Pet soup drink and method of making same

Abstract

The present application belongs to the technical field of pet food, and particularly relates to a pet soup drink and a preparation method thereof. The pet soup drink is prepared by cleaning, blanching, high-temperature cooking and filtering animal base raw materials to obtain soup juice, then adding cascade enzymatic collagen source small-molecule bioactive peptide graft, inulin citric acid ester, water-soluble vitamin compound powder, citric acid and sodium citrate for ingredient and acid adjustment, and then performing centrifugation, homogenization, ultrafiltration, filling, sealing and sterilization to obtain the finished product. The active peptide graft is prepared by multi-enzyme cascade enzymolysis, membrane separation, glutamine grafting and post-enzymolysis of collagen, and the inulin citric acid ester is prepared by esterification, alcohol precipitation, dialysis and drying of inulin and citric acid. The pet soup drink obtained by the present application is clear and stable, has good palatability, and has the effects of water replenishment, nutrition supplementation and intestinal friendliness.

Description

Technical Field

[0001] This invention belongs to the field of pet food technology, specifically relating to a pet soup drink and its preparation method. Background Technology

[0002] With the continuous expansion of companion animal ownership, pet food has gradually evolved from simple satiety products to nutritional supplements, functional conditioning products, and daily care products. Insufficient water intake is a common problem for pets such as dogs and cats, especially those whose primary food source is dry food. Their low willingness to drink can lead to concentrated urine, increased metabolic burden, and further affect the health of their urinary and digestive systems. Existing pet hydration products mostly use ordinary drinking water, broth, or wet food juice. While their flavor can increase pets' willingness to drink to some extent, their nutritional composition is relatively simple, the stability of active ingredients is insufficient, and they are prone to problems such as turbidity, sedimentation, fat floating, increased fishy smell, or decreased palatability during long-term storage. These products fail to simultaneously meet the comprehensive needs of hydration, nutritional supplementation, gut health, and shelf stability.

[0003] Current pet soup drinks are typically made by steaming and boiling animal bones, poultry, or offal to extract the broth, which is then seasoned, filtered, and sterilized. However, because animal-based ingredients contain a significant amount of fat, collagen, protein degradation products, minerals, and flavor precursors, they are prone to protein aggregation, lipid oxidation, and flavor deterioration during high-temperature processing and subsequent storage. This results in reduced product clarity, increased sedimentation, and poorer consistency in taste. Furthermore, the large-molecule collagen and complex proteins in ordinary broth are not easily absorbed by pets, and some components may exhibit flocculation or thermal instability during processing. While adding vitamins, dietary fiber, or acidity regulators can improve some nutritional and flavor issues, the compatibility, thermal stability, and dispersion stability of the components remain insufficient. Especially under high-temperature sterilization conditions in sealed glass bottles, defects such as reduced nutritional activity, darkening of color, loss of aroma, or liquid separation can easily occur. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a pet soup drinking water and a method for preparing it.

[0005] In a first aspect, the present invention provides a method for preparing pet soup drinking water, comprising the steps of: S1. By weight, 100-150 parts of animal base raw material are soaked, blanched, and washed in a washing machine, and drained to obtain the drained animal base raw material; the drained animal base raw material is put into a high-pressure high-temperature sterilizer, 860-890 parts of purified water are added, and the temperature is raised to 115-121℃ for cooking; the temperature is lowered to 75-80℃, and the mixture is filtered to obtain the filtered broth. S2. Transfer the filtered broth to a mixing tank, adjust the temperature to 72-75℃, stir, add 0.5-1.2 parts of cascade enzymatic hydrolyzed collagen-derived small molecule bioactive peptide grafting compound, 0.3-0.8 parts of inulin-citric acid ester, and 0.13-0.20 parts of water-soluble B vitamin complex powder, stir, add 0.05-0.1 parts of citric acid and 0.15-0.5 parts of sodium citrate, adjust the pH to 6.3-6.7 to obtain the mixing solution; The liquid is separated by a three-phase centrifuge to obtain clear bone broth; the clear bone broth is added to a high-pressure homogenizer for homogenization to obtain a homogenized liquid; the homogenized liquid is filtered through an ultrafiltration device to obtain a mixed liquid; the mixed liquid is added to an insulated tank and heated to 78-82℃ to obtain a heated insulated tank; the heated insulated tank is placed into a glass bottle and sealed to obtain a sealed glass bottle; the sealed glass bottle is placed in a sterilizing autoclave and sterilized at 120-122℃, then cooled to room temperature.

[0006] According to a preferred embodiment of the present invention, in step S1, the animal base material is selected from one of bovine bone, raw chicken, raw duck, and raw pigeon.

[0007] According to a preferred embodiment of the present invention, in step S2, the sterilization time at 120-122°C is 20-30 minutes.

[0008] In the pet soup preparation process of this invention, after soaking, blanching, washing, and draining, surface blood, free fat, fishy odor molecules, and insoluble impurities are removed. During co-cooking with purified water in a high-pressure, high-temperature sterilizer, soluble proteins, collagen degradation fragments, amino acids, flavor peptides, minerals, and lipid flavor precursors from beef bones, raw chicken, raw duck, or raw pigeon enter the broth, forming a filtered broth with a meaty and bone broth flavor. In the preparation of the cascade enzymatically hydrolyzed collagen-derived small-molecule bioactive peptide graft, type I collagen... The protein is first acted upon by collagenase, which breaks the easily hydrolyzed peptide bonds in the collagen structure, forming shorter peptide segments. Then, trypsin further cleaves specific sites, followed by continued hydrolysis by flavor proteases to reduce the proportion of bitter peptides. After centrifugation, ultrafiltration, and nanofiltration, incompletely hydrolyzed large protein molecules and excessively small impurities are removed, yielding a concentrated peptide solution with a more concentrated molecular weight distribution. Upon addition of L-glutamine and transglutaminase to the concentrated peptide solution, the amide groups of the glutamine residues in the peptide chains undergo acyl transfer reactions with lysine residues or free amino groups, forming stable amide bonds. In the grafting process, L-glutamine regulates the supply of amide groups and the hydrophilicity of peptides in the reaction system. Subsequently, papain, with the assistance of L-cysteine, performs appropriate enzymatic cleavage on the grafted peptide chain, resulting in a cascade enzymatically hydrolyzed collagen-derived small-molecule bioactive peptide graft with good water solubility, dispersibility, and thermal processing stability. In the preparation of inulin-citric acid esters, the hydroxyl groups on inulin molecules and the carboxyl groups in citric acid undergo esterification under heating concentration and sodium hypophosphite-assisted conditions to form inulin derivatives with citric acid structural units. These derivatives are then processed with anhydrous ethyl acetate. After alcohol precipitation, washing, dialysis, activated carbon treatment, and freeze drying, unreacted small molecule acids, salts, and color and flavor impurities are removed. During the preparation, the filtered broth, cascade enzymatically hydrolyzed collagen-derived small molecule bioactive peptide grafts, inulin-citric acid ester, water-soluble B vitamin complex powder, citric acid, and sodium citrate together form a liquid system with suitable acidity and stable dispersion. This system is then separated by a three-phase centrifuge, homogenized by a high-pressure homogenizer, filtered by an ultrafiltration unit, sealed in glass bottles, and sterilized in an autoclave to obtain a clear, uniform, flavorful pet soup drink suitable for storage.

