Slow-release fat powder for pigs and preparation method thereof

Abstract

The application belongs to the technical field of feed additives, and more particularly relates to a slow-release fat powder for pigs and a preparation method thereof. The slow-release fat powder for pigs comprises a gastric adhesion-slow-release layer, a pre-small-intestine bile acid response controlled-release layer, and a post-small-intestine microorganism response slow-release layer. The slow-release fat powder for pigs prepared by the application has good stability and can achieve precise release of different nutrients at different parts of the gastrointestinal tract of pigs, thereby providing strong support for the sustainable development of the pig breeding industry.

Description

Technical Field

[0001] This invention belongs to the field of feed additive technology, and more specifically, relates to a slow-release pig fat powder and its preparation method. Background Technology

[0002] With the improvement of living standards, people's demand for high-quality pork is increasing, making precision feeding a key factor in the pig farming industry. Fat is a high-energy nutrient; the energy produced by the oxidation of each gram of fat is approximately twice that of carbohydrates and proteins. Fat meal plays a vital role in pig farming. First, it provides pigs with high energy, meeting their energy needs at different growth stages, promoting growth and development, and improving lean meat percentage and pork quality. Second, fat meal improves feed palatability, increasing feed intake and helping pigs absorb more sufficient nutrients. Third, it promotes the absorption of fat-soluble vitamins, ensuring normal physiological functions, immunity, and reproductive performance in pigs.

[0003] As omnivores, pigs possess unique physiological characteristics in their gastrointestinal tract: a highly acidic stomach with a pH value typically between 1.5 and 3.5. While this acidic environment facilitates initial protein digestion and sterilization, it also easily leads to the degradation and inactivation of nutrients in feed. The small intestine, reaching 15-20 times the body length, provides a vast surface area for digestion and absorption, and the concentration of bile acids in the anterior segment of the small intestine is significantly higher than in the posterior segment. This distribution characteristic allows for rapid emulsification and digestion of fats in the anterior segment. Simultaneously, the microbial community enriched in the posterior segment of the small intestine can secrete glycosidases, aiding in the deep breakdown of carbohydrates. However, existing pig fat powders are mostly ordinary formulations, which are difficult to match the complex digestive environment of the pig's gastrointestinal tract. Problems include the easy decomposition of nutrients in the highly acidic gastric environment, uneven fat digestion efficiency in different segments of the small intestine, and an inability to coordinate with intestinal microbial metabolism, resulting in low fat utilization and increased breeding costs.

[0004] In view of the above, the present invention provides a slow-release fat powder to solve the problem that ordinary fat powder has poor stability and cannot achieve precise energy release. Summary of the Invention

[0005] This invention aims to provide a slow-release swine fat powder and its preparation method. Through innovative structural design and component combination, it achieves precise release of different nutrients in different parts of the pig's gastrointestinal tract, improves the absorption and utilization rate of nutrients, reduces breeding costs, and enhances the growth performance and health of pigs.

[0006] This invention provides a sustained-release porcine fat powder, comprising: a gastric adhesion-sustaining layer, a bile acid-responsive controlled-release layer in the anterior segment of the small intestine, and a microbial-responsive sustained-release layer in the posterior segment of the small intestine.

[0007] Preferably, the gastric adhesion-sustaining layer comprises, by weight: 25-35 parts xanthan gum, 5-7 parts porcine gastric mucin, 0.1-0.6 parts glycine, 0.2-0.4 parts genipin, 25-35 parts dopamine hydrochloride, 5-8 parts sodium butyrate-sodium bicarbonate effervescent microspheres, 10-20 parts chitosan, and 4-20 parts pepsin-trehalose crystals@SiO2 nanoparticles.

[0008] Preferably, the bile acid-responsive controlled-release layer of the anterior small intestine comprises, by weight: 7-10 parts of sodium cholate, 35-40 parts of dimethylaminoethyl methacrylate, 15-20 parts of ethylene glycol dimethacrylate, 0.1-0.3 parts of azobisisobutyronitrile, 10-19 parts of glyceryl caprylate, 10-19 parts of monodecanoate, 5-7 parts of gelatin, 0.05-0.1 parts of Tween-80, and 0.2-0.5 parts of calcium chloride.

[0009] Preferably, the microbial response sustained-release layer of the posterior small intestine comprises, by weight, 10-15 parts linoleic acid, 10-15 parts linolenic acid, 1-3 parts docosahexaenoic acid, 15-20 parts palmitic acid, 1-3 parts vitamin A, 1-3 parts vitamin E, 0.6-1 part lecithin, 0.6-1 part Tween 80, 31-58 parts β-glucan, 0.3-0.8 parts calcium chloride, 2-4 parts xanthan gum, and 1-3 parts gum arabic.

[0010] Preferably, the method for preparing the gastric adhesion-sustained-release layer includes the following steps:

[0011] S1: Add xanthan gum, porcine gastric mucoprotein and glycine to deionized water, stir and heat to 50°C; cool to room temperature, add genipin, stir and react for 4 hours to form a colloidal matrix;

[0012] S2: Prepare a 10% chitosan ionic aqueous solution, dissolve sodium butyrate and sodium bicarbonate in the chitosan solution, spray dry, and spray with sodium alginate to obtain sodium butyrate-sodium bicarbonate effervescent microspheres with a diameter of 100–150 μm.

[0013] S3: First, pepsin and trehalose are co-crystallized at a mass ratio of 1:1; the crystals are then immersed in a porous SiO2 solution for adsorption and loading, and vacuum dried to obtain pepsin-trehalose crystals@SiO2 nanoparticles.

[0014] S4: Add the effervescent microspheres prepared in S2 and the nanoparticles prepared in S3 to the colloidal matrix prepared in S1; stir evenly to form a colloidal suspension;

[0015] S5: Polydopamine coating: The colloidal suspension obtained in S4 was placed in tris(hydroxymethyl)aminomethane hydrochloride buffer solution, and dopamine hydrochloride was added; the mixture was stirred at 25°C for 12 hours to form a polydopamine coating; after filtration, it was washed with pure water to obtain the gastric adhesion-sustaining layer.

[0016] Preferably, the mass ratio of sodium butyrate to sodium bicarbonate is 1:1 by weight.

