A kind of pet food which is easy to digest and absorb and its preparation process

Abstract

The present invention relates to the field of animal feed technology, and in particular to a pet food that is easily digestible and absorbable and a preparation process thereof. The preparation process comprises the following steps: preparing a chitin nanofiber suspension; preparing a modified pig liver protein solution; preparing a digestive aid additive; and preparing a pet food that is easily digestible and absorbable. The present invention improves the solubility of pig liver protein in water and makes it easier to disperse by grafting maleic anhydride onto pig liver protein. Pig liver protein is rich in high-quality protein. For pets, excessive high-quality protein is not easy to absorb, but will result in overnutrition. After pig liver protein is grafted with maleic anhydride, the surface properties of the protein are changed, which can better improve the absorption rate of organisms. In addition, the introduction of maleic anhydride can reduce the protein content in the modified pig liver protein solution, so that the protein content in the prepared pet food is within the range that the pet can absorb, and the prepared pet food is easy to digest and absorb.

Description

Technical Field

[0001] The invention relates to the technical field of animal feed, and in particular to easily digestible and absorbable pet food and a preparation process thereof. Background Art

[0002] Pet food is food specially provided for pets and small animals. It is a high-end animal food between human food and traditional livestock and poultry feed. It covers six major nutrients, including water, protein, crude fat, crude ash, crude fiber, and nitrogen-free extract. It provides the most basic nutrients needed for life guarantee, growth and development, and health for various pets.

[0003] Pet food is divided into staple food, freeze-dried snacks, and functional food such as hair removal cream and calcium supplements. Compared with staple food, functional food focuses more on solving the problems of hair loss and calcium deficiency in pets during their growth and development. For example, hair removal cream contains a large amount of vegetable oil and cellulose, which can lubricate the pet's intestines and promote gastrointestinal motility, helping pets to better expel hair in the stomach and intestines. However, since hair removal cream cannot provide pets with enough nutrients, they still need to feed staple food or freeze-dried snacks to provide daily nutritional intake for pets. At this time, since hair removal cream can provide a better lubrication effect for the pet's stomach and intestines, conventional high-protein staple food or freeze-dried snacks will become difficult to absorb after feeding hair removal cream. In addition, since the vegetable oil component in the hair removal cream lubricates the intestines, pets may experience indigestion and diarrhea.

[0004] Therefore, in general, when people feed pets with hair removal paste, they need to feed some staple foods with high cellulose content and low moisture content at the same time to promote the gastrointestinal motility of the pets and improve the digestive ability of the pets. In addition, the stomach and intestines of pets cannot decompose cellulose-level proteins, which leads to the problem of insufficient protein intake of pets during the feeding of hair removal paste. Therefore, the present invention provides a pet food that is easily digestible and absorbable to solve the above problems during the feeding of hair removal paste. Summary of the invention

[0005] In view of the shortcomings of the prior art, the object of the present invention is to provide a pet food that is easily digestible and absorbable and a preparation process thereof.

[0006] A process for preparing easily digestible and absorbable pet food comprises the following steps:

[0007] S1: Preparation of chitin nanofiber suspension

[0008] The shrimp shells are placed in a NaOH solution to remove protein, washed to neutrality, and then placed in a mixed buffer solution of pepsin and acid protease, heated and stirred to obtain purified chitin, NaOH and sodium borohydride are mixed to obtain a mixed reducing solution, the purified chitin is placed in the mixed reducing solution to obtain deacetylated chitin, and the deacetylated chitin is dispersed in an acetic acid solution to prepare a chitosan nanofiber suspension, wherein the mass ratio of pepsin to acid protease is (2-3):(4-5);

[0009] S2: Preparation of modified porcine liver protein solution

[0010] The pig liver is minced into a paste and added into ultrapure water, homogenized and then centrifuged to prepare a pig liver protein solution, maleic anhydride is added into the pig liver protein solution, magnetic stirring is performed, dialyzed and freeze-dried to obtain a modified pig liver protein solution;

[0011] S3: Preparation of digestive supplements

[0012] The chitosan nanofiber suspension is mixed with corn oil, and dispersed at high speed to obtain a uniform emulsion, and then a modified pig liver protein solution is added to obtain emulsion A, pig skin gelatin is mixed with distilled water and stirred to dissolve to obtain emulsion B, emulsion A and emulsion B are mixed, glycerol is added, stirred and mixed, and an emulsifier Tween 80 is added, and after homogenization and drying, a digestive additive is obtained;

[0013] S4: Preparation of easily digestible pet food

[0014] Meat, egg yolk, barley flour, fish oil and water are mixed and stirred, freeze-dried, crushed, and then digestive additives and vitamin B are added. Water is added to granulate, dry, and package to obtain easily digestible and absorbable pet food.

[0015] Furthermore, step S1 of preparing a chitosan nanofiber suspension comprises the following steps:

[0016] S1.1: Add shrimp shells to a (1-1.5) mol / L NaOH solution at room temperature (22-24°C), with the material-liquid ratio of shrimp shells to NaOH solution being 1 g: (9-10) mL, mechanically stir for 20-24 h to remove protein, wash to neutrality and place in a mixed buffer solution of pepsin and acid protease and heat and stir at 60-80°C for 2-3 h. The preparation method of the mixed buffer solution of pepsin and acid protease is as follows: mix pepsin and acid protease in a mass ratio of (2-3): (4-5) and add to 2 volumes of PBS buffer, and adjust the pH of the solution to 4-4.5 to obtain a mixed buffer solution of pepsin and acid protease, wash again and repeat mechanical stirring to remove protein, and obtain purified chitin;

[0017] S1.2: NaOH and sodium borohydride are mixed in a volume ratio of (100-110):1 to obtain a mixed reducing solution, the purified chitosan is placed in the mixed reducing solution, stirred at 80-90°C for 2-2.5h, filtered and washed until the pH is neutral, and then dried to obtain deacetylated chitosan;

[0018] S1.3: Disperse deacetylated chitosan in 2-2.5% acetic acid solution with a solid-liquid ratio of 1 g: (19-20) mL. Stir magnetically for 70-72 h to obtain a suspension. Disperse evenly under 900-950 W ultrasound for 1-2 h. Dialyze until neutral and then centrifuge to remove the undissolved part. Vacuum evaporate the supernatant to remove half of the water to obtain a chitosan nanofiber suspension.

