Green feed additive and preparation method thereof

Abstract

This invention discloses a green feed additive and its preparation method, relating to the field of feed additive technology. The key technical points include the following steps: Step 1: Mixing glyceryl butyrate, fumaric acid, citric acid, plant essential oil, hydrogenated vegetable oil, glyceryl monostearate, and lecithin, followed by melt emulsification and spray condensation granulation to obtain acid-oil composite core particles; Step 2: Placing the acid-oil composite core particles in a coating solution formed by zein, low-methoxyl pectin, and sodium alginate, followed by fluidized bed spray coating and calcium ion solidification to obtain intestinal slow-release acid-oil microparticles; By first preparing acid-oil composite core particles from organic acids, glyceryl butyrate, and plant essential oil, and then coating them with zein, low-methoxyl pectin, and sodium alginate, and solidifying them with calcium ions, intestinal slow-release acid-oil microparticles are formed.

Description

Technical Field

[0001] This invention relates to the field of feed additive technology, specifically to a green feed additive and its preparation method. Background Technology

[0002] With the implementation of the ban on antibiotics in feed, the use of growth-promoting drug feed additives in livestock and poultry diets has been restricted. Therefore, the development of green feed additives using organic acids, plant essential oils, probiotics, prebiotics, and natural antioxidants has become an important direction for antibiotic-free feed development.

[0003] Weaned piglets have incompletely developed digestive systems and limited gastric acid secretion capacity, making their gut microbiota susceptible to weaning stress, dietary transitions, and environmental changes. In antibiotic-free, low-zinc diets, feed companies typically use butyrate, fumaric acid, citric acid, plant essential oils, Bacillus subtilis, and oligosaccharides to improve the intestinal environment. However, in some piglet compound feeds using 80-85℃ pelleting processes, ordinary direct-mix additives still have the following shortcomings: organic acids and plant essential oils, when added directly to the feed, are released too quickly in the foregut, easily producing strong odors and acid irritation, affecting palatability, and making it difficult to ensure that effective components reach the hindgut; plant essential oils and organic acids have certain antibacterial properties, and if they come into direct contact with probiotics for a long time, they can easily reduce the viability of Bacillus subtilis, especially when the product is damp, heat-treated, or when storage conditions fluctuate. Summary of the Invention

[0004] The purpose of this invention is to provide a green feed additive and its preparation method to solve the problems of excessively rapid initial release, decreased probiotic activity, loss of essential oils due to volatilization, and insufficient adaptability to heat pelleting when organic acids, plant essential oils, and probiotics are directly compounded in existing antibiotic-free piglet feeds.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a green feed additive and its preparation method, comprising the following steps: Step 1: Mix glyceryl butyrate, fumaric acid, citric acid, plant essential oil, hydrogenated vegetable oil, glyceryl monostearate and lecithin, and perform melt emulsification and spray condensation granulation to obtain acid-oil composite core particles; Step 2: The acid-oil composite core particles are placed in a coating solution formed by zein, low-methoxyl pectin and sodium alginate, and then coated by fluidized bed spray coating and calcium ion solidification to obtain intestinal slow-release acid-oil microparticles. Step 3: Mix yeast cell wall, resistant dextrin, xylooligosaccharide, sodium alginate, trehalose and deionized water and granulate to obtain prebiotic carrier wet particles. Then load Bacillus subtilis spore powder and Bacillus coagulans spore powder into the prebiotic carrier wet particles to obtain probiotic carrier particles. Step 4: Coat the probiotic carrier particles with resistant starch, zein and low-methoxyl pectin in a low-temperature fluidized bed to obtain granulation-resistant probiotic microparticles; Step 5: Mix the intestinal slow-release acid oil microparticles, granulation-resistant probiotic microparticles, yeast selenium, rosemary extract and rice bran fiber to obtain a green feed additive.

[0006] Furthermore, the specific preparation steps of the acid-oil composite core particles are as follows: Hydrogenated vegetable oil, glyceryl monostearate, and lecithin are added to a melting vessel and stirred for 20-40 minutes at 65-80℃ and 300-600 r / min to obtain a molten wall material. Glyceryl butyrate, fumaric acid, citric acid, and vegetable essential oil are added to the molten wall material and emulsified for 10-25 minutes at 65-75℃ and 800-1200 r / min. Then, the mixture is spray-condensed and granulated at an inlet air temperature of 10-18℃ and an atomization pressure of 0.20-0.45 MPa to obtain acid-oil composite core particles.

[0007] Furthermore, the ratio of butyrate, fumaric acid, citric acid, plant essential oil, hydrogenated vegetable oil, glyceryl monostearate, and lecithin is 25-45g: 8-20g: 5-15g: 1.5-6g: 18-35g: 5-12g: 0.5-2g; the plant essential oil is one or more of oregano oil, cinnamaldehyde, thymol, and carvacrol.

