Film-forming type functional protein frozen feed and preparation method thereof

Abstract

The invention provides a biofilm culturing type functional protein frozen feed and a preparation method thereof, relates to the field of aquaculture feeds, and solves the problems that in existing carnivorous aquaculture, chilled trash fish has many diseases and serious pollution, complete feed is poor in palatability and high in cost, and a core targeted biofilm culturing process is lacked. The feed comprises a carrier, wherein a high-protein functional biofilm culturing layer is attached to the surface of the carrier; the high-protein functional biofilm culturing layer is prepared from the following components in percentage by mass: 65%-75% of enzymolysis bait slurry, 3%-5% of a gelatinizing agent, 1%-3% of a bonding auxiliary agent, 0.2%-0.4% of an antioxidant, 2%-3% of probiotics, 0.2%-0.5% of compound vitamins and the balance of water. According to the feed, low-value wild trash fish is used as a natural carrier, through the enzymolysis slurry targeted biofilm formation and low-temperature quick-freezing keep-alive technology, the feed has the excellent palatability of iced fresh fish and the nutrition of compound feed, high-value utilization of low-value resources is achieved, and meanwhile the feed has the advantages of being environmentally friendly and free of chemical resistance in aquaculture.

Description

Technical Field

[0001] This invention relates to the field of aquaculture feed, and in particular to a biofilm-type functional protein frozen feed and its preparation method. Background Technology

[0002] The large-scale farming of high-quality carnivorous freshwater aquatic animals (fish, crustaceans, amphibians and reptiles) is the core direction for the transformation and upgrading of my country's aquaculture industry. Currently, the feeding methods of farmers are mainly divided into two types: feeding fresh wild fish and feeding complete compound pellet feed. Both methods have their advantages and disadvantages.

[0003] Firstly, while feeding fresh wild fish aligns with the natural feeding habits of carnivorous aquatic animals and is palatable, it has several fatal drawbacks: Fresh wild fish have a simple nutritional composition, lacking vitamins, probiotics, and functional nutrients, making it difficult to meet the balanced nutritional needs of farmed organisms; Fresh wild fish easily carry pathogens, parasites, and harmful microorganisms, significantly increasing the risk of disease outbreaks in aquaculture; The feed conversion ratio is low, and a large amount of uneaten feed and metabolic products of farmed organisms enter the water, causing a significant exceedance of ammonia nitrogen and nitrite levels in the aquaculture water, inducing fish diseases and water quality deterioration, further increasing the risk of aquaculture and the cost of water treatment and medication.

[0004] Secondly, while feeding complete formulated pelleted feed has the advantages of balanced nutrition and better environmental protection for water bodies, its palatability is poor: pelleted feed is less palatable to carnivorous animals than fresh wild fish, and carnivorous aquatic animals are difficult to train to eat and have low feeding rates, which easily leads to a large amount of feed waste; the production cost of formulated pelleted feed for high-end carnivorous aquatic animals is relatively high, with raw material and processing costs accounting for more than 70%, resulting in small profit margins for large-scale farming; and the low protein digestibility of pelleted feed can easily lead to problems such as fatty liver and intestinal diseases in farmed animals, affecting the survival rate of farmed animals.

[0005] Existing technologies for improving chilled fish only focus on simple preservation and sterilization processes, such as low-temperature refrigeration and ozone sterilization. These technologies only address the hygiene and safety issues of chilled fish and do not incorporate functional optimization based on the feeding habits, physiological characteristics, and nutritional needs of carnivorous aquatic animals. They lack core targeted biofilm formation technology and precise biofilm formation formulation systems for different species, and therefore cannot simultaneously ensure the excellent palatability of chilled fish and the nutritional value and functionality of formulated feed.

[0006] Therefore, developing a specialized frozen feed that can preserve the natural palatability of fresh fish, provide high-protein balanced nutrition, achieve functional improvements, solve the problem of aquaculture water pollution, and has controllable raw material costs and is palatable to different types of carnivorous aquatic animals has become a core technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] This invention addresses the problems in existing carnivorous aquaculture technologies, such as the prevalence of diseases and pollution in fresh fish (feed) and the poor palatability and high cost of complete feeds, as well as the lack of a core targeted biofilm formation process that fails to simultaneously achieve the excellent palatability of fresh fish and the nutritional and functional properties of formulated feeds. The invention provides a biofilm-type functional protein frozen feed. This biofilm-type functional protein frozen feed uses low-value wild fish as a natural carrier, employing enzymatic hydrolysis slurry targeted biofilm formation and low-temperature rapid freezing for preservation. It combines the excellent palatability of fresh fish with the nutritional value of formulated feeds, achieving high-value utilization of low-value resources while promoting the development of aquaculture towards green and antibiotic-free practices. This invention also provides a method for preparing the biofilm-type functional protein frozen feed.

[0008] The present invention solves its problems through the following technical solution: the biofilm-type functional protein frozen feed includes a carrier, the surface of which is coated with a high-protein functional biofilm layer; the high-protein functional biofilm layer is composed of the following components by mass percentage: 65%-75% enzymatically hydrolyzed feed slurry, 3%-5% gelling agent, 1%-3% binding agent, 0.2%-0.4% antioxidant, 2%-3% probiotics, 0.2%-0.5% compound multivitamins, and the balance being water; the sum of the mass percentages of all components is 100%.

[0009] Furthermore, the carrier is a low-value wild fish; the wild fish is a freshwater fish, selected from at least one of crucian carp, chub, and bitterling;

[0010] The enzymatically hydrolyzed bait slurry is a liquid slurry obtained from miscellaneous fish and water fleas through an enzymatic hydrolysis process;

[0011] The gelling agent is sodium alginate;

[0012] The antioxidant is selected from vitamin E;

[0013] The adhesive additive is soybean lecithin;

[0014] The probiotics are selected from Bacillus;

[0015] The multivitamin is at least two of vitamin E, B vitamins, and niacin.