[0019] Furthermore, in step S1.2, the material-liquid ratio of purified chitosan and mixed reducing solution is 1 g: (18-20) mL.

[0020] Furthermore, step S2 of modifying the pig liver protein solution comprises the following steps:

[0021] S2.1: mince the pig liver into a paste, add 5-5.5 times the volume of ultrapure water, homogenize and adjust the pH value to 11-12, centrifuge at 9000-10000 r / min for 20-25 min at 4°C, filter through 4 layers of gauze to remove the upper fat and fascia to obtain an intermediate protein solution, add HCl to the protein solution to adjust the pH value of the protein solution to 5-6, let it stand for 10-15 min, centrifuge at 9000-10000 r / min for 20-25 min at 0-4°C, take the lower precipitate, add ultrapure water to the lower precipitate to a concentration of 10 mg / mL, and adjust the pH value to 6-7 to obtain a pig liver protein solution, and put it in a 0-4°C refrigerator for later use;

[0022] S2.2: Adjust the pH value of the pig liver protein solution to 10-11, add maleic anhydride to the pig liver protein solution, the solid-liquid ratio of maleic anhydride to pig liver protein solution is (0.8-1) g: 200 mL, stir magnetically at room temperature 22-24°C, and then use NaOH to maintain the pH value stable at 8-9. After reacting for 30-35 minutes, ice bath for 10 minutes to terminate the reaction, and adjust the pH to 6-7. Dialyze at 0-4°C for 20-24 hours, freeze-dry, and obtain a modified pig liver protein solution, which is stored at -20-0°C for future use.

[0023] Furthermore, in step S2.2, the pH value of the pig liver protein solution is adjusted using 1-3 wt % NaOH solution.

[0024] Furthermore, step S3 of preparing a digestive aid additive comprises the following steps:

[0025] S3.1: The chitosan nanofiber suspension was mixed with corn oil in a volume ratio of (8-9):1, and dispersed at a high speed of 8000-10000 r / min for 3-5 min to obtain a uniform emulsion, and then 50-55% of the total volume of the system was added with a modified pig liver protein solution, and stirred at a high speed for another 5-10 min to obtain an emulsion A;

[0026] S3.2: Pigskin gelatin and distilled water were mixed and stirred to dissolve at a solid-liquid ratio of 1 g: (100-105) mL, expanded in cold water at 10-15°C for 30-35 min, and then dissolved in a water bath at 35-40°C with magnetic stirring for 3-4 h to obtain emulsion B;

[0027] S3.3: Emulsion A and emulsion B are mixed in a volume ratio of (6-7): (1-2), and then 70-75% of the total volume of glycerol is added, stirring and mixing for 30-35 minutes, and emulsifier Tween 80 is added. Homogenize at 13000-14000r / min for 5-10 minutes, heat and stir at 60-80℃ for 35-40 minutes, cool to room temperature (22-24℃), vacuum pump for 30-50 minutes to remove bubbles, and then place in a constant temperature and humidity chamber at 24-26℃, RH48-52% to dry for 44-48 hours to obtain a digestive additive.

[0028] Furthermore, step S4 prepares easily digestible and absorbable pet food, comprising the following steps:

[0029] S4.1: Mix 75-85 parts by weight of meat, 5-10 parts by weight of egg yolk, 3-8 parts by weight of barley flour, 3-5 parts by weight of fish oil and 5-8 parts by weight of water for 20-25 minutes, freeze-dry for 3-4 hours, and crush for 3-5 hours;

[0030] S4.2: Add 20-40 parts by weight of digestive additives and 0.05-0.08 parts by weight of vitamin B, add water to granulate, dry for 6-8 hours, pass through a 600-650 mesh sieve, and package to obtain easily digestible and absorbable pet food.

[0031] A pet food that is easily digestible and absorbable is prepared by the preparation process of the pet food that is easily digestible and absorbable.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects:

[0033] 1. The present invention grafts maleic anhydride onto pig liver protein, thereby introducing hydrophilic groups, improving the hydrophilicity of the pig liver protein solution, improving the solubility of the pig liver protein in water, and making it easier to disperse. After the pig liver protein is grafted with maleic anhydride, the surface properties of the protein are changed, the biocompatibility is improved, and the biological absorption rate can be better improved. In addition, the maleic anhydride group can be adsorbed on the glycerol component of the hair removal cream. After feeding the hair removal cream to pets, the glycerol in the hair removal cream adheres to the intestinal wall of the pet, and the pet food carrying the maleic anhydride group adheres to the glycerol, thereby prolonging the time of the pet food in the gastrointestinal tract of the animal, improving the absorption effect of the gastrointestinal tract of the animal on the pet food, and thus improving the animal's absorption rate of the protein in the pet food.