[0008] Furthermore, the specific preparation steps of the intestinal sustained-release acid oil microparticles are as follows: Zeat protein was dissolved in a 70-85 wt% ethanol solution, and low-methoxyl pectin and sodium alginate were added. The mixture was stirred at 25-35℃ for 30-50 min to obtain a coating solution. The acid-oil composite core particles were placed in a fluidized bed and sprayed with the coating solution under the conditions of an inlet air temperature of 35-45℃ and an atomization pressure of 0.12-0.30 MPa. Then, calcium chloride aqueous solution was sprayed for calcium ion solidification. The mixture was dried at 40-45℃ for 20-40 min to obtain intestinal slow-release acid-oil microparticles.

[0009] Furthermore, the ratio of the acid oil composite core particles, zein, low-methoxyl pectin, sodium alginate, and calcium chloride is 100g:4-10g:2-6g:1-4g:0.5-2g; the D50 particle size of the intestinal slow-release acid oil microparticles is 150-450μm, the release rate in simulated gastric fluid at pH 2.0 is 10-35% in 2 hours, and the cumulative release rate in simulated intestinal fluid at pH 6.8 is 70-95% in 6 hours.

[0010] Furthermore, the specific preparation steps of the probiotic carrier particles are as follows: Yeast cell walls, resistant dextrin, xylooligosaccharides, sodium alginate, trehalose, and deionized water are added to a granulator and granulated at 20-30℃ and 200-500 r / min to obtain prebiotic carrier wet granules. When the moisture content of the prebiotic carrier wet granules is 18-26wt%, Bacillus subtilis spore powder and Bacillus coagulans spore powder are added and mixed at 20-28℃ for 10-20 min to load the spore powder onto the surface and pores of the prebiotic carrier wet granules, thus obtaining probiotic carrier granules.

[0011] Furthermore, the ratio of yeast cell wall, resistant dextrin, xylooligosaccharide, sodium alginate, trehalose, Bacillus subtilis spore powder, and Bacillus coagulans spore powder is 20-40g: 15-35g: 5-15g: 1-5g: 2-8g: 5-15g: 3-10g; the viable count of the Bacillus subtilis spore powder is not less than 1.0×10¹. 0 The viable count of the Bacillus coagulans spore powder is not less than 1.0 × 10¹ CFU / g. 0 CFU / g.

[0012] Furthermore, the specific preparation steps of the granulation-resistant probiotic microparticles are as follows: Probiotic carrier particles are placed in a fluidized bed and sprayed with a protective coating solution composed of resistant starch, zein, and low-methoxyl pectin under conditions of inlet air temperature of 30-40℃ and material temperature not exceeding 38℃. After spraying, the particles are dried at 35-40℃ for 25-50 minutes to obtain granulation-resistant probiotic microparticles. The ratio of probiotic carrier particles, resistant starch, zein, and low-methoxyl pectin is 100g:8-20g:2-8g:1-5g.

[0013] Furthermore, in step five, the ratio of the intestinal slow-release acid oil microparticles, granulation-resistant probiotic microparticles, yeast selenium, rosemary extract, and rice bran fiber is 35-55g: 30-50g: 0.05-0.30g: 0.5-3g: 8-25g; the mixing temperature is 20-30℃, the mixing time is 8-20min, and the moisture content of the green feed additive obtained after mixing is not higher than 8wt%, and the D50 particle size is 250-700μm.

[0014] A green feed additive is prepared by the above-described preparation method. The green feed additive includes intestinal slow-release acid oil microparticles and granulation-resistant probiotic microparticles that are independently distributed. The intestinal slow-release acid oil microparticles are used to delay the release of organic acids and plant essential oils, and the granulation-resistant probiotic microparticles are used to improve the viable bacteria retention rate of probiotics during granulation and storage. The total viable bacteria retention rate of the green feed additive is not less than 75% after heat treatment at 85°C for 90 seconds.

[0015] Compared with existing technologies, this invention provides a green feed additive and its preparation method, which has the following beneficial effects: Organic acids, butyrate glycerides, and plant essential oils are first prepared into acid-oil composite core particles, which are then coated with zein, low-methoxyl pectin, and sodium alginate and solidified with calcium ions to form intestinal slow-release acid-oil microparticles. This structure can reduce the rapid release of organic acids and plant essential oils in the forestomy, reduce the impact of acidity and essential oil odor on palatability, and increase the proportion of effective components reaching the intestines.