[0016] Furthermore, the high-protein functional biofilm layer is composed of the following components by mass percentage:

[0017] The formula consists of 70%-75% enzymatic hydrolysed bait slurry, 3%-4% gelling agent, 1%-2% binder, 0.2%-0.4% antioxidant, 2% probiotics, 0.2%-0.5% compound multivitamins, and the remainder is water. This formula is suitable for predatory carnivorous fish such as mandarin fish and bream that prefer high-protein diets.

[0018] Furthermore, the high-protein functional biofilm layer is composed of the following components by mass percentage:

[0019] The formula consists of 65%-70% enzymatically hydrolyzed bait slurry, 4%-5% gelling agent, 2%-3% adhesive additive, 0.2%-0.4% antioxidant, 2.5%-3% probiotics, 0.2%-0.5% compound multivitamins, and the remainder is water. This formula is suitable for eels and crabs that have a strong need for solid film formation.

[0020] This invention also provides a method for preparing the aforementioned biofilm-type functional protein frozen feed, comprising the following steps:

[0021] S1. Select feed materials to obtain pretreated fish carriers;

[0022] S2. Preparation of film-coated slurry: Weigh the raw materials according to the formula ratio of the corresponding aquaculture object, and then pre-treat the raw materials, perform double enzymatic hydrolysis on the pre-treated slurry, post-treat, and mix and blend the raw material components to obtain the film-coated slurry.

[0023] S3. Targeted Film Formation: Using a cold immersion film formation process, the pretreated fish carrier obtained in S1 is immersed in the film formation slurry prepared in S2. The mass ratio of the film formation slurry to the pretreated fish carrier and the soaking time are controlled to ensure that the slurry is evenly attached to the carrier surface. After removal, the slurry is drained to form a basic film layer. After the film formation is completed, the feed is placed in a ventilated place to drain at low temperature, allowing the film layer to fully gel and form a dense gel structure high-protein functional film formation layer, thus obtaining film-formed feed.

[0024] S4. Quick-freeze and inhibit bacteria in the attached-film formed feed.

[0025] Furthermore, the method for selecting materials in step S1 includes: selecting fresh, non-deteriorated, and disease-free low-value wild fish, removing impurities and diseased individuals, washing with clean water to remove mucus and attached impurities from the body surface, draining and cutting into pieces according to the appropriate size for aquaculture, and draining until there is no free water on the body surface to obtain a pre-treated fish carrier for later use.

[0026] Furthermore, in step S2, raw materials are weighed according to the formula ratio corresponding to the aquaculture object, and the raw materials are pretreated, subjected to double enzymatic hydrolysis, post-treatment, and compounded and mixed to obtain the film-coating slurry. The specific process includes the following steps:

[0027] S21. Raw material pretreatment: Mix the miscellaneous fish and water fleas in the bait, and grind them into a paste using a colloid mill to obtain pretreated slurry;

[0028] S22. Double enzymatic hydrolysis of pretreated slurry: Add 0.5 times the mass of water to the pretreated slurry for conditioning. First, perform a first enzymatic hydrolysis with alkaline protease at a reaction temperature of 44-46℃ and a system pH of 7.0-8.5 for 4-6 hours. After the first enzymatic hydrolysis, adjust the system pH to 6.5-7.5 and add flavor protease for a second enzymatic hydrolysis at a reaction temperature of 50-55℃ for 2-4 hours. After the double enzymatic hydrolysis, raise the system temperature to 80-85℃ and keep it at that temperature for 10-15 minutes to inactivate the enzymes. Filter the solution through a 100-mesh filter cloth to remove unhydrolyzed fish bones, residues, and other impurities. Collect the filtrate to obtain the enzymatically hydrolyzed slurry and cool it to 30-35℃.

[0029] S23. Mixing and blending: Add gelling agent to the enzymatic hydrolysate in proportion and stir until completely dissolved; then add adhesive, antioxidant and compound multivitamin in sequence, and continue stirring for 10-15 minutes until the system is uniform; finally, add probiotics while maintaining the system temperature at 30-35℃ to obtain a uniform film-coating slurry.

[0030] Furthermore, in step S21, the miscellaneous fish and water fleas are mixed in a mass ratio of 7:3; and in step S22, the enzymatic hydrolysate prepared has a protein content of ≥35%.

[0031] Furthermore, in step S3, the mass ratio of the biofilm slurry to the pretreated fish carrier is controlled to be 1:4-6. The fish is soaked for 2-5 minutes to ensure that the slurry is evenly attached to the surface of the carrier. After soaking, the fish is drained to form a basic biofilm layer. According to the high protein requirements of farmed fish, a second biofilm is applied. After the biofilm is applied, the feed is placed in a ventilated place at a low temperature of 4-10°C to drain, allowing the biofilm layer to fully gel and form a dense gel structure high-protein functional biofilm layer, thus obtaining biofilm-formed feed.

[0032] Furthermore, the specific method for quick-freezing and antibacterial treatment of the attached-film feed in step S4 is as follows:

[0033] The film-forming feed obtained from S3 is spread evenly on a quick-freezing tray and placed in a quick-freezing warehouse at -35℃, so that the core temperature of the feed drops to below -18℃ within 60 minutes; refrigerated trucks are used for cold chain transportation throughout the process, and the ambient temperature is maintained below -18℃ during transportation; the product can be fed directly after natural thawing or thawing with running water.

[0034] The functions of each component in this invention's biofilm-attached functional protein frozen feed are as follows:

[0035] Using low-value wild fish as a carrier, it retains the natural appeal of food, improves the palatability of feed, and has low raw material prices, making costs controllable.

[0036] Enzymatic hydrolyzed fish and water flea slurry: This is a high-protein slurry prepared by double enzymatic hydrolysis of alkaline protease and flavor protease. It serves as the main protein source and attractant carrier in the formula, with a protein content of ≥35% (wet basis). The small peptides after enzymatic hydrolysis can be directly absorbed by farmed organisms after ingestion, reducing the digestive and absorptive burden on the gastrointestinal tract and significantly improving protein utilization and palatability.

[0037] Gelation agent (sodium alginate): Used to form and stabilize the three-dimensional gel network structure of the attached film layer, providing key film-forming properties, water resistance and freeze-thaw resistance, ensuring that the film layer remains intact in water.