[0017] Preferably, the method for preparing the bile acid-responsive controlled-release layer in the anterior segment of the small intestine includes the following steps:

[0018] S1: Dissolve sodium cholate, dimethylaminoethyl methacrylate, and ethylene glycol dimethacrylate in a mixture of 40 mL and 10 mL of deionized water; control the temperature at 60 °C and react for 4–6 hours to form a particulate polymer; elute three times with methanol-acetic acid at a volume ratio of 9:1 until sodium cholate residue is undetectable by HPLC; vacuum dry to obtain the bile acid molecularly imprinted polymer;

[0019] S2: Add caprylic acid glyceryl ester and capric acid monoester to 10 mL of an aqueous solution of gelatin and Tween-80, and control the temperature at 40℃; emulsify into small droplets using a high-shear emulsifier.

[0020] S3: The polymer particles obtained in S1 are slowly added to the emulsion system prepared in S2, and CaCl2 is added for crosslinking; the mixture is stirred at 40°C for 2 hours to obtain bile acid-responsive controlled-release composite microspheres in the anterior segment of the small intestine; the particle size distribution is controlled at 150–300 μm.

[0021] Preferably, the method for preparing the microbial responsive sustained-release layer of the posterior small intestine includes the following steps:

[0022] S1: Linoleic acid, linolenic acid, docosahexaenoic acid, palmitic acid, vitamin A, vitamin E, lecithin, and Tween-80 were added to 50 mL of deionized water, processed with a high-shear homogenizer, and then ultrasonically emulsified for 2.5 hours to obtain nano-emulsified nutrients.

[0023] S2: The nanoemulsified nutrients obtained in S1 were mixed with β-glucan solution, and 0.2M CaCl2 solution was added dropwise to crosslink into microgels. The mixture was allowed to stand and solidify for 30 minutes, centrifuged, and washed 3 times to obtain microgel particles with a particle size of 150–250 μm.

[0024] S3: Dissolve xanthan gum and gum arabic in 10 mL of deionized water, add calcium chloride, stir for 30 minutes, add the microgel particles obtained in S2, stir for 3 hours, and spray dry to obtain the final particles.

[0025] This invention also provides a method for preparing a sustained-release porcine fat powder, comprising the following steps:

[0026] S1: Place the microbial-responsive sustained-release layer particles of the posterior small intestine in a fluidized bed, and atomize them into the bile acid-responsive controlled-release layer microspheres of the anterior small intestine at a pressure of 0.5-1.0 MPa. The inlet air temperature is 25-30℃, and genipin is sprayed simultaneously. The bed temperature is 25℃, and the reaction is carried out for 3 hours to form a uniform intermediate layer.

[0027] S2: Place the intermediate layer particles obtained in S1 in a fluidized bed, atomize them at an inlet air temperature of 40℃ and spray them into the stomach to form an adhesion-slow-release layer. Then, use cold air at 10-15℃ to instantly solidify the outer layer, thus obtaining the final product.

[0028] Preferably, the mass ratio of genipin to the bile acid-responsive controlled-release microspheres in the anterior small intestine is 1:0.005.

[0029] The gastric adhesion-slow-release layer primarily relies on the acidic environment of the stomach to release nutrients. Firstly, in the acidic environment of the stomach, sodium butyrate-sodium bicarbonate effervescent microspheres react with gastric acid to produce carbon dioxide gas, disrupting the microsphere structure and rapidly releasing the encapsulated sodium butyrate. Simultaneously, this neutralizes the gastric acid, creating an optimal pH (2.5-3.5) for pepsin. Chitosan, with its viscosity and gelling properties, slows the release rate of the sodium butyrate and sodium bicarbonate microspheres in the stomach. Pepsin-trehalose crystals are embedded in porous silica, protecting pepsin's activity in the suitable acidic environment of the stomach and preventing premature degradation. Xanthan gum is covalently cross-linked with porcine gastric mucin, and polydopamine undergoes protonation at pH < 3, electrostatically adsorbing onto gastric epithelial cells and enhancing gastric wall adhesion. This structure mimics the viscoelasticity of the porcine gastric mucus layer, prolonging the residence time of nutrients in the stomach for optimal absorption and utilization.

[0030] The design of the bile acid-responsive controlled-release layer in the proximal small intestine is based on the presence of bile acids in this region. The bile acid molecularly imprinted polymer is formed by reacting porcine sodium cholate with dimethylaminoethyl methacrylate and ethylene glycol dimethacrylate under specific conditions. It dissociates when the porcine bile acid concentration is >2 mM, exhibiting specific recognition capabilities for the porcine small intestinal environment. When the fat powder enters the proximal small intestine, the polymer structure changes when the porcine bile acid concentration reaches the polymer's response threshold, thereby controlling the gradual release of the encapsulated nutrients. Caprylic glyceride and caprylic acid monoester gradually dissolve and diffuse in the physiological environment of the proximal small intestine, while gelatin and Tween-80 components help maintain the structural stability of the microspheres and promote nutrient release.

[0031] The release of the slow-release layer in the posterior small intestine (PSI) primarily depends on the activity of PSI microbes. Xanthan gum and gum arabic form a three-dimensional network structure through ionic cross-linking under the influence of calcium chloride, encapsulating nutrients protected by β-glucan. This structure exhibits high stability, remaining intact within the physiological environment of the stomach and anterior small intestine, preventing premature nutrient release. The PSI microbial community secretes xanthanase and arabinogalactase, which recognize and hydrolyze the β-D-mannuronic acid backbone and α-L-arabinofuranose side chains of xanthan gum and gum arabic. These enzymes progressively degrade the microgel network structure by cleaving glycosidic bonds. As the microgel network is disrupted, the encapsulated nutrients are gradually released into the intestinal lumen. The release rate is influenced by microbial enzyme activity, microgel cross-linking density, and the binding force between nutrients and the matrix. Due to the relatively stable types and numbers of PSI microbes, the release process is controllable, ensuring efficient nutrient absorption at specific sites.