[0016] By loading Bacillus subtilis spore powder and Bacillus coagulans spore powder into prebiotic carrier particles formed by yeast cell walls, resistant dextrin, and xylooligosaccharides, and then coating them at low temperature with resistant starch, zein, and low-methoxyl pectin, granulation-resistant probiotic microparticles are obtained. This structure can reduce the damage to Bacillus spores caused by heat, acid, and essential oils during hot granulation and storage.

[0017] By having intestinal slow-release acid oil microparticles and granulation-resistant probiotic microparticles exist as independent functional microparticles, rather than directly mixing acids, essential oils and probiotics in the same particle, the direct contact between acidic components and plant essential oils and probiotics is structurally reduced, thereby improving the live bacteria stability of the product under humid, heat-granulated and storage conditions.

[0018] Using yeast selenium and rosemary extract as auxiliary functional components can improve the antioxidant stability of the product; rice bran fiber as a dispersing carrier helps to improve the product's flowability, mixing uniformity and feed compatibility. Attached Figure Description

[0019] Figure 1 The image shows a cross-sectional SEM image of the intestinal sustained-release acid oil microparticles of Example 3 and the uncoated acid oil composite core particles of Comparative Example 1.

[0020] Figure 2 The images show surface SEM images of the granulated probiotic microparticles of Example 3 and the unprotected coated probiotic carrier particles of Comparative Example 3 after heat treatment at 85°C for 90 seconds. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figures 1-2 This invention provides a technical solution for a green feed additive and its preparation method: Unless otherwise specified, in the following examples and comparative examples, the plant essential oil is composed of oregano oil, thymol, and carvacrol in a mass ratio of 2:1:1; the viable count of Bacillus subtilis spores is 2.0 × 10¹. 0 CFU / g, viable count of Bacillus coagulans spores was 1.5 × 10¹ 0 CFU / g; Corn gliadin, low-methoxyl pectin, sodium alginate, resistant starch, resistant dextrin, xylooligosaccharides, yeast cell wall, trehalose, yeast selenium, rosemary extract and rice bran fiber are all feed-grade raw materials.

[0023] Example 1: A method for preparing a green feed additive, comprising the following steps: S1: Add 18g hydrogenated vegetable oil, 5g glyceryl monostearate and 0.5g lecithin to a melting vessel and stir for 20min at 65℃ and 300r / min to obtain molten wall material; add 25g glyceryl butyrate, 8g fumaric acid, 5g citric acid and 1.5g vegetable essential oil to the molten wall material and emulsify for 10min at 65℃ and 800r / min, then spray condense and granulate under an inlet air temperature of 10℃ and an atomization pressure of 0.20MPa to obtain acid-oil composite core particles.

[0024] S2: Dissolve zein in a 70wt% ethanol solution, add low-methoxyl pectin and sodium alginate, and stir at 25℃ for 30 min to obtain a coating solution; place 100g of acid-oil composite core particles in a fluidized bed, and spray with a coating solution containing 4g zein, 2g low-methoxyl pectin and 1g sodium alginate under the conditions of inlet air temperature of 35℃ and atomization pressure of 0.12MPa, and then spray with an aqueous solution containing 0.5g calcium chloride for calcium ion solidification, and dry at 40℃ for 20 min to obtain intestinal slow-release acid-oil microparticles.

[0025] S3: Add 20g yeast cell wall, 15g resistant dextrin, 5g xylooligosaccharide, 1g sodium alginate, 2g trehalose and deionized water to a granulator and granulate at 20℃ and 200r / min to obtain prebiotic carrier wet granules with a water content of 26wt%; add 5g Bacillus subtilis spore powder and 3g Bacillus coagulans spore powder and mix at 20℃ for 10min to obtain probiotic carrier granules.

[0026] S4: Place 100g of probiotic carrier particles in a fluidized bed. Under the conditions of an inlet air temperature of 30℃ and a material temperature not exceeding 38℃, spray a protective coating solution consisting of 8g of resistant starch, 2g of zein and 1g of low methoxyl pectin. After spraying, dry at 35℃ for 25min to obtain granulation-resistant probiotic microparticles.

[0027] S5: Mix 35g of intestinal slow-release acid oil microparticles, 50g of granulation-resistant probiotic microparticles, 0.05g of yeast selenium, 0.5g of rosemary extract and 8g of rice bran fiber, and mix at 20℃ for 8 minutes to obtain a green feed additive.

[0028] Example 2, a method for preparing a green feed additive, comprising the following steps: S1: Add 22g hydrogenated vegetable oil, 7g glyceryl monostearate and 0.8g lecithin to a melting vessel and stir for 25min at 68℃ and 380r / min to obtain molten wall material; add 30g glyceryl butyrate, 11g fumaric acid, 7.5g citric acid and 2.5g vegetable essential oil to the molten wall material and emulsify for 14min at 68℃ and 900r / min, then spray condense and granulate under an inlet air temperature of 12℃ and an atomization pressure of 0.26MPa to obtain acid-oil composite core particles.

