Preparation process of live microorganism fermented high-protein pet food

Abstract

The invention discloses a preparation process of a live microorganism fermented high-protein pet food, and relates to the technical field of animal feeds, prepared raw materials are added according to nutritional requirements, the raw materials are one or more of chicken meal, deep sea fish meal, low-temperature detoxified soybean meal and puffed soybean meal, the raw materials are subjected to live microorganism fermentation treatment, and the high-protein pet food is obtained. The live microorganisms are a combination of at least two of mould, bacillus, saccharomycetes and lactic acid bacteria, and sequential control is implemented based on synergistic fermentation of multiple live microorganisms. According to the invention, through sequential control of aerobic, facultative and anaerobic, growth characteristics of mould, bacillus, saccharomycetes and lactic acid bacteria are accurately adapted, and strain nutrition competition and metabolism antagonism are eliminated. The raw materials are enzymatically hydrolyzed by the mould, the bacillus degrades protein, the yeast optimizes flavor, the lactic acid bacteria inhibits bacteria and protects intestines, and the whole link synergistically exerts power, so that the defect that the function of a single strain is poor is avoided, and more efficient nutrition conversion and function enhancement effects are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of animal feed, in particular to a preparation process of high-protein pet food fermented by living microorganisms. BACKGROUND

[0002] In the field of feed fermentation, living microorganisms refer to microbial individuals that have life activity, can grow and reproduce under suitable conditions of nutrition, temperature, humidity, etc., and can decompose macromolecular substances of feed raw materials and synthesize beneficial metabolites through their own metabolic activities. They are the core functional carriers of fermented feed.

[0003] For feed fermentation, there are four core strains: mold, bacillus, yeast, and lactic acid bacteria. Mold belongs to filamentous fungi in the fungal kingdom and is a typical enzyme-producing living microorganism in feed fermentation. Bacillus belongs to gram-positive bacillus and is an aerobic or facultative anaerobic spore-producing living microorganism. It can not only assist in decomposing macromolecular proteins into small molecular peptides, but also germinate into vegetative cells in the intestinal tract of pets. Yeast belongs to single-cell microorganisms in the fungal kingdom and is a facultative anaerobic living microorganism. It can utilize sugar in raw materials for fermentation to produce flavor substances to improve the palatability of pet food and directly improve the nutritional density of pet food. It also assists in decomposing proteins in cooperation with other strains. Lactic acid bacteria belong to gram-positive bacteria and are anaerobic or facultative anaerobic non-spore-forming living microorganisms. Lactic acid can inhibit the growth of spoilage bacteria and pathogenic bacteria in raw materials, prolong the shelf life of fermented pet food, and decompose proteins to produce small peptides and amino acids to improve protein utilization.

[0004] However, in the production of high-protein pet food fermented by living microorganisms, in order to meet the needs of efficient protein decomposition, flavor optimization, antibacterial preservation, and intestinal probiotics of the finished product, it is often necessary to cooperate with four types of strains with different functions, such as mold, bacillus, yeast, and lactic acid bacteria, for synergistic fermentation. However, due to significant differences in growth and metabolism characteristics of different strains, mold is aerobic, bacillus and yeast are facultative anaerobic bacteria, and lactic acid bacteria are anaerobic. Their adaptation intervals for key parameters such as ventilation, temperature, and pH value of the fermentation system are different. Therefore, in the actual fermentation process, slight fluctuations in these parameters can easily cause imbalance in the proportion of strains. Once a certain type of strain becomes the dominant strain, it will directly disrupt the fermentation rhythm: for example, excessive proliferation of mold may produce harmful toxins such as aflatoxin, and rapid proliferation of lactic acid bacteria may reduce the pH value of the system too early, which will inhibit the enzyme activity of mold and bacillus, ultimately leading to insufficient decomposition of raw material proteins and seriously affecting the stability of the pet food fermentation process and the quality of the finished product. SUMMARY