[0034] 2. The present invention prepares chitosan nanofiber suspension into an emulsion loaded with modified pig liver protein. Chitosan can help improve the intestinal health of pets and promote the normal functioning of the digestive system. In addition, chitosan loaded with pig liver protein can reduce the release rate of pig liver protein and prolong the release time of pig liver protein, so that pets can slowly absorb pig liver protein. Since chitosan is made into chitosan nanofibers, chitosan nanofibers and pig liver protein have a certain ability to adhere to and attract each other. When absorbing pig liver protein, pets will also absorb a small amount of chitosan. The two are absorbed at the same time, which not only improves the digestion and absorption function of the pet's intestines, but also improves the pet's absorption rate of chitosan and pig liver protein.

[0035] 3. The present invention utilizes pepsin and acid protease to purify and deproteinize shrimp shells in a specific ratio of (2-3): (4-5). The two enzymes hydrolyze the shrimp shells to different degrees within different acid ranges. When used in combination, the protein in the shrimp shells can be first decomposed into large fragments and then further decomposed into smaller polypeptide fragments, thereby improving the efficiency and degree of deproteinization. The obtained chitosan does not contain large molecular proteins, and the small molecular proteins are more convenient for pets to digest and absorb during feeding with hair removal paste. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable those skilled in the relevant art to make and use the present disclosure.

[0037] Figure 1 The present invention is a flow chart of a process for preparing an easily digestible and absorbable pet food used in an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0039] Embodiment 1:

[0040] A process for preparing easily digestible and absorbable pet food, such as Figure 1 As shown, the following steps are included:

[0041] S1: Preparation of chitin nanofiber suspension

[0042] S1.1: Add shrimp shells to a 1 mol / L NaOH solution at room temperature of 22°C, with a material-liquid ratio of shrimp shells to NaOH solution of 1 g:10 mL, mechanically stir for 24 h to remove protein, wash to neutrality and place in a mixed buffer solution of pepsin and acid protease and heat and stir at 80°C for 3 h. The preparation method of the mixed buffer solution of pepsin and acid protease is as follows: mix pepsin and acid protease in a mass ratio of 2:5 and add them to 2 volumes of PBS buffer, and adjust the pH of the solution to 4, wash again and repeat mechanical stirring to remove protein, and obtain purified chitin;

[0043] S1.2: NaOH and sodium borohydride are mixed in a volume ratio of 100:1 to obtain a mixed reducing solution, and the purified chitosan is placed in the mixed reducing solution, the solid-liquid ratio of the purified chitosan and the mixed reducing solution is 1g:20mL, stirred at 90°C for 2h, filtered and washed until the pH is neutral, and then dried to obtain deacetylated chitosan;

[0044] S1.3: Disperse deacetylated chitosan in 2% acetic acid solution with a solid-liquid ratio of 1 g:19 mL. Stir magnetically for 72 h to obtain a suspension. Disperse evenly under 900 W ultrasound for 1 h. Dialyze until neutral and then centrifuge to remove the insoluble part. Rotary evaporate the supernatant to remove half of the water to obtain a chitosan nanofiber suspension.

[0045] S2: Preparation of modified porcine liver protein solution

[0046] S2.1: mince the pig liver into a paste and add 5 times the volume of ultrapure water, adjust the pH value to 11 after homogenization, centrifuge at 10000r / min for 20min at 4℃, filter through 4 layers of gauze to remove the upper fat and fascia to obtain the middle layer protein solution, add HCl to the protein solution to adjust the pH value of the protein solution to 5, let it stand for 10min, centrifuge at 10000r / min for 20min at 4℃, take the lower precipitate, add ultrapure water to the lower precipitate to a concentration of 10mg / mL, and adjust the pH value to 7 to obtain the pig liver protein solution, and put it in a 4℃ refrigerator for later use;

[0047] S2.2: Adjust the pH value of the pig liver protein solution to 11 with 1wt% NaOH solution, add maleic anhydride to the pig liver protein solution, the solid-liquid ratio of maleic anhydride to pig liver protein solution is 0.8g:200mL, stir magnetically at room temperature 22℃, and then use NaOH to maintain the pH value stable at 8. After reacting for 30min, terminate the reaction in an ice bath for 10min, and adjust the pH to 7. Dialyze at 4℃ for 24h, freeze-dry, and obtain a modified pig liver protein solution, which is stored at -20℃ for later use.

[0048] S3: Preparation of digestive supplements

[0049] S3.1: chitosan nanofiber suspension and corn oil were mixed in a volume ratio of 9:1, dispersed at a high speed of 10000 r / min for 3 min to obtain a uniform emulsion, and then 50% of the total volume of the system was added with modified pig liver protein solution, and stirred at a high speed for another 5 min to obtain emulsion A;

[0050] S3.2: Pigskin gelatin and distilled water were mixed and stirred at a solid-liquid ratio of 1 g:100 mL to dissolve, expanded in 10°C cold water for 30 min, and then dissolved in a 35°C water bath with magnetic stirring for 3 h to obtain emulsion B;

[0051] S3.3: Mix emulsion A and emulsion B in a volume ratio of 7:2, add glycerol accounting for 70% of the total volume of the system, stir and mix for 30 minutes, add emulsifier Tween 80, homogenize at 13000r / min for 5 minutes, heat and stir at 60℃ for 35 minutes, cool to room temperature 22℃, vacuum pump for 30 minutes to remove bubbles, and then place in a constant temperature and humidity chamber at 24℃, RH48% to dry for 48 hours to obtain a digestive additive.