[0029] S2: Dissolve zein in a 74wt% ethanol solution, add low-methoxyl pectin and sodium alginate, and stir at 28℃ for 35 min to obtain a coating solution; place 100g of acid-oil composite core particles in a fluidized bed, and spray with a coating solution containing 5.5g zein, 3g low-methoxyl pectin and 1.8g sodium alginate under the conditions of inlet air temperature of 38℃ and atomization pressure of 0.16MPa, and then spray with an aqueous solution containing 0.9g calcium chloride for calcium ion solidification, and dry at 41℃ for 25 min to obtain intestinal slow-release acid-oil microparticles.

[0030] S3: Add 25g yeast cell wall, 20g resistant dextrin, 7g xylooligosaccharide, 2g sodium alginate, 3.5g trehalose and deionized water to a granulator and granulate at 23℃ and 280r / min to obtain prebiotic carrier wet granules with a water content of 24wt%; add 8g Bacillus subtilis spore powder and 4.5g Bacillus coagulans spore powder and mix at 22℃ for 12min to obtain probiotic carrier granules.

[0031] S4: Place 100g of probiotic carrier particles in a fluidized bed. Under the conditions of an inlet air temperature of 32℃ and a material temperature not exceeding 38℃, spray a protective coating solution consisting of 11g of resistant starch, 3.5g of zein and 2g of low methoxyl pectin. After spraying, dry at 36℃ for 30min to obtain granulation-resistant probiotic microparticles.

[0032] S5: Mix 40g of intestinal slow-release acid oil microparticles, 45g of granulation-resistant probiotic microparticles, 0.10g of yeast selenium, 1g of rosemary extract and 12g of rice bran fiber, and mix at 23℃ for 10 minutes to obtain a green feed additive.

[0033] Example 3, a method for preparing a green feed additive, comprising the following steps: S1: Add 26.5g hydrogenated vegetable oil, 8.5g glyceryl monostearate and 1.25g lecithin to a melting vessel and stir for 30min at 72℃ and 450r / min to obtain molten wall material; add 35g glyceryl butyrate, 14g fumaric acid, 10g citric acid and 3.8g vegetable essential oil to the molten wall material and emulsify for 18min at 70℃ and 1000r / min, then spray condense and granulate under an inlet air temperature of 14℃ and an atomization pressure of 0.32MPa to obtain acid-oil composite core particles.

[0034] S2: Dissolve zein in a 78wt% ethanol solution, add low-methoxyl pectin and sodium alginate, and stir at 30℃ for 40 min to obtain a coating solution; place 100g of acid-oil composite core particles in a fluidized bed, and spray with a coating solution containing 7g zein, 4g low-methoxyl pectin and 2.5g sodium alginate under the conditions of inlet air temperature of 40℃ and atomization pressure of 0.20MPa, and then spray with an aqueous solution containing 1.2g calcium chloride for calcium ion solidification, and dry at 42℃ for 30 min to obtain intestinal slow-release acid-oil microparticles.

[0035] S3: Add 30g yeast cell wall, 25g resistant dextrin, 10g xylooligosaccharide, 3g sodium alginate, 5g trehalose and deionized water to a granulator and granulate at 25℃ and 350r / min to obtain prebiotic carrier wet granules with a water content of 22wt%; add 10g Bacillus subtilis spore powder and 6.5g Bacillus coagulans spore powder and mix at 25℃ for 15min to obtain probiotic carrier granules.

[0036] S4: Place 100g of probiotic carrier particles in a fluidized bed. Under the conditions of an inlet air temperature of 35℃ and a material temperature not exceeding 38℃, spray a protective coating solution consisting of 14g of resistant starch, 5g of zein and 3g of low methoxyl pectin. After spraying, dry at 38℃ for 38 minutes to obtain granulation-resistant probiotic microparticles.

[0037] S5: Mix 45g of intestinal slow-release acid oil microparticles, 40g of granulation-resistant probiotic microparticles, 0.18g of yeast selenium, 1.8g of rosemary extract and 16g of rice bran fiber, and mix at 25℃ for 14 minutes to obtain a green feed additive.

[0038] Example 4: A method for preparing a green feed additive, comprising the following steps: S1: Add 31g hydrogenated vegetable oil, 10g glyceryl monostearate and 1.6g lecithin to a melting vessel and stir for 35min at 76℃ and 520r / min to obtain molten wall material; add 40g glyceryl butyrate, 17g fumaric acid, 12.5g citric acid and 5g vegetable essential oil to the molten wall material and emulsify for 22min at 73℃ and 1100r / min, then spray condense and granulate under an inlet air temperature of 16℃ and an atomization pressure of 0.38MPa to obtain acid-oil composite core particles.