[0005] The present application aims to provide a preparation process of high-protein pet food fermented by living microorganisms to solve the problems raised in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a preparation process for high-protein pet food fermented with live microorganisms, comprising adding raw materials according to nutritional requirements, wherein the raw materials are one or more of chicken meal, deep-sea fish meal, low-temperature detoxified soybean meal, and extruded soybean meal, and the raw materials are subjected to live microbial fermentation treatment, wherein the live microorganisms are a combination of at least two of molds, Bacillus, yeasts, and lactic acid bacteria, and the process is based on the time-sequential control of the synergistic fermentation of multiple live microorganisms, including the following steps: Step 1: Preparation of pet food ingredients: The proportion of high-protein ingredients is controlled according to the pet's nutritional needs. After the ingredients are evenly mixed, they are pre-treated by low-temperature microwave. Step 2: Perform multi-strain gradient activation: Place different strains in specific culture media according to the required conditions to prepare corresponding bacterial suspensions; Step 3: Staged Sequential Co-fermentation: Utilizing the different characteristics of the microbial strains—aerobic, facultative, and anaerobic—the fermentation stages are planned, specifically as follows: Aerobic enzymatic hydrolysis stage: Set the initial ventilation rate and temperature, and inoculate the pretreated raw material with a fungal suspension; Facultative synergistic quality improvement stage: Adjust ventilation and temperature, and inoculate with a Bacillus and yeast complex bacterial suspension; Anaerobic antibacterial and gut-protecting stage: An anaerobic environment is created in the sealed fermentation chamber, and a lactic acid bacteria complex suspension is introduced; Step 4: Post-processing of pet food: After the fermentation products are dried at low temperature and cold-pressed into granules, they are mixed with compound vitamins and minerals to form the finished pet food product; By setting fermentation parameters for phased, sequential, and synergistic fermentation, the growth and metabolic needs of the dominant microbial species in each phase are adapted, and the premature recovery or excessive proliferation of other microbial species is specifically inhibited, thereby eliminating direct nutrient competition and metabolic antagonism between different microbial species.

[0007] Preferably, in step one, the high-protein raw materials are composed of the following components by weight: 40-50 parts chicken meal, 40-45 parts low-temperature detoxified soybean meal, 25-30 parts deep-sea fish meal, and 5-10 parts puffed soybean meal; the processing parameters for the low-temperature microwave pretreatment are: power 450-550W, time 2-3min, and temperature 60-70℃.

[0008] Preferably, the specific strains in step two are: The mold strain was *Aspergillus oryzae*, and the concentration of the activated spore suspension was 1×10⁻⁶. 7 —1.5×10 7 cells / mL; The Bacillus subtilis strain and the yeast strain are Candida utilis. A composite strain is formed by mixing Bacillus subtilis and Candida utilis at a live cell ratio of 3:2. After activation, the concentration of the composite bacterial suspension is ≥1.5 × 10⁻⁶. 9 CFU / mL; The lactic acid bacteria consist of *Lactobacillus plantarum* and *Bifidobacterium*. A composite strain is formed by mixing *Lactobacillus plantarum* and *Bifidobacterium* at a live bacteria ratio of 2:1, and the concentration of the activated bacterial suspension is ≥1×10⁻⁶. 9 CFU / mL.

[0009] Preferably, the inoculation amount of the mold suspension is 4%-6% (v / w), the inoculation amount of the Bacillus and yeast complex suspension is 2%-4% (v / w), and the inoculation amount of the lactic acid bacteria complex suspension is 3%-5% (v / w).

[0010] Preferably, in step three: The fermentation parameters for the aerobic enzymatic hydrolysis stage are: temperature in the range of 27-29℃, aeration rate in the range of 0.9-1.1 vvm, pH value in the range of 6.5-6.8, and fermentation time in the range of 20-24h. The fermentation parameters for the facultative synergistic quality improvement stage are: temperature in the range of 29-31℃, aeration rate in the range of 0.2-0.4 vvm, pH value naturally transitioning to the range of 5.5-6.2 through fermentation, and fermentation time in the range of 16-20h. The fermentation parameters for the anaerobic antibacterial and gut-protecting stage are: temperature within the range of 36-38℃, pH value stable within the range of 4.2-4.5, and fermentation time within the range of 10-14h.

