Pig milk fat substitute lipid microcapsules, and preparation method and application thereof

Abstract

The application discloses a pig milk fat substitute fat microcapsule and a preparation method and application thereof, and belongs to the technical field of biology.The application provides a pig milk fat substitute fat microcapsule, which is based on the microcapsule embedding technology and the spray drying technology and further improves the particle size of fat, increases the contact area of the fat with fat enzymes in the body, so that the fat digestion rate of piglets is improved, the growth performance of the piglets is improved, and the diarrhea rate and mortality of the piglets are reduced.The preparation method can also significantly reduce the oxidation of fat, avoids the influence of oil oxidation on the feed intake and the health of the piglets, provides a new material resource for the preparation of healthy feed for piglets, and is helpful to promoting the development of the pig industry.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of biotechnology, in particular to a pig milk fat substitute lipid microcapsule and a preparation method and application thereof. BACKGROUND

[0002] Pig milk as an ideal source of nutrition, the fat can provide sufficient energy to support the growth of piglets and reduce the mortality rate before weaning. Its fat content accounts for 7%-10%, 98% of which is triglyceride, providing more than 50% of energy for piglets, so the digestion and absorption of fat is crucial to the growth of piglets. After weaning, the mortality rate of piglets is high. The main reason is that the nutrition source of piglets changes from high-fat liquid milk to low-fat solid feed, which leads to low digestibility and further causes nutritional diarrhea.

[0003] In order to meet the rapid growth needs of piglets during the transition period before and after weaning, reduce diarrhea and mortality, it is necessary to add easily digestible and absorbable fat to the piglet transition diet to meet the energy needs of piglets. Studies have found that the composition and structure of pig milk fat and feed added fat are different, which is one of the main reasons for the low fat digestibility of piglets. The esterification position of fatty acids on the glycerol skeleton is named as sn-1, sn-2 and sn-3, and the structural formula is as follows:

[0004] .

[0005] The most common type of triglyceride in pig milk is USU type (i.e. saturated fatty acid at sn-2 position, and unsaturated fatty acid at sn-1, 3 position; U: unsaturated fatty acid; S: saturated fatty acid), mainly including OPL, LPL and OPO (three kinds of triglycerides are 1-oleic acid-2-palmitic acid-3-linoleic acid triglyceride, 1, 3-dilinoleic acid-2-palmitic acid triglyceride, 1, 3-dioleic acid-2-palmitic acid triglyceride). This unique fatty acid composition and position distribution has a great influence on the digestion, absorption and metabolism of fat, has physiological functions such as promoting the absorption of fatty acids, improving constipation, preventing the loss of mineral calcium, protecting the liver, and plays an important role in the growth and development of piglets. The lipase secreted by the pancreas of piglets will preferentially hydrolyze the fatty acids at sn-1 or sn-3 position, and the fatty acids at sn-2 position are directly absorbed in the form of monoglyceride. However, the oil or fat powder added in the feed has a high content of saturated fatty acids, and C16:0 (palmitic acid) is mainly distributed at sn-1 and sn-3 positions. The free palmitic acid released by lipase hydrolysis combines with mineral calcium to form insoluble soap, resulting in the loss of calcium. In addition, the fatty acid composition of exogenous fat is quite different from that of pig milk fat.

[0006] Therefore, in the case of insufficient breast milk supply, selecting a fat similar to the fat composition and structure in pig milk as a substitute helps to improve the fat digestibility. Through enzyme engineering technology, using the directional catalytic properties of specific biological enzymes, and through ester exchange reaction, structured oil rich in OPO can be obtained, which can greatly simulate the fat composition in pig milk, thereby promoting the absorption of fat by piglets. However, compared with the fat in pig milk, the particle size of the exogenous fat in the feed is larger than that in pig milk, which also reduces the contact area of lipase and is still not conducive to digestion in piglets. SUMMARY

[0007] The purpose of the present application is to provide a pig milk fat substitute fat microcapsule and its preparation method and application to solve the problems existing in the prior art. The present application provides a pig milk fat substitute fat microcapsule, which is based on microcapsule embedding technology and spray drying technology to further improve the particle size of fat, increase its contact area with fat enzymes in vivo, thereby improving the fat digestibility of piglets, improving the growth performance of piglets, and reducing the diarrhea rate and mortality rate of piglets. The preparation method of the present application can also significantly reduce the oxidation of fat, avoid the influence of oil oxidation on the feed intake and health of piglets, provide a new material resource for the preparation of healthy feed for piglets, and help to promote the development of pig industry.

