Preparation method of protein-based microcapsule coated emulsified feed

Abstract

The invention discloses a preparation method of a protein-based micro-capsule coated emulsified feed, and relates to the technical field of feeds. The method comprises the following steps: S1, adding a functional core material into a protein solution, emulsifying and cross-linking to obtain a protein-based microcapsule suspension; s2, performing low-temperature pre-drying on the protein-based microcapsule suspension to obtain a pre-dried material, and performing pulse vacuum drying to obtain protein-based microcapsule particles; s3, uniformly mixing the protein-based microcapsule particles with corn flour and bean foil powder to obtain the protein-based microcapsule coated emulsified feed. According to the method, an optimized drying process of low-temperature pre-drying and pulse vacuum drying is adopted, premature deformation of protein is avoided in the low-temperature pre-drying stage, and due to the alternating action of pulse vacuum, moisture in a material is periodically and rapidly volatilized, shrinkage and breakage of a micro-capsule structure are reduced, and the embedding rate is effectively increased. The method can shorten the feed preparation period and is suitable for large-scale production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of feed, in particular to a preparation method of protein-based microcapsule coated emulsified feed. BACKGROUND

[0002] China is a populous country and also a large country of animal husbandry. In 2020, China's pig population was 527 million, and the pork output was 41.13 million tons. In 2019, the total output of pork, beef, mutton and poultry meat was 76.49 million tons. Among them, the output of pork was 42.55 million tons, the output of beef was 6.67 million tons, the output of mutton was 4.88 million tons, the output of poultry meat was 22.39 million tons, the output of eggs was 33.09 million tons, and the output of milk was 32.01 million tons. In 2020, China's feed production was 253 million tons, up 10.4% year on year. Among them, the output of compound feed, concentrated feed and premixed feed additive was 230.705 million tons, 15.148 million tons and 5.945 million tons respectively. In 2020, China imported 100.33 million tons of soybeans from abroad. Therefore, in recent years, the shortage of feed resources has gradually become a bottleneck problem restricting the development of China's feed industry and animal husbandry.

[0003] In the prior art, emulsified feed has become an important development direction of the feed industry because it can improve the digestion and absorption rate of nutrients and improve the utilization rate of feed. Protein-based microcapsule coating technology can encapsulate functional ingredients such as oil, vitamins and probiotics in the microcapsule by the film-forming property of protein (such as soybean protein isolate, whey protein, fish protein, etc.), so as to avoid oxidation, degradation or loss of the functional ingredients during storage, transportation and processing, and at the same time reduce the adverse effects of functional ingredients on the palatability of feed. In the preparation process of protein-based microcapsule coated emulsified feed, the drying process is a key link affecting the integrity of the microcapsule, the embedding rate and the final quality of the feed. The commonly used drying methods in the industry include spray drying, freeze drying and hot air drying, but all have obvious defects: spray drying has high drying efficiency, but the protein is easily denatured excessively during atomization (the inlet air temperature is usually 180-220℃), which destroys the microcapsule structure and reduces the embedding rate; and the microcapsule particles after atomization are easy to agglomerate, which affects the dispersibility and palatability of the feed. Freeze drying can maximize the preservation of protein activity and microcapsule integrity, but the equipment cost is high, the energy consumption is large, and the drying period is long (usually 12-24h), which is difficult to realize industrialized mass production. The temperature uniformity of hot air drying is poor, the surface of the material is easy to form a hard shell, and the internal moisture is difficult to volatilize, which leads to incomplete drying, and long-term high temperature can easily cause oil oxidation and vitamin degradation, reducing the nutritional value of the feed.

[0004] Therefore, it is a core requirement for the industrialized production of protein-based microcapsule coated emulsified feed to develop a drying process with low energy consumption, high efficiency, and consideration of microcapsule integrity and nutritional retention rate. SUMMARY

[0005] The application aims to provide a preparation method of protein-based microcapsule coated emulsified feed to solve the problems of easy destruction of microcapsule structure and low embedding rate during the drying process of protein-based microcapsule coated emulsified feed.