[0038] Adhesive additive (soy lecithin): Soy lecithin has multiple functions, including emulsifying fats, improving membrane toughness, and physiological regulation.

[0039] Probiotics: Selected from Bacillus subtilis, used to improve the intestinal health of farmed organisms, secrete digestive enzymes to promote nutrient absorption, and enhance immunity.

[0040] Antioxidants (Vitamin E): Prevent unsaturated fatty acids and fat-soluble vitamins in feed from oxidizing and becoming rancid, thus ensuring the freshness and nutritional value of the feed.

[0041] Multivitamins: Supplement essential vitamins (such as vitamins B, E, niacin, etc.) to meet the micronutrient needs of farmed animals and maintain normal metabolism and health.

[0042] Compared with the above-mentioned background technology, the present invention has the following beneficial effects:

[0043] 1. This invention employs a dual-enzyme hydrolysis process using alkaline protease and flavor protease to convert low-value wild fish protein into high-content, easily absorbed small molecule peptides. These small peptides can be directly absorbed through the intestinal peptide transport system without digestion, resulting in rapid absorption, low energy consumption, and high feed utilization. Feeding trials with large whitefish have shown that, under the same feed dosage, the feed of this invention increases specific growth rates by 20%, significantly reduces the risk of fatty liver, and significantly improves the survival rate of farmed fish.

[0044] 2. This invention provides one feed per fish to meet the differentiated needs of different aquaculture species. This invention designs special formulas for each species based on their diet, physiological and nutritional needs. By optimizing the content of protein, gelling agent, binding agent, probiotics and other components, it achieves precise supply of "one feed per fish" and solves the problem of insufficient adaptability of traditional feeds.

[0045] 3. The "functional biofilm" created in this invention integrates probiotics, multivitamins and other functional components into the biofilm, realizing multiple functions such as intestinal regulation, immune enhancement and disease prevention in farmed animals. It effectively reduces diseases such as intestinal diseases, fatty liver, and oxidative damage, and significantly reduces mortality. It does not require the addition of chemically synthesized antibiotics, which is in line with the trend of antibiotic-free farming.

[0046] 4. The portion of the biofilm layer that detaches after entering the water is rich in nutrients such as small peptides and amino acids, which can serve as a high-quality nitrogen source for phytoplankton. The probiotics in the biofilm layer use organic debris in the water as a carrier to help form bioflocs, effectively adsorbing harmful substances such as ammonia nitrogen and nitrite in the water. This helps maintain a low-nitrogen environment in the water and reduces pollution from aquaculture. Experiments have verified that after using the feed of this invention for 45 days, the ammonia nitrogen level in the aquaculture water is slightly higher but stable, remaining at a low and stable level, and the nitrite content remains low, thus reducing pollution in the aquaculture water.

[0047] 5. This invention has strong feeding attraction and high feeding efficiency: This invention uses low-value wild fish as a natural carrier, fully preserving the superposition of endogenous feeding substances and exogenous feeding substances in the biofilm layer, effectively solving the problems of difficulty in training carnivorous aquatic animals and uneven feeding, significantly improving the feeding rate and training success rate of carnivorous aquatic animals, and reducing feed waste.

[0048] 6. This invention is safe and controllable, green and residue-free, and meets food safety requirements: the raw materials undergo multiple cleaning, screening and physical reduction of initial microbial load, and adopt a -35℃ low temperature quick-freezing process to inhibit the reproduction of putrefactive bacteria and pathogenic bacteria and the generation of harmful substances during processing and storage; no chemically synthesized antibiotics, prohibited drugs and preservatives are added throughout the processing, ensuring that the product has no drug residues and that the aquaculture products meet green and healthy standards.

[0049] 7. This invention boasts superior quality, enhances the commercial value of farmed products, and aligns with consumption upgrades: It conforms to the natural feeding habits of carnivorous aquatic animals that "eat fish of fish," and through the synergistic effects of small peptide nutrition, probiotic regulation, and antioxidants to reduce oxidative damage, it makes farmed products have firm meat and a flavor close to that of wild products, meeting consumers' expectations for green, healthy, and safe food and enhancing market competitiveness.

[0050] 8. This invention offers cost control and enables the high-value utilization of low-value resources, making it suitable for large-scale aquaculture: Using low-priced wild fish as the main raw material, it achieves high-value utilization of these resources through enzymatic hydrolysis, biofilm formation, and other value-added technologies, resulting in a comprehensive cost far lower than high-end formulated feeds. No additional processing is required, significantly reducing the barriers to entry and labor costs for large-scale aquaculture; the process allows for industrialized production, has a long shelf life, is easy to use, and meets the needs of large-scale aquaculture of carnivorous aquatic animals.

[0051] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0052] Figure 1 This is a flowchart of the process for the membrane-attached functional protein frozen feed of the present invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0054] This invention provides a biofilm-type functional protein frozen feed, comprising a carrier, the surface of which is coated with an easily absorbable high-protein functional biofilm layer; the high-protein functional biofilm layer is composed of the following components by mass percentage: 65%-75% enzymatically hydrolyzed feed slurry, 3%-5% gelling agent, 1%-3% binding agent, 0.2%-0.4% antioxidant, 2%-3% probiotics, 0.2%-0.5% compound multivitamins, and the balance being water; the sum of the mass percentages of all components is 100%.

[0055] The carrier is a low-value wild fish; the wild fish is a freshwater fish, selected from at least one of crucian carp, chub, and bitterling;

[0056] The enzymatically hydrolyzed bait slurry is a liquid slurry obtained from miscellaneous fish and water fleas through an enzymatic hydrolysis process;

[0057] The gelling agent is sodium alginate; the antioxidant is vitamin E; the adhesive is soybean lecithin; the probiotics are selected from Bacillus; and the compound multivitamin is at least two of vitamin E, B vitamins, and niacin.

[0058] The high-protein functional biofilm layer is composed of the following components by weight percentage: 70%-75% enzymatically hydrolyzed bait slurry, 3%-4% gelling agent, 1%-2% adhesive aid, 0.2%-0.4% antioxidant, 2% probiotics, 0.2%-0.5% compound multivitamins, and the remainder is water; this formulation is used for predatory carnivorous fish such as mandarin fish and bream that prefer high protein.