[0008] To achieve the above purpose, the present application provides the following scheme:

[0009] The present application provides a preparation method of a pig milk fat substitute fat microcapsule, comprising the following steps:

[0010] (1) After heating and melting the pig milk fat substitute fat, add an oleophilic emulsifier to obtain a core material;

[0011] (2) Mix the protein wall material, carbohydrate wall material and colloid wall material to obtain a wall material; dissolve the wall material in water, add a hydrophilic emulsifier to prepare a wall material solution;

[0012] (3) Mix the core material and the wall material solution, emulsify and homogenize, and then spray dry to obtain the pig milk fat substitute fat microcapsule;

[0013] The pig milk fat substitute fat is obtained by mixing peanut oil and palm oil, adding rice root mold lipase and then reacting;

[0014] The sample flow rate of the spray drying is 15%-35%, the air inlet flow rate is 60%-100%, and the air inlet temperature is 180-190℃.

[0015] Optionally, the preparation method of the pig milk fat substitute fat is as follows: mix peanut oil and palm oil at a molar ratio of 1-2:1, add 3wt%-5wt% of rice root mold lipase, and react at 50-55℃ for 1-3 h.

[0016] Further, the mass ratio of the protein wall material, the carbohydrate wall material and the colloid wall material is 3-5:4-6:1.

[0017] Optionally, the protein wall material is soybean protein isolate, whey protein or sodium caseinate; the carbohydrate wall material is beta-cyclodextrin, maltodextrin or modified starch; and the colloid wall material is gum arabic, pectin or sodium alginate.

[0018] Further, the mass ratio of the core material and the wall material is 0.5-2:0.5-2; and the wall material is 10%-30% of the mass of the water.

[0019] Optionally, the lipophilic emulsifier includes any one or several of glycerol monostearate, Span 80, acetyl tartaric acid monoglyceride; and the hydrophilic emulsifier includes any one or several of soybean phospholipid, bile acid and sucrose fatty acid ester.

[0020] Glycerol monostearate, Span 80 and acetyl tartaric acid monoglyceride are commonly used lipophilic emulsifiers in the market, and all have good emulsifying effect. In some embodiments of the present application, glycerol monostearate is preferably used. Glycerol monostearate has the functions of emulsifier and stabilizer, and can prevent oil droplets and water droplets from gathering after homogenization and emulsification in the oil-water mixture, so as to ensure the stability of the oil-in-water system and prevent the particle size of the oil droplets from becoming large, thereby providing favorable conditions for subsequent spray drying.

[0021] Soybean phospholipid, bile acid and sucrose fatty acid ester are common hydrophilic emulsifiers. In some embodiments of the present application, bile acid is preferably used. As an endogenous emulsifier of the body, bile acid has better solubility and better hydrophilic and lipophilic properties than soybean phospholipid and sucrose fatty acid ester. For piglets, weaning stress leads to insufficient secretion of bile acid, and the addition of bile acid in the emulsification process also helps the piglets to digest other fats, so compared with other hydrophilic emulsifiers, bile acid has good emulsifying effect.

[0022] Further, the addition amount of the lipophilic emulsifier is 2%-4% of the mass of the pig milk fat substitute fat; and the addition amount of the hydrophilic emulsifier is 2%-4% of the mass of the wall material.

[0023] Optionally, the emulsification homogenization is shear emulsification, and the time of shear emulsification is 30-150 min.

[0024] The present application also provides a pig milk fat substitute fat microcapsule prepared by the preparation method.

[0025] The present application also provides application of the pig milk fat substitute fat microcapsule in preparation of piglet feed for improving the growth performance of piglets and reducing the diarrhea rate of piglets.