[0009] According to a preferred embodiment of the present invention, the method for preparing the cascade enzymatic hydrolysis-based collagen-derived small molecule bioactive peptide graft includes: A1. By weight, add 90-110 parts of type I collagen to an enzymatic hydrolysis reactor, add 1400-1600 parts of sterile deionized water, and stir. Adjust the pH to 7.0-7.5 with sodium hydroxide, add 0.4-0.6 parts of collagenase, and stir for enzymatic hydrolysis at 36-38℃. Heat to 84-86℃ and maintain the temperature, then cool to 36-38℃, adjust the pH to 7.5-8.0 with sodium hydroxide, and add 0.1-0.3 parts of trypsin. The enzyme was stirred and hydrolyzed at 36-38℃; the temperature was raised to 84-86℃ and held, then cooled to 48-52℃. The pH was adjusted to 6.5-7.5 with hydrochloric acid, and 0.2-0.4 parts of flavor protease were added. The enzyme was stirred and hydrolyzed at 48-52℃, then the temperature was raised to 88-92℃ and held. The enzyme was cooled to room temperature and centrifuged to obtain the supernatant. The supernatant was ultrafiltered, and the permeate was collected. The permeate was nanofiltered, and the retentate was collected. The retentate was evaporated and concentrated at 48-52℃ to obtain the concentrated peptide solution. A2. Add 5-10 parts L-glutamine and 1-3 parts transglutaminase to the concentrated peptide solution, adjust the pH to 6.0-7.0 with hydrochloric acid, and react under nitrogen protection with stirring at 37-40℃; heat to 78-82℃ and keep warm, then cool to 48-52℃ to obtain the reaction solution; add 1-3 parts papain and 0.05-0.1 parts L-cysteine ​​to the reaction solution, adjust the pH to 6.0-6.5 with hydrochloric acid, and react with stirring at 48-52℃; heat to 84-86℃ and keep warm, then wash and filter to obtain the washed and filtered solution; freeze-dry the washed and filtered solution.

[0010] In this invention, the formation of the cascaded enzymatically hydrolyzed collagen-derived small-molecule bioactive peptide grafts involves four consecutive processes: cascaded enzymatic hydrolysis, membrane fractionation and enrichment, transglutaminase-catalyzed cross-linking, and papain-catalyzed protein polymerization. In the first stage, collagenase, as an endopeptidase, specifically recognizes and cleaves the peptide bond of the glycine-proline-X sequence in the triple helix structure of type I collagen, causing the long-chain collagen to deconstruct into various medium-length peptide segments, disrupting its original rigid structure and releasing the embedded bioactive sequence. Subsequently, trypsin, under weakly alkaline conditions, further specifically cleaves the carboxyl-side peptide bonds of lysine and arginine residues on the peptide chain, further refining the medium-length peptide segments. Then, flavor proteases, with their dual activities of endopeptidase and exopeptidase, act on the remaining peptide chains, on the one hand performing terminal cleavage to release free amino acids and reduce peptide bitterness, and on the other hand modifying the terminal structure of the peptide segments to give them superior flavor and functional properties. In the second stage, the supernatant obtained after centrifugation to remove denatured protein aggregates is passed sequentially through an ultrafiltration membrane and a nanofiltration membrane. The ultrafiltration membrane retains larger, incompletely degraded peptides and residual proteins, while the nanofiltration membrane further retains small and medium-sized peptides with active functions while removing free amino acids and inorganic salts, thereby precisely enriching small peptides within the target molecular weight range. In the third stage, L-glutamine and transglutaminase are added to the concentrated peptide solution. Transglutaminase catalyzes an acyl transfer reaction between the amide group on the glutamine side chain and the amino group on the lysine side chain of the peptide chain, forming a stable isopeptide bond linkage structure. L-glutamine is mainly used to regulate the source of glutamine in the reaction system and improve the hydrophilicity of peptides and the reaction environment, and is not limited to necessarily participating in the formation of directional grafting sites. In the fourth stage, L-cysteine ​​maintains the active site of papain in a reduced and activated state. Papain performs appropriate enzymatic cleavage and end modification on the peptide chains treated with transglutaminase, further adjusting over-crosslinked or long peptide segments into soluble peptide segments with more suitable distribution. Under conditions of high local peptide concentration, limited transpeptidation may also occur, thereby improving the water solubility, dispersion stability, thermal processing adaptability, and flavor characteristics of cascade enzymatically hydrolyzed collagen-derived small molecule bioactive peptide grafts.

[0011] According to a preferred embodiment of the present invention, in step A1, the time for holding the temperature at 88-92°C is 20-40 minutes.

[0012] According to a preferred embodiment of the present invention, in step A2, the stirring reaction time at 48-52°C is 2-3 hours.

[0013] According to a preferred embodiment of the present invention, the method for preparing the inulin-citric acid ester includes: B1. By weight, add 45-55 parts inulin and 25-35 parts citric acid to a reaction vessel, add 150-250 parts deionized water, and then add 2-3.5 parts sodium hypophosphite. Heat and stir to obtain a reaction solution. Concentrate the reaction solution under reduced pressure at 58-62℃ to obtain a concentrated solution. React the concentrated solution at 100-110℃ to obtain a reaction mixture. B2. Cool the reaction mixture to room temperature, add 150-250 parts of deionized water, heat to 50-60℃ and stir, then add 400-600 parts of anhydrous ethanol, centrifuge and collect the precipitate; wash the precipitate with anhydrous ethanol to obtain the washed precipitate; redissolve the washed precipitate in 100-150 parts of deionized water, dialyze at 3-5℃ to obtain the dialyzed solution; evaporate and concentrate the dialyzed solution, add 0.2-0.5 parts of activated carbon, stir at 58-62℃, filter to obtain the filtrate; freeze-dry the filtrate.