[0032] In the three-layer composite process, genipin is atomized and sprayed to ensure uniform distribution on the surface of the microbial-responsive sustained-release layer particles in the posterior small intestine. When it comes into contact with the bile acid-responsive controlled-release microspheres in the anterior small intestine, the catechol structure of genipin forms a molecular spatial network with the functional groups in the gelatin, polysaccharides, and bile acid molecularly imprinted polymers in both layers. This cross-linked network structure not only enhances the interlayer mechanical strength but also prevents the microgel particles from detaching during processing or storage through steric hindrance. The microgel particles of the posterior small intestine microbial-responsive sustained-release layer and the composite microspheres of the anterior small intestine controlled-release layer achieve partial interlocking through airflow collision in the fluidized bed process. The rough structure of the microgel surface and the pores of the controlled-release layer microspheres form a mechanical interlock, enhancing the interfacial bonding force. Furthermore, the genipin-induced cross-linking reaction promotes the interpenetration of molecular chains at the interface between the two layers, forming a continuous transition region and further preventing interlayer separation. This stable interlayered structure ensures that the fat powder remains structurally intact and stable even under external physical influences, including vibrations during mixing and transportation, and fluctuations in ambient temperature and humidity. Simultaneously, the stable layered structure also helps control the fat release rate, allowing for slow and continuous fat release according to the needs of different digestive stages in pigs, thus improving fat utilization.

[0033] Beneficial effects

[0034] Precisely targeted release: The three-layer gradient response structure is designed for the physiological environment characteristics of different parts of the pig's gastrointestinal tract. Through the characteristics of different response materials, short-chain fatty acids are released in the stomach, medium-chain fatty acids are controlled to be released in the front of the small intestine, and long-chain fatty acids and nutritional fortification factors are slowly released in the back of the small intestine. This precisely matches the digestion and absorption patterns of different parts of the pig's gastrointestinal tract, and the fat digestibility exceeds 90% compared to traditional fat powder.

[0035] Synergistic effect of ingredients: Nutrients and functional substances in each layer work together to improve the digestive environment in the stomach. Sodium butyrate and pepsin in the stomach work together to improve the digestive environment in the stomach. Porcine bile acid produced by the decomposition of bile acid molecular imprinted polymers in the anterior small intestine can enhance the digestion of medium-chain fatty acids. Vitamins and long-chain fatty acids in the posterior small intestine work together to promote the growth and development of pigs. The synergistic effect of multiple ingredients comprehensively improves the health level and growth performance of pigs. Compared with traditional fat powder, the daily weight gain of piglets is increased by 37%.

[0036] Improved stability: In the three-layer composite process, the catechol structure of genipin forms a molecular spatial network with the functional groups in the gelatin, polysaccharides, and bile acid molecularly imprinted polymers in the gastric release layer and the proximal small intestine sustained-release layer. The microgel particles in the proximal small intestine microbial-responsive sustained-release layer and the composite microspheres in the proximal small intestine controlled-release layer achieve partial interlocking through airflow collision in the fluidized bed process, forming a stable interlayer bond. This structure ensures good stability of the fat powder during transportation and use.

[0037] To more clearly explain this invention, the technical solutions in the embodiments will be described in detail and accurately below with reference to specific examples. The embodiments described herein are only some examples of this invention and not all of it. All other implementation methods obtained by those skilled in the art based on the embodiments provided by this invention without creative effort are covered within the protection scope of this invention. Unless otherwise specified, the experimental methods in the following embodiments are conventional methods. Unless otherwise specified, the materials and reagents used in the following embodiments and comparative examples were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Detailed Implementation

[0038] Example 1

[0039] Example 1 provides a sustained-release porcine fat powder, comprising: a gastric adhesion-sustaining layer, a bile acid-responsive controlled-release layer in the anterior segment of the small intestine, and a microbial-responsive sustained-release layer in the posterior segment of the small intestine.

[0040] The preparation method of the sustained-release porcine fat powder includes the following steps:

[0041] S1: Place the microbial response sustained-release layer particles of the posterior segment of the small intestine in a fluidized bed, and spray them into the bile acid response controlled-release layer microspheres of the anterior segment of the small intestine at a pressure of 0.6 MPa. The inlet air temperature is 28℃, and genipin is sprayed simultaneously. The bed temperature is 25℃, and the reaction is carried out for 3 hours to form a uniform intermediate layer.

[0042] S2: Place the intermediate layer particles obtained in S1 in a fluidized bed, atomize them at an inlet air temperature of 40°C and spray them into the stomach to form an adhesion-slow-release layer, and then instantly solidify the outer layer with 12°C cold air to obtain the final product.

[0043] The gastric adhesion-sustaining layer, by weight, comprises: 30 parts xanthan gum, 6 parts porcine gastric mucin, 0.3 parts glycine, 0.3 parts genipin, 30 parts dopamine hydrochloride, 6 parts sodium butyrate-sodium bicarbonate effervescent microspheres, 16 parts chitosan, and 11.4 parts pepsin-trehalose crystals@SiO2 nanoparticles.

[0044] The bile acid responsive controlled-release layer of the anterior small intestine, by weight, comprises: 8 parts of sodium cholate, 38 parts of dimethylaminoethyl methacrylate, 17 parts of ethylene glycol dimethacrylate, 0.2 parts of azobisisobutyronitrile, 15 parts of octanoic acid glyceride, 15.3 parts of monodecanoic acid ester, 6 parts of gelatin, 0.08 parts of Tween-80, and 0.42 parts of calcium chloride.

[0045] The microbial response sustained-release layer of the posterior small intestine, by weight, comprises: 13 parts linoleic acid, 13 parts linolenic acid, 2 parts docosahexaenoic acid, 18 parts palmitic acid, 2 parts vitamin A, 2 parts vitamin E, 0.8 parts lecithin, 0.8 parts Tween 80, 42.9 parts β-glucan, 0.5 parts calcium chloride, 3 parts xanthan gum, and 2 parts gum arabic.

[0046] The method for preparing the gastric adhesion-sustained-release layer includes the following steps:

[0047] S1: Add xanthan gum, porcine gastric mucoprotein and glycine to deionized water, stir and heat to 50°C; cool to room temperature, add genipin, stir and react for 4 hours to form a colloidal matrix;

[0048] S2: Prepare a 10% chitosan ionic aqueous solution, dissolve sodium butyrate and sodium bicarbonate in the chitosan solution, spray dry, and spray with sodium alginate to obtain sodium butyrate-sodium bicarbonate effervescent microspheres with a diameter of 100–150 μm.

[0049] S3: First, pepsin and trehalose are co-crystallized at a mass ratio of 1:1; the crystals are then immersed in a porous SiO2 solution (pore size 5nm) for adsorption and loading, and vacuum dried to obtain pepsin-trehalose crystals@SiO2 nanoparticles.