[0059] The high-protein functional biofilm layer is composed of the following components by weight percentage: 65%-70% enzymatically hydrolyzed bait slurry, 4%-5% gelling agent, 2%-3% adhesive agent, 0.2%-0.4% antioxidant, 2.5%-3% probiotics, 0.2%-0.5% compound multivitamins, and the remainder is water; this formulation is intended for eels and crabs that have a strong need for biofilm formation.

[0060] like Figure 1 As shown, the preparation method of the biofilm-type functional protein frozen feed provided by the present invention includes the following steps:

[0061] S1. Select feed materials to obtain pretreated fish carriers;

[0062] Select fresh, unspoiled, and disease-free low-value wild fish, remove impurities and diseased individuals, wash with clean water to remove mucus and attached impurities from the body surface, drain and cut into pieces according to the appropriate farming conditions, drain until there is no free water on the body surface, and obtain pre-treated fish carriers for later use.

[0063] S2. Preparation of Film-Carrying Slurry: Weigh the raw materials according to the formula ratio corresponding to the aquaculture species, and prepare the film-carrying slurry by pretreatment of the raw materials, double enzymatic hydrolysis of the pretreated slurry, post-treatment, and compounding and mixing of each raw material component; the specific process includes:

[0064] S21. Raw material pretreatment: Mix the miscellaneous fish and water fleas in the bait (the miscellaneous fish and water fleas are mixed in a mass ratio of 7:3), and grind them into a paste using a colloid mill to obtain a pretreated slurry;

[0065] S22. Double enzymatic hydrolysis of pretreated slurry: Add 0.5 times the mass of water to the pretreated slurry for conditioning. First, perform a primary enzymatic hydrolysis with alkaline protease at a reaction temperature of 44-46℃ and a system pH of 7.0-8.5, and maintain this temperature for 4-6 hours. After the primary hydrolysis, adjust the system pH to 6.5-7.5, add flavor protease for a secondary enzymatic hydrolysis at a reaction temperature of 50-55℃ and maintain this temperature for 2-4 hours. After the double hydrolysis, raise the system temperature to 80-85℃ and incubate for 10-15 minutes to inactivate the enzymes. Filter the solution through a 100-mesh filter cloth to remove unhydrolyzed fish bones, residues, and other impurities. Collect the filtrate to obtain the enzymatically hydrolyzed slurry, and cool it to 30-35℃. The resulting enzymatically hydrolyzed slurry has a protein content ≥35% (wet basis).

[0066] S23. Mixing and blending: Add gelling agent to the enzymatic hydrolysate in proportion and stir until completely dissolved; then add adhesive, antioxidant and compound multivitamin in sequence, and continue stirring for 10-15 minutes until the system is uniform; finally, add probiotics while maintaining the system temperature at 30-35℃ to obtain a uniform film-coating slurry.

[0067] S3. Targeted Film Formation: Using a cold immersion film formation process, the pretreated fish carrier obtained in S1 is immersed in the film formation slurry prepared in S23. The mass ratio of the film formation slurry to the pretreated fish carrier is controlled at 1:4-6. The slurry is soaked for 2-5 minutes to ensure that the slurry is evenly attached to the surface of the carrier. After removal, it is drained to form a basic film layer. According to the high protein requirements of farmed fish, a second film formation is performed. After the film formation is completed, the feed is placed in a ventilated place at a low temperature (4-10°C) to drain, so that the film layer can be fully gelled to form a dense gel structure high-protein functional film layer, thus obtaining film-formed feed.

[0068] S4. Quick-freeze and inhibit bacteria in the attached-film formed feed;

[0069] The film-forming feed obtained from S3 is spread evenly on a quick-freezing tray and placed in a quick-freezing warehouse at -35℃, so that the core temperature of the feed drops to below -18℃ within 60 minutes; refrigerated trucks are used for cold chain transportation throughout the process, and the ambient temperature is maintained below -18℃ during transportation; the product can be fed directly after natural thawing or running water thawing, without any additional processing.

[0070] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below using the Culter alburnus (big white fish), mandarin fish, yellow eel, and Chinese mitten crab as examples.

[0071] In the following embodiment:

[0072] The enzymatically hydrolyzed bait slurry is an enzymatically hydrolyzed slurry of miscellaneous fish and water fleas; it is a liquid slurry obtained by enzymatic hydrolysis of miscellaneous fish and water fleas.

[0073] The gelling agent is sodium alginate;

[0074] The antioxidant is selected from vitamin E;

[0075] The adhesive additive is soybean lecithin;

[0076] The probiotics are selected from Bacillus;

[0077] The multivitamin contains vitamin E and B vitamins.

[0078] Unless otherwise specified, the experimental and detection methods described in each embodiment are conventional methods; unless otherwise specified, the reagents and materials described are available in the general market.

[0079] Example 1: Feed and preparation method for Culter alburnus (large whitefish);

[0080] 1. Culter alburnus (Big Whitefish) feed formula: 75% enzymatically hydrolyzed feed slurry, 3% gelling agent, 1.5% binding agent, 2% probiotics, 0.2% antioxidant, 0.3% compound multivitamin, and the remainder is water;

[0081] 2. Feed preparation method for Culter alburnus:

[0082] S1. Material selection: Select fresh, non-deteriorated, and disease-free low-value wild fish, remove impurities and diseased individuals, wash with clean water to remove mucus and attached impurities from the body surface, drain and cut into pieces according to the appropriate breeding conditions, drain until there is no free water on the body surface, and obtain pre-treated fish carriers for later use.

[0083] S2. Preparation of biofilm slurry: Weigh the raw materials according to the formula ratio, and prepare the biofilm slurry through raw material pretreatment, double enzymatic hydrolysis, post-treatment, and compounding and mixing. Specifically, this includes:

[0084] S21. Raw material pretreatment: After pretreatment, small crucian carp and water fleas are put into a meat grinder and minced into fish paste at a mass ratio of 7:3 (the finer the better). Add 0.5 times the mass of water to make a paste.