[0052] S4: Preparation of easily digestible pet food

[0053] S4.1: 75 parts by weight of meat, 5 parts by weight of egg yolk, 3 parts by weight of barley flour, 3 parts by weight of fish oil and 5 parts by weight of water were mixed and stirred for 20 minutes, freeze-dried at -20°C for 3 hours, and crushed for 3 hours;

[0054] S4.2: Add 20 parts by weight of digestive additives and 0.05 parts by weight of vitamin B, add water to granulate, dry for 6 hours, pass through a 600-mesh sieve, and package to obtain easily digestible and absorbable pet food.

[0055] Embodiment 2:

[0056] A process for preparing easily digestible and absorbable pet food, such as Figure 1 As shown, the following steps are included:

[0057] S1.1: Add shrimp shells to a 1 mol / L NaOH solution at room temperature of 22°C, with a material-liquid ratio of shrimp shells to NaOH solution of 1 g:9 mL, mechanically stir for 24 h to remove protein, wash to neutrality and place in a mixed buffer solution of pepsin and acid protease and heat and stir at 80°C for 3 h. The preparation method of the mixed buffer solution of pepsin and acid protease is as follows: mix pepsin and acid protease in a mass ratio of 3:4 and add them to 2 volumes of PBS buffer, and adjust the pH of the solution to 4, wash again and repeat mechanical stirring to remove protein, and obtain purified chitin;

[0058] S1.2: NaOH and sodium borohydride are mixed in a volume ratio of 110:1 to obtain a mixed reducing solution, and purified chitosan is placed in the mixed reducing solution, the material-liquid ratio of purified chitosan and the mixed reducing solution is 1g:18mL, stirred at 90°C for 2h, filtered and washed until the pH is neutral, and then dried to obtain deacetylated chitosan;

[0059] S1.3: Disperse deacetylated chitosan in 2% acetic acid solution with a solid-liquid ratio of 1 g:20 mL. Stir magnetically for 72 h to obtain a suspension. Disperse evenly under 900 W ultrasound for 1 h. Dialyze to neutrality and then centrifuge to remove the insoluble part. Rotary evaporate the supernatant to remove half of the water to obtain a chitosan nanofiber suspension.

[0060] S2: Preparation of modified porcine liver protein solution

[0061] S2.1: mince the pig liver into a paste and add 5 times the volume of ultrapure water, adjust the pH value to 11 after homogenization, centrifuge at 10000r / min for 20min at 4℃, filter through 4 layers of gauze to remove the upper fat and fascia to obtain the middle layer protein solution, add HCl to the protein solution to adjust the pH value of the protein solution to 5, let it stand for 10min, centrifuge at 10000r / min for 20min at 4℃, take the lower precipitate, add ultrapure water to the lower precipitate to a concentration of 10mg / mL, and adjust the pH value to 7 to obtain the pig liver protein solution, and put it in a 4℃ refrigerator for later use;

[0062] S2.2: Adjust the pH value of the pig liver protein solution to 11 with 1wt% NaOH solution, add maleic anhydride to the pig liver protein solution, the solid-liquid ratio of maleic anhydride to pig liver protein solution is 1g:200mL, stir magnetically at room temperature 22℃, and then use NaOH to maintain the pH value stable at 8. After reacting for 30min, terminate the reaction in an ice bath for 10min, and adjust the pH to 7. Dialyze at 4℃ for 24h, freeze-dry, and obtain a modified pig liver protein solution, which is stored at -20℃ for later use.

[0063] S3: Preparation of digestive supplements

[0064] S3.1: chitosan nanofiber suspension and corn oil were mixed in a volume ratio of 8:1, dispersed at a high speed of 10000 r / min for 3 min to obtain a uniform emulsion, and then 55% of the total volume of the system was added with modified pig liver protein solution, and stirred at a high speed for another 5 min to obtain emulsion A;

[0065] S3.2: Pigskin gelatin and distilled water were mixed and stirred at a solid-liquid ratio of 1 g:105 mL to dissolve, expanded in 10°C cold water for 30 min, and then dissolved in a 35°C water bath with magnetic stirring for 3 h to obtain emulsion B;

[0066] S3.3: Mix emulsion A and emulsion B in a volume ratio of 6:1, add glycerol accounting for 75% of the total volume of the system, stir and mix for 30 minutes, add emulsifier Tween 80, homogenize at 13000r / min for 5 minutes, heat and stir at 60℃ for 35 minutes, cool to room temperature 22℃, vacuum pump for 30 minutes to remove bubbles, and then place in a constant temperature and humidity chamber at 24℃, RH48% to dry for 48 hours to obtain a digestive additive.

[0067] S4: Preparation of easily digestible pet food

[0068] S4.1: 85 parts by weight of meat, 10 parts by weight of egg yolk, 8 parts by weight of barley flour, 5 parts by weight of fish oil and 8 parts by weight of water were mixed and stirred for 20 minutes, freeze-dried at -20°C for 3 hours, and crushed for 3 hours;

[0069] S4.2: Add 40 parts by weight of digestive additives and 0.08 parts by weight of vitamin B, add water to granulate, dry for 6 hours, pass through a 600-mesh sieve, and package to obtain easily digestible and absorbable pet food.