[0050] S4: Add the effervescent microspheres prepared in S2 and the nanoparticles prepared in S3 to the colloidal matrix prepared in S1; stir evenly to form a colloidal suspension.

[0051] S5: Polydopamine coating: The colloidal suspension obtained in S4 was placed in tris(hydroxymethyl)aminomethane hydrochloride buffer (pH 8.5), and dopamine hydrochloride was added; the mixture was stirred at 25°C for 12 h to form a polydopamine coating; after filtration, it was washed with pure water to obtain the gastric adhesion-sustaining layer.

[0052] The method for preparing the bile acid-responsive controlled-release layer of the anterior small intestine includes the following steps:

[0053] S1: Dissolve sodium cholate, dimethylaminoethyl methacrylate, and ethylene glycol dimethacrylate in a mixture of 40 mL and 10 mL of deionized water; control the temperature at 60 °C and react for 4 hours to form a particulate polymer; elute three times with methanol-acetic acid (9:1, v / v) until sodium cholate residue is undetectable by HPLC; vacuum dry to obtain the bile acid molecularly imprinted polymer.

[0054] S2: Add caprylic acid glyceryl ester and capric acid monoester to 10 mL of an aqueous solution of gelatin and Tween-80, and control the temperature at 40℃; emulsify into small droplets using a high-shear emulsifier (10000 rpm, 3 min).

[0055] S3: The polymer particles obtained in S1 are slowly added to the emulsion system prepared in S2, and CaCl2 is added for crosslinking; the mixture is stirred at 40°C for 2 hours to obtain bile acid-responsive controlled-release composite microspheres in the anterior segment of the small intestine; the particle size distribution is controlled at 150–300 μm.

[0056] The method for preparing the microbial-responsive sustained-release layer of the posterior small intestine includes the following steps:

[0057] S1: Linoleic acid, linolenic acid, docosahexaenoic acid, palmitic acid, vitamin A, vitamin E, lecithin, and Tween-80 were added to 50 mL of deionized water, processed with a high-shear homogenizer, and then ultrasonically emulsified for 2.5 hours to obtain nano-emulsified nutrients.

[0058] S2: The nanoemulsified nutrients obtained in S1 were mixed with β-glucan solution, and 0.2M CaCl2 solution was added dropwise to crosslink into microgels. The mixture was allowed to stand and solidify for 30 minutes, centrifuged, and washed 3 times to obtain microgel particles with a particle size of 150–250 μm.

[0059] S3: Dissolve xanthan gum and gum arabic in 10 mL of deionized water, add calcium chloride, stir for 30 minutes, add the microgel particles obtained in S2, stir for 3 hours, and spray dry to obtain the final particles.

[0060] In the preparation method of the sustained-release porcine fat powder, the mass ratio of genipin to the bile acid-responsive controlled-release microspheres of the anterior small intestine is 1:0.005.

[0061] In the method for preparing the gastric adhesion-sustaining layer, the mass ratio of sodium butyrate to sodium bicarbonate is 1:1.

[0062] Example 2

[0063] Example 2 provides a sustained-release porcine fat powder, comprising: a gastric adhesion-sustaining layer, a bile acid-responsive controlled-release layer in the anterior small intestine, and a microbial-responsive sustained-release layer in the posterior small intestine. It differs from Example 1 in that the process parameters and the proportions of various material components are different.

[0064] The preparation method of the sustained-release porcine fat powder includes the following steps:

[0065] S1: Place the microbial response sustained-release layer particles of the posterior segment of the small intestine in a fluidized bed, and spray them into the bile acid response controlled-release layer microspheres of the anterior segment of the small intestine at a pressure of 0.5 MPa. The air inlet temperature is 25℃, and genipin is sprayed simultaneously. The bed temperature is 25℃, and the reaction is carried out for 3 hours to form a uniform intermediate layer.

[0066] S2: Place the intermediate layer particles obtained in S1 in a fluidized bed, atomize them at an inlet air temperature of 40°C and spray them into the stomach to form an adhesion-slow-release layer. Then, use 10°C cold air to instantly solidify the outer layer.

[0067] The gastric adhesion-sustaining layer, by weight, comprises 25 parts xanthan gum, 5 parts porcine gastric mucin, 0.1 parts glycine, 0.2 parts genipin, 25 parts dopamine hydrochloride, 5 parts sodium butyrate-sodium bicarbonate effervescent microspheres, 20 parts chitosan, and 19.7 parts pepsin-trehalose crystals@SiO2 nanoparticles.

[0068] The bile acid responsive controlled-release layer in the anterior segment of the small intestine, by weight, comprises: 7 parts sodium cholate, 35 parts dimethylaminoethyl methacrylate, 16 parts ethylene glycol dimethacrylate, 0.15 parts azobisisobutyronitrile, 18.3 parts octanoic acid glyceride, 18.3 parts monodecanoic acid ester, 5 parts gelatin, 0.05 parts Tween-80, and 0.2 parts calcium chloride.

[0069] The microbial response sustained-release layer of the posterior small intestine, by weight, comprises: 10 parts linoleic acid, 10 parts linolenic acid, 1 part docosahexaenoic acid, 15 parts palmitic acid, 1 part vitamin A, 1 part vitamin E, 0.6 parts lecithin, 0.6 parts Tween 80, 57.5 parts β-glucan, 0.3 parts calcium chloride, 2 parts xanthan gum, and 1 part gum arabic.

[0070] The method for preparing the gastric adhesion-sustained-release layer includes the following steps:

[0071] S1: Add xanthan gum, porcine gastric mucoprotein and glycine to deionized water, stir and heat to 50°C; cool to room temperature, add genipin, stir and react for 4 hours to form a colloidal matrix;

[0072] S2: Prepare a 10% chitosan ionic aqueous solution, dissolve sodium butyrate and sodium bicarbonate in the chitosan solution, spray dry, and spray with sodium alginate to obtain sodium butyrate-sodium bicarbonate effervescent microspheres with a diameter of 100–150 μm.

[0073] S3: First, pepsin and trehalose are co-crystallized at a mass ratio of 1:1; the crystals are then immersed in a porous SiO2 solution (pore size 5nm) for adsorption and loading, and vacuum dried to obtain pepsin-trehalose crystals@SiO2 nanoparticles.

[0074] S4: Add the effervescent microspheres prepared in S2 and the nanoparticles prepared in S3 to the colloidal matrix prepared in S1; stir evenly to form a colloidal suspension.