[0039] S2: Dissolve zein in an 82wt% ethanol solution, add low-methoxyl pectin and sodium alginate, and stir at 33℃ for 45 min to obtain a coating solution; place 100g of acid-oil composite core particles in a fluidized bed, and spray with a coating solution containing 8.5g zein, 5g low-methoxyl pectin and 3.2g sodium alginate under the conditions of inlet air temperature of 43℃ and atomization pressure of 0.25MPa, and then spray with an aqueous solution containing 1.6g calcium chloride for calcium ion solidification, and dry at 44℃ for 35 min to obtain intestinal slow-release acid-oil microparticles.

[0040] S3: Add 35g yeast cell wall, 30g resistant dextrin, 12g xylooligosaccharide, 4g sodium alginate, 6.5g trehalose and deionized water to a granulator and granulate at 28℃ and 420r / min to obtain prebiotic carrier wet granules with a water content of 20wt%; add 12g Bacillus subtilis spore powder and 8g Bacillus coagulans spore powder and mix at 27℃ for 18min to obtain probiotic carrier granules.

[0041] S4: Place 100g of probiotic carrier particles in a fluidized bed. Under the conditions of an inlet air temperature of 38℃ and a material temperature not exceeding 38℃, spray a protective coating solution consisting of 17g of resistant starch, 6.5g of zein and 4g of low-methoxyl pectin. After spraying, dry at 39℃ for 45min to obtain granulation-resistant probiotic microparticles.

[0042] S5: Mix 50g of intestinal slow-release acid oil microparticles, 35g of granulation-resistant probiotic microparticles, 0.24g of yeast selenium, 2.4g of rosemary extract and 20g of rice bran fiber, and mix at 28℃ for 17 minutes to obtain a green feed additive.

[0043] Example 5: A method for preparing a green feed additive, comprising the following steps: S1: Add 35g hydrogenated vegetable oil, 12g glyceryl monostearate and 2g lecithin to a melting vessel and stir for 40min at 80℃ and 600r / min to obtain molten wall material; add 45g glyceryl butyrate, 20g fumaric acid, 15g citric acid and 6g vegetable essential oil to the molten wall material and emulsify for 25min at 75℃ and 1200r / min, then spray condense and granulate under an inlet air temperature of 18℃ and an atomization pressure of 0.45MPa to obtain acid-oil composite core particles.

[0044] S2: Dissolve zein in an 85wt% ethanol solution, add low-methoxyl pectin and sodium alginate, and stir at 35℃ for 50 min to obtain a coating solution; place 100g of acid-oil composite core particles in a fluidized bed, and spray with a coating solution containing 10g of zein, 6g of low-methoxyl pectin and 4g of sodium alginate under the conditions of inlet air temperature of 45℃ and atomization pressure of 0.30MPa, and then spray with an aqueous solution containing 2g of calcium chloride for calcium ion solidification, and dry at 45℃ for 40 min to obtain intestinal slow-release acid-oil microparticles.

[0045] S3: Add 40g yeast cell wall, 35g resistant dextrin, 15g xylooligosaccharide, 5g sodium alginate, 8g trehalose and deionized water to a granulator and granulate at 30℃ and 500r / min to obtain prebiotic carrier wet granules with a water content of 18wt%; add 15g Bacillus subtilis spore powder and 10g Bacillus coagulans spore powder and mix at 28℃ for 20min to obtain probiotic carrier granules.

[0046] S4: Place 100g of probiotic carrier particles in a fluidized bed. Under the conditions of an inlet air temperature of 40℃ and a material temperature not exceeding 38℃, spray a protective coating solution consisting of 20g of resistant starch, 8g of zein and 5g of low methoxyl pectin. After spraying, dry at 40℃ for 50min to obtain granulation-resistant probiotic microparticles.

[0047] S5: Mix 55g of intestinal slow-release acid oil microparticles, 30g of granulation-resistant probiotic microparticles, 0.30g of yeast selenium, 3g of rosemary extract and 25g of rice bran fiber, and mix at 30℃ for 20 minutes to obtain a green feed additive.

[0048] The difference between Comparative Example 1 and Example 3 is that in step S2, zein, low-methoxyl pectin and sodium alginate coating are not used, and calcium ion curing is not performed. The acid-oil composite core particles obtained in step S1 are directly used as acid-oil microparticles. The remaining steps and parameters are the same as in Example 3.

[0049] The difference between Comparative Example 2 and Example 3 is that after spraying the coating liquid in step S2, calcium chloride aqueous solution is no longer sprayed for calcium ion curing. The remaining steps and parameters are the same as in Example 3.