[0011] Preferably, in step four, the low-temperature drying parameters are: temperature in the range of 40-50℃, drying to a material moisture content of ≤10%; and cold-pressing granulation temperature ≤55℃, with a particle size in the range of 1.5-4mm.

[0012] Preferably, in step three, the water content of the fermentation system in the aerobic enzymatic hydrolysis stage is 48%–52%; the water content of the fermentation system in the facultative synergistic quality improvement stage is 45%–48%; and in the anaerobic antibacterial and gut-protecting stage, sterile nitrogen is used to replace the residual air in the fermentation chamber, with an oxygen concentration ≤1% and a water content of 42%–45%.

[0013] Preferably, in the aerobic enzymatic hydrolysis stage and the facultative synergistic quality improvement stage, the gas introduced is sterile air; in the anaerobic antibacterial and gut-protecting stage, after sealing the fermentation chamber, a vacuum is first drawn to a negative pressure of 0.05-0.08 MPa, and then sterile nitrogen is introduced.

[0014] Preferably, the finished pet food product has the following specifications: crude protein content ≥33%, small molecule peptide content (molecular weight <3000 Da) ≥9%, and total live bacteria count ≥1.2 × 10⁻⁶. 7 CFU / g, trypsin inhibitor degradation rate ≥93%, phytic acid degradation rate ≥90%.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. In this invention, through sequential control of "aerobic → facultative → anaerobic," the growth characteristics of molds, Bacillus, yeasts, and lactic acid bacteria are precisely adapted, eliminating nutrient competition and metabolic antagonism among the strains. Compared with the non-sequential control method of traditional mixed fermentation processes, the pet food prepared by this method shows a significant reduction in diarrhea rates after pets consume it, and a significant increase in the survival rate of live bacteria in the finished product during fermentation. Mold enzymatic hydrolysis of raw materials, Bacillus protein degradation, yeast flavor optimization, and lactic acid bacteria antibacterial and gut-protecting effects work synergistically across the entire chain, avoiding the functional limitations of single strains and achieving more efficient nutrient conversion and functional enhancement.

[0016] 2. In this invention, the preparation process promotes the degradation of large protein molecules into small peptide molecules, increases the degradation rate of trypsin inhibitors and phytic acid, and reduces the digestive burden. Combined with a balanced ingredient ratio, this increases the average daily weight gain of pets, improves feed conversion rate, fully meets the high-protein nutritional needs of pets, and promotes growth and development.

[0017] 3. In this invention, yeast is used to degrade odor-causing substances such as trimethylamine, and precise fermentation parameters are used to enhance pets' willingness to eat. The ingredient ratio can be finely adjusted according to needs, supporting basic protein fortification as well as functional nutrition and energy supplementation, while avoiding digestive burden caused by imbalanced ratios, making it suitable for pets at different growth stages and with different nutritional needs.

[0018] 4. In this invention, fermentation parameters such as temperature, pH, and aeration rate are clearly quantified, and key indicators such as moisture content and oxygen concentration are controllable throughout the process, with comprehensive measures for preventing contamination by miscellaneous bacteria. Low-temperature drying and cold-pressing pelleting processes ensure that the finished product has a low moisture content, resulting in uniform feed particle size, stable crude protein content that meets standards, and a long shelf life at room temperature, making it suitable for large-scale industrial production.

[0019] 5. In this invention, during the anaerobic stage, lactic acid bacteria produce acid to maintain a suitable pH environment, inhibiting the growth of other bacteria, reducing the rate of diarrhea in pets, and ensuring that the number of beneficial bacteria in the pet's intestines meets the standards. The entire process involves low-temperature processing to preserve the total number of live bacteria, strengthen the balance of intestinal flora, reduce the rate of skin inflammation, and ensure the safety of pet food and their physiological health. Attached Figure Description