[0085] S22, Double Enzymatic Hydrolysis: The first enzymatic hydrolysis uses alkaline protease, with the temperature controlled at 45℃ and the solution pH adjusted to 7.5-8.5, and isothermal hydrolysis for 4-6 hours. After the first enzymatic hydrolysis, the pH is adjusted to 6.5-7.0, and flavor protease is added for the second enzymatic hydrolysis, with the temperature controlled at 52℃, and isothermal hydrolysis continued for 2-4 hours. After the enzymatic hydrolysis reaction is completed, the system is heated to 80℃ and kept at that temperature for 15 minutes to complete enzyme inactivation. The unhydrolyzed fish bones, residues, and other impurities are removed by filtration through a 100-mesh filter cloth, and the filtrate is collected to obtain the enzymatic hydrolysate. The filtrate is then cooled to 30-35℃.

[0086] S23. Mixing and blending: Add gelling agent to the enzymatic hydrolysate in proportion and stir until completely dissolved; then add adhesive, antioxidant and compound multivitamin in sequence, and continue stirring for 10-15 minutes until the system is uniform; finally, under the condition of maintaining the system temperature at 30-35℃, add probiotics to avoid probiotic inactivation and obtain a uniform film-coating slurry.

[0087] S3. Targeted Film Formation: Using a cold immersion film formation process, the pretreated fish carrier obtained in S1 is immersed in the film formation slurry prepared in S23. The mass ratio of the film formation slurry to the pretreated fish carrier is controlled at 1:6. The slurry is soaked for 2-5 minutes to allow it to adhere evenly to the carrier surface. After soaking, it is removed and drained to form a basic film layer, i.e., the first film formation. According to the high protein requirements of the cultured organisms, a second film formation is performed. After the film formation is completed, the feed is placed in a ventilated place to drain at low temperature, allowing the film layer to fully gel and form a dense gel structure high-protein functional film layer, resulting in film-formed feed.

[0088] S4. Quick-freezing and antibacterial treatment: Spread the film-forming feed obtained in S3 evenly on a quick-freezing tray and place it in a quick-freezing room at -35℃. The feed must be quick-frozen so that the core temperature drops to below -18℃ within 60 minutes.

[0089] S5. Cold chain storage and transportation: After the feed is quick-frozen in S4, it is packaged and stored frozen at -18℃ or below. It is transported by refrigerated trucks with a cold chain throughout the process, and the ambient temperature is maintained below -18℃ during transportation. The product can be fed directly after natural thawing or thawing with running water, without any additional processing.

[0090] Performance Test Example 1

[0091] 1. Protein content of enzymatically hydrolyzed slurry:

[0092] Experimental results: The protein content of the prepared enzymatic hydrolysate was tested and found to be ≥35% (on a wet basis). The small peptides formed after enzymatic hydrolysis have good digestibility, palatability and membrane forming strength.

[0093] 2. Physicochemical property testing of the membrane layer:

[0094] This embodiment tests the core physicochemical properties of the feed film prepared by the dual-enzyme hydrolysis + targeted biofilm formation process of the present invention. A single-enzyme hydrolysis and single-biofilm formation feed was used as a blank control group to verify the performance improvement effect of the process of the present invention on the film layer. Test indicators included film adhesion, film toughness, freeze-thaw stability, and solubility loss rate. All tests were conducted using common testing methods in the aquatic feed industry. The test results are shown in Table 1 below.

[0095] Table 1

[0096]

[0097] The test results show that the dual-enzyme hydrolysis targeted biofilm process (secondary biofilm formation) of the present invention significantly improves the adhesion, toughness, freeze-thaw stability of the biofilm, reduces the loss rate, ensures the stability of the biofilm in water, reduces feed loss, and improves feed utilization.

[0098] 3. Functional ingredient activity retention test

[0099] This embodiment quantitatively tests the retention of the core functional components in the feed film layer under all process conditions of the present invention, verifying the protective effects of processes such as low-temperature quick-freezing and gentle film formation on the functional components. All test methods adopted are industry standard methods, and the test results are as follows:

[0100] (1) Protein retention rate: The protein retention rate of the membrane layer prepared by the double-enzyme hydrolysis process was ≥90% and there was no obvious degradation, as determined by high performance liquid chromatography.

[0101] (2) Probiotic survival rate (Bacillus): The plate count method was used to determine the survival rate. Assuming the survival rate was 100% when the slurry was prepared, the probiotic survival rate was 82-85% after cooling and quick-freezing at -35℃ (freezing time 60 minutes). When the core temperature dropped to -18℃ after quick-freezing (freezing time 120 minutes), the overall survival rate of probiotics was 64-68%, which met the technical requirements of the present invention and could fully exert the functions of intestinal regulation and immune enhancement. The dynamic relationship between temperature change and probiotic survival rate in the quick-freezing process of this embodiment is shown in Table 2.

[0102] Table 2

[0103]

[0104] As shown in Table 2, the quick-freezing process of the present invention can quickly pass through the maximum ice crystal formation zone, effectively reducing bacterial cell damage and better preserving the activity of probiotics.

[0105] (3) Retention rate of compound multivitamins: The retention rate of vitamin E in compound multivitamins is ≥75% and the retention rate of vitamin (B group) is ≥70%, which can meet the nutritional needs of aquaculture species.

[0106] (4) Retention rate of soybean lecithin activity: The emulsification activity retention rate of soybean lecithin was determined by thin-layer chromatography to be ≥80%, which can fully exert the functions of emulsifying fat and improving membrane toughness.

[0107] Application Example 1: Verification of the effect of the feed in this embodiment on the culture of Culter alburnus (large whitefish).

[0108] 1. Experimental Design: The feed of this invention was prepared according to the special formula for Culter alburnus. Unprocessed ordinary frozen wild fish and enzymatically hydrolyzed biofilm feed were used as two control groups. A comparative experiment was conducted on Culter alburnus fish cultured for 45 days. The culture subjects were healthy Culter alburnus juveniles with an initial weight of 100g. The ponds were all 30 mu in size, and the number of fry was 1000 per mu, for a total of 30,000 fish per pond (starting from June 26, 2025, location: Xingkai Lake Fishery, Jixi City, Heilongjiang Province). The culture conditions of each experimental group were completely identical. During the experiment, the fish were fed twice a day at regular intervals, with the amount of feed being 2%-3% of the fish's body weight (150 catties / time). Fish growth indicators, survival rate, and intestinal and liver health indicators were monitored regularly by sampling.