[0050] The difference between Comparative Example 3 and Example 3 is that in step S4, resistant starch, zein and low methoxyl pectin are not used to protect the probiotic carrier particles. Instead, the probiotic carrier particles obtained in step S3 are directly used as probiotic microparticles. The remaining steps and parameters are the same as in Example 3.

[0051] The difference between Comparative Example 4 and Example 3 is that the intestinal slow-release acid oil microparticles and granulation-resistant probiotic microparticles are not distributed independently. Instead, an equal amount of acid oil composite core particles from Example 3 are added together with Bacillus subtilis spore powder and Bacillus coagulans spore powder into prebiotic carrier wet particles to form the same composite particles. Then, the same coating is performed according to step S4 of Example 3. The remaining steps and parameters are the same as in Example 3.

[0052] The difference between Comparative Example 5 and Example 3 is that yeast cell walls, resistant dextrin, and xylooligosaccharides are not added in step S3, but an equal mass of rice bran fiber is used to form carrier particles. The remaining steps and parameters are the same as in Example 3.

[0053] Performance testing methods (1) Moisture test: The test was conducted in accordance with GB / T 6435-2014 "Determination of moisture in feed". Each group was tested in parallel for 3 times and the average value was taken.

[0054] (2) Particle size test: The particle size was tested according to GB / T 5917.1-2008 "Determination of particle size of feed crushing by two-layer sieve sieving method" and the D50 particle size was measured by laser particle size analyzer. Each group was tested 3 times and the average value was taken.

[0055] (3) Viable count test: Bacillus subtilis was tested according to GB / T 26428-2010 "Detection of Bacillus subtilis in feed microbial preparations"; Bacillus coagulans was counted using the same type of Bacillus plate counting method, and the results were expressed as total viable count.

[0056] (4) Heat treatment viable cell retention rate test: The sample was placed in a simulated granulation heat treatment device and treated at 85℃ for 90s. After cooling to room temperature, the total viable cell count was measured, and the viable cell retention rate was calculated according to the following formula: Viable cell retention rate / % = Total viable cells after heat treatment / Total viable cells before heat treatment × 100%.

[0057] (5) Test of viable bacteria retention rate: The sample was sealed and stored in a constant temperature and humidity chamber at 40℃ and 75% relative humidity for 60 days. After storage, the total number of viable bacteria was measured and the viable bacteria retention rate was calculated.

[0058] (6) Release rate test: The test was conducted in accordance with the "Dissolution and Release Determination Method" in General Chapter 0931 of the 2025 edition of the Chinese Pharmacopoeia. The sample was placed in simulated gastric fluid at pH 2.0 and released at 37°C and 100 r / min for 2 h. The combined release rate of butyric acid glyceride, fumaric acid and citric acid was then determined. Subsequently, the sample was transferred to simulated intestinal fluid at pH 6.8 and released for another 6 h. The cumulative release rate was then determined.

[0059] (7) Salmonella test: The test shall be conducted in accordance with GB / T 13091-2018 "Determination of Salmonella in Feed".

[0060] (8) Tests for lead, total arsenic and cadmium: conducted in accordance with GB / T 13080-2018, GB / T 13079-2022 and GB / T13082-2021 respectively.

[0061] Table 1

[0062] Table 2

[0063] Table 3 shows the test results of the safety indicators of the green feed additive obtained in Example 3.

[0064] As shown in Tables 1 and 2, the moisture content of the green feed additives obtained in Examples 1-5 is all below 8 wt%, and the D50 particle size is 286-642 μm, which is within the range of 250-700 μm defined in the claims. This indicates that the preparation method of the present invention can form a particle morphology suitable for compound feed mixing and pelleting.

[0065] Examples 1-5 showed a release rate of 18.2-28.6% in simulated gastric juice after 2 hours and a cumulative release rate of 76.4-89.5% in simulated intestinal juice after 6 hours, exhibiting a clear characteristic of low release in the stomach and high release in the intestine. Specifically, Example 3 showed a release rate of 18.2% in simulated gastric juice after 2 hours and a cumulative release rate of 89.5% in simulated intestinal juice after 6 hours, indicating that the coating structure composed of zein, low-methoxyl pectin, sodium alginate, and calcium ion solidification can effectively delay the release of acidic oil components in the anterior stomach.

[0066] In Comparative Example 1, without the acid-oil microparticle coating structure, the release rate of simulated gastric juice increased to 69.4% after 2 hours, while the cumulative release rate of simulated intestinal juice was only 55.8% after 6 hours. This indicates that the acid-oil component is released in large quantities prematurely in the gastric juice stage, which is detrimental to its release and stable utilization in the hindgut. In Comparative Example 2, after removing calcium ion solidification, the release rate of simulated gastric juice increased to 43.7% after 2 hours, indicating that calcium ion solidification can improve the structural stability of the low-methoxyl pectin and sodium alginate coating layers.