[0006] The application can achieve the above-mentioned purpose through the following technical solutions. The application provides a preparation method of protein-based microcapsule coated emulsified feed, which comprises the following steps: S1. Adding a functional core material to a protein solution, and performing emulsification and cross-linking to obtain a protein-based microcapsule suspension; S2. Pre-drying the protein-based microcapsule suspension at low temperature to obtain a pre-dried material, and then performing pulse vacuum drying to obtain protein-based microcapsule particles; S3. Mixing the protein-based microcapsule particles with corn powder and soybean meal powder uniformly to obtain protein-based microcapsule coated emulsified feed.

[0007] The application provides a preparation method of protein-based microcapsule coated emulsified feed, which has at least the following beneficial effects: In the emulsification process, the functional core material is uniformly dispersed and wrapped inside the protein matrix to form a stable microcapsule structure, and the cross-linking enhances the structural strength and integrity of the microcapsule; the optimized drying process of low-temperature pre-drying and pulse vacuum drying can effectively improve the microcapsule embedding rate, reduce the oxidation and degradation of functional ingredients, and prolong the shelf life of the feed; the low-temperature pre-drying stage avoids premature deformation of the protein, so that the protein-based microcapsule surface layer slowly forms a dense but not hard membrane structure; through the alternating action of pulse vacuum, the internal moisture of the material is periodically and rapidly volatilized, while the destruction of the protein structure and the core material components by high temperature is avoided; the mild conditions of low temperature and pulse vacuum throughout the process can reduce the shrinkage and rupture of the microcapsule structure, thereby effectively improving the embedding rate. The physical properties of the protein-based microcapsule particles are similar to those of corn powder and soybean meal powder, and they are not prone to stratification or sedimentation when mixed; the three have good palatability, which improves the animal's feed intake; at the same time, the porous and loose structure of the microcapsule particles does not affect the flowability of the feed, which is convenient for subsequent processing. The method can shorten the feed preparation period and is suitable for large-scale production.

[0008] Further, in S1, the functional core material is composed of oil, vitamins and probiotics in a mass ratio of 5-8:1-2:0.5-1. Under this ratio, the animal can be provided with reasonable energy, essential trace elements and intestinal regulating factors, avoiding excessive or insufficient single nutrition, and improving the overall nutritional value of the feed; the solubility and wrapping effect of oil on vitamins can improve the retention rate of vitamins in the subsequent emulsification and drying process; the survival rate of probiotics in the water phase emulsion system is improved after being wrapped by the oil phase.

[0009] Further, the oil is one or any combination of fish oil and vegetable oil; the vitamin is any two or more of vitamin A, vitamin D, and vitamin E in any combination; and the probiotic is any combination of Bacillus subtilis and lactic acid bacteria. The combination of selected materials forms a uniform oil phase mixture, providing a basis for subsequent emulsification.

[0010] Further, in S1, the protein solution is composed of protein and deionized water in a solid-liquid ratio of 1:6-8, and the protein is one or any combination of soybean protein concentrate and rice protein concentrate. This solid-liquid ratio allows the protein solution to be placed at room temperature for 24 hours without stratification or precipitation, providing a stable aqueous phase system for subsequent emulsification. The appropriate concentration of the protein solution allows the thickness of the microcapsule wall material formed by subsequent cross-linking to be controlled at 1-3 μm, ensuring the core material wrapping rate and avoiding the difficulty of animal digestion and absorption caused by excessive wall material thickness.

[0011] Further, in S1, the mass of the functional core material is 12-18% of the mass of the protein solution. This ensures that the emulsion does not stratify when placed at room temperature, and avoids excessive or insufficient core material.

[0012] Further, in S1, the emulsification process includes first stirring at 60-70°C and a rotation speed of 900-1200 rpm for 20-30 min, and then homogenizing in a high-pressure homogenizer at 30-50 MPa for 2-3 times. After 2-step emulsification, the particle size distribution of the emulsion is uniform, and there is no stratification, which provides conditions for subsequent cross-linking to form uniform microcapsules.

[0013] Further, in S1, the cross-linking process includes adding sodium alginate to the emulsified material, stirring at 50-60°C and a rotation speed of 500-600 rpm for 15-20 min; and the amount of sodium alginate is 6-8% of the mass of the protein solution.