[0109] 2. Experimental Results: Compared with the control group of ordinary chilled fish, the aquaculture effect of the feed group of this invention was significantly improved. The core indicators are as follows:

[0110] Feed conversion ratio: With the same amount of feed, after 45 days, the average growth of the ordinary frozen fish group was 210-230 grams, while the growth of the fish group fed with the feed of this invention was 260-280 grams, and the feed utilization rate was greatly improved.

[0111] Specific growth rate: With the same amount of feed, after 45 days, the average length of ordinary frozen fish was 14-15 cm, while the average growth of fish in the feed group of this invention was 16-17 cm, and the growth rate of fish was significantly accelerated.

[0112] Survival rate: With the same amount of feed, after 45 days, 882 fish died in the ordinary group of frozen fish, while only 236 fish died in the group fed with the feed of this invention, showing a significant improvement in the survival rate of aquaculture.

[0113] Liver health: After dissection, the liver cells of the fish fed with this invention showed intact structure, without vacuolation or fatty infiltration. The liver health index was significantly better than that of the ordinary frozen fish group, and the risk of fatty liver was greatly reduced.

[0114] Example 2: Mandarin Fish Feed and Preparation Method

[0115] 1. Feed formulation: 75% enzymatically hydrolyzed feed slurry, 3% gelling agent, 1.5% binding agent, 2% probiotics, 0.2% antioxidant, 0.3% compound multivitamin, and the remainder is water;

[0116] 2. The preparation method is the same as in Example 1.

[0117] Performance Test Example 2

[0118] The performance test in this embodiment is the same as in embodiment 1.

[0119] Application Example 2: Verification of the effect of the feed on mandarin fish farming in this embodiment.

[0120] 1. Experimental Design: A 45-day comparative experiment was conducted on the feed of this invention, formulated specifically for domesticated mandarin fish, using unprocessed ordinary chilled crucian carp and enzymatically hydrolyzed biofilm feed as two control groups. The subjects were healthy mandarin fish with an initial weight of 120g, in ponds of 10 mu (approximately 667 square meters), with 4000 fry per mu, totaling 40,000 fish per pond (starting June 5, 2025, at Xinyuan Mandarin Fish Nursery in Huangpi District, Wuhan City). The rearing conditions were identical for each experimental group. During the experiment, fish were fed twice daily at a rate of 2%-3% of their body weight (approximately 240 catties per feeding). Regular harvesting and observation were conducted to record the success rate of feeding, fish growth indicators, survival rate, and liver health indicators.

[0121] 2. Experimental Results: The feed of this invention significantly improves the pain points of mandarin fish farming, such as difficulty in training them to eat and high risk of fatty liver. Compared with the control group of ordinary frozen fish, the core indicators are improved as follows:

[0122] Feed conversion ratio: With the same amount of feed, after 45 days, the average growth of the ordinary frozen fish group was 230-260 grams, while the growth of the fish group fed with the feed of this invention was 280-320 grams, and the feed utilization rate was greatly improved.

[0123] Specific growth rate: With the same amount of feed, after 45 days, the average length of ordinary frozen fish was 12-14 cm, while the average growth of fish in the feed group of this invention was 15-17 cm, and the growth rate of fish was significantly accelerated.

[0124] Survival rate: With the same amount of feed, after 45 days, 1224 fish died in the group of ordinary frozen fish, while 358 fish died in the group fed with the feed of this invention, showing a significant improvement in the survival rate of aquaculture.

[0125] Liver-to-body ratio: With the same feed dosage, after 45 days, the fatty liver of fish fed with the feed of this invention was within the normal range, and no significant changes were found.

[0126] Feeding success rate: With the same amount of feed, after 45 days, no uneaten food was found in the stomachs of dead fish in the ordinary frozen fish group, while very few uneaten food was found in the stomachs of dead fish in the feed group of this invention.

[0127] Example 3: Eel feed and its preparation method

[0128] 1. Feed formulation: 65% enzymatically hydrolyzed feed slurry, 5% gelling agent, 3% binding agent, 2.5% probiotics, 0.2% antioxidant, 0.3% compound multivitamins, and the remainder is water;

[0129] 2. The preparation method is the same as in Example 1.

[0130] Performance Test Example 3

[0131] The performance test in this embodiment is the same as in embodiment 1.

[0132] Application Example 3: Verification of the effect of the feed of the present invention on the farming of eels

[0133] 1. Experimental Design: The feed of this invention was prepared according to the special formula for swamp eels. Unprocessed ordinary frozen crucian carp and enzymatically hydrolyzed attached feed were used as two control groups to conduct a 45-day comparative experiment on swamp eel farming. The farming subjects were healthy swamp eels with an initial weight of 150g. There were 40 swamp eel cages (divided into 2 groups) for comparison farming, with 1,000 eels per cage, for a total of 40,000 eels per cage (starting from June 12, 2025, at Ruihong Fish Fry Base, Yugan County, Jiangxi Province). The farming conditions were completely identical for each experimental group. During the experiment, the eels were fed twice a day at regular intervals, with a feeding amount of 2%-3% of their body weight (about 300 catties / feed). The success rate of feeding, growth indicators, survival rate, and liver health indicators were observed and recorded regularly.

[0134] 2. Experimental Results: The feed of this invention is precisely tailored to the characteristics of eels, such as their fragile intestines. Compared with the control group of ordinary chilled fish, the core indicators are improved as follows:

[0135] Feed conversion ratio: With the same amount of feed, after 45 days, the average growth of the ordinary frozen fish group was 240-260 grams, while the average growth of the feed group of this invention was 280-300 grams, and the feed utilization rate was greatly improved.

[0136] Specific growth rate: With the same amount of feed, after 45 days, the average length of ordinary frozen fish was 28-35 cm, while the average growth of the feed group of this invention was 34-38 cm, and the growth rate of the fish was significantly accelerated.