[0075] S5: Polydopamine coating: The colloidal suspension obtained in S4 was placed in tris(hydroxymethyl)aminomethane hydrochloride buffer (pH 8.5), and dopamine hydrochloride was added; the mixture was stirred at 25°C for 12 h to form a polydopamine coating; after filtration, it was washed with pure water to obtain the gastric adhesion-sustaining layer.

[0076] The method for preparing the bile acid-responsive controlled-release layer of the anterior small intestine includes the following steps:

[0077] S1: Dissolve sodium cholate, dimethylaminoethyl methacrylate, and ethylene glycol dimethacrylate in a mixture of 40 mL and 10 mL of deionized water; control the temperature at 60 °C and react for 4 hours to form a particulate polymer; elute three times with methanol-acetic acid (9:1, v / v) until sodium cholate residue is undetectable by HPLC; vacuum dry to obtain the bile acid molecularly imprinted polymer.

[0078] S2: Add caprylic acid glyceryl ester and capric acid monoester to 10 mL of an aqueous solution of gelatin and Tween-80, and control the temperature at 40℃; emulsify into small droplets using a high-shear emulsifier (10000 rpm, 3 min).

[0079] S3: The polymer particles obtained in S1 are slowly added to the emulsion system prepared in S2, and CaCl2 is added for crosslinking; the mixture is stirred at 40°C for 2 hours to obtain bile acid-responsive controlled-release composite microspheres in the anterior segment of the small intestine; the particle size distribution is controlled at 150–300 μm.

[0080] The method for preparing the microbial-responsive sustained-release layer of the posterior small intestine includes the following steps:

[0081] S1: Linoleic acid, linolenic acid, docosahexaenoic acid, palmitic acid, vitamin A, vitamin E, lecithin, and Tween-80 were added to 50 mL of deionized water, processed with a high-shear homogenizer, and then ultrasonically emulsified for 2.5 hours to obtain nano-emulsified nutrients.

[0082] S2: The nanoemulsified nutrients obtained in S1 were mixed with β-glucan solution, and 0.2M CaCl2 solution was added dropwise to crosslink into microgels. The mixture was allowed to stand and solidify for 30 minutes, centrifuged, and washed 3 times to obtain microgel particles with a particle size of 150–250 μm.

[0083] S3: Dissolve xanthan gum and gum arabic in 10 mL of deionized water, add calcium chloride, stir for 30 minutes, add the microgel particles obtained in S2, stir for 3 hours, and spray dry to obtain the final particles.

[0084] In the preparation method of the sustained-release porcine fat powder, the mass ratio of genipin to the bile acid-responsive controlled-release microspheres of the anterior small intestine is 1:0.005.

[0085] In the method for preparing the gastric adhesion-sustaining layer, the mass ratio of sodium butyrate to sodium bicarbonate is 1:1.

[0086] Example 3

[0087] Example 3 provides a sustained-release porcine fat powder, comprising: a gastric adhesion-sustaining layer, a bile acid-responsive controlled-release layer in the anterior small intestine, and a microbial-responsive sustained-release layer in the posterior small intestine. It differs from Example 1 in that the process parameters and the proportions of the various material components are different.

[0088] The preparation method of the sustained-release porcine fat powder includes the following steps:

[0089] S1: Place the microbial response sustained-release layer particles of the posterior small intestine in a fluidized bed, and atomize them into the bile acid response controlled-release layer microspheres of the anterior small intestine at a pressure of 1 MPa. The inlet air temperature is 30°C, and genipin is sprayed simultaneously. The bed temperature is 25°C. The reaction is carried out for 3 hours to form a uniform intermediate layer.

[0090] S2: Place the intermediate layer particles obtained in S1 in a fluidized bed, atomize them at an inlet air temperature of 40°C and spray them into the stomach to form an adhesion-slow-release layer, and then instantly solidify the outer layer with 15°C cold air to obtain the final product.

[0091] The gastric adhesion-sustaining layer, by weight, comprises 35 parts xanthan gum, 7 parts porcine gastric mucin, 0.6 parts glycine, 0.4 parts genipin, 35 parts dopamine hydrochloride, 8 parts sodium butyrate-sodium bicarbonate effervescent microspheres, 10 parts chitosan, and 4 parts pepsin-trehalose crystals@SiO2 nanoparticles.

[0092] The bile acid responsive controlled-release layer in the anterior segment of the small intestine, by weight, comprises: 10 parts of sodium cholate, 40 parts of dimethylaminoethyl methacrylate, 19 parts of ethylene glycol dimethacrylate, 0.25 parts of azobisisobutyronitrile, 11.5 parts of glyceryl caprylate, 11.68 parts of monodecanoate, 7 parts of gelatin, 0.07 parts of Tween-80, and 0.5 parts of calcium chloride.

[0093] The microbial response sustained-release layer of the posterior small intestine, by weight, comprises: 15 parts linoleic acid, 15 parts linolenic acid, 3 parts docosahexaenoic acid, 20 parts palmitic acid, 3 parts vitamin A, 3 parts vitamin E, 1 part lecithin, 1 part Tween 80, 31.2 parts β-glucan, 0.8 parts calcium chloride, 4 parts xanthan gum, and 3 parts gum arabic.

[0094] The method for preparing the gastric adhesion-sustained-release layer includes the following steps:

[0095] S1: Add xanthan gum, porcine gastric mucoprotein and glycine to deionized water, stir and heat to 50°C; cool to room temperature, add genipin, stir and react for 4 hours to form a colloidal matrix;

[0096] S2: Prepare a 10% chitosan ionic aqueous solution, dissolve sodium butyrate and sodium bicarbonate in the chitosan solution, spray dry, and spray with sodium alginate to obtain sodium butyrate-sodium bicarbonate effervescent microspheres with a diameter of 100–150 μm.

[0097] S3: First, pepsin and trehalose are co-crystallized at a mass ratio of 1:1; the crystals are then immersed in a porous SiO2 solution (pore size 5nm) for adsorption and loading, and vacuum dried to obtain pepsin-trehalose crystals@SiO2 nanoparticles.

[0098] S4: Add the effervescent microspheres prepared in S2 and the nanoparticles prepared in S3 to the colloidal matrix prepared in S1; stir evenly to form a colloidal suspension.