[0026] The present application discloses the following technical effects:

[0027] The present application provides a pig milk fat substitute fat microcapsule, which is based on the microcapsule embedding technology and the spray drying technology, and further improves the particle size of fat, increases the contact area of fat with fat enzymes in vivo, so as to improve the fat digestibility of piglets, improve the growth performance of piglets, and reduce the diarrhea of piglets. The preparation method of the present application can also significantly reduce the oxidation of fat, avoid the influence of oil oxidation on the feed intake and the health of piglets; the obtained pig milk fat substitute fat microcapsule has uniform particle size, smooth surface without obvious wrinkles and cracks, simple operation, and can maintain the scale and industrialization while ensuring the product quality and quality stability, providing a new material resource for the preparation of healthy feed for piglets, and helping to promote the development of pig industry. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0029] Figure 1 X-ray diffraction pattern of the microcapsule of Example 1;

[0030] Figure 2 Scanning electron microscope image of the microcapsule of Example 1; wherein, A is the microcapsule under 500 times magnification; B is the microcapsule under 1000 times magnification; C is the microcapsule under 1500 times magnification; D is the microcapsule under 2000 times magnification;

[0031] Figure 3 Peroxide value detection result graph of the microcapsule (coated) and the substitute fat (uncoated) of Example 1. DETAILED DESCRIPTION

[0032] The various exemplary embodiments of the present application will now be described in detail, which should not be considered as limiting the present application, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present application.

[0033] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0034] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0035] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0036] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0037] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the instruments and equipment used in the following examples are all conventional laboratory instruments and equipment; unless otherwise specified, the experimental materials used in the following examples were all purchased from conventional biochemical reagent stores.

[0038] The high-oleic peanut oil in the following examples, with an oleic acid content >75%, was purchased from Shandong Luhua Group Co., Ltd.; the Rhizopus miltiorrhiza lipase was purchased from Sigma, immobilized on Immobead 150, and derived from the thermophilic mycelium, with a concentration ≥3000 U / g.

[0039] Example 1

[0040] This embodiment provides a porcine milk fat substitute microcapsule, and the specific preparation process is as follows:

[0041] (1) High oleic peanut oil and palm oil were mixed at a molar ratio of 2:1, and 4% (w / w) of Rhizopus oryzae lipase was added. The mixture was reacted at 50°C for 2 h to obtain a mixed oil (substitute fat) rich in OPO.

[0042] (2) Heat the substitute fat to 75°C, add 2.5% by weight of the substitute fat glyceryl monostearate as a lipophilic emulsifier, and stir until the emulsifier is completely melted;

[0043] (3) Mix sodium caseinate, pectin and maltodextrin in a mass ratio of 4:5:1, add 15% (w / w) to sterile water and stir until completely dissolved, then add 2.5% (w / w) of hydrophilic emulsifier bile acid to the wall material until the material is completely dissolved.

[0044] (4) Mix the emulsified substitute grease from step (2) and the wall material solution prepared in step (3) evenly according to the wall material and core material mass ratio of 1:1, turn on the shearing machine and shear for more than 60 minutes;

[0045] (5) The stable solution obtained in step (4) is spray-dried at an injection flow rate of 27%, an air inlet flow rate of 95% (maximum air flow rate of 72 mL / min), and an air inlet temperature of 185°C.

[0046] The encapsulation efficiency of the obtained microcapsule products was determined, and under these conditions, the encapsulation efficiency was 88.75%.

[0047] Example 2

[0048] This embodiment provides a porcine milk fat substitute microcapsule, and the specific preparation process is as follows:

[0049] (1) High oleic peanut oil and palm oil were mixed at a molar ratio of 2:1, and 4% (w / w) of Rhizopus oryzae lipase was added. The mixture was reacted at 50°C for 2 h to obtain a mixed oil (substitute fat) rich in OPO.

[0050] (2) Heat the substitute fat to 75°C, add 2.5% by weight of the substitute fat glyceryl monostearate as a lipophilic emulsifier, and stir until the emulsifier is completely melted;

[0051] (3) Mix sodium caseinate, pectin and maltodextrin in a mass ratio of 4:5:1, add 15% (w / w) to sterile water and stir until completely dissolved, then add 2.5% (w / w) of hydrophilic emulsifier bile acid to the wall material until the material is completely dissolved.