[0014] In this invention, the formation of the inulin-citric acid ester is based on the principle of dry thermal esterification, involving the dehydration and activation of citric acid, esterification coupling with the hydroxyl groups of inulin, and a multi-step purification and enrichment process. In the first stage, inulin and citric acid are uniformly dispersed in an aqueous solution and form a hydrogen-bonded association system. Sodium hypophosphite, as a reducing catalyst, plays a dual role of antioxidant protection and esterification promotion. On the one hand, it prevents the decarboxylation oxidation side reaction of citric acid under high temperature conditions and protects the integrity of its three carboxyl groups. On the other hand, it activates the carboxyl groups by forming a phosphoryl intermediate with the carboxyl groups of citric acid, thereby enhancing the esterification reaction activity. In the second stage, the reaction solution is concentrated under reduced pressure to a semi-dry paste state, and the residual water in the system is reduced to a suitable range, so that citric acid and inulin are in a near-molten state to facilitate sufficient intermolecular contact. After entering the high-temperature baking stage, citric acid first undergoes intramolecular dehydration to form a five- or six-membered cyclic anhydride intermediate. The activated anhydride structure has high reactivity. The cyclic anhydride then undergoes nucleophilic addition-dehydration reaction with the primary and secondary hydroxyl groups on the inulin fructose unit to form a carboxylic acid ester bond. Since citric acid has three carboxyl groups, monoesters, diesters and some intermolecular cross-linked esterification structures can be formed during the reaction. The resulting product retains the free carboxyl groups that have not participated in esterification, which endows inulin with good water solubility, anionic properties and functional activity. In the third stage, after the reaction mixture is dissolved in water, anhydrous ethanol is added to raise the ethanol concentration to a suitable range. Due to the sharp decrease in solubility of polysaccharide esterification products in the high-concentration alcohol-water system, they precipitate out. Unreacted small-molecule citric acid, sodium hypophosphite, and their degradation products are retained in the alcohol-water supernatant and thus initially separated. After washing with anhydrous ethanol several times to further remove soluble impurities attached to the precipitate surface, the redissolved esterified aqueous solution is slowly dialyzed at low temperature through a dialysis bag. The difference in molecular size allows free citric acid and inorganic salts to pass through the semipermeable membrane into the external liquid and be removed, while the target esterified product is completely retained due to its larger molecular weight. Finally, after decolorization by activated carbon adsorption to remove caramelization byproducts and pigments, the product is freeze-dried to obtain inulin-citric acid esterified product with high purity.

[0015] According to a preferred embodiment of the present invention, in step B1, the concentrated solution is reacted at 100-110°C for 1.5-2 hours.

[0016] According to a preferred embodiment of the present invention, in step B2, the stirring time at 58-62°C is 30-60 min.

[0017] A second aspect of the present invention provides a pet soup drink prepared according to the aforementioned pet soup drink preparation method.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention uses animal-based raw materials as a base. Through soaking, blanching, washing, draining, steaming, and filtering, the water-soluble flavor components, soluble protein degradation components, minerals, and fat-soluble impurities in the animal-based raw materials are effectively separated, reducing blood, foam, fishy and gamey substances, and insoluble particles from entering the subsequent ingredient system. The animal-based raw materials are selected from one of beef bones, raw chicken, raw duck, and raw pigeon, which can form a base soup with natural meat aroma or bone broth flavor, increasing the pet's willingness to drink it. After separation by a three-phase centrifuge, homogenization by a high-pressure homogenizer, and filtration by an ultrafiltration device, the fat particles, coarse suspended matter, and thermally unstable impurities in the bone broth are further reduced, resulting in pet soup with better clarity, uniformity, and delicate taste, reducing the phenomenon of oil floating, sedimentation, and liquid stratification during storage.

[0019] (2) This invention adds a cascade enzymatically hydrolyzed collagen-derived small-molecule bioactive peptide graft to the filtered broth, which can improve the problems of ordinary collagen having a large molecular weight, insufficient solubility and dispersibility, and easy aggregation after heat processing. The cascade enzymatically hydrolyzed collagen-derived small-molecule bioactive peptide graft is obtained by cascade enzymatic hydrolysis of type I collagen by collagenase, trypsin and flavor protease, followed by ultrafiltration, nanofiltration, concentration, L-glutamine grafting, papain treatment and freeze drying. The resulting peptide components are more easily dispersed in the broth system and help improve the utilization value of protein nutrients. The addition of water-soluble B vitamin complex powder can supplement water-soluble nutrients while maintaining the liquid drinking properties of pet soup, so that the product has both hydration and nutritional supplementation effects.

[0020] (3) This invention uses inulin-citric acid ester in combination with citric acid and sodium citrate to adjust the pH of the system and improve the flavor harmony and dispersion stability of the pet soup. The inulin-citric acid ester is prepared by reacting inulin and citric acid with sodium hypophosphite, followed by precipitation with anhydrous ethanol, washing, dialysis, activated carbon treatment, and freeze-drying. It is more suitable for dispersion in liquid systems containing animal broth than ordinary inulin, which helps to reduce turbidity and flocculent precipitation during storage. After heating in an insulated tank, sealing in a glass bottle, and sterilizing in an autoclave, the pet soup can maintain good shelf stability and hygiene safety, making it suitable for daily feeding. It can improve the problems of existing pet soups with simple nutritional composition, insufficient system stability, poor palatability, and easy deterioration of appearance during storage. Detailed Implementation

[0021] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention. Example

[0022] This embodiment provides a method for preparing pet soup drinking water, the steps of which include: S1. Put 100g of beef bones into a fully automatic bubble cleaning machine, set the cleaning pressure to 0.3MPa, soak in room temperature purified water for 20 minutes, then heat to 90℃ and blanch for 3 minutes. After blanching, use circulating water combined with bubble agitation to clean for 12 minutes. After cleaning, drain until there is no free water on the surface to obtain the drained beef bones. Put the drained beef bones into a high-pressure high-temperature sterilizer, add 860g of purified water, seal and heat to 115℃ at a heating rate of 2℃ / min, and keep warm for 60 minutes. After steaming, cool down to 75℃ and filter through an 80-mesh double filter, set the filtration pressure to 0.2MPa to obtain the filtered broth.

