol gradually mixed with the aqueous phase. The complex dispersion structure formed by curcumin and soybean lecithin was further stabilized by the chitosan oligosaccharide. The amino and hydroxyl groups in the chitosan oligosaccharide molecules formed hydrogen bonds and electrostatic interactions with the phenolic hydroxyl groups in the curcumin molecules and the polar groups in the soybean lecithin. The hydrophobic portion of the soybean lecithin helped to maintain the dispersion of curcumin, thus forming a supported structure in which chitosan oligosaccharide, soybean lecithin, and curcumin all participated. This process should not be described as a covalent grafting of curcumin and chitosan oligosaccharide, nor as a simple mixing, but rather as a supported system formed by the solubilization and dispersion of soybean lecithin, the stabilization of the chitosan oligosaccharide aqueous phase, and the non-covalent intermolecular interactions. After removing anhydrous ethanol by vacuum decompression, followed by filtration, spray drying and sieving, chitosan oligosaccharide lecithin curcumin loading was obtained, which improved the dispersibility of curcumin in subsequent composite wall material liquid, chitosan coating system and oil coating system, and reduced the problems of agglomeration and uneven distribution caused by direct addition of curcumin.

[0017] According to a preferred embodiment of the present invention, in step B2, the reaction time at 45-55°C is 2-4 hours.

[0018] According to a preferred embodiment of the present invention, in step B2, the inlet air temperature of the spray drying is 110-130°C, and the outlet air temperature of the spray drying is 55-65°C.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention constructs a composite wall material system using sodium alginate, whey protein powder, maltodextrin, resistant starch, inulin, locust bean gum, and glycerol, and uses succinyl fructooligosaccharide quercetin loading material and chitosan oligosaccharide lecithin curcumin loading material to ensure uniform encapsulation of feed-grade Lactobacillus plantarum freeze-dried powder, feed-grade Lactobacillus acidophilus freeze-dried powder, and feed-grade Pediococcus lactis freeze-dried powder. Sodium alginate forms a gel structure with anhydrous calcium chloride, which can provide primary protection for lactic acid bacteria; whey protein powder, maltodextrin, resistant starch, inulin, and locust bean gum can improve the film-forming properties, filling properties, and drying protection of the wall material system; glycerol can improve the flexibility of the wall layer, thereby reducing the activity loss of lactic acid bacteria during mixing, granulation, drying, and storage.

[0020] (2) In this invention, chitosan is used to form a chitosan coating solution in an aqueous solution of glacial acetic acid, which is then used to coat the primary microcapsules of lactic acid bacteria, resulting in a continuous outer layer structure on the surface of the lactic acid bacteria composite microcapsules. This outer layer structure can reduce the direct impact of gastric acid and bile salts on the lactic acid bacteria cells and improve the release stability of the lactic acid bacteria composite microcapsules in the intestinal environment. Succinyl fructooligosaccharide quercetin loading material can improve the dispersion state of quercetin in the composite wall material system and enhance the antioxidant protection capacity of the wall material system; chitosan oligosaccharide lecithin curcumin loading material can improve the compatibility between curcumin and polysaccharide, protein and lipid components, reduce the aggregation of hydrophobic active substances, and make the wall layer structure of the lactic acid bacteria composite microcapsules more stable.

[0021] (3) In this invention, a basic pelleted feed is prepared from corn flour, soybean meal, fermented soybean meal, wheat bran, fish meal, rice bran meal, dicalcium phosphate, calcium carbonate, sodium chloride, L-lysine hydrochloride, DL-methionine, DL-α-tocopherol acetate powder, and zinc sulfate monohydrate. A microcapsule coating mixture is then formed using lactic acid bacteria microcapsules, soybean lecithin, soybean oil, and molten palm fat powder, and coated onto the surface of the basic pelleted feed. This ensures that the lactic acid bacteria microcapsules are stably attached to the outer layer of the basic pelleted feed. Soybean lecithin improves the interfacial bonding between the lactic acid bacteria microcapsules and the oil phase, while soybean oil and palm fat powder form a hydrophobic protective layer. This reduces the impact of moisture absorption during storage, particle friction, and external oxidation on the activity of lactic acid bacteria, and improves the effective delivery of lactic acid bacteria into the animal's intestines and the feed utilization effect. Detailed Implementation