[0099] S5: Polydopamine coating: The colloidal suspension obtained in S4 was placed in tris(hydroxymethyl)aminomethane hydrochloride buffer (pH 8.5), and dopamine hydrochloride was added; the mixture was stirred at 25°C for 12 h to form a polydopamine coating; after filtration, it was washed with pure water to obtain the gastric adhesion-sustaining layer.

[0100] The method for preparing the bile acid-responsive controlled-release layer of the anterior small intestine includes the following steps:

[0101] S1: Dissolve sodium cholate, dimethylaminoethyl methacrylate, and ethylene glycol dimethacrylate in a mixture of 40 mL and 10 mL of deionized water; control the temperature at 60 °C and react for 4 hours to form a particulate polymer; elute three times with methanol-acetic acid (9:1, v / v) until sodium cholate residue is undetectable by HPLC; vacuum dry to obtain the bile acid molecularly imprinted polymer.

[0102] S2: Add caprylic acid glyceryl ester and capric acid monoester to 10 mL of an aqueous solution of gelatin and Tween-80, and control the temperature at 40℃; emulsify into small droplets using a high-shear emulsifier (10000 rpm, 3 min).

[0103] S3: The polymer particles obtained in S1 are slowly added to the emulsion system prepared in S2, and CaCl2 is added for crosslinking; the mixture is stirred at 40°C for 2 hours to obtain bile acid-responsive controlled-release composite microspheres in the anterior segment of the small intestine; the particle size distribution is controlled at 150–300 μm.

[0104] The method for preparing the microbial-responsive sustained-release layer of the posterior small intestine includes the following steps:

[0105] S1: Linoleic acid, linolenic acid, docosahexaenoic acid, palmitic acid, vitamin A, vitamin E, lecithin, and Tween-80 were added to 50 mL of deionized water, processed with a high-shear homogenizer, and then ultrasonically emulsified for 2.5 hours to obtain nano-emulsified nutrients.

[0106] S2: The nanoemulsified nutrients obtained in S1 were mixed with β-glucan solution, and 0.2M CaCl2 solution was added dropwise to crosslink into microgels. The mixture was allowed to stand and solidify for 30 minutes, centrifuged, and washed 3 times to obtain microgel particles with a particle size of 150–250 μm.

[0107] S3: Dissolve xanthan gum and gum arabic in 10 mL of deionized water, add calcium chloride, stir for 30 minutes, add the microgel particles obtained in S2, stir for 3 hours, and spray dry to obtain the final particles.

[0108] In the preparation method of the sustained-release porcine fat powder, the mass ratio of genipin to the bile acid-responsive controlled-release microspheres of the anterior small intestine is 1:0.005.

[0109] In the method for preparing the gastric adhesion-sustaining layer, the mass ratio of sodium butyrate to sodium bicarbonate is 1:1.

[0110] Comparative Example 1

[0111] Comparative Example 1 provides an uncoated ordinary fat powder.

[0112] The method for preparing the uncoated ordinary fat powder is as follows:

[0113] Sodium butyrate, pepsin, glycine, caprylic acid glyceride, decanoic acid monoester, linoleic acid, linolenic acid, docosahexaenoic acid, palmitic acid, vitamin A, and vitamin E were directly mixed evenly to obtain the product, with the same mass ratio as in Example 1.

[0114] Comparative Example 2

[0115] Comparative Example 2 provides a single-layer coated fat powder comprising: a microbial-responsive sustained-release layer in the lower small intestine and other nutrients.

[0116] The method for preparing the single-layer coated fat powder includes the following steps:

[0117] The microbial response sustained-release layer of the posterior small intestine was obtained by directly mixing sodium butyrate, pepsin, glycine, caprylic glyceride, and decanoic acid monoester, with the same mass ratio as in Example 1.

[0118] The preparation method of the microbial response sustained-release layer in the posterior segment of the small intestine is the same as in Example 1.

[0119] Comparative Example 3

[0120] Comparative Example 3 provides a double-coated fat powder comprising: a bile acid-responsive controlled-release layer in the anterior small intestine and a microbial-responsive sustained-release layer in the posterior small intestine, as well as other nutrients.

[0121] The method for preparing the double-coated fat powder includes the following steps:

[0122] The bile acid-responsive controlled-release layer of the anterior small intestine and the microbial-responsive sustained-release layer of the posterior small intestine were combined according to the method in Example 1 to obtain a composition. Then, the composition was directly mixed with pepsin, sodium butyrate and glycine to obtain a homogeneous mixture with the same mass ratio as in Example 1.

[0123] The preparation methods for the bile acid-responsive controlled-release layer in the anterior segment of the small intestine and the microbial-responsive sustained-release layer in the posterior segment of the small intestine are the same as in Example 1.

[0124] The fat powder prepared in Example 1 and the fat powders of Comparative Examples 1-3 were subjected to experiments simulating the gastrointestinal environment of pigs. The experimental results are shown in Tables 2 and 3. The specific experimental methods are as follows:

[0125] Experimental conditions for simulating nutrient release at each layer: Fat powder from Example 1 and Comparative Examples 1-3 were added to four thermostatically heated magnetically stirred reaction vessels, respectively. The temperature was set at 37±0.5℃. Hydrochloric acid / sodium bicarbonate buffer solution was added, and the pH value was changed from 2.5→5.8→6.6 (switching time ≤5 minutes). The magnetic stirring speed was adjusted to simulate the environment of pig gastric juice, the anterior segment of the small intestine, and the posterior segment of the small intestine, respectively. The specific experimental parameters are shown in Table 1.

[0126] Table 1. Simulation experiment parameter settings for nutrient release at each layer.

[0127]

[0128] Testing steps:

[0129] Gastric fluid samples: After centrifugation and filtration, sodium butyrate was directly detected by ultraviolet spectrophotometry at a wavelength of 205 nm. Gastric fluid sampling time points: 0.5, 1, 1.5, and 2 hours.

[0130] Small intestine samples: Homogenize the small intestine sample, extract with a methanol:chloroform mixture (2:1, v / v) by shaking; after centrifugation and separation, collect the organic phase, concentrate to dryness under nitrogen, centrifuge to collect the upper oil layer, and methylate it using concentrated sulfuric acid-methanol (5% v / v) for HPLC detection. HPLC detection conditions: Column: C18 reversed-phase column (4.6 mm × 250 mm, 5 μm); Mobile phase: acetonitrile-0.1% phosphoric acid solution (60:40, v / v); Flow rate: 1.0 mL / min; Detection wavelength: 254 nm. Sampling time points of the anterior segment of the small intestine: 3, 4, 5, and 6 hours; Sampling time points of the posterior segment of the small intestine: 8, 12, 18, and 24 hours.