[0052] (4) Mix the emulsified substitute grease from step (2) and the wall material solution prepared in step (3) evenly according to the wall material and core material mass ratio of 1:1, turn on the shearing machine and shear for more than 60 minutes;

[0053] (5) The stable solution obtained in step (4) is spray-dried at an injection flow rate of 30%, an air inlet flow rate of 80% (maximum air flow rate of 72 mL / min), and an air inlet temperature of 170°C.

[0054] The encapsulation efficiency of the obtained microcapsule product was determined, and the encapsulation efficiency was 67.46% under the specified conditions. Under these conditions, the encapsulation efficiency suddenly decreased, which is related to the state of the emulsion in the chamber during spray drying. Compared with other embodiments, its feeding speed is fast, and the air inlet speed and air inlet temperature are low, resulting in poor flowability of the emulsion after atomization and poor drying effect, leading to a low encapsulation efficiency.

[0055] Example 3

[0056] This embodiment provides a porcine milk fat substitute microcapsule, and the specific preparation process is as follows:

[0057] (1) High oleic peanut oil and palm oil were mixed at a molar ratio of 2:1, and 4% (w / w) of Rhizopus oryzae lipase was added. The mixture was reacted at 50°C for 2 h to obtain a mixed oil (substitute fat) rich in OPO.

[0058] (2) Heat the substitute fat to 75°C, add 2.5% by weight of the substitute fat glyceryl monostearate as a lipophilic emulsifier, and stir until the emulsifier is completely melted;

[0059] (3) Mix sodium caseinate, pectin and maltodextrin in a mass ratio of 4:5:1, add 15% (w / w) to sterile water and stir until completely dissolved, then add 2.5% (w / w) of hydrophilic emulsifier bile acid to the wall material until the material is completely dissolved.

[0060] (4) Mix the emulsified substitute grease from step (2) and the wall material solution prepared in step (3) evenly according to the wall material and core material mass ratio of 1:1, turn on the shearing machine and shear for more than 60 minutes;

[0061] (5) The stable solution obtained in step (4) is spray-dried at an injection flow rate of 30%, an air inlet flow rate of 80% (maximum air flow rate of 72 mL / min) and an air inlet temperature of 190°C.

[0062] The encapsulation efficiency of the obtained microcapsule products was determined, and under these conditions, the encapsulation efficiency was 76.84%.

[0063] Example 4

[0064] This embodiment provides a porcine milk fat substitute microcapsule, and the specific preparation process is as follows:

[0065] (1) High oleic peanut oil and palm oil were mixed at a molar ratio of 2:1, and 4% (w / w) of Rhizopus oryzae lipase was added. The mixture was reacted at 50°C for 2 h to obtain a mixed oil (substitute fat) rich in OPO.

[0066] (2) Heat the substitute fat to 75°C, add 2.5% by weight of the substitute fat glyceryl monostearate as a lipophilic emulsifier, and stir until the emulsifier is completely melted;

[0067] (3) Mix sodium caseinate, pectin and maltodextrin in a mass ratio of 4:5:1, add 15% (w / w) to sterile water and stir until completely dissolved, then add 2.5% (w / w) of hydrophilic emulsifier bile acid to the wall material until the material is completely dissolved.

[0068] (4) Mix the emulsified substitute grease from step (2) and the wall material solution prepared in step (3) evenly according to the wall material and core material mass ratio of 1:1, turn on the shearing machine and shear for more than 60 minutes;

[0069] (5) The stable solution obtained in step (4) is spray-dried at an injection flow rate of 30%, an air inlet flow rate of 100% (maximum air flow rate of 72 mL / min), and an air inlet temperature of 190°C.

[0070] The encapsulation efficiency of the obtained microcapsule products was determined, and under these conditions, the encapsulation efficiency was 83.09%.

[0071] Example 5

[0072] This embodiment provides a porcine milk fat substitute microcapsule, and the specific preparation process is as follows:

[0073] (1) High oleic peanut oil and palm oil were mixed at a molar ratio of 2:1, and 4% (w / w) of Rhizopus oryzae lipase was added. The mixture was reacted at 50°C for 2 h to obtain a mixed oil (substitute fat) rich in OPO.