[0014] Sodium alginate is an anionic polysaccharide that can form a cross-linked structure with protein (soybean / rice protein concentrate is an amphoteric electrolyte, which is negatively charged under neutral conditions) through "electrostatic interaction" and "hydrogen bonding". The carboxyl group (-COOH) of sodium alginate and the amino group (-NH2) or hydroxyl group (-OH) of protein form hydrogen bonds, and the negative charge groups (-COO - of sodium alginate and -COO - of protein can be cross-linked by Ca 2+ (microamount of Ca 2+ in the protein solution or Ca 2+) form "ionic bridge", further strengthen the cross-linking effect. This cross-linking structure can make the primary wall material formed by protein more dense and stable, avoiding the microcapsule from breaking in the subsequent drying process. The dense cross-linked wall material can effectively prevent the evaporation and loss of core material (especially oil and vitamins) during drying, so as to improve the retention rate of oil and vitamins and the survival rate of probiotics.

[0015] Further, in S2, the low-temperature pre-drying includes controlling the temperature to be 35-45℃, the relative humidity to be 30%-40%, and the wind speed to be 1-1.5m / s in a low-temperature drying box, and drying for 20-30min. The low temperature of 35-45℃ is adopted to avoid the protein from denaturing too early. By controlling the humidity and the wind speed, a dense but not hard film structure is slowly formed on the surface of the microcapsule, which not only fixes the shape of the microcapsule, but also reserves a channel for water evaporation during the subsequent vacuum drying.

[0016] Further, in S2, the pulse vacuum drying includes controlling the vacuum degree to be 0.08-0.09MPa, the vacuum maintaining time in the pulse cycle to be 5-8min, the vacuum breaking time to be 1-2min, the drying temperature to be 40-50℃, and the drying time to be 60-90min in a pulse vacuum drying device. The vacuum environment reduces the boiling point of water, so that the material can be quickly dried at a low temperature of 40-50℃, reducing the oxidation of oil and the degradation of vitamins. The periodic breaking of the "air film resistance" on the surface of the material in the pulse cycle accelerates the internal water diffusion, so that the drying efficiency is improved compared with the traditional freeze-drying, and the energy consumption is effectively reduced. The pulse pressure change can form a loose and porous structure inside the microcapsule, which is not only beneficial to the subsequent mixing with corn meal and soybean meal powder (increasing the contact area and making the mixing more uniform), but also can quickly absorb water and swell in the animal intestinal tract to release the core material, improving the digestion and absorption rate.

[0017] Further, in S3, the mass ratio of the protein-based microcapsule particles to the corn meal and the soybean meal powder is 1:5:5. The fine powder form and moderate hygroscopicity of the corn meal and the soybean meal powder can make the microcapsule particles uniformly dispersed without obvious agglomeration during the mixing process. DETAILED DESCRIPTION

[0018] The specific embodiments of the present application are described in detail below, but it should be understood that the scope of protection of the present application is not limited by the specific embodiments.

[0019] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0020] It should be understood that the magnitude of the serial number of each process in various embodiments of the present application does not mean the order of execution, and part or all of the steps can be executed in parallel or in sequence, and the execution order of each process should be determined according to its function and internal logic, and should not constitute any limitation on the implementation process of the implementation regulations of the present application.

[0021] The weight of the related components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also represent the weight ratio relationship between each component, therefore, as long as the content of the related components in the embodiment description of the present application is enlarged or reduced in proportion, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass mentioned in the embodiment description of the present application can be μg, mg, g, kg and other mass units commonly known in the chemical field.

[0022] Unless otherwise defined, all the professional terms used below have the same meaning as generally understood by those skilled in the art. The professional terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present application.

[0023] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0024] In the following examples and comparative examples, the related raw materials and the proportion are summarized in Table 1.

[0025] Table 1

[0026] The following will be further illustrated with specific examples.