[0020] Figure 1 This is a process flow diagram of the preparation process of a high-protein pet food fermented by live microorganisms according to the present invention. Figure 2 This is a flowchart of the staged, sequential, and synergistic fermentation process in step three of the preparation process of a live microbial fermented high-protein pet food according to the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1: According to Figure 1 and Figure 2 As shown, a preparation process for high-protein pet food fermented with live microorganisms involves adding raw materials according to nutritional requirements. The raw materials are one or more of chicken meal, deep-sea fish meal, low-temperature detoxified soybean meal, and extruded soybean meal. The raw materials undergo live microbial fermentation treatment. The live microorganisms are combinations of at least two of molds, Bacillus, yeasts, and lactic acid bacteria. The process utilizes time-sequential control based on the synergistic fermentation of multiple live microorganisms, and includes the following steps: Step 1: Preparation of pet food ingredients: The proportion of high-protein ingredients is controlled according to the pet's nutritional needs. After the ingredients are evenly mixed, they are pre-treated by low-temperature microwave. The high-protein raw materials are composed of the following parts by weight: 45 parts chicken meal, 42.5 parts low-temperature detoxified soybean meal, 27.5 parts deep-sea fish meal, and 7.5 parts puffed soybean meal; the processing parameters for low-temperature microwave pretreatment are: power 450-550W, time 2-3min, and temperature 60-70℃.

[0023] Step 2: Perform multi-strain gradient activation: Place different bacterial strains in specific culture media according to the required conditions to prepare corresponding bacterial suspensions, specifically as follows: The mold strain was *Aspergillus oryzae*, and the concentration of the activated spore suspension was 1×10⁻⁶. 7 —1.5×10 7 cells / mL; Aspergillus oryzae activation medium: 200 g / L potato (boiled juice), 20 g / L glucose, 10 g / L peptone, 20 g / L agar, pH 6.5, sterilized at 121℃ for 20 min.

[0024] The Bacillus subtilis strain and the yeast strain are Candida utilis. A composite strain is formed by mixing Bacillus subtilis and Candida utilis at a live cell ratio of 3:2. After activation, the concentration of the composite bacterial suspension is ≥1.5 × 10⁻⁶. 9 CFU / mL; Bacillus subtilis + Candida utilis compound culture medium: corn flour 30 g / L, soybean meal 20 g / L, yeast extract 5 g / L, sucrose 10 g / L, KH2PO4 1 g / L, pH 6.2, sterilized at 121℃ for 20 min.

[0025] The lactic acid bacteria consist of *Lactobacillus plantarum* and *Bifidobacterium*. A composite strain is formed by mixing *Lactobacillus plantarum* and *Bifidobacterium* at a live bacteria ratio of 2:1, and the concentration of the activated bacterial suspension is ≥1×10⁻⁶. 9 CFU / mL.

[0026] Lactic acid bacteria compound culture medium: glucose 20g / L, peptone 10g / L, yeast extract 5g / L, sodium acetate 5g / L, diammonium citrate 2g / L, pH 6.0, sterilized at 115℃ for 30min.

[0027] The inoculation amount for mold suspensions is 4%–6% (v / w), for Bacillus and yeast complex suspensions is 2%–4% (v / w), and for lactic acid bacteria complex suspensions is 3%–5% (v / w).

[0028] The sources (strain numbers) of the microbial strains used above are as follows: Aspergillus oryzae: ATCC 22542; Bacillus subtilis: CGMCC 1.1086; Candida utilis: ATCC 22023; Lactobacillus plantarum: CGMCC 1.557; Bifidobacterium: CGMCC 1.396.

[0029] Step 3: Staged Sequential Co-fermentation: Utilizing the different characteristics of the microbial strains—aerobic, facultative, and anaerobic—the fermentation stages are planned, specifically as follows: Aerobic enzymatic hydrolysis stage: Set the initial ventilation rate and temperature, and inoculate the pretreated raw material with a fungal suspension; The fermentation parameters for the aerobic enzymatic hydrolysis stage are: temperature in the range of 27-29℃, aeration rate in the range of 0.9-1.1 vvm, pH value in the range of 6.5-6.8, and fermentation time in the range of 20-24h.

[0030] Facultative synergistic quality improvement stage: Adjust ventilation and temperature, and inoculate with a Bacillus and yeast complex bacterial suspension; The fermentation parameters for the facultative synergistic quality improvement stage are: temperature in the range of 29-31℃, aeration rate in the range of 0.2-0.4 vvm, pH value naturally transitioning to the range of 5.5-6.2 through fermentation, and fermentation time in the range of 16-20h.