[0074] (2) Heat the substitute fat to 75°C, add 2.5% by weight of the substitute fat glyceryl monostearate as a lipophilic emulsifier, and stir until the emulsifier is completely melted;

[0075] (3) Mix sodium caseinate, pectin and maltodextrin in a mass ratio of 4:5:1, add 15% (w / w) to sterile water and stir until completely dissolved, then add 2.5% (w / w) of hydrophilic emulsifier bile acid to the wall material until the material is completely dissolved.

[0076] (4) Mix the emulsified substitute grease from step (2) and the wall material solution prepared in step (3) evenly according to the wall material and core material mass ratio of 1:1, turn on the shearing machine and shear for more than 60 minutes;

[0077] (5) The stable solution obtained in step (4) is spray-dried at an injection flow rate of 25%, an air inlet flow rate of 90% (maximum air flow rate of 72 mL / min), and an air inlet temperature of 190°C.

[0078] The encapsulation efficiency of the obtained microcapsule products was determined, and under these conditions, the encapsulation efficiency was 77.97%.

[0079] Example 6

[0080] This embodiment provides a porcine milk fat substitute microcapsule, and the specific preparation process is as follows:

[0081] (1) High oleic peanut oil and palm oil were mixed at a molar ratio of 2:1, and 4% (w / w) of Rhizopus oryzae lipase was added. The mixture was reacted at 50°C for 2 h to obtain a mixed oil (substitute fat) rich in OPO.

[0082] (2) Heat the substitute fat to 75°C, add 2.5% by weight of the substitute fat glyceryl monostearate as a lipophilic emulsifier, and stir until the emulsifier is completely melted;

[0083] (3) Mix sodium caseinate, pectin and maltodextrin in a mass ratio of 4:5:1, add 15% (w / w) to sterile water and stir until completely dissolved, then add 2.5% (w / w) of hydrophilic emulsifier bile acid to the wall material until the material is completely dissolved.

[0084] (4) Mix the emulsified substitute grease from step (2) and the wall material solution prepared in step (3) evenly according to the wall material and core material mass ratio of 1:1, turn on the shearing machine and shear for more than 60 minutes;

[0085] (5) The stable solution obtained in step (4) is spray-dried at an injection flow rate of 35%, an air inlet flow rate of 90% (maximum air flow rate of 72 mL / min), and an air inlet temperature of 190°C.

[0086] The encapsulation efficiency of the obtained microcapsule products was determined, and under these conditions, the encapsulation efficiency was 78.04%.

[0087] Example 7

[0088] This embodiment provides a porcine milk fat substitute microcapsule, and the specific preparation process is as follows:

[0089] (1) High oleic peanut oil and palm oil were mixed at a molar ratio of 2:1, and 4% (w / w) of Rhizopus oryzae lipase was added. The mixture was reacted at 50°C for 2 h to obtain a mixed oil (substitute fat) rich in OPO.

[0090] (2) Heat the substitute fat to 75°C, add 2.5% by weight of the substitute fat glyceryl monostearate as a lipophilic emulsifier, and stir until the emulsifier is completely melted;

[0091] (3) Mix sodium caseinate, pectin and maltodextrin in a mass ratio of 4:5:1, add 15% (w / w) to sterile water and stir until completely dissolved, then add 2.5% (w / w) of hydrophilic emulsifier bile acid to the wall material until the material is completely dissolved.

[0092] (4) Mix the emulsified substitute grease from step (2) and the wall material solution prepared in step (3) evenly according to the wall material and core material mass ratio of 1:1, turn on the shearing machine and shear for more than 60 minutes;

[0093] (5) The stable solution obtained in step (4) is spray-dried at an injection flow rate of 35%, an air inlet flow rate of 100% (maximum air flow rate of 72 mL / min), and an air inlet temperature of 180°C.

[0094] The encapsulation efficiency of the obtained microcapsule products was determined, and under these conditions, the encapsulation efficiency was 80.16%.