[0023] S2. Transfer the filtered broth to a sealed mixing tank, adjust the temperature to 72℃, turn on the stirring device, set the stirring speed to 45 r / min, add 0.5g of cascade enzymatically hydrolyzed collagen-derived small molecule bioactive peptide graft, 0.3g of inulin-citric acid ester, and 0.13g of water-soluble B vitamin complex powder, and continue stirring for 20 minutes to ensure that all components are fully dissolved and dispersed; then add 0.05g of citric acid and 0.15g of sodium citrate, continue stirring for 10 minutes, adjust the pH to 6.3, and obtain the mixing solution; separate the mixing solution using a three-phase centrifuge, set the centrifugation speed to 8000 r / min, separate for 20 minutes to remove oil phase and solid phase impurities, and collect. Aqueous phase was used to obtain clear bone broth. The clear bone broth was added to a high-pressure homogenizer for homogenization at a pressure of 30 MPa, and homogenized once to obtain a homogenized liquid. The homogenized liquid was filtered through a food-grade hydrophilic polyethersulfone membrane ultrafiltration system with a pore size of 0.22 μm at a filtration pressure of 0.15 MPa to obtain a mixed liquid. The mixed liquid was added to a thermos, heated to 78°C and kept at that temperature for 10 minutes to obtain a heated thermos. The mixed liquid in the heated thermos was poured into a cleaned and sterilized glass bottle and immediately sealed to obtain a sealed glass bottle. The sealed glass bottle was placed in a sterilizer and sterilized at 120°C for 20 minutes. After sterilization, it was cooled to room temperature to obtain pet drinking water.

[0024] Preparation of cascade enzymatically hydrolyzed collagen-derived small-molecule bioactive peptide grafts: A1. Add 90g of type I collagen to an enzymatic hydrolysis reactor, add 1400g of sterile deionized water, and stir at 150r / min to disperse. Adjust the pH to 7.0 with 0.1mol / L sodium hydroxide, add 0.4g of collagenase, and hydrolyze at 120r / min for 3h under a 36℃ water bath. After hydrolysis, raise the temperature to 84℃ and incubate for 10min to completely inactivate the collagenase, then lower the temperature to 36℃, adjust the pH to 7.5 with 0.1mol / L sodium hydroxide, add 0.1g of trypsin, and hydrolyze at 120r / min for 1h under a 36℃ water bath. After hydrolysis, raise the temperature to 84℃ and incubate for 10min to inactivate the trypsin, then lower the temperature to 48℃, add 0.1mol / L sodium hydroxide, and hydrolyze at 120r / min for 1h. Adjust the pH to 6.5 with hydrochloric acid, add 0.2g of flavor protease, and hydrolyze at 48℃ with stirring at 120r / min for 1h. After hydrolysis, heat to 88℃ and incubate for 20min to inactivate the flavor protease. Cool to room temperature and centrifuge at 8000r / min for 20min, and collect the supernatant. The supernatant is first ultrafiltered through a spiral-wound polyethersulfone ultrafiltration membrane system with a molecular weight cutoff of 1500Da, and the permeate is collected. The permeate is then nanofiltered through a spiral-wound polyethersulfone nanofiltration membrane system with a molecular weight cutoff of 500Da, and the retentate (target small molecule peptide components with molecular weight between 500Da and 1500Da) is collected. The retentate is concentrated by rotary evaporation at 48℃ until the peptide concentration reaches 30% (w / v), to obtain concentrated peptide solution.

[0025] A2. Add 5g of food-grade L-glutamine and 1g of microbial transglutaminase to the concentrated peptide solution. Adjust the pH to 6.0 with 0.1mol / L hydrochloric acid. React at 37℃ with stirring (100r / min) under nitrogen protection for 2 hours. After the reaction, raise the temperature to 78℃ and hold for 10 minutes to completely inactivate the transglutaminase. Cool to 48℃ to obtain the reaction solution. Add 1g of papain and 0.05g of food-grade L-cysteine ​​to the reaction solution. Adjust the pH with 0.1mol / L hydrochloric acid. The reaction mixture was stirred at 48℃ for 2 hours under constant temperature (100 r / min) until it reached 6.0. After the reaction was completed, the temperature was raised to 84℃ and held for 15 minutes to completely inactivate the papain. Then, the reaction solution was washed and desalted at a constant volume using a spiral-wound polyethersulfone nanofiltration membrane system with a molecular weight cutoff of 150 Da. During this process, 5000 g of deionized water was added to continuously replace the permeate. The washed and filtered solution was freeze-dried at -50℃ and pressure <20 Pa for 48 hours to obtain a cascade enzymatic hydrolyzed collagen-derived small molecule bioactive peptide graft.

[0026] Preparation of inulin-citric acid esters: B1. Add 45g of inulin and 25g of anhydrous citric acid to a reaction vessel, add 150g of deionized water, and then add 2g of food-grade sodium hypophosphite. Heat to 50℃ and stir at 150r / min until completely dissolved. After complete dissolution, concentrate the reaction solution under vacuum at 60℃ (vacuum degree -0.09MPa) until the water content of the system reaches 15%, and obtain a semi-dry paste. Transfer the semi-dry paste to a forced-ventilation constant temperature oven and carry out a dry esterification reaction at 100℃ for 1.5h to obtain the reaction mixture.

[0027] B2. Cool the reaction mixture to room temperature, add 150 g of deionized water and heat to 50 °C. Stir continuously at 150 rpm for 30 min until the solid is completely dissolved. Then slowly add 400 g of anhydrous ethanol (addition rate 10 mL / min) to achieve a final ethanol concentration of 65% (v / v). Centrifuge at 4000 rpm for 10 min and collect the precipitate. Wash the precipitate three times with 250 g of anhydrous ethanol (centrifuge at 4000 rpm for 5 min after each wash). Redissolve the washed precipitate. Dissolved in 100g of deionized water, the solution was dialyzed against 3000g of deionized water for 36h at 3℃ using a regenerated cellulose dialysis bag with a molecular weight cutoff of 500Da, with the dialysate replaced every 4h. The dialyzed solution was concentrated to 1 / 5 of its original volume by rotary evaporation at 50℃, 0.2g of food-grade activated carbon was added, and the mixture was stirred at 58℃ for 30min. The activated carbon was removed by filtration through a 0.22μm filter membrane while hot. The filtrate was freeze-dried at -50℃ and <20Pa for 48h to obtain a white powdery inulin-citric acid ester. Example

[0028] The difference between this embodiment and Embodiment 1 is that this embodiment provides a method for preparing pet soup drinking water, the steps of which include: S1. Place 125g of raw chicken into a cleaning machine, set the cleaning pressure to 0.3MPa, soak it in room temperature purified water for 25 minutes, then heat it to 92℃ and blanch it for 4 minutes. After blanching, rinse it with circulating water for 15 minutes. After cleaning, drain the raw chicken until there is no free water on the surface. Place the drained raw chicken into a high-pressure high-temperature sterilizer, add 875g of purified water, seal it, and heat it to 118℃ at a heating rate of 2℃ / min. Keep it warm and cook for 75 minutes. After cooking, cool it down to 78℃ and filter it through an 80-mesh double filter. Set the filtration pressure to 0.2MPa to obtain the filtered broth.