[0031] Anaerobic antibacterial and gut-protecting stage: An anaerobic environment is created in the sealed fermentation chamber, and a lactic acid bacteria complex suspension is introduced; The fermentation parameters for the anaerobic antibacterial and gut-protecting stage are: temperature within the range of 36-38℃, pH value stable within the range of 4.2-4.5, and fermentation time within the range of 10-14h.

[0032] In the aerobic enzymatic hydrolysis stage and the facultative synergistic quality improvement stage, the gas introduced is sterile air; in the anaerobic antibacterial and intestinal protection stage, the vacuum is first drawn to a negative pressure of 0.05-0.08 MPa, and then sterile nitrogen is introduced.

[0033] The three-stage fermentation endpoint monitoring, with "time range coverage + key indicator compliance" as its core, is combined with real-time monitoring by online sensors to replace single-time judgment, avoid fermentation deviations caused by fluctuations in raw materials and inoculants, and ensure process stability.

[0034] aerobic bacterial fermentation stage Dual judgment conditions: fermentation for 20-24 hours and crude fiber degradation rate ≥30% (tested according to GB / T6434-2006); Degradation rate monitoring scheme: Near-infrared online sensor is used, and the test is performed once every 2 hours; Triggering mechanism: If the degradation rate meets the standard for two consecutive tests and the time limit is less than 24 hours, the fermentation will automatically enter the facultative stage; if the standard is not met after 24 hours, add 2% Aspergillus oryzae suspension to extend the fermentation to 26 hours.

[0035] Fermentation stage of facultative strains Dual criteria: fermentation for 16-20 hours and trimethylamine degradation rate ≥80% (tested according to GB / T30385-2013); Degradation rate monitoring scheme: Electrochemical trimethylamine sensor, detection once every 1.5 hours; Triggering mechanism: If the degradation rate meets the standard and does not exceed 20 hours, the anaerobic environment construction will be automatically started; if the standard is not met after 20 hours, 1% compound bacterial suspension will be added to extend the fermentation to 22 hours.

[0036] anaerobic fermentation stage Dual criteria: fermentation for 10-14 hours and pH stable at 4.2-4.5 for 2 hours (fluctuation ≤ ±0.1). Monitoring scheme: Three online pH sensors are used, and the average value is taken every 15 minutes. Triggering mechanism: If the pH value is stable and within 14 hours, it will automatically enter the post-processing stage; if the value is not met within 12 hours, 0.8% lactic acid bacteria suspension will be added, and the detection will be intensified until the value is met.

[0037] Step 4: Post-processing of pet food: The fermented products are dried at low temperature, cold-pressed into granules, and then mixed with compound vitamins and minerals to form the finished pet food product. The finished pet food product has the following specifications: crude protein content ≥33%, small molecule peptide content (molecular weight <3000Da) ≥9%, and total viable bacteria count ≥1.2×10⁻⁶. 7 CFU / g, trypsin inhibitor degradation rate ≥93%, phytic acid degradation rate ≥90%; The low-temperature drying parameters are: temperature in the range of 40-50℃, drying until the moisture content of the material is ≤10%; cold pressing granulation temperature ≤55℃, and particle size in the range of 1.5-4mm.

[0038] By setting fermentation parameters for phased, sequential, and synergistic fermentation, the growth and metabolic needs of the dominant microbial species in each phase are adapted, and the premature recovery or excessive proliferation of other microbial species is specifically inhibited, thereby eliminating direct nutrient competition and metabolic antagonism between different microbial species.

[0039] Example 2: The difference between this example and Example 1 lies in step three, specifically: The fermentation parameters for the aerobic enzymatic hydrolysis stage are as follows: temperature set within the range of 36-38℃, aeration rate within the range of 0.9-1.1 vvm, pH value controlled within the range of 5.5-6.2, and fermentation time within the range of 20-24h.