[0070] Embodiment 3:

[0071] A process for preparing easily digestible and absorbable pet food, such as Figure 1 As shown, the following steps are included:

[0072] S1: Preparation of chitin nanofiber suspension

[0073] S1.1: Add shrimp shells to a 1.5 mol / L NaOH solution at room temperature of 24°C, with a solid-liquid ratio of shrimp shells to NaOH solution of 1 g:10 mL, mechanically stir for 20 h to remove protein, wash to neutrality and place in a mixed buffer solution of pepsin and acid protease and heat and stir at 60°C for 2 h. The preparation method of the mixed buffer solution of pepsin and acid protease is as follows: mix pepsin and acid protease in a mass ratio of 2:5 and add them to 2 times the volume of PBS buffer, and adjust the pH of the solution to 4.5, wash again and repeat the above steps once to obtain purified chitin;

[0074] S1.2: NaOH and sodium borohydride are mixed in a volume ratio of 100:1 to obtain a mixed reducing solution, and purified chitosan is placed in the mixed reducing solution, the material-liquid ratio of purified chitosan and the mixed reducing solution is 1g:20mL, stirred at 80°C for 2.5h, filtered and washed until the pH is neutral, and then dried to obtain deacetylated chitosan;

[0075] S1.3: Disperse deacetylated chitosan in 2% acetic acid solution with a solid-liquid ratio of 1 g:19 mL. Stir magnetically for 70 h to obtain a suspension. Disperse evenly under 950 W ultrasound for 1.5 h. Dialyze to neutrality and then centrifuge to remove the insoluble part. Evaporate the supernatant to remove half of the water to obtain a chitosan nanofiber suspension.

[0076] S2: Preparation of modified porcine liver protein solution

[0077] S2.1: mince the pig liver into a paste and add 5 times the volume of ultrapure water, adjust the pH value to 12 after homogenization, centrifuge at 9000r / min for 25min at 4℃, filter through 4 layers of gauze to remove the upper fat and fascia to obtain the middle layer protein solution, add HCl to the protein solution to adjust the pH value of the protein solution to 5, let it stand for 15min, centrifuge at 9000r / min for 25min at 4℃, take the lower precipitate, add ultrapure water to the lower precipitate to a concentration of 10mg / mL, and adjust the pH value to 6.5 to obtain the pig liver protein solution, and put it in a 0℃ refrigerator for later use;

[0078] S2.2: Adjust the pH value of the pig liver protein solution to 11 with 3wt% NaOH solution, add maleic anhydride to the pig liver protein solution, the solid-liquid ratio of maleic anhydride to pig liver protein solution is 0.8g:200mL, stir magnetically at room temperature 24℃, and use NaOH to maintain the pH value stable at 8. After reacting for 35min, terminate the reaction in an ice bath for 15min, and adjust the pH to 7. Dialyze at 4℃ for 20h, freeze-dry, and obtain a modified pig liver protein solution, which is stored at -20℃ for later use.

[0079] S3: Preparation of digestive supplements

[0080] S3.1: The chitosan nanofiber suspension was mixed with corn oil in a volume ratio of 9:1, and dispersed at a high speed of 9000 r / min for 5 min to obtain a uniform emulsion, and then 50% of the total volume of the system was added with a modified pig liver protein solution, and stirred at a high speed for another 10 min to obtain emulsion A;

[0081] S3.2: Pigskin gelatin and distilled water were mixed and stirred at a solid-liquid ratio of 1 g:100 mL to dissolve, expanded in 15°C cold water for 35 min, and then dissolved in a 40°C water bath with magnetic stirring for 4 h to obtain emulsion B;

[0082] S3.3: Mix emulsion A and emulsion B in a volume ratio of 7:2, add glycerol accounting for 70% of the total volume of the system, stir and mix for 30 minutes, add emulsifier Tween 80, homogenize at 13000r / min for 5 minutes, heat and stir at 60℃ for 35 minutes, cool to room temperature 22℃, vacuum pump for 40 minutes to remove bubbles, and then place in a constant temperature and humidity chamber at 26℃, RH48% to dry for 44 hours to obtain a digestive additive.

[0083] S4: Preparation of easily digestible pet food

[0084] S4.1: 75 parts by weight of meat, 5 parts by weight of egg yolk, 3 parts by weight of barley flour, 3 parts by weight of fish oil and 5 parts by weight of water were mixed and stirred for 20 minutes, freeze-dried at -20°C for 3 hours, and crushed for 4 hours;

[0085] S4.2: Add 40 parts by weight of digestive additives and 0.08 parts by weight of vitamin B, add water to granulate, dry for 8 hours, pass through a 650-mesh sieve, and package to obtain easily digestible and absorbable pet food.

[0086] Comparative Example 1:

[0087] Compared with Example 1, the difference of Comparative Example 1 is that maleic anhydride is not added in step S2.2, but succinic anhydride is used instead of maleic anhydride, specifically "S2.2: adjust the pH value of the pig liver protein solution to 11 with 1wt% NaOH solution, add succinic anhydride to the pig liver protein solution, the solid-liquid ratio of succinic anhydride to pig liver protein solution is 0.8g:200mL, magnetic stirring is carried out at room temperature of 22°C, and then NaOH is used to maintain the pH value stable at 8-9. After reacting for 30 minutes, the reaction is terminated by ice bathing for 10 minutes, and the pH is adjusted to 7, dialyzed at 4°C for 24 hours, freeze-dried, to obtain a modified pig liver protein solution, and stored at -20°C for standby use", the other steps remain unchanged, and the prepared easily digestible and absorbable pet food is recorded as Comparative Example 1.

[0088] Comparative Example 2:

[0089] Compared with Example 1, the difference of Comparative Example 2 is that step S2.2 is not performed, and in step S3.1, pig liver protein solution is used instead of modified pig liver protein solution, specifically: "S3.1: Mix the chitosan nanofiber suspension and corn oil in a volume ratio of 9:1, disperse at a high speed at 10000 r / min for 3 minutes to obtain a uniform emulsion, and then add 50% of the total volume of the system. Pork liver protein is stirred at a high speed for 5 minutes again to obtain emulsion A", and the other steps remain unchanged. The prepared easily digestible and absorbable pet food is recorded as Comparative Example 2.