[0095] Example 8

[0096] This embodiment provides a porcine milk fat substitute microcapsule, and the specific preparation process is as follows:

[0097] (1) High oleic peanut oil and palm oil were mixed at a molar ratio of 2:1, and 4% (w / w) of Rhizopus oryzae lipase was added. The mixture was reacted at 50°C for 2 h to obtain a mixed oil (substitute fat) rich in OPO.

[0098] (2) Heat the substitute fat to 75°C, add 2.5% by weight of the substitute fat glyceryl monostearate as a lipophilic emulsifier, and stir until the emulsifier is completely melted;

[0099] (3) Mix sodium caseinate, pectin and maltodextrin in a mass ratio of 4:5:1, add 15% (w / w) to sterile water and stir until completely dissolved, then add 2.5% (w / w) of hydrophilic emulsifier bile acid to the wall material until the material is completely dissolved.

[0100] (4) Mix the emulsified substitute grease from step (2) and the wall material solution prepared in step (3) evenly according to the wall material and core material mass ratio of 1:1, turn on the shearing machine and shear for more than 60 minutes;

[0101] (5) The stable solution obtained in step (4) is spray-dried at an injection flow rate of 30%, an air inlet flow rate of 90% (maximum air flow rate of 72 mL / min), and an air inlet temperature of 180°C.

[0102] The encapsulation efficiency of the obtained microcapsule products was determined, and under these conditions, the encapsulation efficiency was 88.17%.

[0103] Experimental Example 1

[0104] The encapsulation efficiency of the microcapsule products prepared in Examples 1-8 was measured, revealing that the preparation method in Example 1 was the optimal method. Table 1 shows the change in lipid droplet size before and after lipid replacement coating in Example 1; it can be seen that the lipid droplet size decreased significantly after coating. Table 2 shows the test results of the physicochemical properties of the microcapsules in Example 1.

[0105] Table 1. Results of the detection of lipid droplet size changes before and after fat substitution with porcine milk fat.

[0106]

[0107] Table 2. Results of routine physicochemical property determination of porcine milk fat substitute microcapsules

[0108]

[0109] Further X-ray diffraction was used to analyze the structure of the microcapsules of Example 1 and their components (sodium caseinate, maltodextrin, and pectin). The results are as follows: Figure 1 As shown, the raw materials sodium caseinate (5.18°, 18.72°, 21.1°, 24.56°, 30.26°, 35.54°), pectin (8.14°, 11.4°, 12.92°, 24.6°, 31.72°, 38.32°), and maltodextrin (16.38°, 19.9°, 23.46°, 26.1°) all exhibit strong diffraction peaks, indicating that these three substances are crystalline compounds with regular structures and relatively complete crystalline forms. However, the microcapsule spectrum of the substituted lipids shows significant changes compared to the spectra of the three raw materials, lacking a fine peak structure and exhibiting a large peak at a specific angle of 20°. This indicates that the mixture undergoes complexation changes under high-temperature conditions, altering its crystalline state and transforming it into an amorphous compound, while also indicating the formation of an encapsulating material.

[0110] The microstructure of the microcapsules in Example 1 was further observed using scanning electron microscopy, and the results are as follows: Figure 2 As shown in the image, most of the microcapsules are spherical, with relatively uniform particle size and no clumping, indicating that the spray drying effect is good. Figure 2 (A). However, a small number of particles exhibited cracking and wrinkling, which may be due to the wall material curing before the moisture completely evaporates during the spray drying process, followed by shrinkage of the wall material after cooling. Figure 2 B and Figure 3 C). Magnified analysis of these broken and wrinkled particles revealed that this was not caused by the spray drying process, but rather by the microcapsules being damaged and fragmented during the scanning electron microscopy sample preparation process. Figure 2 The scanning electron microscopy analysis of the microcapsules showed that the microcapsule wall material had a compact structure, uniform particles, few cracks or wrinkles, and no clumping or large number of particles adhering together. This indicates that the spray drying conditions of Example 1 can prepare high-quality microcapsule oils.