[0022] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0023] Example 1 This embodiment provides a method for preparing lactic acid bacteria microencapsulated feed, the steps of which include: S1. Disperse 2.5g sodium alginate, 3.5g whey protein powder, 5.5g maltodextrin, 7g resistant starch, 4g inulin, 0.5g locust bean gum, 1g glycerol, 1g succinyl fructooligosaccharide quercetin loading material, and 0.75g chitosan oligosaccharide lecithin curcumin loading material in 260g deionized water, and stir at 500r / min for 40min to obtain a composite wall material solution; heat-treat the composite wall material solution at 85℃ for 20min, stirring at 300r / min during the heat treatment, then cool to 35℃, add 4g feed-grade Lactobacillus plantarum freeze-dried powder, 2.5g feed-grade Lactobacillus acidophilus freeze-dried powder, and 2g feed-grade Pediococcus lactis freeze-dried powder, adjust the pH to 6.15, and stir at 150r / min for 10min to obtain a lactic acid bacteria composite wall material suspension; mix 1.4g anhydrous calcium chloride with 120g deionized water. Deionized water was mixed and stirred at 25°C for 10 min to obtain a calcium chloride curing solution. Using a 300 μm pore size nozzle, the lactic acid bacteria composite wall material suspension was added dropwise to the calcium chloride curing solution. During the dropwise addition, the calcium chloride curing solution was stirred at 100 r / min. The solution was cured at 11.5°C for 30 min, filtered, and primary lactic acid bacteria microcapsules were obtained. 0.75 g of chitosan was dispersed in 120 g of glacial acetic acid aqueous solution, which was prepared by mixing 1.2 g of glacial acetic acid and 118.8 g of deionized water. The solution was stirred at 25°C and 300 r / min for 60 min to obtain a chitosan coating solution. The primary lactic acid bacteria microcapsules were added to the chitosan coating solution and coated at 25°C and 100 r / min for 20 min. The solution was filtered, washed twice with 100 g of deionized water each time, to obtain the lactic acid bacteria composite microcapsules. S2. Add 45g corn flour, 20g soybean meal, 8.5g fermented soybean meal, 7g wheat bran, 4g fish meal, 5.5g rice bran meal, 1.2g dicalcium phosphate, 0.85g calcium carbonate, 0.35g sodium chloride, 0.4g L-lysine hydrochloride, 0.2g DL-methionine, 0.05g DL-α-tocopherol acetate powder, and 0.065g zinc sulfate monohydrate to a mixer and mix at 25℃ for 15 minutes to obtain a basic feed mixture. Pelletize the basic feed mixture at 74℃ with a die diameter of 2.5mm. After pelleting and cooling to 30°C, a basic pelleted feed is obtained. Lactic acid bacteria compound microcapsules, 0.65g soybean lecithin, 2g soybean oil and 3.25g molten palm fat powder are mixed and stirred at 35°C for 10 minutes to obtain a microcapsule coating mixture. The microcapsule coating mixture is added to the basic pelleted feed and mixed and coated at 30°C for 15 minutes to ensure that the microcapsule coating mixture is evenly attached to the surface of the basic pelleted feed. Then, it is dried at 30°C until the moisture content is no more than 10%, and the fine powder is removed by passing it through a 1.0mm sieve to obtain lactic acid bacteria microcapsule coated feed.

[0024] Preparation steps of succinyl fructooligosaccharide quercetin loading: A1. Add 27.5g of fructooligosaccharide, 5.5g of succinic anhydride, and 220g of deionized water to a reaction vessel equipped with a mechanical stirrer and temperature control device. Stir at 300r / min for 20min to completely dissolve the fructooligosaccharide and uniformly disperse the succinic anhydride. Adjust the pH to 8.5 with 1mol / L sodium hydroxide aqueous solution. Raise the system temperature to 50℃ and react at 50℃ and 300r / min for 5h. Check the pH every 30min during the reaction and maintain the pH at 8.0 with 1mol / L sodium hydroxide aqueous solution. After the reaction, cool the system to 25℃ and adjust the pH to 4.5 with 1mol / L hydrochloric acid. Use an ultrafiltration membrane with a molecular weight cutoff of 500Da for ultrafiltration at a pressure of 0.10MPa until the conductivity of the permeate is less than 100μS / cm. Collect the retentate to obtain the succinyl fructooligosaccharide intermediate solution. A2. Add 10g of quercetin to 150g of anhydrous ethanol and stir at 25℃ and 300r / min for 30min to obtain a quercetin ethanol solution. While stirring at 300r / min, add the quercetin ethanol solution to the succinyl fructooligosaccharide intermediate solution obtained in A1 over 30min. After the addition is complete, adjust the pH to 7.25 with 1mol / L sodium hydroxide aqueous solution. React at 47.5℃ and 300r / min for 3h to load quercetin into the succinyl fructooligosaccharide intermediate solution. After completion, anhydrous ethanol was removed under reduced pressure at 40℃ and -0.08MPa. Ultrafiltration was performed using an ultrafiltration membrane with a molecular weight cutoff of 500Da at an ultrafiltration pressure of 0.10MPa. The permeate was washed with deionized water until it was clear and the conductivity was less than 100μS / cm. The retentate was collected, pre-frozen at -40℃ for 6h, and then freeze-dried at a cold trap temperature of -50℃ and a vacuum degree of less than 100Pa for 24h. The dried product was pulverized and passed through a 180μm sieve to obtain succinyl fructooligosaccharide quercetin-loaded product.