[0131] Take 5 mL of medium for each group, and immediately add an equal volume of fresh medium. The test results are shown in Tables 2 and 3.

[0132] Table 2. Cumulative release rate of sodium butyrate in the gastric fluid environment of Example 1 and Comparative Examples 1-3

[0133] Group 0.5 hours 1 hour 1.5 hours 2 hours Example 1 27.5％ 55.8％ 82.5％ 95.5％ Comparative Example 1 82.6％ 95.6％ 96.2％ 96.5％ Comparative Example 2 74.6％ 89.4％ 94.3％ 95.8％ Comparative Example 3 68.9％ 83.5％ 93.9％ 96.3％

[0134] Table 3. Cumulative release rates of nutrients in different gastrointestinal tract layers in Examples 1 and Comparative Examples 1-3

[0135]

[0136]

[0137] The gastric release kinetic curve was fitted over a period of 0-1.5 hours. R0 2 =0.98, k0=55% / h, which conforms to the zero-order kinetic release model. As can be seen from Table 1, the gastric-soluble polymer as a carrier does not affect the release rate. However, the short-chain fatty acids in Comparative Examples 1-3 did not use gastric-soluble polymer carriers, and the sodium butyrate release rate exceeded 60% at 0.5h, indicating a significant risk of burst release.

[0138] As shown in Table 3, the cumulative release rate of the gastric adhesion-slow-release layer of the fat powder provided in Example 1 reached 90% after 2 hours, while the cumulative release rate of medium-chain fatty acids in the bile acid-responsive controlled-release layer of the anterior small intestine was only 15% after 6 hours, whereas the cumulative release rate of medium-chain fatty acids in Comparative Examples 1-3 all exceeded 45% after 6 hours. The cumulative release rate of long-chain fatty acids in the microbial-responsive controlled-release layer of the posterior small intestine was only 20% after 24 hours, while the cumulative release rate of long-chain fatty acids in Comparative Examples 1-3 all exceeded 50% after 24 hours. This indicates that the fat powder structure provided in Example 1 has a good slow-release effect and can achieve precise release of nutrients. Comparative Examples 1-3, which did not use a slow-release structure or only partially used a slow-release structure, could not achieve the effect of precise release of nutrients.

[0139] In vitro mechanical stability tests were performed on Example 1 and Comparative Examples 1-3. The test method was as follows:

[0140] The specific method is referred to the Chinese Pharmacopoeia. High-speed stirring simulation: The fat powder of Example 1 and Comparative Examples 1-3 were placed in a stirrer at 500 rpm for 30 minutes. Breakage rate determination: A laser particle size analyzer, model Malvern 3000, was used to detect the change in particle size distribution and calculate the fragment ratio (D90 / D10 ratio change). The test results are shown in Table 4.

[0141] Table 4. Stability test results of Example 1 and Comparative Examples 1-3

[0142] Group Initial particle size (μm) Particle size (μm) after stirring Fragmentation percentage (%) Example 1 150±12 155±15 8.2±1.5 Comparative Example 1 148±10 210±25 42.7±3.8 Comparative Example 2 152±11 185±20 28.5±2.6 Comparative Example 3 154±13 170±18 18.9±2.1

[0143] As shown in Table 4, after 30 minutes of high-speed stirring, the fragmentation ratio of Example 1 was only 8%, while the fragmentation ratio of Comparative Examples 1-3 all reached more than 19%, indicating that the three-layer gradient response structure of the fat powder provided in Example 1 has good stability.

[0144] Actual breeding experiments were conducted on Example 1 and Comparative Examples 1-3 to test three core indicators: daily weight gain, feed conversion ratio, and fat digestibility. The experimental results are shown in Table 5.

[0145] The experimental method is as follows:

[0146] Animal selection: 200 healthy weaned piglets (weighing 8-10kg) were randomly divided into 4 groups of 50 each (half male and half female);

[0147] Group settings:

[0148] Control group: Basal diet (excluding experimental fat powder);

[0149] Experimental group 1: Basal diet + fat powder from Example 1 (3% added);

[0150] Experimental Group 2: Basal diet + Comparative Example 1 fat powder (3% added);

[0151] Experimental group 3: basal diet + comparative example 2 fat powder (3% added);

[0152] Experimental Group 4: Basal diet + Comparative Example 3 fat powder (3% added).

[0153] Experimental period and husbandry management:

[0154] The adaptation period is 7 days, during which the diet is gradually transitioned to the experimental diet.

[0155] The official period lasts 28 days, during which participants have free access to food and water, with an ambient temperature of 25±2℃ and humidity of 65%.

[0156] Data recording: Daily feed intake is recorded, weekly weight is recorded, and fecal samples are collected regularly.

[0157] Measurement Indicators and Methods

[0158] Daily weight gain: Weighing was performed after fasting for 12 hours at the beginning and end of the experiment, and the total weight gain was calculated.

[0159] Daily weight gain (g / d) = (final weight - initial weight) / number of experimental days.

[0160] Feed conversion ratio = Total feed intake (kg) / Total weight gain (kg);

[0161] Fat digestibility: Fecal samples were collected for three consecutive days, dried, pulverized, and the acid-insoluble ash (AIA) content was determined. Fat digestibility (%) = [1 - (AIA in feed / AIA in feces) × (Fat in feces / Fat in feed)] × 100.

[0162] Table 5. Results of actual aquaculture experiments in Example 1 and Comparative Examples 1-3

[0163]

[0164]

[0165] The data in the table show that feeding the fat powder provided in Example 1 significantly increased the daily weight gain of piglets in the experimental group, which was 36.8% higher than that of the control group and 30% higher than that of Comparative Example 1; the feed conversion rate was 46% lower than that of Comparative Example 1, thus reducing breeding costs; and the fat digestibility exceeded 90%, which was 15.2% higher than that of Comparative Example 1, further proving that the three-layer slow-release structure can effectively prolong the nutrient release time, improve feed utilization, and reduce breeding costs.