[0040] Example 3: The difference between this example and Example 1 lies in step three, specifically: The fermentation parameters for the facultative synergistic quality improvement stage are: temperature in the range of 36-38℃, aeration rate in the range of 0.2-0.4 vvm, pH value stabilized in the range of 4.2-4.5, and fermentation time in the range of 16-20h.

[0041] Example 4: The difference between this example and Example 1 lies in step three, specifically: The fermentation parameters for the anaerobic antibacterial and gut-protecting stage are: temperature within the range of 29-31℃, and pH value stable within the range of 5.5-6.2.

[0042] Comparative Example 1: The fermentation process of this comparative example is the same as that of Example 1, except that the high-protein raw materials are composed of the following parts by weight: 50 parts chicken meal, 45 parts low-temperature detoxified soybean meal, 25 parts deep-sea fish meal, and 5 parts extruded soybean meal, for a total of 125 parts by weight. Among them, the chicken meal and low-temperature detoxified soybean meal account for 76% of the total, forming the core basic protein system of the feed.

[0043] The core objective of this comparative study is to verify the impact of dual fortification of basal protein on pet growth performance and gastrointestinal tolerance. Specifically, by comparing the original formula with the control group, we will observe growth indicators such as average daily weight gain and crude protein digestibility to determine whether excessive basal protein supply can further enhance growth rate. Simultaneously, we will focus on monitoring gastrointestinal indicators such as diarrhea rate and fecal formation rate to explore whether a high basal protein ratio will lead to decreased intestinal tolerance due to increased protein digestion burden, thus clarifying the optimal boundary for basal protein supply. Furthermore, we will also assist in testing feed conversion ratio to assess whether excessive basal protein leads to nutrient waste, providing data support for cost optimization of feed formulation.

[0044] Comparative Example 2: The fermentation process of this comparative example is the same as that of Example 1, except that the high-protein raw materials are composed of the following by weight: 40 parts chicken meal, 40 parts low-temperature detoxified soybean meal, 30 parts deep-sea fish meal, and 10 parts extruded soybean meal, for a total of 120 parts by weight. Among them, the total proportion of deep-sea fish meal and extruded soybean meal is 33.3%, which constitutes the core system of functional nutrition and energy in the feed.

[0045] The core objective of this comparative study is to verify the beneficial effects of functional nutrition and high-energy fortification on specific physiological indicators in pets. Specifically, this includes: coat condition (shine, smoothness), assessing the improving effects of Omega-3 on skin and coat; immunity levels (serum total protein, immunoglobulin IgG content), exploring the strengthening effects of taurine and selenium on immune function; exercise endurance (daily activity duration, resting heart rate recovery speed), detecting the effect of high-energy supply on improving pet physical performance; and simultaneously monitoring indicators such as body fat percentage and blood glucose levels to determine whether high-energy ratios pose potential risks such as obesity and metabolic disorders, clarifying the optimal ratio of functional ingredients to energy supply, and providing a basis for the formulation design of high-end functional pet foods.

[0046] Performance testing and results analysis Average daily weight gain, average feed intake, and feed conversion ratio: tested based on Appendix A, "Feeding Test Methods," of GB / T 34240-2017 "Pet Food - Dog Food." Diarrhea rate determination standard: based on Appendix A "Feeding Test Method" of GB / T 34240-2017 "Pet Food - Dog Food"; The standard for determining the rate of skin inflammation is based on the requirements of "Safety Evaluation" in GB / T 34240-2017 "Pet Food - Dog Food". Standard for determining fecal formation rate: The test is conducted based on the requirements of Appendix A "Feeding Test Methods" of GB / T 34240-2017 "Pet Food - Dog Food"; Standard for determining the number of beneficial intestinal bacteria: Tested according to the requirements of GB / T 34724-2017 "Microbiological Examination of Pet Food"; The animal feeds prepared in Examples 1-4 and Comparative Examples 1-2 were subjected to performance tests, and the relevant data were recorded in Table 1. Table 1: Pet Food Performance Test Data Recording Table

[0047] Experimental verification shows that Example 1 is the optimal solution. The core logic is: balanced raw material ratio and precise matching of time-sequential synergistic fermentation parameters to achieve synergistic effects of molds, Bacillus, yeasts and lactic acid bacteria throughout the entire chain, without efficiency loss caused by antagonism or functional deficiency of microorganisms. Therefore, it has the highest average daily weight gain (28.5±1.2g / d), the best feed conversion rate (0.436, the highest weight gain / feed intake ratio), and the lowest diarrhea rate (5.0%), with overall performance significantly better than other groups.