[0025] Preparation steps of chitosan oligosaccharide lecithin curcumin loading: B1. Disperse 32.5g of chitosan oligosaccharide in 185g of deionized water, stir at 50℃ and 300r / min for 30min, add 10g of food-grade citric acid, continue stirring for 20min, adjust the pH to 5.15 with 1mol / L sodium hydroxide aqueous solution or 1mol / L hydrochloric acid to obtain the chitosan oligosaccharide aqueous phase; add 7g of curcumin and 3g of soybean lecithin to 100g of anhydrous ethanol, stir at 40℃ and 300r / min for 30min to obtain the curcumin lecithin ethanol phase; B2. Under stirring at 300 r / min, the curcumin-lecithin ethanol phase was added dropwise to the chitosan oligosaccharide aqueous phase over a period of 30 min. After the addition was complete, the pH was adjusted to 5.25, and the reaction was carried out at 50℃ and 300 r / min for 3 h. After the reaction was completed, anhydrous ethanol was removed under reduced pressure at 40℃ and -0.08 MPa. The mixture was filtered through a 0.45 μm filter membrane, and the filtrate was spray-dried at an inlet air temperature of 120℃, an outlet air temperature of 60℃, and a feed flow rate of 5 mL / min. The resulting powder was passed through an 180 μm sieve to obtain the chitosan oligosaccharide-lecithin-curcumin loading.

[0026] Example 2 The difference between this embodiment and Embodiment 1 is that this embodiment provides a method for preparing lactic acid bacteria microencapsulated feed, the steps of which include: S1. Disperse 1.5g sodium alginate, 2g whey protein powder, 3g maltodextrin, 4g resistant starch, 2g inulin, 0.2g locust bean gum, 0.5g glycerol, 0.5g succinyl fructooligosaccharide quercetin loading material, and 0.3g chitosan oligosaccharide lecithin curcumin loading material in 200g deionized water and stir until uniform to obtain a composite wall material solution; heat-treat the composite wall material solution at 80℃ for 15min, then cool to 32℃, and add 2g of feed-grade Lactobacillus plantarum freeze-dried bacterial powder, 1g of feed-grade Lactobacillus acidophilus freeze-dried bacterial powder, and 1g of feed-grade Pediococcus lactis freeze-dried bacterial powder. Adjust the pH to 5.8 and stir until the bacterial powder is evenly distributed to obtain a lactic acid bacteria composite wall material suspension; mix 0.8g of anhydrous calcium chloride with 80g of deionized water to obtain a calcium chloride curing solution; add the lactic acid bacteria composite wall material suspension dropwise to the calcium chloride curing solution, cure at 8℃ for 20min, filter to obtain primary lactic acid bacteria microcapsules; disperse 0.3g of chitosan in 80g of glacial acetic acid aqueous solution and stir until a uniform chitosan coating solution is formed; add the primary lactic acid bacteria microcapsules to the chitosan coating solution, coat at 20℃, filter, and wash with deionized water to obtain lactic acid bacteria composite microcapsules; S2. Mix 35g corn flour, 15g soybean meal, 5g fermented soybean meal, 4g wheat bran, 2g fish meal, 3g rice bran meal, 0.8g dicalcium phosphate, 0.5g calcium carbonate, 0.2g sodium chloride, 0.2g L-lysine hydrochloride, 0.1g DL-methionine, 0.02g DL-α-tocopherol acetate powder, and 0.03g zinc sulfate monohydrate evenly to obtain a basic feed mixture. Pelletize the basic feed mixture at 70℃ and cool it to 25℃ to obtain basic pelleted feed. Mix lactic acid bacteria compound microcapsules, 0.3g soybean lecithin, 1g soybean oil, and 1.5g molten palm fat powder evenly to obtain a microcapsule coating mixture. Coat the surface of the basic pelleted feed with the microcapsule coating mixture, dry it at 25℃, and sieve it to obtain lactic acid bacteria microcapsule coated feed.