[0027] Example 1

[0028] A preparation method of a protein-based microcapsule coated emulsified feed, comprising the following steps: S1. Deionized water was added to the protein at a solid-liquid ratio of 1 g:7 mL, and stirred at 45°C and 400 rpm for 35 min to obtain a protein solution; oil, vitamins and probiotics were mixed according to a mass ratio of 6:1.5:0.8, and ultrasonic dispersion was performed for 15 min to obtain a uniform functional core material; the functional core material was added to the protein solution at a mass of 15% of the mass of the protein solution, and the obtained mixture was first stirred at 65°C and 1000 rpm for 25 min, and then homogenized in a high-pressure homogenizer at 40 MPa for 3 times to obtain an emulsified material, and sodium alginate was added to the emulsified material at a mass of 7% of the mass of the protein solution, and stirred at 55°C and 550 rpm for 20 min to obtain a protein-based microcapsule suspension; S2. The protein-based microcapsule suspension is sprayed onto a stainless steel tray and placed in a low-temperature drying box, with a temperature of 40°C, a relative humidity of 35±1%, and a wind speed of 1.2 m / s, for 25 minutes of low-temperature pre-drying. After obtaining the pre-dried material, it is placed in a pulse vacuum drying device, with a vacuum degree of 0.08-0.09 MPa, a vacuum holding time of 6 minutes in the pulse cycle, a vacuum breaking time of 1.5 minutes, and a drying temperature of 45°C, for 70 minutes of pulse vacuum drying, to obtain protein-based microcapsule particles; S3. The protein-based microcapsule particles are mixed with corn meal and soybean meal at a mass ratio of 1:5:5 after being passed through a 100-mesh sieve, to obtain a protein-based microcapsule coated emulsified feed.

[0029] Example 2

[0030] A method for preparing a protein-based microcapsule coated emulsified feed, which differs from Example 1 in that, in S1, the solid-liquid ratio of protein to deionized water is 1g:6mL; the remaining steps and parameters remain unchanged.

[0031] Example 3

[0032] A method for preparing a protein-based microcapsule coated emulsified feed, which differs from Example 1 in that, in S1, the solid-liquid ratio of protein to deionized water is 1g:8mL; the remaining steps and parameters remain unchanged.

[0033] Example 4

[0034] A method for preparing a protein-based microcapsule coated emulsified feed, which differs from Example 1 in that, in S1, the mass of the functional core material is 12% of the mass of the protein solution; the remaining steps and parameters remain unchanged.

[0035] Example 5

[0036] A method for preparing a protein-based microcapsule coated emulsified feed, which differs from Example 1 in that, in S1, the mass of the functional core material is 18% of the mass of the protein solution; the remaining steps and parameters remain unchanged.

[0037] Comparative Example 1

[0038] A method for preparing a protein-based microcapsule coated emulsified feed, comprising the following steps: S1. The same as Example 1; S2. The protein-based microcapsule suspension is directly pulse vacuum dried, specifically by spraying the protein-based microcapsule suspension onto a stainless steel tray and placing it in a pulse vacuum drying device, with a vacuum degree of 0.08-0.09 MPa, a vacuum holding time of 6 minutes in the pulse cycle, a vacuum breaking time of 1.5 minutes, and a drying temperature of 45°C, for 95 minutes of pulse vacuum drying, to obtain protein-based microcapsule particles; S3. Same as Example 1.

[0039] Comparative Example 2

[0040] A preparation method of a protein-based microcapsule coated emulsified feed, comprising the following steps: S1. Same as Example 1; S2. Spray drying is adopted, specifically, the protein-based microcapsule suspension is passed through a spray drying device, the gold temperature is 182℃, the air outlet temperature is 82℃, the feeding speed is 12mL / min, the atomization pressure is 0.25MPa, and the fan rotating speed is 2800r / min, so as to obtain protein-based microcapsule particles; S3. Same as Example 1.

[0041] The emulsified feeds prepared in Examples 1-5 and Comparative Examples 1-2 are subjected to the following performance tests: (1) Microcapsule coating rate (oil and fat): the mass m1 of free oil and fat on the surface of the protein-based microcapsule particles and the mass m2 of all the oil and fat released by destroying the structure of the microcapsule particles are extracted, and the microcapsule coating rate is calculated by (m2-m1) / m2; (2) Oil and fat oxidation value (PV): GB 5009.227-2016 “Determination of Peroxide Value in Food Safety National Standard” is referred to; (3) Vitamin retention rate: HPLC method is used for testing; The test results are shown in Table 2.