[0048] In Example 2, the parameters of the aerobic enzymatic hydrolysis stage (36-38℃, pH 5.5-6.2) approached the anaerobic stage, leading to the inactivation of the mold (Aspergillus oryzae): the degradation of crude fiber and macromolecular protein was incomplete, nutrient digestion and absorption were hindered, the average daily weight gain decreased by 28.8% (20.3±1.5g / d) compared to Example 1, the number of beneficial intestinal bacteria decreased by 19.1% (7.2±0.4logCFU / g feces), and the diarrhea rate increased to 17.5%, highlighting the necessity of mold enzymatic hydrolysis function for raw material pretreatment.

[0049] In Example 3, the parameters of the facultative synergistic quality improvement stage (36-38℃, pH 4.2-4.5) approached the anaerobic stage, leading to metabolic disorders in Bacillus and yeast: insufficient protein degradation, hindered odor removal, decreased pets' willingness to eat, and an average feed intake that decreased by 10.6% (52.4±2.6g / d) compared to Example 1. The skin inflammation rate increased to 10.0% (undegraded protein and residual odor caused allergies), and the fecal formation rate decreased to 87.5%, confirming the core role of facultative bacteria in feed palatability and protein utilization.

[0050] Example 4 shows that the parameters of the anaerobic antibacterial and intestinal-protecting stage (29-31℃, pH 5.5-6.2) approached the facultative stage, resulting in insufficient function of lactic acid bacteria: the ability to produce acid and inhibit bacteria decreased, the risk of the growth of miscellaneous bacteria increased, the diarrhea rate soared to 25.0% (the highest among all groups), the feed conversion rate dropped to 0.360 (the lowest among all groups), and the weight gain performance was the worst. This indicates that the adaptability of lactic acid bacteria to the anaerobic acidic environment is the key to ensuring the intestinal health of pets.

[0051] The data from Comparative Example 1 show that the redundancy of basic proteins leads to an increased digestive burden on the intestines. Although the fermentation process is complete, the nutrient absorption efficiency is limited, indicating that excessive fortification of basic proteins cannot improve growth performance, but instead leads to a decrease in gastrointestinal tolerance. The data from Comparative Example 2 show that the amino acid composition is unbalanced, and the functional components and energy supply deviate from the pet's basal metabolic needs, indicating that simply fortifying functional nutrition and energy cannot replace the core value of a balanced ratio of raw materials.

[0052] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for preparing a high-protein pet food fermented by living microorganisms, the raw materials being prepared according to nutritional requirements, the raw materials being one or more of chicken meal, deep-sea fish meal, low-temperature detoxified soybean meal, and puffed soybean meal, characterized in that, The raw materials are subjected to fermentation treatment by living microorganisms, and the living microorganisms are a combination of at least two of molds, bacillus, yeast, and lactic acid bacteria. The fermentation is implemented based on time sequence control of the synergistic fermentation of multiple living microorganisms, including the following steps: S1, raw material preparation of pet food: the proportion of high-protein raw materials is controlled according to the nutritional requirements of pets, and the raw materials are uniformly mixed and then subjected to low-temperature microwave pretreatment; S2, multi-strain gradient activation: different strains are placed in specific culture media according to the required conditions to prepare corresponding bacterial suspensions; S3, stage time sequence synergistic fermentation: the different characteristics of aerobic, facultative and anaerobic strains are utilized to plan the fermentation stages, specifically: S31, aerobic enzyme hydrolysis stage: the initial aeration amount and temperature are set, and mold bacterial suspension is inoculated into the pretreated raw materials; S32, facultative synergistic upgrading stage: the aeration amount and temperature are adjusted, and bacillus and yeast complex bacterial suspension is inoculated; S33, anaerobic bacteria inhibition and intestinal protection stage: the fermentation tank is sealed to form an anaerobic environment, and lactic acid bacteria complex bacterial suspension is inoculated; S4, post-treatment of pet food: the fermentation product is dried at low temperature, cold-pressed and granulated, and then mixed with complex vitamins and minerals to form the finished pet food product; In step S3, the stage time sequence fermentation parameters are set to adapt to the metabolic requirements of the dominant strains, inhibit the growth of other strains, and eliminate strain nutritional competition and metabolic antagonism.