[0027] Preparation steps of succinyl fructooligosaccharide quercetin loading: A1. Add 20g of fructooligosaccharide, 4g of succinic anhydride and 180g of deionized water to a reaction vessel and mix them evenly with stirring. Adjust the pH to 8.0 with sodium hydroxide aqueous solution to ensure that the fructooligosaccharide and succinic anhydride are in a uniformly dispersed state. Then react at 45℃ for 4h. During the reaction, keep the system in a stirable and flowable state. After the reaction is completed, adjust the pH to 4.0 with hydrochloric acid. Then remove unreacted small molecules and soluble salts by ultrafiltration. Collect the retentate to obtain succinyl fructooligosaccharide intermediate solution. A2. Add 8g of quercetin to 120g of anhydrous ethanol and stir until uniformly dispersed to form a quercetin ethanol solution. While stirring, add the quercetin ethanol solution to the succinyl fructooligosaccharide intermediate solution obtained in A1, adjust the pH to 7.0, and react at 45℃ for 2h to load quercetin into the succinyl fructooligosaccharide intermediate solution. After the reaction is completed, remove the anhydrous ethanol under reduced pressure, ultrafilter, wash with deionized water until the filtrate is clear, freeze dry, pulverize, and sieve to obtain the succinyl fructooligosaccharide quercetin-loaded product.

[0028] Preparation steps of chitosan oligosaccharide lecithin curcumin loading: B1. Disperse 25g of chitosan oligosaccharide in 150g of deionized water and stir at 45℃ until uniformly dispersed. Add 8g of food-grade citric acid and adjust the pH to 4.8 to obtain the chitosan oligosaccharide aqueous phase. Add 5g of curcumin and 2g of soybean lecithin to 80g of anhydrous ethanol and stir at 35℃ until uniformly dispersed to obtain the curcumin lecithin ethanol phase. B2. Under stirring, the curcumin lecithin ethanol phase was added dropwise to the chitosan oligosaccharide aqueous phase, the pH was adjusted to 5.0, and the reaction was carried out at 45℃ for 2 hours. After the reaction was completed, the anhydrous ethanol was removed under reduced pressure, filtered, and spray-dried. The inlet air temperature of the spray dryer was 110℃, the outlet air temperature of the spray dryer was 55℃, and the mixture was sieved to obtain the chitosan oligosaccharide lecithin curcumin loading.

[0029] Example 3 The difference between this embodiment and Embodiment 1 is that this embodiment provides a method for preparing lactic acid bacteria microencapsulated feed, the steps of which include: S1. Disperse 3.5g sodium alginate, 5g whey protein powder, 8g maltodextrin, 10g resistant starch, 6g inulin, 0.8g locust bean gum, 1.5g glycerol, 1.5g succinyl fructooligosaccharide quercetin loading material, and 1.2g chitosan oligosaccharide lecithin curcumin loading material in 320g deionized water and stir until uniform to obtain a composite wall material solution; heat-treat the composite wall material solution at 90℃ for 25min, then cool to 38℃, add 6g feed-grade Lactobacillus plantarum freeze-dried powder, 4g feed-grade Lactobacillus acidophilus freeze-dried powder, and 3g feed-grade Pediococcus lactis freeze-dried powder, and adjust... Adjust the pH to 6.5 and stir until the bacterial powder is evenly distributed to obtain a lactic acid bacteria composite wall material suspension; mix 2.0g of anhydrous calcium chloride with 160g of deionized water to obtain a calcium chloride curing solution; add the lactic acid bacteria composite wall material suspension dropwise to the calcium chloride curing solution, cure at 15℃ for 40min, filter to obtain primary lactic acid bacteria microcapsules; disperse 1.2g of chitosan in 160g of glacial acetic acid aqueous solution and stir until a uniform chitosan coating solution is formed; add the primary lactic acid bacteria microcapsules to the chitosan coating solution, coat at 30℃, filter, and wash with deionized water to obtain lactic acid bacteria composite microcapsules; S2. Mix 55g corn flour, 25g soybean meal, 12g fermented soybean meal, 10g wheat bran, 6g fish meal, 8g rice bran meal, 1.6g dicalcium phosphate, 1.2g calcium carbonate, 0.5g sodium chloride, 0.6g L-lysine hydrochloride, 0.3g DL-methionine, 0.08g DL-α-tocopherol acetate powder, and 0.10g zinc sulfate monohydrate evenly to obtain a basic feed mixture. Granulate the basic feed mixture at 78℃ and cool it to 35℃ to obtain basic pelleted feed. Mix lactic acid bacteria compound microcapsules, 1.0g soybean lecithin, 3g soybean oil, and 5.0g molten palm fat powder evenly to obtain a microcapsule coating mixture. Coat the surface of the basic pelleted feed with the microcapsule coating mixture, dry it at 35℃, and sieve it to obtain lactic acid bacteria microcapsule coated feed.