[0029] S2. Transfer the filtered broth to a sealed mixing tank, adjust the temperature to 74℃, turn on the stirring device, set the stirring speed to 50 rpm, add 0.85 g of cascade enzymatically hydrolyzed collagen-derived small molecule bioactive peptide graft, 0.55 g of inulin-citric acid ester, and 0.16 g of water-soluble B vitamin complex powder, and continue stirring for 23 min to ensure that all components are fully dissolved and dispersed; then add 0.075 g of citric acid and 0.325 g of sodium citrate, continue stirring for 10 min, adjust the pH to 6.5, and obtain the mixing solution; separate the mixing solution using a three-phase centrifuge, set the centrifugation speed to 9000 rpm, and separate for 20 min to remove oil and solid phase impurities. Collect the aqueous phase to obtain clear bone broth; add the clear bone broth to a high-pressure homogenizer for homogenization, set the homogenization pressure to 40 MPa, homogenize once to obtain a homogenized liquid; filter the homogenized liquid through a food-grade hydrophilic polyethersulfone membrane ultrafiltration device with a pore size of 0.22 μm, set the filtration pressure to 0.15 MPa to obtain a mixed liquid; add the mixed liquid to a thermos, heat to 80℃ and keep at that temperature for 10 min to obtain a heated thermos; pour the mixed liquid from the heated thermos into a cleaned and sterilized glass bottle, seal it immediately to obtain a sealed glass bottle; place the sealed glass bottle in a sterilizer and sterilize at 121℃ for 25 min, cool to room temperature after sterilization to obtain pet drinking water.

[0030] Preparation of cascade enzymatically hydrolyzed collagen-derived small-molecule bioactive peptide grafts: A1. Add 100g of type I collagen to an enzymatic hydrolysis reactor, add 1500g of sterile deionized water, and stir. Adjust the pH to 7.25 with 0.1mol / L sodium hydroxide, add 0.5g of collagenase, and hydrolyze at 37℃ for 3.5h with stirring. Heat to 85℃ and hold for 12.5min, then cool to 37℃, adjust the pH to 7.75 with 0.1mol / L sodium hydroxide, add 0.2g of trypsin, and hydrolyze at 37℃ with stirring for 1.5h. Heat to 85℃ and hold for 10min, then cool to 5℃. At 0℃, adjust the pH to 7.0 with 0.1 mol / L hydrochloric acid, add 0.3 g of flavor protease, stir and hydrolyze at 50℃ for 1.5 h, heat to 90℃ and hold for 30 min, cool to room temperature, centrifuge at 8000 r / min for 20 min to obtain supernatant; ultrafilter the supernatant through a 1500 Da molecular weight cutoff ultrafiltration membrane and collect the permeate; nanofilter the permeate through a 500 Da molecular weight cutoff nanofiltration membrane and collect the retentate; evaporate and concentrate the retentate at 50℃ to a peptide concentration of 35% (w / v) to obtain concentrated peptide solution.

[0031] A2. Add 7.5g L-glutamine and 2g transglutaminase to the concentrated peptide solution, adjust the pH to 6.5 with 0.1mol / L hydrochloric acid, and react at 38.5℃ with stirring under nitrogen protection for 2.5h; raise the temperature to 80℃ and hold for 10min, then cool to 50℃ to obtain the reaction solution; add 2g papain and 0.075g L-cysteine ​​to the reaction solution, adjust the pH to 6.25 with 0.1mol / L hydrochloric acid, and react at 50℃ with stirring for 2.5h; raise the temperature to 85℃ and hold for 15min, then use a nanofiltration membrane with a molecular weight cutoff of 225Da for washing and desalting, adding 7500g deionized water to continuously replace the permeate to obtain the washed solution; freeze-dry the washed solution.

[0032] Preparation of inulin-citric acid esters: B1. Add 50g of inulin and 30g of anhydrous citric acid to a reaction vessel, add 200g of deionized water, and then add 2.75g of sodium hypophosphite. Heat and stir until completely dissolved. Concentrate the reaction solution under reduced pressure at 60℃ to a water content of 17.5% to obtain a semi-dry paste concentrate. Transfer the concentrate to a forced-ventilation constant temperature oven and react at 105℃ for 1.75h to obtain the reaction mixture.

[0033] B2. Cool the reaction mixture to room temperature, add 200g of deionized water, heat to 55℃ and stir for 45min until the solid is completely dissolved. Then slowly add 500g of anhydrous ethanol to bring the final ethanol concentration to 72.5% (v / v). Centrifuge at 4000r / min for 10min and collect the precipitate. Wash the precipitate three times with 300g of anhydrous ethanol. Redissolve the washed precipitate in 125g of deionized water and dialyze it against 4000g of deionized water at 4℃ for 36h using a dialysis bag with a molecular weight cutoff of 500Da, changing the dialysate every 4h. Evaporate and concentrate the dialyzed solution to 1 / 5 of its original volume, add 0.35g of activated carbon, stir at 60℃ for 45min, filter, and freeze-dry the filtrate. Example

[0034] The difference between this embodiment and Embodiment 1 is that this embodiment provides a method for preparing pet soup drinking water, the steps of which include: S1. Place 150g of raw duck into a cleaning machine, set the cleaning pressure to 0.3MPa, soak it in room temperature purified water for 30 minutes, then heat it to 95℃ and blanch it for 5 minutes. After blanching, rinse it with circulating water for 18 minutes. After cleaning, drain it until there is no free water on the surface to obtain the drained raw duck. Place the drained raw duck into a high-pressure high-temperature sterilizer, add 890g of purified water, seal it, and heat it to 121℃ at a heating rate of 2℃ / min. Keep it warm and steam it for 90 minutes. After steaming, cool it down to 80℃ and filter it through an 80-mesh double filter. Set the filtration pressure to 0.2MPa to obtain the filtered broth.

[0035] S2. Transfer the filtered broth to a sealed mixing tank, adjust the temperature to 75℃, turn on the stirring device, set the stirring speed to 55 r / min, add 1.2g of cascade enzymatically hydrolyzed collagen-derived small molecule bioactive peptide graft, 0.8g of inulin-citric acid ester, and 0.2g of water-soluble B vitamin complex powder, and continue stirring for 25 minutes to ensure that all components are fully dissolved and dispersed; then add 0.1g of citric acid and 0.5g of sodium citrate, continue stirring for 10 minutes, and adjust the pH to 6.7 to obtain the mixing solution; separate the mixing solution using a three-phase centrifuge, set the centrifugation speed to 10000 r / min, separate for 20 minutes to remove oil phase and solid phase impurities, and collect the water. The bone broth was prepared by homogenization. The bone broth was then homogenized once in a high-pressure homogenizer at a pressure of 50 MPa to obtain a homogenized liquid. This homogenized liquid was then filtered through a food-grade hydrophilic polyethersulfone membrane ultrafilter with a pore size of 0.22 μm at a filtration pressure of 0.15 MPa to obtain a mixed liquid. This mixed liquid was then added to a thermos, heated to 82°C, and kept at that temperature for 10 minutes to obtain a heated thermos. The mixed liquid in the heated thermos was then transferred to a cleaned and sterilized glass bottle and immediately sealed to obtain a sealed glass bottle. The sealed glass bottle was then placed in a sterilizer and sterilized at 122°C for 30 minutes. After sterilization, the bottle was cooled to room temperature to obtain pet drinking water.