[0090] Comparative Example 3:

[0091] Compared with Example 1, the difference of Comparative Example 3 is that step S3.1 is not performed, and modified pig liver protein solution is used instead of emulsion A, specifically: "S3: Preparation of digestive additives

[0092] S3.1: Pigskin gelatin and distilled water were mixed and stirred at a solid-liquid ratio of 1 g:100 mL to dissolve, expanded in 10°C cold water for 30 min, and then dissolved in a 35°C water bath with magnetic stirring for 3 h to obtain emulsion B;

[0093] S3.2: The modified pig liver protein solution and emulsion B were mixed in a volume ratio of 7:2, and 70% of the total volume of glycerol was added, and the mixture was stirred for 30 minutes. Emulsifier Tween 80 was added, and homogenization was carried out at 13000r / min for 5 minutes. The mixture was heated and stirred at 60°C for 35 minutes, and the mixture was cooled to room temperature of 22°C. The mixture was vacuumed by a vacuum pump for 30 minutes to remove bubbles, and the mixture was placed in a constant temperature and humidity chamber at 24°C and RH48% for drying for 48 hours to obtain a digestive additive. The remaining steps remained unchanged, and the prepared easily digestible and absorbable pet food was recorded as Comparative Example 3.

[0094] Comparative Example 4:

[0095] Compared with Example 1, the difference of Comparative Example 4 is that pepsin is not added in step S1.1, and only acid protease is added, specifically: "S1.1: Add shrimp shells to 1 mol / L NaOH solution at room temperature 22°C, the solid-liquid ratio of shrimp shells to NaOH solution is 1 g:10 mL, mechanically stir for 24 hours to deproteinize, wash to neutrality and place in a buffer solution of acid protease and heat with stirring at 80°C for 3 hours; the preparation method of the buffer solution of acid protease is: add acid protease to PBS buffer, and adjust the pH of the solution to 4, wash again and repeat the above steps once to obtain purified chitin", the other steps remain unchanged, and the prepared easily digestible and absorbable pet food is recorded as Comparative Example 4.

[0096] Comparative Example 5:

[0097] Compared with Example 1, the difference of Comparative Example 5 is that no acidic protease is added in step S1.1, and only pepsin is added, specifically: "S1.1: Add shrimp shells to 1 mol / L NaOH solution at room temperature 22°C, the solid-liquid ratio of shrimp shells to NaOH solution is 1 g:10 mL, mechanically stir for 24 hours to deproteinize, wash to neutrality and place in a pepsin buffer solution and heat and stir at 80°C for 3 hours. The preparation method of the pepsin buffer solution is: add pepsin to 2 times the volume of PBS buffer, and adjust the pH of the solution to 4, wash again and repeat the above steps once to obtain purified chitin", the other steps remain unchanged, and the prepared easily digestible and absorbable pet food is recorded as Comparative Example 5.

[0098] Comparative Example 6:

[0099] Compared with Example 1, the difference of Comparative Example 6 is that the addition ratio of pepsin and acid protease in step S1.1 is 1:4, specifically: "S1.1: Add shrimp shells to 1 mol / L NaOH solution at room temperature 22°C, the solid-liquid ratio of shrimp shells and NaOH solution is 1 g:10 mL, mechanically stir for 24 hours to deproteinize, wash to neutrality and place in a mixed buffer solution of pepsin and acid protease and heat and stir at 80°C for 3 hours. The preparation method of the mixed buffer solution of pepsin and acid protease is: mix pepsin and acid protease in a mass ratio of 1:5 and add them to 2 volumes of PBS buffer, and adjust the pH of the solution to 4, wash again and repeat the above steps once to obtain purified chitin", the other steps remain unchanged, and the prepared easily digestible and absorbable pet food is recorded as Comparative Example 6.

[0100] Comparative Example 7:

[0101] Compared with Example 1, the difference of Comparative Example 7 is that the addition ratio of pepsin and acid protease in step S1.1 is 1:1, specifically: "S1.1: Add shrimp shells to 1 mol / L NaOH solution at room temperature 22°C, the solid-liquid ratio of shrimp shells to NaOH solution is 1 g:10 mL, mechanically stir for 24 hours to deproteinize, wash to neutrality and place in a mixed buffer solution of pepsin and acid protease and heat and stir at 80°C for 3 hours, the preparation method of the mixed buffer solution of pepsin and acid protease is: mix pepsin and acid protease in a mass ratio of 2:1 and add them to 2 times the volume of PBS buffer, and adjust the pH of the solution to 4, wash again and repeat the above steps once to obtain purified chitin", the other steps remain unchanged, and the prepared easily digestible and absorbable pet food is recorded as Comparative Example 7.

[0102] 1.2 Experimental animal management and index determination

[0103] 20 healthy short-haired cats aged 1-3 years old and weighing 3-4 kg were selected for the test. According to gender and weight, they were divided into 10 groups, 2 in each group, 9 experimental groups and 1 control group. The experimental group was given the pet food of Examples 1-3 and Comparative Examples 1-6 during the time period of 8:30-17:30 every day, and the control group was given the commercially available cat food during the time period of 8:30-17:30 every day. The whole feeding cycle was 16 days, and the experimental group and the control group were fed with hair-removing cream while feeding the pet food, and the hair-removing cream was fed once at 12:00 noon every 4 days, and the feeding amount of the hair-removing cream was 2 g each time.

[0104] Each cat was housed individually in a cat cage (120 cm × 60 cm × 70 cm), maintained at a temperature (25°C), humidity (65%), and natural light (12 h light / 12 h dark) environment, and had free access to clean water during the entire experiment. Each cat was guaranteed to spend 1 h with humans every day.