[0111] The peroxide values ​​of the microcapsules (coated) and the alternative lipids (uncoated) from Example 1 were further tested. The testing process was as follows:

[0112] Using an oven-accelerated oxidation method, the prepared powdered microcapsules and alternative lipids were placed in an oven at 62℃. One day at this temperature is equivalent to 30 days at room temperature. This process was repeated for one week, with samples taken daily at fixed times to determine the peroxide value. Samples were weighed into brown iodine flasks, with 0.02g papain and 0.02g amylase added per 1g of sample. Twice the sample volume of water was added and mixed thoroughly, then the flask was capped. The iodine flask was placed in a 50℃ constant-temperature water bath and shaken at 100 times / min for 30 minutes, then cooled. An equal volume of acetone was added and mixed thoroughly. Three times the sample volume of petroleum ether was added and the mixture was shaken for 1 minute. The mixture was then transferred to a separatory funnel and allowed to stand for 30 minutes to separate the layers. The lower layer was discarded. If emulsification occurred, the layers could be separated by high-speed centrifugation (5000r / min, 15℃, 3 minutes), and the organic phase was then transferred to a separatory funnel. Wash the organic phase with an equal volume of water to petroleum ether, discard the lower layer, and transfer the upper organic phase into a funnel containing anhydrous sodium sulfate for filtration. Transfer the filtrate to a brown rotary evaporator flask, and evaporate the petroleum ether to dryness under reduced pressure in a water bath not exceeding 40 °C. The residue is the test sample, and the extraction amount should not be less than 5 g.

[0113] The peroxide value of the proposed test sample was determined according to GB / T5538-2023: Weigh 3 g of the sample (accurate to 0.001 g), place it in a 250 mL iodine flask, add 30 mL of chloroform-glacial acetic acid solution, and gently shake the sample until completely dissolved. Accurately add 1.00 mL of saturated potassium iodide solution, tighten the cap, and gently shake for 0.5 min, then place in the dark for 3 min. Remove the flask, add 100 mL of water, shake well, and immediately titrate the precipitated iodine with sodium thiosulfate standard titration solution (0.002 mol / L standard titration solution for estimated peroxide value of 0.15 g / 100 g or less; 0.01 mol / L standard titration solution for estimated peroxide value greater than 0.15 g / 100 g). Titrate until the solution turns pale yellow, add 1 mL of starch indicator, continue titrating and shake vigorously until the blue color disappears as the endpoint. A blank test was performed simultaneously. The volume V of sodium thiosulfate standard titration solution consumed in the blank test group shall not exceed 0.1 mL. Substitute the measured data into the following formula to calculate the peroxide value:

[0114] Oil peroxide value = 1000c (V1-V2) / 2M.

[0115] In the formula, V1 is the volume of sodium thiosulfate solution consumed (mL); V2 is the volume of sodium thiosulfate solution consumed by the blank test group (mL); c is the concentration of the titrant (sodium thiosulfate solution) (mol); and M is the sample mass (g).

[0116] The results are as follows Figure 3As shown, at 62°C, the peroxide value of both the alternative lipid and the alternative lipid microcapsules increases continuously with storage time. However, the increase in peroxide value of the coated alternative lipid microcapsules slows down, indicating that the antioxidant capacity of the alternative lipid microcapsules prepared in this invention is significantly enhanced compared to the uncoated ones.

[0117] Experimental Example 2

[0118] Two hundred suckling piglets with the same birth date, similar litter weight, and good health were randomly divided into 5 groups, with 5 replicates per group and 8 piglets per replicate. The experimental period started on day 28 after weaning and lasted for 14 days. The treatments were as follows: 1) Soybean oil group (CON): The basal diet with antibiotic substitute removed was replaced with soybean oil at a content of 2%; 2) Oil mixture group: Basal diet + 2 wt% mixed oil (high oleic peanut oil and palm oil mixed at a molar ratio of 2:1); 3) Low microcapsule treatment group: Basal diet + 2 wt% substitute lipid microcapsules. Due to the low amount of substitute lipid microcapsules, the dietary energy was insufficient, so 0.6% soybean oil was added to ensure consistent net energy across groups; 4) Medium microcapsule treatment group: Basal diet + 4 wt% substitute lipid microcapsules; 5) High microcapsule treatment group: Basal diet + 8 wt% substitute lipid microcapsules. The substitute lipid microcapsules in the above groups were the porcine milk fat substitute lipid microcapsules prepared in Example 1. The basal diet was formulated according to the "Nutritional Requirements for Pigs" (GB / T39235-2020), and the specific composition and nutrient levels are shown in Table 3. Feed was allowed freely. The experimental results are shown in Tables 4 and 5.