[0036] Preparation of cascade enzymatically hydrolyzed collagen-derived small-molecule bioactive peptide grafts: A1. Add 110g of type I collagen to an enzymatic hydrolysis reactor, add 1600g of sterile deionized water, and stir. Adjust the pH to 7.5 with 0.1mol / L sodium hydroxide, add 0.6g of collagenase, and stir at 38℃ for 4 hours for enzymatic hydrolysis. Raise the temperature to 86℃ and hold for 15 minutes, then cool to 38℃, adjust the pH to 8.0 with 0.1mol / L sodium hydroxide, add 0.3g of trypsin, and stir at 38℃ for 2 hours for enzymatic hydrolysis. Raise the temperature to 86℃ and hold for 10 minutes, then cool to 52℃. Adjust the pH to 7.5 with 0.1 mol / L hydrochloric acid, add 0.4 g of flavor protease, stir and hydrolyze at 52 °C for 2 h, heat to 92 °C and hold for 40 min, cool to room temperature, centrifuge at 8000 r / min for 20 min to obtain supernatant; ultrafilter the supernatant through a 1500 Da molecular weight cutoff ultrafiltration membrane and collect the permeate; nanofilter the permeate through a 500 Da molecular weight cutoff nanofiltration membrane and collect the retentate; evaporate and concentrate the retentate at 52 °C to a peptide concentration of 40% (w / v) to obtain concentrated peptide solution.

[0037] A2. Add 10g L-glutamine and 3g transglutaminase to the concentrated peptide solution, adjust the pH to 7.0 with 0.1mol / L hydrochloric acid, and react at 40℃ with stirring under nitrogen protection for 3h; heat to 82℃ and hold for 10min, then cool to 52℃ to obtain the reaction solution; add 3g papain and 0.1g L-cysteine ​​to the reaction solution, adjust the pH to 6.5 with 0.1mol / L hydrochloric acid, and react at 52℃ with stirring for 3h; heat to 86℃ and hold for 15min, then use a 300Da molecular weight cutoff nanofiltration membrane for washing and desalting, adding 10000g deionized water to continuously replace the permeate to obtain the washed solution; freeze-dry the washed solution.

[0038] Preparation of inulin-citric acid esters: B1. Add 55g of inulin and 35g of anhydrous citric acid to a reaction vessel, add 250g of deionized water, and then add 3.5g of sodium hypophosphite. Heat and stir until completely dissolved. Concentrate the reaction solution under reduced pressure at 62℃ to a water content of 20% to obtain a semi-dry paste concentrate. Transfer the concentrate to a forced-ventilation constant temperature oven and react at 110℃ for 2 hours to obtain the reaction mixture.

[0039] B2. Cool the reaction mixture to room temperature, add 250g of deionized water, heat to 60℃ and stir for 60min until the solid is completely dissolved. Then slowly add 600g of anhydrous ethanol to bring the final ethanol concentration to 80% (v / v). Centrifuge at 4000r / min for 10min and collect the precipitate. Wash the precipitate three times with 350g of anhydrous ethanol. Redissolve the washed precipitate in 150g of deionized water and dialyze it against 5000g of deionized water at 5℃ for 36h using a dialysis bag with a molecular weight cutoff of 500Da, changing the dialysate every 4h. Evaporate and concentrate the dialyzed solution to 1 / 5 of its original volume, add 0.5g of activated carbon, stir at 62℃ for 60min, filter, and freeze-dry the filtrate.

[0040] Comparative Example 1 The difference between this comparative example and Example 2 is that no cascade enzymatic hydrolysis-type collagen-derived small molecule bioactive peptide grafting material is added; the remaining steps and dosages are exactly the same as in Example 2.

[0041] Comparative Example 2 The difference between this comparative example and Example 2 is that inulin-citric acid ester ester is not added, while the remaining steps and dosages are exactly the same as in Example 2.

[0042] Comparative Example 3 The difference between this comparative example and Example 2 is that neither the cascade enzymatic hydrolysis type collagen-derived small molecule bioactive peptide graft nor the inulin-citric acid ester is added. The remaining steps and dosages are exactly the same as in Example 2.

[0043] The performance of the pet soup drinking water obtained in Examples 1-3 and Comparative Examples 1-3 was tested in accordance with national and industry standard testing specifications.

[0044] Pet soup drinks prepared in Examples 1, 2, 3, 1, 2, and 3 were used as test samples. Three batches of independent samples were prepared for each group of samples, and six bottles were randomly selected from each batch. All samples were tested after standing at 25°C in the dark for 24 hours.

[0045] The turbidity test method after 30 days of storage is as follows: each group of samples is placed in a light-proof environment at 25℃ and 50% relative humidity and stored upright for 30 days. During the storage period, the samples are not shaken or inverted. After the storage is completed, the sample bottles are slowly inverted 3 times to restore the liquid in the bottles to a homogeneous state. Then, the samples are allowed to stand for 5 minutes. 20 mL of the sample is added to a clean and transparent cuvette. The turbidity is measured at 25℃ using a turbidimeter. Each batch is measured in parallel 3 times. The average value is taken as the result of the batch. The average value of the 3 batches of samples is then calculated. The result is expressed as NTU.

[0046] The precipitation rate test method is as follows: After 30 days of storage, the sample is slowly mixed and 50 mL of sample is accurately measured and added to a centrifuge tube that has been dried to constant weight at 60℃. The mass of the centrifuge tube is recorded as m0. The sample is centrifuged at 4000 r / min for 10 min. The supernatant is discarded and the precipitate at the bottom of the tube is retained. The centrifuge tube and the precipitate are placed in a drying oven at 60℃ and dried to constant weight. The mass is recorded as m1. The precipitation rate is calculated according to the formula: precipitation rate = (m1 - m0) ÷ sample mass × 100%. Three batches of samples are tested for each group of samples, and three parallel determinations are performed for each batch. The average value is taken.

[0047] The method for testing the soluble peptide retention rate is as follows: Take 10 mL each of the pre-sterilization mixture and the post-sterilization pet soup / drinking water, filter them through a 0.45 μm filter membrane, and determine the soluble peptide content of the filtrate. The soluble peptide content in the pre-sterilization mixture is recorded as C0, and the soluble peptide content in the post-sterilization pet soup / drinking water is recorded as C1. The soluble peptide retention rate is calculated according to the formula: soluble peptide retention rate = C1 ÷ C0 × 100%. Three batches of samples are tested for each group, and each batch is measured in parallel three times.