[0137] Survival rate: With the same amount of feed, after 45 days, 1046 eels died in the ordinary frozen eel group, while 328 eels died in the feed group of this invention. The survival rate of the farmed eels was significantly improved, and the resistance of the eels to environmental changes was significantly enhanced.

[0138] Example 4: Formula and preparation method of Chinese mitten crab;

[0139] 1. Feed formulation: 65% enzymatically hydrolyzed feed slurry, 5% gelling agent, 3% binding agent, 3% probiotics, 0.2% antioxidant, 0.3% compound multivitamins, and the remainder is water;

[0140] 2. The preparation method is the same as in Example 1.

[0141] Performance Test Example 4

[0142] The performance test in this embodiment is the same as in embodiment 1.

[0143] Application Example 4: Verification of the effect of the feed of the present invention on the farming of Chinese mitten crab:

[0144] 1. Experimental Design: The feed of this invention was prepared according to the optimal formula for crabs. Unprocessed ordinary frozen crucian carp and enzymatically hydrolyzed biofilm feed were used as two control groups to conduct a 45-day comparative experiment on the rearing of juvenile Chinese mitten crabs. The rearing subjects were healthy juvenile Chinese mitten crabs with an initial weight of 30g. Each pond was 50 mu (approximately 3.3 hectares), with 600 crabs / mu per pond, for a total of 30,000 crabs / mu (approximately 20,000 crabs / mu). (Starting from June 5, 2025, at the crab breeding base in Shagou Town, Yancheng City, Jiangsu Province). The rearing conditions were completely identical for each experimental group. During the experiment, the crabs were fed twice a day at regular intervals, with a feeding amount of 1.5%-2.5% of their body weight (approximately 36 jin / feed). The growth indicators, survival rate, and water quality indicators of the aquaculture water were regularly sampled and observed.

[0145] 2. Experimental Results: The feed of this invention is precisely tailored to the characteristics of Chinese mitten crabs, such as slow feeding, weak intestinal digestive capacity, and susceptibility to water pollution. Compared with the control group of ordinary frozen fish, the core indicators are improved as follows:

[0146] Feed conversion ratio: With the same amount of feed, after 45 days, the final weight of crabs in the ordinary frozen crucian carp group was 30-40g, while the final weight of crabs in the feed group of this invention reached 40-50g, and the feed utilization rate was significantly improved.

[0147] Survival rate and stress resistance: With the same amount of feed, after 45 days, the survival rate of ordinary frozen crucian carp was 90% (with signs of death), while the survival rate of the feed group of the present invention was 95% (with no obvious signs). The survival rate of the feed group of the present invention was significantly improved. At the same time, the crabs' stress resistance to environmental changes such as water temperature and dissolved oxygen was significantly enhanced.

[0148] Water quality improvement: Ammonia nitrogen content in aquaculture water was controlled below 0.5 mg / L and nitrite content was controlled below 0.1 mg / L, both significantly lower than the control group, resulting in a substantial reduction in water pollution.

[0149] Application Example 5: Verification of the comprehensive improvement effect of the feed of this invention on aquaculture water.

[0150] 1. Experimental Design: Using Culter alburnus as the cultured species, the experimental group was fed the special formula feed corresponding to this invention, while the control group was fed unprocessed ordinary frozen wild fish. A 45-day comparative experiment on the improvement of water quality in the culture water was conducted, with the culture conditions being consistent with those in the application examples. During the experiment, water samples were collected from the culture water every 15 days, and ammonia nitrogen and nitrite levels were measured using a water quality analyzer to analyze the impact of the feed of this invention on the water quality of Culter alburnus.

[0151] 2. Experimental Results: As shown in Table 3, the feed of this invention achieves the dual effects of providing nutritional support for aquaculture and protecting the aquatic ecosystem. It has a significant effect on improving the water quality of Culter alburnus aquaculture. Compared with the control group, the water quality indicators of the experimental group show significant advantages.

[0152] Ammonia nitrogen: The initial concentration in the experimental group was 0.1 mg / L, which increased to 0.42 mg / L after 45 days. The increase was slightly higher than the initial value but still controllable. In the control group, the concentration rose to 1.61 mg / L after 45 days, which was significantly higher than the initial value, indicating serious ammonia nitrogen pollution in the water.

[0153] Nitrite: The initial content in the experimental group was 0.06-0.08 mg / L, and it was 0.12 mg / L after 45 days. The increase was slight but controllable. In the control group, the content rose to 0.95 mg / L after 45 days, which far exceeded the safety standard for aquaculture (≤0.1 mg / L).

[0154] Table 3 compares the effects of the feed of the present invention (Culter alburnus) and ordinary frozen fish on the water quality indicators of the aquaculture water.

[0155] Table 3:

[0156]

[0157] As shown in Table 3, during the 45-day culture cycle of Culter alburnus, the ammonia nitrogen and nitrite levels in the water of the attached-film frozen fish culture remained stable at low levels. The ammonia nitrogen levels at 15 days, 30 days, and 45 days were 0.25, 0.35, and 0.42 mg / L, respectively, and the nitrite levels were 0.06, 0.09, and 0.12 mg / L, respectively. In contrast, the ammonia nitrogen and nitrite levels in the water of the control group of ordinary frozen fish continued to rise. At 45 days, the ammonia nitrogen level was 1.61 mg / L and the nitrite level was 0.95 mg / L, significantly exceeding the aquaculture safety standards (ammonia nitrogen ≤ 0.5 mg / L, nitrite ≤ 0.1 mg / L). The culture conditions were 1000 fish / mu in ponds.

[0158] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the implementation methods of the present invention, and should be understood that the scope of protection of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of the present invention.

Claims

1. A biofilm-type functional protein frozen feed, characterized in that, The product includes a carrier, the surface of which is coated with a high-protein functional biofilm layer. The high-protein functional biofilm layer is composed of the following components by mass percentage: 65%-75% enzymatically hydrolyzed bait slurry, 3%-5% gelling agent, 1%-3% adhesive agent, 0.2%-0.4% antioxidant, 2%-3% probiotics, 0.2%-0.5% compound multivitamins, and the balance being water. The sum of the mass percentages of all components is 100%.