[0030] Preparation steps of succinyl fructooligosaccharide quercetin loading: A1. Add 35g of fructooligosaccharide, 7g of succinic anhydride and 260g of deionized water to a reaction vessel and mix them evenly with stirring. Adjust the pH to 9.0 with sodium hydroxide aqueous solution to ensure that the fructooligosaccharide and succinic anhydride are in a uniformly dispersed state. Then react at 55℃ for 6h. During the reaction, keep the system in a stirable and flowable state. After the reaction is completed, adjust the pH to 5.0 with hydrochloric acid. Then remove unreacted small molecules and soluble salts by ultrafiltration. Collect the retentate to obtain succinyl fructooligosaccharide intermediate solution. A2. Add 12g of quercetin to 180g of anhydrous ethanol and stir until uniformly dispersed to form a quercetin ethanol solution. While stirring, add the quercetin ethanol solution to the succinyl fructooligosaccharide intermediate solution obtained in A1, adjust the pH to 7.5, and react at 50℃ for 4h to load quercetin onto the succinyl fructooligosaccharide intermediate solution. After the reaction is complete, remove the anhydrous ethanol under reduced pressure, ultrafilter, wash with deionized water until the filtrate is clear, freeze dry, pulverize, and sieve to obtain the succinyl fructooligosaccharide quercetin-loaded product.

[0031] Preparation steps of chitosan oligosaccharide lecithin curcumin loading: B1. Disperse 40g of chitosan oligosaccharide in 220g of deionized water and stir at 55℃ until uniformly dispersed. Add 12g of food-grade citric acid and adjust the pH to 5.5 to obtain the chitosan oligosaccharide aqueous phase. Add 9g of curcumin and 4g of soybean lecithin to 120g of anhydrous ethanol and stir at 45℃ until uniformly dispersed to obtain the curcumin lecithin ethanol phase. B2. Under stirring, the curcumin lecithin ethanol phase was added dropwise to the chitosan oligosaccharide aqueous phase, the pH was adjusted to 5.5, and the reaction was carried out at 55℃ for 4 hours. After the reaction was completed, the anhydrous ethanol was removed under reduced pressure, filtered, and spray-dried. The inlet air temperature of the spray dryer was 130℃, the outlet air temperature of the spray dryer was 65℃, and the mixture was sieved to obtain the chitosan oligosaccharide lecithin curcumin loading.

[0032] Comparative Example 1 The difference between this comparative example and Example 1 is that no succinyl fructooligosaccharide quercetin loading was prepared or added, and 1g of fructooligosaccharide was used instead of 1g of succinyl fructooligosaccharide quercetin loading. The rest is the same as in Example 1.

[0033] Comparative Example 2 The difference between this comparative example and Example 1 is that the chitosan oligosaccharide lecithin curcumin loading is not prepared and not added, and 0.75g of chitosan oligosaccharide is used instead of 0.75g of chitosan oligosaccharide lecithin curcumin loading. The rest is the same as in Example 1.

[0034] Comparative Example 3 The difference between this comparative example and Example 1 is that succinyl fructooligosaccharide quercetin loading material and chitosan oligosaccharide lecithin curcumin loading material are not prepared and added. 1g of fructooligosaccharide is used instead of 1g of succinyl fructooligosaccharide quercetin loading material, and 0.75g of chitosan oligosaccharide is used instead of 0.75g of chitosan oligosaccharide lecithin curcumin loading material. The rest is the same as in Example 1.

[0035] The performance of the lactic acid bacteria microencapsulated feeds obtained in Examples 1-3 and Comparative Examples 1-3 was tested in accordance with national and industry standard testing specifications.

[0036] The lactic acid bacteria microencapsulated feeds prepared in Examples 1-3 and Comparative Examples 1-3 were used as test samples. Before the test, the samples were placed in a constant temperature and humidity environment of 25°C and 50% relative humidity for 12 hours to equilibrate. Three parallel samples were taken for each sample and the average value was taken.