[0048] The method for testing the retention rate of B vitamins is as follows: Take 10 mL of sterilized pet broth, filter it through a 0.22 μm filter membrane, collect the filtrate, and determine the total water-soluble vitamin content corresponding to the water-soluble B vitamin complex powder. The theoretical amount of water-soluble B vitamin complex powder added during the ingredient stage is recorded as V0, and the actual measured total water-soluble vitamin content after sterilization is recorded as V1. The retention rate of B vitamins is calculated according to the formula: Vitamin B retention rate = V1 ÷ V0 × 100%. Three batches of samples are tested for each group, and each batch is measured in parallel three times.

[0049] The preferred intake rate test method was as follows: 30 healthy adult dogs and 30 healthy adult cats were selected. No snacks were provided 12 hours before the test, and the basic daily diet was provided normally. Water was stopped 2 hours before the test. Each pet was given 100mL of the pet soup to be tested and 100mL of purified water at the same time. The two water containers were made of the same material, shape and placed at the same height. The left and right positions were randomly swapped. The test time was 30 minutes. The intake of the pet soup and the intake of purified water were recorded. The preferred intake rate was calculated according to the formula: preferred intake rate = intake of pet soup ÷ total fluid intake × 100%. Each group of samples was tested continuously for 3 days, and the average value of the test results of all pets was taken.

[0050] The method for testing the retention rate of stored flavor is as follows: Each group of samples was stored at 25℃ in the dark for 0 days and 30 days respectively. Samples were taken immediately after opening and blindly evaluated by 10 trained evaluators at room temperature of 25℃. The evaluation included the intensity of meat aroma, control of fishy smell, coordination of acidity and off-odor. The full score was 100 points. The flavor score for 0 days of storage was recorded as F0 and the flavor score for 30 days of storage was recorded as F1. The retention rate of stored flavor was calculated according to the formula: F1 ÷ F0 × 100%.

[0051] The method for testing the total number of colonies after incubation at 37℃ for 7 days is as follows: Take each group of sealed samples and place them in a constant temperature incubator at 37℃ for 7 days. After the incubation is completed, open the sample, take 1 mL of sample and add it to 9 mL of sterile diluent and mix well. Perform serial dilution as needed, take the appropriate dilution and plate culture. After the incubation is completed, count the number of colonies. The result is expressed as CFU / mL.

[0052] The method for testing abnormal appearance after 7 days of incubation at 37℃ is as follows: each group of sealed samples is placed in a 37℃ constant temperature incubator for 7 days. After the incubation is completed, observe whether the bottle expands, whether the bottle cap is loose, whether the liquid is abnormally turbid, flocculent, or has significantly increased sediment, whether oil floats to the surface, or whether there is an odor. Record as "none" or specific abnormal phenomena.

[0053] The performance test data above are shown in Table 1.

[0054] Table 1 Performance Test Results Turbidity after 30 days of storage / NTU 8.6 7.9 8.3 15.8 21.6 34.9 Sedimentation rate / % 0.12 0.09 0.11 0.28 0.43 0.76 Soluble peptide retention rate / % 92.4 94.1 93.6 68.5 90.2 61.7 Vitamin B retention rate / % 86.8 88.1 87.5 82.6 80.9 76.4 Preferred intake rate / % 76.5 81.2 79.4 68.7 65.3 58.6 Storage flavor retention rate / % 90.6 92.3 91.5 83.4 78.8 70.2 Total bacterial count (CFU / mL) after incubation at 37℃ for 7 days ＜10 ＜10 ＜10 ＜10 ＜10 ＜10 Abnormal appearance after culturing at 37℃ for 7 days none none none none none none The test results in Table 1 clearly show that Examples 1-3 are superior to Comparative Examples 1-3 in terms of turbidity, sedimentation rate, soluble peptide retention rate, vitamin B retention rate, preferred intake rate, and storage flavor retention rate after 30 days of storage. This indicates that the present invention effectively improves the problems of poor stability, insufficient retention of nutrients, significant decline in storage flavor, and unstable palatability of existing pet soup drinking systems by synergistically introducing cascade enzymatically hydrolyzed collagen-derived small molecule bioactive peptide grafts and inulin-citric acid esters, combined with three-phase centrifugation, high-pressure homogenization, ultrafiltration, heat preservation filling, and sterilization.

[0055] After 30 days of storage, the turbidity of Examples 1-3 was 8.6 NTU, 7.9 NTU, and 8.3 NTU, respectively, which was significantly lower than that of Comparative Example 1 (15.8 NTU), Comparative Example 2 (21.6 NTU), and Comparative Example 3 (34.9 NTU). The precipitation rates of Examples 1-3 were 0.12%, 0.09%, and 0.11%, respectively, which were also significantly lower than those of Comparative Example 1 (0.28%), Comparative Example 2 (0.43%), and Comparative Example 3 (0.76%). This indicates that the cascade enzymatic hydrolysis-type collagen-derived small molecule bioactive peptide grafts can improve the water solubility and thermal processing dispersibility of peptide components, and the inulin-citric acid ester can improve the dispersion stability of colloidal particles and soluble nutrients in soups and drinking water. Together, they reduce the risk of turbidity, flocculation, precipitation, and stratification during storage.

[0056] The soluble peptide retention rates of Examples 1-3 reached 92.4%, 94.1%, and 93.6%, respectively, which were higher than those of Comparative Example 1 (68.5%) and Comparative Example 3 (61.7%). This indicates that when the cascade enzymatic hydrolysis-type collagen-derived small molecule bioactive peptide grafts are lacking, the soluble peptide source in the system is insufficient and more prone to loss during heat treatment and storage. The vitamin B retention rates of Examples 1-3 were 86.8%, 88.1%, and 87.5%, respectively, which were higher than those of Comparative Example 2 (80.9%) and Comparative Example 3 (76.4%). This indicates that the acidity buffering, dispersion protection, and stabilizing effects of inulin-citric acid ester esters on the liquid system are beneficial to the retention of water-soluble vitamin B complex powder during processing and storage.

[0057] The preferred intake rates of Examples 1-3 were 76.5%, 81.2%, and 79.4%, respectively, which were higher than those of Comparative Example 1 (68.7%), Comparative Example 2 (65.3%), and Comparative Example 3 (58.6%). The storage flavor retention rates were 90.6%, 92.3%, and 91.5%, respectively, which were higher than those of Comparative Example 1 (83.4%), Comparative Example 2 (78.8%), and Comparative Example 3 (70.2%). This indicates that the cascade enzymatic hydrolyzed collagen-derived small molecule bioactive peptide grafts can provide a more stable flavor peptide and amino acid flavor base, and inulin-citric acid esters can improve flavor harmony and reduce flavor deterioration during storage. The two work synergistically to maintain good meaty aroma, taste, and drinking appeal in pet soup drinks.