[0105] During the experiment, the amount of food intake and feces was recorded every day, the health conditions of the experimental group and the control group were observed, and an animal nutritional digestion test was carried out on the last two days of the experiment. The feces of each cat were completely collected in a clean cat litter box every day. Each time the feces were collected, they were weighed and 10% hydrochloric acid was added to fix nitrogen. The collected feces were placed in a 65°C oven to dry, and then crushed through a 40-mesh sieve to obtain feces samples for testing. The apparent digestibility of nutrients for 2 days was averaged to obtain the data in Table 1.

[0106] Apparent digestibility of nutrients (%) = (1-amount of nutrients excreted in feces / amount of nutrients in ingested feed) × 100%.

[0107] The amount of nutrients in the excreted feces = the total amount of feces excreted by the animal during the entire manure collection period × the nutrient ratio in the feces.

[0108] The amount of nutrients in the ingested feed = the total amount of feed consumed by the animal during the entire manure collection period × the nutrient ratio in the feed.

[0109] Nutrient ratio detection method in feed and feces: The crude protein content detection method in feed and feces refers to GB / T6432-2018 "Determination of crude protein in feed"; the crude fat content detection method in feed and feces refers to GB / T6433-2006 "Determination of crude fat in feed", and the data are shown in Table 1.

[0110] Table 1

[0111]

[0112] The crude protein digestibility of Examples 1-3 is as high as 87.27% and as low as 86.35%, and the crude fat digestibility is as high as 93.48% and as low as 92.86%, all of which are higher than those of the comparative examples. It can be seen that the pet food of the embodiments is easier to absorb. The crude protein digestibility of Comparative Example 1 is 62.45%, and the crude fat digestibility is 81.73%. It can be seen that after the pig liver protein is grafted with maleic anhydride, the surface properties of the protein are changed, the biocompatibility is improved, and the biological absorption rate can be better improved. Although succinic anhydride can also be grafted with pig liver protein, the grafting effect is not good, and it cannot adhere to the glycerol of the hair removal paste, so the effect of improving the crude protein absorption rate cannot be achieved.

[0113] The crude protein digestibility of Comparative Example 2 is 60.36%, and the crude fat digestibility is 80.37%. It can be seen that without modifying the pig liver protein, the pig liver protein is difficult to be absorbed, and the digestibility of pet food by experimental animals is further reduced.

[0114] The crude protein digestibility of Comparative Example 3 is 55.24%, and the crude fat digestibility is 67.39%. The emulsion-loaded modified pig liver protein prepared by chitin nanofibers can better enable pets to absorb pig liver protein and chitin, while the pig liver protein without the emulsion load is difficult to absorb. In addition, chitin nanofibers have the function of assisting absorption. When chitin nanofibers are not added, the apparent digestibility of experimental animals is very low.

[0115] The crude protein digestibility of Comparative Example 4 is 68.48%, and the crude fat digestibility is 77.44%. The crude protein digestibility of Comparative Example 5 is 67.62%, and the crude fat digestibility is 74.69%. It can be seen that the deproteinization efficiency of shrimp shells is higher when pepsin and acid protease are mixed to purify and deproteinize. The obtained chitin does not contain large molecular proteins and is better absorbed; while the crude protein digestibility of Comparative Example 6 is 70.49%, and the crude fat digestibility is 78.61%. The crude protein digestibility of Comparative Example 7 is 63.81%, and the crude fat digestibility is 69.46%. The ratio of pepsin to acid protease in Comparative Example 6 is 1:5, the ratio of pepsin to acid protease in Comparative Example 7 is 1:1, and the ratio of pepsin to acid protease in Example 1 is 2:5. It can be seen that the effect of mixing pepsin and acid protease in a specific ratio is significantly improved. After the ratio is changed, the effect achieved by mixing the two enzymes may be worse than that of a single enzyme.

[0116] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A process for preparing easily digestible and absorbable pet food, characterized in that: The steps include: S1: Preparation of chitin nanofiber suspension The shrimp shells are placed in a NaOH solution to remove protein, washed to neutrality, and then placed in a mixed buffer solution of pepsin and acid protease, heated and stirred to obtain purified chitin, NaOH and sodium borohydride are mixed to obtain a mixed reducing solution, the purified chitin is placed in the mixed reducing solution to obtain deacetylated chitin, and the deacetylated chitin is dispersed in an acetic acid solution to prepare a chitosan nanofiber suspension, wherein the mass ratio of pepsin to acid protease is (2-3):(4-5); S2: Preparation of modified porcine liver protein solution The pig liver is minced into a paste and added into ultrapure water, homogenized and then centrifuged to prepare a pig liver protein solution, maleic anhydride is added into the pig liver protein solution, magnetic stirring is performed, dialyzed and freeze-dried to obtain a modified pig liver protein solution; S3: Preparation of digestive supplements The chitosan nanofiber suspension is mixed with corn oil, and dispersed at high speed to obtain a uniform emulsion, and then a modified pig liver protein solution is added to obtain emulsion A, pig skin gelatin is mixed with distilled water and stirred to dissolve to obtain emulsion B, emulsion A and emulsion B are mixed, glycerol is added, stirred and mixed, and an emulsifier Tween 80 is added, and after homogenization and drying, a digestive additive is obtained; S4: Preparation of easily digestible pet food Meat, egg yolk, barley flour, fish oil and water are mixed and stirred, freeze-dried, crushed, and then digestive additives and vitamin B are added. Water is added to granulate, dry, and package to obtain easily digestible and absorbable pet food.