[0037] For the test of viable bacteria count in the finished product, weigh 10g of sample and place it in a sterile conical flask. Add 90mL of sterile physiological saline and shake at 25°C and 150r / min for 30min to fully disperse the lactic acid bacteria complex microcapsules from the surface of the basic pelleted feed. After standing for 2min, take the supernatant and perform serial dilutions at a 10-fold ratio. Take 1mL of each appropriate dilution and spread it on a lactic acid bacteria selective medium. Incubate anaerobically at 37°C for 48h. Select plates with colony counts of 30-300 for counting and convert the count to CFU / g.

[0038] When testing the viable bacteria retention rate after coating and drying, the theoretical viable bacteria count of the lactic acid bacteria composite microcapsules before coating and drying is first calculated based on the initial viable bacteria counts of the added feed-grade Lactobacillus plantarum freeze-dried powder, feed-grade Lactobacillus acidophilus freeze-dried powder, and feed-grade Pediococcus lactis freeze-dried powder. Then, the finished viable bacteria count in the lactic acid bacteria microcapsule-coated feed is tested according to the finished product viable bacteria count test method. The viable bacteria retention rate after coating and drying is calculated by dividing the finished product viable bacteria count by the theoretical viable bacteria count and then multiplying by 100%.

[0039] For the 60-day viable cell retention rate test at room temperature, each sample was placed in a sealed bag and stored in an environment of 25°C and 60% relative humidity for 60 days. After storage, 10g of sample was weighed and the viable cell count after storage was determined according to the method for testing the viable cell count of the finished product. The viable cell retention rate at room temperature for 60 days was calculated by dividing the viable cell count after storage by the viable cell count of the finished product before storage and then multiplying by 100%.

[0040] In the simulated gastric fluid survival rate test, 5g of sample was weighed and added to 50mL of simulated gastric fluid with a pH of 2.0. The mixture was shaken at 37°C and 100r / min for 2h. After the treatment, the pH was immediately adjusted to 7.0 with sterile buffer. The number of viable bacteria after treatment was then determined according to the method for testing the viable bacteria count of finished products. The simulated gastric fluid survival rate was calculated by dividing the number of viable bacteria after treatment by the number of viable bacteria before treatment and then multiplying by 100%.

[0041] In the simulated bile salt survival rate test, 5g of sample was weighed and added to 50mL of simulated intestinal fluid containing 0.3% bile salt and pH 7.0. The sample was shaken at 37°C and 100r / min for 4h. After the treatment, the number of viable bacteria after treatment was determined according to the method for testing the viable bacteria count of finished products. The simulated bile salt survival rate was calculated by dividing the number of viable bacteria after treatment by the number of viable bacteria before treatment and then multiplying by 100%.

[0042] During the microcapsule encapsulation rate test, a sample of the lactic acid bacteria composite wall material suspension before curing was taken to determine the total number of viable bacteria before curing. At the same time, a sample of the lactic acid bacteria composite microcapsule after curing, coating, and washing was taken, the microcapsules were broken and the internal lactic acid bacteria were released, and the number of viable bacteria in the microcapsules was determined. The microcapsule encapsulation rate was calculated by dividing the number of viable bacteria in the microcapsules by the total number of viable bacteria before curing and then multiplying by 100%.

[0043] The performance test data above are shown in Table 1.

[0044] Table 1: Performance Test Results

[0045] The test results in Table 1 above clearly show that the viable bacterial counts of the finished products in Examples 1-3 were 3.8 × 10⁻⁶, respectively. 8 CFU / g, 2.7×10 8 CFU / g and 4.5×10 8 The CFU / g values ​​were all higher than those of Comparative Example 1 (2.6 × 10⁻⁶). 8 CFU / g, 2.4 × 10⁻⁶ in Comparative Example 2 8 CFU / g and 1.9×10⁻⁶ in Comparative Example 3 8 The CFU / g indicates that the simultaneous addition of succinyl fructooligosaccharide quercetin loading material and chitosan oligosaccharide lecithin curcumin loading material significantly reduced the loss of lactic acid bacteria during preparation, coating, and drying, and could increase the content of effective live bacteria in lactic acid bacteria microencapsulated feed.

[0046] The viable bacteria retention rates after coating and drying in Examples 1-3 were 89.4-92.6%, significantly higher than those in Comparative Example 1 (84.7%), Comparative Example 2 (82.9%), and Comparative Example 3 (76.5%). This indicates that the absence of either succinyl fructooligosaccharide-quercetin loading material or chitosan-oligosaccharide-lecithin-curcumin loading material alone weakens the protective effect of the microcapsule wall material on lactic acid bacteria. The loss of viable bacteria is most significant when both are absent simultaneously, indicating that the composite wall material system formed by these two materials, along with sodium alginate, chitosan, whey protein powder, maltodextrin, resistant starch, inulin, locust bean gum, and glycerol, has a synergistic protective effect.