2. The process for preparing a live microorganism fermented high-protein pet food according to claim 1, characterized in that, In step S1, the high-protein raw materials are composed of 40-50 parts of chicken meal, 40-45 parts of low-temperature detoxified soybean meal, 25-30 parts of deep-sea fish meal, and 5-10 parts of puffed soybean meal. The low-temperature microwave pretreatment parameters are: power 450-550 W, time 2-3 min, and temperature 60-70℃.

3. The process for preparing a live microorganism fermented high-protein pet food according to claim 1, characterized in that, In step S2, the specific strains are: The mold strain is Aspergillus oryzae, and the concentration of activated spore suspension is 1 x 10 7 -1.5 x 10 7 individuals / mL. The bacillus is bacillus subtilis, and the yeast is candida utilis. The bacillus subtilis and the candida utilis are mixed in a ratio of 3:2 to form a complex bacterial strain. After activation, the concentration of the complex bacterial suspension is ≥1.5×10 9 CFU / mL. The lactic acid bacteria are lactobacillus plantarum and bifidobacterium, the lactobacillus plantarum and the bifidobacterium are mixed in a live bacteria ratio of 2:1 to form a complex bacterial strain, and the concentration of the activated bacterial suspension is greater than or equal to 1×10 9 CFU / mL.

4. The process for preparing a live microorganism fermented high-protein pet food according to claim 3, characterized in that: The inoculation amount of the mold bacterial suspension is 4%-6% (v / w), the inoculation amount of the bacillus and yeast complex bacterial suspension is 2%-4% (v / w), and the inoculation amount of the lactic acid bacteria complex bacterial suspension is 3%-5% (v / w).

5. The process for preparing a live microorganism fermented high-protein pet food according to claim 1, characterized in that, In step S3: The fermentation parameters of the aerobic enzyme hydrolysis stage are: temperature in the range of 27-29℃, aeration amount in the range of 0.9-1.1vvm, pH value in the range of 6.5-6.8, and fermentation time in the range of 20-24h; The fermentation parameters of the facultative synergistic upgrading stage are: temperature in the range of 29-31℃, aeration amount in the range of 0.2-0.4vvm, natural transition pH value to the range of 5.5-6.2, and fermentation time in the range of 16-20h; The fermentation parameters of the anaerobic bacteria inhibition and intestinal protection stage are: temperature in the range of 36-38℃, pH value stable in the range of 4.2-4.5, and fermentation time in the range of 10-14h.

6. The process for preparing a live microorganism fermented high-protein pet food according to claim 1, characterized by, In step S3, the moisture content of the fermentation system in the aerobic enzyme hydrolysis stage is 48%-52%, the moisture content of the fermentation system in the facultative synergistic upgrading stage is 45%-48%, and the oxygen concentration in the fermentation tank is ≤1% after the residual air is replaced by sterile nitrogen in the anaerobic bacteria inhibition and intestinal protection stage, and the moisture content of the fermentation system is 42%-45%.

7. The process for preparing a live microorganism fermented high-protein pet food according to claim 1, characterized by, In step S31 and step S32, the gas is sterile air; in step S33, after the fermentation bin is sealed, vacuum is first extracted to a negative pressure of 0.05-0.08 MPa, and then sterile nitrogen is introduced.

8. The process for preparing a live microorganism fermented high-protein pet food according to claim 1, characterized by, In step S4, the low-temperature drying parameters are that the temperature is in the range of 40-50 DEG C, and the material is dried to a moisture content of ≤10%; the cold-pressing granulation temperature is ≤55 DEG C, and the particle size is in the range of 1.5-4 mm.

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