2. The process for preparing an easily digestible and absorbable pet food according to claim 1, characterized in that: Step S1: preparing a chitosan nanofiber suspension, comprising the following steps: S1.1: Add shrimp shells to a (1-1.5) mol / L NaOH solution at room temperature (22-24°C), with the material-liquid ratio of shrimp shells to NaOH solution being 1 g: (9-10) mL, mechanically stir for 20-24 h to remove protein, wash to neutrality and place in a mixed buffer solution of pepsin and acid protease and heat and stir at 60-80°C for 2-3 h. The preparation method of the mixed buffer solution of pepsin and acid protease is as follows: mix pepsin and acid protease in a mass ratio of (2-3): (4-5) and add to 2 volumes of PBS buffer, and adjust the pH of the solution to 4-4.5 to obtain a mixed buffer solution of pepsin and acid protease, wash again and repeat mechanical stirring to remove protein, and obtain purified chitin; S1.2: NaOH and sodium borohydride are mixed in a volume ratio of (100-110):1 to obtain a mixed reducing solution, the purified chitosan is placed in the mixed reducing solution, stirred at 80-90°C for 2-2.5h, filtered and washed until the pH is neutral, and then dried to obtain deacetylated chitosan; S1.3: Disperse deacetylated chitosan in 2-2.5% acetic acid solution with a solid-liquid ratio of 1 g: (19-20) mL. Stir magnetically for 70-72 h to obtain a suspension. Disperse evenly under 900-950 W ultrasound for 1-2 h. Dialyze until neutral and then centrifuge to remove the undissolved part. Vacuum evaporate the supernatant to remove half of the water to obtain a chitosan nanofiber suspension.

3. The process for preparing a pet food that is easily digestible and absorbable according to claim 2, characterized in that: The material-liquid ratio of purified chitin and mixed reducing solution in step S1.2 is 1 g: (18-20) mL.

4. The process for preparing an easily digestible and absorbable pet food according to claim 1, characterized in that: Step S2: modifying the pig liver protein solution, comprising the following steps: S2.1: mince the pig liver into a paste, add 5-5.5 times the volume of ultrapure water, homogenize and adjust the pH value to 11-12, centrifuge at 9000-10000 r / min for 20-25 min at 4°C, filter through 4 layers of gauze to remove the upper fat and fascia to obtain an intermediate protein solution, add HCl to the protein solution to adjust the pH value of the protein solution to 5-6, let it stand for 10-15 min, centrifuge at 9000-10000 r / min for 20-25 min at 0-4°C, take the lower precipitate, add ultrapure water to the lower precipitate to a concentration of 10 mg / mL, and adjust the pH value to 6-7 to obtain a pig liver protein solution, and put it in a 0-4°C refrigerator for later use; S2.2: Adjust the pH value of the pig liver protein solution to 10-11, add maleic anhydride to the pig liver protein solution, the solid-liquid ratio of maleic anhydride to pig liver protein solution is (0.8-1) g: 200 mL, stir magnetically at room temperature 22-24°C, and then use NaOH to maintain the pH value stable at 8-9. After reacting for 30-35 minutes, ice bath for 10 minutes to terminate the reaction, and adjust the pH to 6-7. Dialyze at 0-4°C for 20-24 hours, freeze-dry, and obtain a modified pig liver protein solution, which is stored at -20-0°C for future use.

5. The process for preparing an easily digestible and absorbable pet food according to claim 4, characterized in that: In step S2.2, the pH value of the pig liver protein solution is adjusted using 1-3wt% NaOH solution.

6. The process for preparing an easily digestible and absorbable pet food according to claim 1, characterized in that: Step S3: preparing a digestive aid additive, comprising the following steps: S3.1: The chitosan nanofiber suspension was mixed with corn oil in a volume ratio of (8-9):1, and dispersed at a high speed of 8000-10000 r / min for 3-5 min to obtain a uniform emulsion, and then 50-55% of the total volume of the system was added with a modified pig liver protein solution, and stirred at a high speed for another 5-10 min to obtain an emulsion A; S3.2: Pigskin gelatin and distilled water were mixed and stirred to dissolve at a solid-liquid ratio of 1 g: (100-105) mL, expanded in cold water at 10-15°C for 30-35 min, and then dissolved in a water bath at 35-40°C with magnetic stirring for 3-4 h to obtain emulsion B; S3.3: Emulsion A and emulsion B are mixed in a volume ratio of (6-7): (1-2), and then 70-75% of the total volume of glycerol is added, stirring and mixing for 30-35 minutes, and emulsifier Tween 80 is added. Homogenize at 13000-14000r / min for 5-10 minutes, heat and stir at 60-80℃ for 35-40 minutes, cool to room temperature (22-24℃), vacuum pump for 30-50 minutes to remove bubbles, and then place in a constant temperature and humidity chamber at 24-26℃, RH48-52% to dry for 44-48 hours to obtain a digestive additive.

7. The process for preparing an easily digestible and absorbable pet food according to claim 1, characterized in that: Step S4 is preparing easily digestible and absorbable pet food, comprising the following steps: S4.1: Mix 75-85 parts by weight of meat, 5-10 parts by weight of egg yolk, 3-8 parts by weight of barley flour, 3-5 parts by weight of fish oil and 5-8 parts by weight of water for 20-25 minutes, freeze-dry for 3-4 hours, and crush for 3-5 hours; S4.2: Add 20-40 parts by weight of digestive additives and 0.05-0.08 parts by weight of vitamin B, add water to granulate, dry for 6-8 hours, pass through a 600-650 mesh sieve, and package to obtain easily digestible and absorbable pet food.

8. An easily digestible and absorbable pet food, which is prepared by the process for preparing an easily digestible and absorbable pet food according to any one of claims 1 to 7.

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