[0047] The viable bacteria retention rate of Examples 1-3 after 60 days of storage at room temperature was 82.5-86.8%, which was higher than that of Comparative Example 1 (74.2%), Comparative Example 2 (72.8%), and Comparative Example 3 (63.5%). This indicates that the present invention can improve the antioxidant, moisture-wicking, and interfacial stability of lactic acid bacteria during storage, and solve the problem of rapid viable bacteria decay in existing lactic acid bacteria-coated feeds during room temperature storage.

[0048] The survival rates of simulated gastric juice in Examples 1-3 were 76.9-81.4%, and the survival rates of simulated bile salts were 79.8-84.7%, both higher than those in Comparative Examples 1-3. In particular, the survival rates in Comparative Example 3 were only 58.6% and 61.2%, respectively. This indicates that the combined addition of succinyl fructooligosaccharide-quercetin loading material and chitosan oligosaccharide-lecithin-curcumin loading material can improve the compactness, acid resistance, and bile salt shock resistance of the lactic acid bacteria composite microcapsule wall layer, enabling the lactic acid bacteria to maintain a high survival rate in the simulated gastrointestinal environment.

[0049] The microcapsule encapsulation rates of Examples 1-3 were 88.2-91.5%, which were higher than those of Comparative Example 1 (84.1%), Comparative Example 2 (82.7%), and Comparative Example 3 (76.8%). This indicates that the composite wall material system of the present invention can more fully encapsulate feed-grade Lactobacillus plantarum freeze-dried powder, feed-grade Lactobacillus acidophilus freeze-dried powder, and feed-grade Pediococcus lactis freeze-dried powder, thereby improving the encapsulation efficiency during the formation of lactic acid bacteria microcapsules.

[0050] Based on the above data, Examples 1-3, compared to Comparative Examples 1-3, solved the technical problems of low viable bacteria count, large loss of viable bacteria after processing and drying, insufficient stability during room temperature storage, low survival rate under gastric acid and bile salt environments, and low microencapsulation rate in existing lactic acid bacteria feeds. The performance decline in Comparative Examples 1 and 2 indicates that the succinyl fructooligosaccharide quercetin loading material and the chitosan oligosaccharide lecithin curcumin loading material each made independent contributions. The most significant performance decline in Comparative Example 3 further illustrates that the combined use of the two can produce a better synergistic protective effect.

Claims

1. A feed coated with microcapsules of lactic acid bacteria, characterized in that, Includes the following components in parts by weight: Corn flour 35-55 parts, soybean meal 15-25 parts, fermented soybean meal 5-12 parts, wheat bran 4-10 parts, fish meal 2-6 parts, rice bran meal 3-8 parts, soybean oil 1-3 parts, dicalcium phosphate 0.8-1.6 parts, calcium carbonate 0.5-1.2 parts, sodium chloride 0.2-0.5 parts, L-lysine hydrochloride 0.2-0.6 parts, DL-methionine 0.1-0.3 parts, DL-α-tocopherol acetate powder 0.02-0.08 parts, zinc sulfate monohydrate 0.03-0.10 parts, feed-grade Lactobacillus plantarum freeze-dried powder 2-6 parts, feed-grade Lactobacillus acidophilus 1-4 parts freeze-dried bacterial powder, 1-3 parts feed-grade Pediococcus lactis freeze-dried bacterial powder, 1.5-3.5 parts sodium alginate, 0.3-1.2 parts chitosan, 2-5 parts whey protein powder, 3-8 parts maltodextrin, 4-10 parts resistant starch, 2-6 parts inulin, 0.5-1.5 parts glycerol, 0.8-2.0 parts anhydrous calcium chloride, 0.2-0.8 parts locust bean gum, 0.3-1.0 parts soybean lecithin, 1.5-5.0 parts palm fat powder, 0.5-1.5 parts succinyl fructooligosaccharide quercetin loading, and 0.3-1.2 parts chitosan oligosaccharide lecithin curcumin loading.