2. The biofilm-type functional protein frozen feed according to claim 1, characterized in that, The high-protein functional biofilm layer is composed of the following components by mass percentage: The composition consists of 70%-75% enzymatically hydrolyzed bait slurry, 3%-4% gelling agent, 1%-2% binder, 0.2%-0.4% antioxidant, 2% probiotics, 0.2%-0.5% compound multivitamins, and the remainder is water.

3. The biofilm-type functional protein frozen feed according to claim 1, characterized in that, The high-protein functional biofilm layer is composed of the following components by mass percentage: The feed slurry contains 65%-70% enzymatic hydrolysis, 4%-5% gelling agent, 2%-3% binder, 0.2%-0.4% antioxidant, 2.5%-3% probiotics, 0.2%-0.5% compound multivitamins, and the remainder is water.

4. The biofilm-type functional protein frozen feed according to claim 1, characterized in that, The carrier is a low-value wild fish; the wild fish is a freshwater fish, selected from at least one of crucian carp, chub, and bitterling; The enzymatically hydrolyzed bait slurry is a liquid slurry obtained from miscellaneous fish and water fleas through an enzymatic hydrolysis process; The gelling agent is sodium alginate; The antioxidant is selected from vitamin E; The adhesive additive is soybean lecithin; The probiotics are selected from Bacillus subtilis; The multivitamin is at least two of vitamin E, B vitamins, and niacin.

5. The method for preparing the biofilm-type functional protein frozen feed according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Select feed materials to obtain pretreated fish carriers; S2. Preparation of film-coated slurry: Weigh the raw materials according to the formula ratio of the corresponding aquaculture object, and then pre-treat the raw materials, perform double enzymatic hydrolysis on the pre-treated slurry, post-treat, and mix and blend the raw material components to obtain the film-coated slurry. S3, Targeted Film Formation: Using a cold immersion film formation process, the pretreated fish carrier obtained in S1 is immersed in the film formation slurry prepared in S2. The mass ratio of the film formation slurry to the pretreated fish carrier and the soaking time are controlled to ensure that the slurry is evenly attached to the surface of the carrier. After being removed and drained, a basic film layer is formed. After the film is attached, the feed is placed in a ventilated place to drain at low temperature, so that the film layer can be fully gelled to form a dense gel structure of high protein functional film layer, thus obtaining film-formed feed. S4. Quick-freeze and inhibit bacteria in the attached-film formed feed.

6. The method for preparing the biofilm-type functional protein frozen feed according to claim 5, characterized in that, The method for material selection in step S1 includes: selecting fresh, non-deteriorated, and disease-free low-value wild fish, removing impurities and diseased individuals, washing with clean water to remove mucus and attached impurities from the body surface, draining and cutting into pieces according to the appropriate size for aquaculture, and draining until there is no free water on the body surface to obtain a pre-treated fish carrier for later use.

7. The method for preparing the biofilm-type functional protein frozen feed according to claim 5, characterized in that, Step S2 involves weighing the raw materials according to the formula ratio for the corresponding aquaculture species, and then pre-treating, hydrolyzing, post-treating, and mixing the raw materials to obtain the film-coating slurry. The specific process includes the following steps: S21. Raw material pretreatment: Mix the miscellaneous fish and water fleas in the bait, and grind them into a paste using a colloid mill to obtain a pretreated slurry; S22. Double enzymatic hydrolysis of pretreated slurry: Add 0.5 times the mass of water to the pretreated slurry for conditioning. First, perform a first enzymatic hydrolysis with alkaline protease at a reaction temperature of 44-46℃ and a system pH of 7.0-8.5 for 4-6 hours. After the first enzymatic hydrolysis, adjust the system pH to 6.5-7.5 and add flavor protease for a second enzymatic hydrolysis at a reaction temperature of 50-55℃ for 2-4 hours. After the double enzymatic hydrolysis, raise the system temperature to 80-85℃ and keep it at that temperature for 10-15 minutes to inactivate the enzymes. Filter the solution through a 100-mesh filter cloth to remove unhydrolyzed fish bones, residues, and other impurities. Collect the filtrate to obtain the enzymatically hydrolyzed slurry and cool it to 30-35℃. S23. Mixing and blending: Add gelling agent to the enzymatic hydrolysate in proportion and stir until completely dissolved; then add adhesive, antioxidant and compound multivitamin in sequence, and continue stirring for 10-15 minutes until the system is uniform; finally, add probiotics while maintaining the system temperature at 30-35℃ to obtain a uniform film-coating slurry.

8. The method for preparing the biofilm-type functional protein frozen feed according to claim 7, characterized in that, In step S21, the miscellaneous fish and water fleas are mixed in a mass ratio of 7:3; in step S22, the enzymatic hydrolysate prepared has a protein content of ≥35%.

9. The method for preparing the biofilm-type functional protein frozen feed according to claim 5, characterized in that, In step S3, the mass ratio of the biofilm slurry to the pretreated fish carrier is controlled at 1:4-6. The fish is soaked for 2-5 minutes to ensure that the slurry is evenly attached to the surface of the carrier. After soaking, the fish is drained to form a basic biofilm layer. According to the high protein requirements of farmed fish, a second biofilm is applied. After the biofilm is applied, the feed is placed in a ventilated place at a low temperature of 4-10°C to drain, allowing the biofilm layer to fully gel and form a dense gel structure high-protein functional biofilm layer, thus obtaining biofilm-formed feed.

10. The method for preparing the biofilm-type functional protein frozen feed according to claim 5, characterized in that, The specific method for quick-freezing and inhibiting bacteria in step S4 of the attached-film-forming feed is as follows: The film-forming feed obtained from S3 is spread evenly on a quick-freezing tray and placed in a quick-freezing warehouse at -35℃, so that the core temperature of the feed drops to below -18℃ within 60 minutes; refrigerated trucks are used for cold chain transportation throughout the process, and the ambient temperature is maintained below -18℃ during transportation; the product can be fed directly after natural thawing or thawing with running water.

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