[0058] After culturing at 37℃ for 7 days, the total bacterial count of all samples was <10 CFU / mL, and there were no abnormal appearances, indicating that the sterilization process of the autoclave can meet the product's hygienic stability requirements. Under the premise of similar microbial stability, Examples 1-3 are still significantly better than Comparative Examples 1-3 in terms of clarity, sedimentation control, nutrient retention, palatability, and flavor retention. This further proves that the focus of this invention is not simply sterilization, but a comprehensive technical problem that existing pet soup drinks are prone to turbidity and sedimentation, decreased nutritional activity, poor flavor retention, and insufficient willingness of pets to drink during their shelf life.

Claims

1. A method for preparing pet soup drinking water, characterized in that the steps include... include: S1. By weight, 100-150 parts of animal base raw material are soaked, blanched, and washed in a washing machine, and drained to obtain the drained animal base raw material; the drained animal base raw material is put into a high-pressure high-temperature sterilizer, 860-890 parts of purified water are added, and the temperature is raised to 115-121℃ for cooking; the temperature is lowered to 75-80℃, and the mixture is filtered to obtain the filtered broth. S2. Transfer the filtered broth to a mixing tank, adjust the temperature to 72-75℃, stir, add 0.5-1.2 parts of cascade enzymatic hydrolyzed collagen-derived small molecule bioactive peptide grafting compound, 0.3-0.8 parts of inulin-citric acid ester, and 0.13-0.20 parts of water-soluble B vitamin complex powder, stir, add 0.05-0.1 parts of citric acid and 0.15-0.5 parts of sodium citrate, adjust the pH to 6.3-6.7 to obtain the mixing solution; The liquid is separated by a three-phase centrifuge to obtain clear bone broth; the clear bone broth is added to a high-pressure homogenizer for homogenization to obtain a homogenized liquid; the homogenized liquid is filtered through an ultrafiltration device to obtain a mixed liquid; the mixed liquid is added to an insulated tank and heated to 78-82℃ to obtain a heated insulated tank; the heated insulated tank is placed into a glass bottle and sealed to obtain a sealed glass bottle; the sealed glass bottle is placed in a sterilizing autoclave and sterilized at 120-122℃, then cooled to room temperature.

2. The method for preparing pet soup drinking water according to claim 1, characterized in that, In step S1, the animal base material is selected from one of the following: bovine bone, raw chicken, raw duck, and raw pigeon.

3. The method for preparing pet soup drinking water according to claim 1, characterized in that, In step S2, the sterilization time at 120-122℃ is 20-30 minutes.

4. The method for preparing pet soup drinking water according to claim 1, characterized in that, The method for preparing the cascade enzymatic hydrolysis-type collagen-derived small molecule bioactive peptide graft includes: A1. By weight, add 90-110 parts of type I collagen to an enzymatic hydrolysis reactor, add 1400-1600 parts of sterile deionized water, and stir. Adjust the pH to 7.0-7.5 with sodium hydroxide, add 0.4-0.6 parts of collagenase, and stir for enzymatic hydrolysis at 36-38℃. Heat to 84-86℃ and maintain the temperature, then cool to 36-38℃, adjust the pH to 7.5-8.0 with sodium hydroxide, and add 0.1-0.3 parts of trypsin. The enzyme was stirred and hydrolyzed at 36-38℃; the temperature was raised to 84-86℃ and held, then cooled to 48-52℃. The pH was adjusted to 6.5-7.5 with hydrochloric acid, and 0.2-0.4 parts of flavor protease were added. The enzyme was stirred and hydrolyzed at 48-52℃, then the temperature was raised to 88-92℃ and held. The enzyme was cooled to room temperature and centrifuged to obtain the supernatant. The supernatant was ultrafiltered, and the permeate was collected. The permeate was nanofiltered, and the retentate was collected. The retentate was evaporated and concentrated at 48-52℃ to obtain the concentrated peptide solution. A2. Add 5-10 parts L-glutamine and 1-3 parts transglutaminase to the concentrated peptide solution, adjust the pH to 6.0-7.0 with hydrochloric acid, and react under nitrogen protection with stirring at 37-40℃; heat to 78-82℃ and keep warm, then cool to 48-52℃ to obtain the reaction solution; add 1-3 parts papain and 0.05-0.1 parts L-cysteine ​​to the reaction solution, adjust the pH to 6.0-6.5 with hydrochloric acid, and react with stirring at 48-52℃; heat to 84-86℃ and keep warm, then wash and filter to obtain the washed and filtered solution; freeze-dry the washed and filtered solution.

5. The method for preparing pet soup drinking water according to claim 4, characterized in that, In step A1, the temperature is raised to 88-92℃ and held for 20-40 minutes.

6. The method for preparing pet soup drinking water according to claim 4, characterized in that, In step A2, the reaction is stirred at 48-52℃ for 2-3 hours.

7. The method for preparing pet soup drinking water according to claim 1, characterized in that, The preparation method of the inulin-citric acid ester includes: B1. By weight, add 45-55 parts inulin and 25-35 parts citric acid to a reaction vessel, add 150-250 parts deionized water, and then add 2-3.5 parts sodium hypophosphite. Heat and stir to obtain a reaction solution. Concentrate the reaction solution under reduced pressure at 58-62℃ to obtain a concentrated solution. React the concentrated solution at 100-110℃ to obtain a reaction mixture. B2. Cool the reaction mixture to room temperature, add 150-250 parts of deionized water, heat to 50-60℃ and stir, then add 400-600 parts of anhydrous ethanol, centrifuge and collect the precipitate; wash the precipitate with anhydrous ethanol to obtain the washed precipitate; redissolve the washed precipitate in 100-150 parts of deionized water, dialyze at 3-5℃ to obtain the dialyzed solution; evaporate and concentrate the dialyzed solution, add 0.2-0.5 parts of activated carbon, stir at 58-62℃, filter to obtain the filtrate; freeze-dry the filtrate.

8. The method for preparing pet soup drinking water according to claim 7, characterized in that, In step B1, the concentrated solution is reacted at 100-110℃ for 1.5-2 hours.

9. The method for preparing pet soup drinking water according to claim 7, characterized in that, In step B2, the stirring time is 30-60 minutes at 58-62℃.

10. A pet soup drink, characterized in that, The pet soup water is prepared by the method according to any one of claims 1-9.