[0166] The above description represents a preferred embodiment of the present invention. It should be noted that those skilled in the art can make a series of improvements and modifications based on the principles of this invention. These improvements and modifications based on the principles of this invention are also covered within the scope of protection of this invention.

Claims

1. A slow-release porcine fat powder, characterized in that, include: Gastric adhesion-sustaining layer, anterior small intestinal bile acid responsive controlled-release layer, and posterior small intestinal microbial responsive sustained-release layer; The method for preparing the gastric adhesion-sustained-release layer includes the following steps: Xanthan gum, porcine gastric mucoprotein, and glycine are added to deionized water, stirred, and heated to 50°C; cooled to room temperature, genipin is added, and the mixture is stirred and reacted for 4 hours to form a colloidal matrix; a 10% chitosan ion-soluble aqueous solution is prepared; sodium butyrate and sodium bicarbonate are dissolved in the chitosan solution, spray-dried, and coated with sodium alginate to obtain sodium butyrate-sodium bicarbonate effervescent microspheres with a diameter of 100–150 μm; pepsin and trehalose are first mixed at a mass ratio of 1...

1. Co-crystallization: The crystals were immersed in a porous SiO2 solution for adsorption and loading, and then vacuum dried to obtain pepsin-trehalose crystals@SiO2 nanoparticles; the prepared effervescent microspheres and nanoparticles were added to the prepared colloidal matrix and stirred uniformly to form a colloidal suspension; Polydopamine coating: The obtained colloidal suspension was placed in tris(hydroxymethyl)aminomethane hydrochloride buffer solution, and dopamine hydrochloride was added; the mixture was stirred at 25°C for 12 h to form a polydopamine coating; after filtration, it was washed with pure water to obtain an intragastric adhesion-sustained-release layer; The preparation method of the bile acid-responsive controlled-release layer of the anterior small intestine includes the following steps: dissolving sodium cholate, dimethylaminoethyl methacrylate, and ethylene glycol dimethacrylate in a mixture of 40 mL and 10 mL of deionized water; controlling the temperature at 60°C and reacting for 4-6 hours to form a particulate polymer; eluting three times with a methanol-acetic acid solution at a volume ratio of 9:1; until sodium cholate residue is undetectable by HPLC, and vacuum drying to obtain a bile acid molecularly imprinted polymer; adding glyceryl caprylate and monodecanoic acid to an aqueous solution of gelatin and Tween-80, controlling the temperature at 40°C; emulsifying into small droplets using a high-shear emulsifier; slowly adding the obtained polymer particles to the prepared emulsion system, adding CaCl2 for crosslinking; stirring and reacting at 40°C for 2 hours to obtain a bile acid-responsive controlled-release layer composite microsphere of the anterior small intestine; the particle size distribution is controlled at 150-300 μm; The preparation method of the microbial responsive sustained-release layer in the posterior segment of the small intestine includes the following steps: linoleic acid, linolenic acid, docosahexaenoic acid, palmitic acid, vitamin A, vitamin E, lecithin, and Tween-80 are added to 50 mL of deionized water, treated with a high-shear homogenizer, and then ultrasonically emulsified for 2.5 hours to obtain nano-emulsified nutrients; the obtained nano-emulsified nutrients are mixed with β-glucan solution, and 0.2 M CaCl2 solution is added dropwise to crosslink into microgels, which are allowed to stand and solidify for 30 minutes, centrifuged, and washed 3 times to obtain microgel particles with a particle size of 150-250 μm; xanthan gum and gum arabic are dissolved in 10 mL of deionized water, calcium chloride is added, and the mixture is stirred for 30 minutes; the obtained microgel particles are added, stirred for 3 hours, and spray-dried to obtain the final particles; The preparation method of the sustained-release porcine fat powder includes the following steps: placing microbial-responsive sustained-release layer particles from the posterior segment of the small intestine in a fluidized bed, atomizing them into bile acid-responsive controlled-release layer microspheres from the anterior segment of the small intestine at a pressure of 0.5-1.0 MPa, with an inlet air temperature of 25-30°C, simultaneously spraying genipin, maintaining a bed temperature of 25°C, and reacting for 3 hours to form a uniform intermediate layer; placing the obtained intermediate layer particles in a fluidized bed, atomizing them into an adhesion-sustain-release layer in the stomach at an inlet air temperature of 40°C, and instantly solidifying the outer layer with cold air at 10-15°C to obtain the final product.

2. The sustained-release porcine fat powder according to claim 1, characterized in that, The gastric adhesion-sustaining layer, by weight, comprises: 25-35 parts xanthan gum, 5-7 parts porcine gastric mucin, 0.1-0.6 parts glycine, 0.2-0.4 parts genipin, 25-35 parts dopamine hydrochloride, 5-8 parts sodium butyrate-sodium bicarbonate effervescent microspheres, 10-20 parts chitosan, and 4-20 parts pepsin-trehalose crystals@SiO2 nanoparticles.

3. The sustained-release porcine fat powder according to claim 1, characterized in that, The bile acid responsive controlled-release layer of the anterior small intestine, by weight, comprises: 7-10 parts of sodium cholate, 35-40 parts of dimethylaminoethyl methacrylate, 15-20 parts of ethylene glycol dimethacrylate, 0.1-0.3 parts of azobisisobutyronitrile, 10-19 parts of glyceryl caprylate, 10-19 parts of monodecanoate, 5-7 parts of gelatin, 0.05-0.1 parts of Tween-80, and 0.2-0.5 parts of calcium chloride.

4. The sustained-release porcine fat powder according to claim 1, characterized in that, The microbial response sustained-release layer of the posterior small intestine, by weight, comprises: 10-15 parts linoleic acid, 10-15 parts linolenic acid, 1-3 parts docosahexaenoic acid, 15-20 parts palmitic acid, 1-3 parts vitamin A, 1-3 parts vitamin E, 0.6-1 part lecithin, 0.6-1 part Tween 80, 31-58 parts β-glucan, 0.3-0.8 parts calcium chloride, 2-4 parts xanthan gum, and 1-3 parts gum arabic.

5. The sustained-release porcine fat powder according to claim 1, characterized in that, The sodium butyrate to sodium bicarbonate ratio is 1:1 by mass.

6. The sustained-release porcine fat powder according to claim 1, characterized in that, The mass ratio of genipin to the bile acid-responsive controlled-release microspheres in the anterior small intestine is 1:0.005.

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