[0119] Table 3. Composition and nutrient levels of basal diet (basal feeding)

[0120]

[0121] The premix provides the following per kilogram of diet: Vitamin A, 12,000 IU; Vitamin D3, 2,500 IU; Vitamin E, 30 IU; Vitamin K3, 30.0 mg; Vitamin B12, 12 μg; Riboflavin, 4.0 mg; D-pantothenic acid, 15.0 mg; Niacin, 40.0 mg; Choline chloride, 400.0 mg; Folic acid, 0.7 mg; Vitamin B1, 1.5 mg; Vitamin B6, 3.0 mg; Biotin, 0.1 mg; Manganese, 40.0 mg; Iron, 90.0 mg; Copper, 8.8 mg; Iodine, 0.35 mg; Selenium, 0.3 mg.

[0122] Table 4. Growth performance of weaned piglets in different groups

[0123]

[0124] Table 5. Diarrhea rate in different groups of weaned piglets

[0125]

[0126] The results in Tables 4 and 5 show that, compared with the soybean oil group and the oil-to-fat mixture group, the body weight of the medium and high microcapsule treatment groups was significantly increased, while the feed conversion ratio of the high microcapsule treatment group was significantly decreased. Compared with the oil-to-fat mixture group, the daily weight gain of the medium and high microcapsule treatment groups was significantly increased. There was no statistically significant difference in diarrhea rate, but the diarrhea rate of the medium and high microcapsule treatment groups was lower than that of the soybean oil group and the oil-to-fat mixture group. These results indicate that adding the porcine milk fat substitute microcapsules of this invention can effectively improve the growth performance and intestinal health of weaned piglets.

[0127] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing porcine milk fat substitute microcapsules, characterized in that, Includes the following steps: (1) After heating and melting the pork milk fat substitute, add an lipophilic emulsifier to obtain the core material; (2) The protein wall material, carbohydrate wall material and colloidal wall material are mixed to obtain the wall material; the wall material is dissolved in water and a hydrophilic emulsifier is added to prepare the wall material solution; the protein wall material is sodium caseinate; the carbohydrate wall material is maltodextrin; the colloidal wall material is pectin; (3) After mixing the core material and the wall material solution, emulsify and homogenize, and then spray dry to obtain the porcine milk fat substitute microcapsules; The pig milk fat substitute is obtained by mixing peanut oil and palm oil, adding Rhizopus oryzae lipase, and then reacting. The preparation method of the pig milk fat substitute is as follows: peanut oil and palm oil are mixed at a molar ratio of 1-2:1, 3wt%-5wt% of Rhizopus oryzae lipase is added, and the mixture is reacted at 50-55℃ for 1-3 h. The injection flow rate of the spray dryer is 15%-35%, the air volume is 60%-100%, and the air temperature is 180-190℃.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the protein wall material, carbohydrate wall material, and colloidal wall material is 3-5:4-6:

1.

3. The preparation method according to claim 1, characterized in that, The mass ratio of the core material to the wall material is 0.5-2:0.5-2; the wall material is 10%-30% of the mass of water.

4. The preparation method according to claim 1, characterized in that, The lipophilic emulsifier includes any one or more of glyceryl monostearate, Span 80, and acetylated tartaric acid mono- and diglycerides; the hydrophilic emulsifier includes any one or more of soybean lecithin, bile acids, and sucrose fatty acid esters.

5. The preparation method according to claim 1, characterized in that, The amount of the lipophilic emulsifier added is 2%-4% of the amount of lipid replaced by porcine milk fat; the amount of the hydrophilic emulsifier added is 2%-4% of the amount of wall material.

6. Porcine milk fat substitute microcapsules prepared by the method according to any one of claims 1-5.

7. The use of the porcine milk fat substitute microcapsules according to claim 6 in the preparation of piglet feed that improves piglet growth performance and reduces piglet diarrhea rate.

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