[0042] Table 2

[0043] As can be seen from the data in Table 2, Examples 1-5 of the present application prove that the liquid content in the protein-based microcapsule suspension before drying has a certain influence on the drying result, but within the water content range of the present application, good levels are maintained; compared with Comparative Example 1 and Comparative Example 1, after canceling the low-temperature pre-drying, the microcapsule embedding efficiency and the core material protection ability are significantly reduced, but the basic microcapsule structure and function can still be maintained, the reason is that the basic cross-linking of protein and sodium alginate has preliminarily formed a gel structure even without pre-drying, and the drying process still has a certain wrapping ability, the pulse vacuum alleviates the oil oxidation and vitamin degradation to a certain extent, and the low-temperature drying does not reach the severe oxidation threshold of oil and fat; compared with Comparative Example 1 and Comparative Example 1, although the material stays in the drying device for a short time during the spray drying process, the oil oxidation and vitamin degradation are accelerated, the protein-sodium alginate composite film may be denatured at high temperature, resulting in a decrease in the compactness of the film structure and local rupture, core material leakage, and a significant decrease in the embedding efficiency of the microcapsule and the stability of the core material.

[0044] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting; thus the use of any

[0045] The foregoing is considered as illustrative only of the principles of the application. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the application to the exact construction and practice described. Accordingly, all such variations are intended to be included within the scope of the present application as defined in the claims below and their equivalents.

Claims

1. A method for the preparation of a protein-based microencapsulated emulsified feed, characterized by, The method comprises the following steps: S1. Adding functional core material to the protein solution, emulsifying and cross-linking to obtain a protein-based microcapsule suspension; S2. Pre-drying the protein-based microcapsule suspension at low temperature to obtain a pre-dried material, and then performing pulse vacuum drying to obtain protein-based microcapsule particles; S3. Mixing the protein-based microcapsule particles with corn meal and bean meal to obtain a protein-based microcapsule coated emulsified feed.

2. The method of claim 1, wherein the protein-based microencapsulated emulsified feed is prepared by the steps of: In S1, the functional core material is composed of oil, vitamins, and probiotics in a mass ratio of 5-8:1-2:0.5-1.

3. The method of claim 2, wherein the protein-based microencapsulated emulsified feed is prepared by the steps of: The oil is one or any combination of fish oil and vegetable oil; the vitamins are any two or more of vitamin A, vitamin D, and vitamin E in any combination; and the probiotics are any combination of Bacillus subtilis and lactic acid bacteria.

4. The method of claim 1, wherein the protein-based microencapsulated emulsified feed is prepared by the steps of: In S1, the protein solution is composed of protein and deionized water in a solid-liquid ratio of 1:6-8.

5. The method of claim 1, wherein the protein-based microencapsulated emulsified feed is prepared by the steps of: In S1, the mass of the functional core material is 12-18% of the mass of the protein solution.

6. The method of claim 1, wherein the protein-based microencapsulated emulsified feed is prepared by the steps of: In S1, the emulsification process includes stirring at 60-70℃ and a rotation speed of 900-1200 rpm for 20-30 min, and then homogenizing 2-3 times in a high-pressure homogenizer at 30-50 MPa.

7. The method of claim 1, wherein the protein-based microencapsulated emulsified feed is prepared by the steps of: In S1, the cross-linking process includes adding sodium alginate to the emulsified material, stirring at 50-60℃ and a rotation speed of 500-600 rpm for 15-20 min; the amount of sodium alginate is 6-8% of the mass of the protein solution.

8. The method of claim 1, wherein the protein-based microencapsulated emulsified feed is prepared by the steps of: In S2, the low-temperature pre-drying includes controlling the temperature to be 35-45℃, the relative humidity to be 30%-40%, and the wind speed to be 1-1.5 m / s in a low-temperature drying box, and drying for 20-30 min.

9. The method of claim 1, wherein the protein-based microencapsulated emulsified feed is prepared by the steps of: In S2, the pulse vacuum drying includes controlling the vacuum degree to be 0.08-0.09 MPa, the vacuum maintaining time in the pulse cycle to be 5-8 min, the vacuum breaking time to be 1-2 min, the drying temperature to be 40-50℃, and the drying time to be 60-90 min in a pulse vacuum drying device.

10. The method of claim 1, wherein the protein-based microencapsulated emulsified feed is prepared by the steps of: In S3, the mass ratio of the protein-based microcapsule particles to corn meal and bean meal is 1:5:5.

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