2. A method for preparing lactic acid bacteria microencapsulated feed according to claim 1, characterized in that the step... include: S1. Under stirring, sodium alginate, whey protein powder, maltodextrin, resistant starch, inulin, sophora japonica gum, glycerol, succinyl fructooligosaccharide quercetin loading material, and chitosan oligosaccharide lecithin curcumin loading material are dispersed in deionized water to obtain a composite wall material solution; the composite wall material solution is heat-treated at 80-90℃, then cooled to 32-38℃, and feed-grade Lactobacillus plantarum freeze-dried powder, feed-grade Lactobacillus acidophilus freeze-dried powder, and feed-grade Pediococcus lactis freeze-dried powder are added, and the pH is adjusted to 5.8-6.5 to obtain a lactic acid bacteria composite wall material suspension; anhydrous calcium chloride is mixed with deionized water to obtain a calcium chloride solidified solution; the lactic acid bacteria composite wall material suspension is added dropwise to the calcium chloride solidified solution, solidified at 8-15℃, filtered, and lactic acid bacteria primary microcapsules are obtained; chitosan is dispersed in glacial acetic acid aqueous solution to obtain a chitosan coating solution; Primary lactic acid bacteria microcapsules were added to chitosan coating solution, coated at 20-30℃, filtered, and washed to obtain lactic acid bacteria composite microcapsules. S2. Mix corn flour, soybean meal, fermented soybean meal, wheat bran, fish meal, rice bran meal, dicalcium phosphate, calcium carbonate, sodium chloride, L-lysine hydrochloride, DL-methionine, DL-α-tocopherol acetate powder, and zinc sulfate monohydrate to obtain a basic feed mixture; granulate the basic feed mixture at 70-78℃ and cool it to 25-35℃ to obtain basic pelleted feed; mix lactic acid bacteria complex microcapsules, soybean lecithin, soybean oil, and molten palm fat powder to obtain a microcapsule coating mixture; coat the surface of the basic pelleted feed with the microcapsule coating mixture, dry it at 25-35℃, and sieve it.

3. The method for preparing lactic acid bacteria microencapsulated feed according to claim 2, characterized in that, In step S1, the heat treatment time at 80-90℃ is 15-25 minutes.

4. The method for preparing lactic acid bacteria microencapsulated feed according to claim 2, characterized in that, In step S1, the curing time at 8-15℃ is 20-40 minutes.

5. The lactic acid bacteria microencapsulated feed according to claim 1, characterized in that, The preparation method of the succinyl fructooligosaccharide quercetin loading includes: A1. By weight, mix 20-35 parts of fructooligosaccharide, 4-7 parts of succinic anhydride and 180-260 parts of deionized water, adjust the pH to 8.0-9.0 with sodium hydroxide aqueous solution, react at 45-55℃, after the reaction is completed, adjust the pH to 4.0-5.0 with hydrochloric acid, and ultrafilter to obtain succinyl fructooligosaccharide intermediate solution; A2. Dissolve 8-12 parts of quercetin in 120-180 parts of anhydrous ethanol to obtain quercetin ethanol solution; add the quercetin ethanol solution to the succinyl fructooligosaccharide intermediate solution with stirring, adjust the pH to 7.0-7.5, and react at 45-50℃; after the reaction is completed, reduce the pressure, ultrafilter, wash, freeze dry, pulverize, and sieve.

6. The lactic acid bacteria microencapsulated feed according to claim 5, characterized in that, In step A1, the reaction time is 4-6 hours at 45-55℃.

7. The lactic acid bacteria microencapsulated feed according to claim 5, characterized in that, In step A2, the reaction time is 2-4 hours at 45-50℃.

8. The lactic acid bacteria microencapsulated feed according to claim 1, characterized in that, The preparation method of the chitosan oligosaccharide lecithin curcumin loading includes: B1. By weight, disperse 25-40 parts of chitosan oligosaccharide in 150-220 parts of deionized water, stir at 45-55℃, add 8-12 parts of food-grade citric acid, and adjust the pH to 4.8-5.5 to obtain the chitosan oligosaccharide aqueous phase; disperse 5-9 parts of curcumin and 2-4 parts of soybean lecithin in 80-120 parts of anhydrous ethanol, stir at 35-45℃ to obtain the curcumin lecithin ethanol phase; B2. Under stirring, add the curcumin lecithin ethanol phase dropwise to the chitosan oligosaccharide aqueous phase, adjust the pH to 5.0-5.5, and react at 45-55℃. After the reaction is complete, reduce the pressure, filter, spray dry, and sieve.

9. The lactic acid bacteria microencapsulated feed according to claim 8, characterized in that, In step B2, the reaction time is 2-4 hours at 45-55℃.

10. The lactic acid bacteria microencapsulated feed according to claim 8, characterized in that, In step B2, the inlet air temperature for spray drying is 110-130℃, and the outlet air temperature for spray drying is 55-65℃.

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