[0067] After heat treatment at 85°C for 90 seconds, the total viable cell retention rate of Examples 1-5 was 76.8%-84.7%, all meeting the requirement of not less than 75% in the claims. Among them, the viable cell retention rate of Example 3 after heat treatment was 84.7%, and the viable cell retention rate after storage at 40°C for 60 days was 79.1%, indicating that the granulation-resistant probiotic microparticles have a good processing and storage protection effect on Bacillus spores.

[0068] In Comparative Example 3, after the probiotic protective coating was removed, the viable bacteria retention rate after heat treatment dropped to 49.5%, and the viable bacteria retention rate after 60 days of storage at 40℃ dropped to 52.4%. This indicates that the low-temperature fluidized bed protective coating composed of resistant starch, zein and low-methoxyl pectin plays a key role in improving the stability of probiotic heat granulation.

[0069] In Comparative Example 4, after eliminating the independent distribution structure of acid oil particles and probiotic particles, the viable bacteria retention rate decreased to 57.1% after heat treatment and to 54.3% after 60 days of storage at 40℃. Simultaneously, the release rate from simulated gastric fluid increased to 33.6% over 2 hours, while the cumulative release rate from simulated intestinal fluid decreased to 71.8% over 6 hours. This indicates that when organic acids, plant essential oils, and spore-forming bacteria are contained within the same particle, the acid oil component causes contact damage to the probiotics and reduces sustained-release stability.

[0070] In Comparative Example 5, after removing the prebiotic carrier composed of yeast cell wall, resistant dextrin, and xylooligosaccharide, although the acid oil release performance was similar to that of Example 3, the viable cell retention rate after heat treatment decreased to 72.6%, and the viable cell retention rate after 60 days of storage decreased to 63.8%. This indicates that the prebiotic carrier is not only a common filler, but can also improve the stability of spore loading and storage stability.

[0071] Figure 1 In Example 3, a continuous and dense coating layer is formed, which can reduce the rapid release into gastric juice; in Comparative Example 1, there is no continuous outer shell structure, and the core material is easily exposed prematurely. Figure 2 In Example 3, after heat treatment at 85°C for 90 seconds, the surface structure remained relatively intact; in Comparative Example 3, due to the lack of protective coating, obvious cracking, collapse, and increased porosity were observed.

[0072] Therefore, this invention, through the independent dual-microparticle structure of intestinal slow-release acid oil microparticles and granulation-resistant probiotic microparticles, combined with prebiotic carriers, low-temperature protective coating, and final low-temperature mixing process, improves the gastrointestinal release, heat granulation survival, and storage stability of green feed additives, demonstrating outstanding substantive features and significant progress.

Claims

1. A method of preparing a green feed additive, characterized by: Includes the following steps: Step 1: Mix glyceryl butyrate, fumaric acid, citric acid, plant essential oil, hydrogenated vegetable oil, glyceryl monostearate and lecithin, and perform melt emulsification and spray condensation granulation to obtain acid-oil composite core particles; Step 2: The acid-oil composite core particles are placed in a coating solution formed by zein, low-methoxyl pectin and sodium alginate, and then coated by fluidized bed spray coating and calcium ion solidification to obtain intestinal slow-release acid-oil microparticles. Step 3: Mix yeast cell wall, resistant dextrin, xylooligosaccharide, sodium alginate, trehalose and deionized water and granulate to obtain prebiotic carrier wet particles. Then load Bacillus subtilis spore powder and Bacillus coagulans spore powder into the prebiotic carrier wet particles to obtain probiotic carrier particles. Step 4: Coat the probiotic carrier particles with resistant starch, zein and low-methoxyl pectin in a low-temperature fluidized bed to obtain granulation-resistant probiotic microparticles; Step 5: Mix the intestinal slow-release acid oil microparticles, granulation-resistant probiotic microparticles, yeast selenium, rosemary extract and rice bran fiber to obtain a green feed additive.

2. The method for preparing a green feed additive according to claim 1, characterized in that: The specific preparation steps of the acid-oil composite core particles are as follows: Hydrogenated vegetable oil, glyceryl monostearate, and lecithin are added to a melting vessel and stirred for 20-40 minutes at 65-80℃ and 300-600 r / min to obtain a molten wall material. Glyceryl butyrate, fumaric acid, citric acid, and vegetable essential oil are added to the molten wall material and emulsified for 10-25 minutes at 65-75℃ and 800-1200 r / min. Then, the mixture is spray-condensed and granulated at an inlet air temperature of 10-18℃ and an atomization pressure of 0.20-0.45 MPa to obtain acid-oil composite core particles.

3. A method of preparing a green feed additive according to claim 2, characterized in that: The ratio of butyric acid glyceride, fumaric acid, citric acid, plant essential oil, hydrogenated vegetable oil, glyceryl monostearate and lecithin is 25-45g: 8-20g: 5-15g: 1.5-6g: 18-35g: 5-12g: 0.5-2g; the plant essential oil is one or more of oregano oil, cinnamaldehyde, thymol and carvacrol.

4. The method for preparing a green feed additive according to claim 1, characterized in that: The specific preparation steps for the intestinal sustained-release acid oil microparticles are as follows: Zeat protein was dissolved in a 70-85 wt% ethanol solution, and low-methoxyl pectin and sodium alginate were added. The mixture was stirred at 25-35℃ for 30-50 min to obtain a coating solution. The acid-oil composite core particles were placed in a fluidized bed and sprayed with the coating solution under the conditions of an inlet air temperature of 35-45℃ and an atomization pressure of 0.12-0.30 MPa. Then, calcium chloride aqueous solution was sprayed for calcium ion solidification. The mixture was dried at 40-45℃ for 20-40 min to obtain intestinal slow-release acid-oil microparticles.

5. The method for preparing a green feed additive according to claim 4, characterized in that: The ratio of the acid oil composite core particles, zein, low-methoxyl pectin, sodium alginate, and calcium chloride is 100g:4-10g:2-6g:1-4g:0.5-2g; the D50 particle size of the intestinal slow-release acid oil microparticles is 150-450μm, the release rate is 10-35% in simulated gastric fluid at pH 2.0 after 2 hours, and the cumulative release rate is 70-95% in simulated intestinal fluid at pH 6.8 after 6 hours.

6. The method for preparing a green feed additive according to claim 1, characterized in that: The specific preparation steps for the probiotic carrier particles are as follows: Yeast cell walls, resistant dextrin, xylooligosaccharides, sodium alginate, trehalose, and deionized water are added to a granulator and granulated at 20-30℃ and 200-500 r / min to obtain prebiotic carrier wet granules. When the moisture content of the prebiotic carrier wet granules is 18-26wt%, Bacillus subtilis spore powder and Bacillus coagulans spore powder are added and mixed at 20-28℃ for 10-20 min to load the spore powder onto the surface and pores of the prebiotic carrier wet granules, thus obtaining probiotic carrier granules.

7. A method of preparing a green feed additive according to claim 6, characterized by: The ratio of yeast cell wall, resistant dextrin, xylooligosaccharide, sodium alginate, trehalose, Bacillus subtilis spore powder, and Bacillus coagulans spore powder is 20-40g: 15-35g: 5-15g: 1-5g: 2-8g: 5-15g: 3-10g; the viable count of the Bacillus subtilis spore powder is not less than 1.0×10¹. 0 The viable count of the Bacillus coagulans spore powder is not less than 1.0 × 10¹ CFU / g. 0 CFU / g.

8. The method for preparing a green feed additive according to claim 1, characterized in that: The specific preparation steps for the granulation-resistant probiotic microparticles are as follows: Probiotic carrier particles are placed in a fluidized bed and sprayed with a protective coating solution composed of resistant starch, zein, and low-methoxyl pectin under conditions of inlet air temperature of 30-40℃ and material temperature not exceeding 38℃. After spraying, the particles are dried at 35-40℃ for 25-50 minutes to obtain granulation-resistant probiotic microparticles. The ratio of probiotic carrier particles, resistant starch, zein, and low-methoxyl pectin is 100g:8-20g:2-8g:1-5g.

9. The method for preparing a green feed additive according to claim 1, characterized in that: In step five, the ratio of the intestinal slow-release acid oil microparticles, granulation-resistant probiotic microparticles, yeast selenium, rosemary extract, and rice bran fiber is 35-55g: 30-50g: 0.05-0.30g: 0.5-3g: 8-25g; the mixing temperature is 20-30℃, the mixing time is 8-20min, and the moisture content of the green feed additive obtained after mixing is not higher than 8wt%, and the D50 particle size is 250-700μm.

10. A green feed additive, characterized by, The green feed additive is prepared by the preparation method according to any one of claims 1-9; the green feed additive includes intestinal slow-release acid oil microparticles and granulation-resistant probiotic microparticles that are independently distributed, wherein the intestinal slow-release acid oil microparticles are used to delay the release of organic acids and plant essential oils, and the granulation-resistant probiotic microparticles are used to improve the viable bacteria retention rate of probiotics during granulation and storage, and the total viable bacteria retention rate of the green feed additive is not less than 75% after heat treatment at 85°C for 90s.

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