A probiotic milk composition and a method for its preparation

Abstract

This invention discloses a fermented milk composition for infant formula and its preparation method, relating to the fields of bio-fermentation and enzyme engineering technology. The fermented milk composition, by mass percentage, comprises a substrate of 55%–68% fermented milk base, 25%–40% infant-appropriate fruit and vegetable ingredients, 1%–2.5% whey protein powder, and 0.5%–1.5% functional excipients. The composition contains 6.0 g / L–8.0 g / L of in-situ biochemically synthesized galactooligosaccharides, 2.5 g / 100 g–3.5 g / 100 g of small molecule sensitizing-eliminating peptides, and ≥6.0 g / L of neutral stable extracellular polysaccharides. The functional excipients are a mixture of citrus fiber and unmodified starch in a 1:1 mass ratio. This invention simplifies the preparation process by constructing an enzymatic hydrolysis-fermentation coupled biochemical synthesis system, generating functional components in situ, and simplifying the ingredients of infant formula. Through a stepwise directional synthesis process, it reduces product allergenicity, improves protein digestibility, ensures long-term storage stability, and meets the needs of infants.

Description

Technical Field

[0001] This invention relates to the field of bio-fermentation and enzyme engineering technology, specifically to an infant formula fermented milk composition and its preparation method. Background Technology

[0002] Parents are increasingly concerned about the safety and nutritional balance of infant and toddler complementary foods. Fermented milk complementary foods provide high-quality protein and promote gut health, making them a common choice for daily complementary feeding. For fermented milk complementary foods for infants and toddlers, there are strict requirements for the selection of raw materials and the addition of ingredients. Minimizing unnecessary additives and ensuring product quality through natural methods are the core research and development directions for these products. Currently, most infant fermented milk products are prepared using conventional processing methods. Optimizing the product preparation process through biochemical reactions and reducing the use of additives is a practical problem that the industry needs to solve.

[0003] Currently, most infant fermented milk products are prepared by separately enzymatically hydrolyzing and inactivating the enzymes in fruits and vegetables, and then physically mixing them with fermented cow's milk. This step-by-step process, where enzymatic hydrolysis and fermentation are independent, fails to create a synergistic effect. It relies on adding various additives to adjust the product's taste, texture, and stability, contradicting the need for simplified ingredients in infant complementary foods. Furthermore, conventional processes cannot generate functional components suitable for infants, making it difficult to improve the allergenicity of milk proteins, resulting in low digestibility of macromolecular nutrients. Long-term storage also leads to problems such as uneven texture and water separation, failing to meet actual usage requirements. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a fermented milk composition for infant formula and its preparation method. By constructing a biochemical synthesis system that simultaneously couples fruit and vegetable biphasic targeted enzymatic hydrolysis with milk fermentation, and combining it with a stepwise directional synthesis process, a fermented milk composition meeting infant formula requirements is prepared. This solution solves the problems of cumbersome preparation processes, the need for exogenous excipients, high allergenicity risk, and poor long-term storage stability of traditional infant formula fermented milk. It eliminates the separate enzyme inactivation step, and can generate three types of functional components in situ within the system without the need for additional stabilizers, flavorings, or other excipients. This reduces product allergenicity, improves protein digestibility, and ensures product texture stability at room temperature, meeting the requirements of simplified, safe, and nutritious ingredients in infant formula.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: On the one hand, an infant-labeled fermented milk composition, wherein the fermented milk composition, by mass percentage, comprises 55%~68% fermented milk base material, 25%~40% infant-suitable fruit and vegetable raw materials, 1%~2.5% whey protein powder, and 0.5%~1.5% functional excipients; The composition contains 6.0 g / L to 8.0 g / L of in-situ biochemically synthesized galactooligosaccharides, which can regulate the balance of intestinal flora in infants and young children and are adapted to the physiological characteristics of infants and young children's intestines; 2.5 g / 100 g to 3.5 g / 100 g of small molecule sensitization-eliminating peptides, which reduce the risk of milk protein sensitization and are more easily digested and absorbed by the delicate gastrointestinal tract of infants and young children; and ≥6.0 g / L of neutral stable extracellular polysaccharides, which form a stable three-dimensional network structure in the system and can avoid product separation and water separation without the need for exogenous stabilizers. The functional excipient is a mixture of citrus fiber and unmodified starch in a mass ratio of 1:1.

[0006] Furthermore, the fermented milk base is whole milk fermented milk with a protein content of ≥3.2g / 100g, which is nutritionally balanced and comprehensive and can meet the daily high-quality protein supplementation needs of infants and young children, or organic A2β-casein milk fermented milk with a mass ratio of ≥65% in the synthetic substrate, which has lower allergenicity, better digestibility and absorption, and is suitable for infants and young children with sensitive stomachs.

[0007] Furthermore, the suitable fruit and vegetable ingredients for infants and young children are one of strawberries, blueberries, apples, and kiwis, with a pure and simple flavor, suitable for infants and young children who are just starting to eat complementary foods, or a mixture of two or more of them in a mass ratio of 1:1 to 3:1, which provides a more balanced nutritional combination and a richer flavor profile, and can meet the diverse complementary food intake needs of infants and young children.

[0008] Furthermore, the molecular weight of the small molecule sensitization-eliminating peptide is 1000Da~3000Da, which can be directly absorbed by the infant's intestines without increasing the digestive burden on the gastrointestinal tract. The total residual amount of β-lactoglobulin and α-lactalbumin in the composition is ≤0.05mg / kg, which minimizes the risk of sensitization by bovine milk protein and ensures the safety of infants and young children.

[0009] Furthermore, the neutral stable extracellular polysaccharide has a molecular weight of 200,000 Da to 500,000 Da, which can form a uniform gel network in the system and maintain the uniform and stable texture of the product for a long time; the pH value of the composition is 4.22 to 4.28, the total acid content is 0.53g / 100g to 0.57g / 100g, the taste is mild and non-irritating, suitable for the taste development characteristics of infants and young children, and can inhibit the growth of harmful microorganisms, extend the shelf life of the product, the protein content is ≥3.2g / 100g, which meets the mandatory requirements for protein content in infant food, ensuring the basic nutritional supply for infants and young children, and the sodium content is ≤1.0mg / 100g, which meets the requirements for low sodium diet for infants and young children and will not increase the metabolic burden on the kidneys of infants and young children.

[0010] Furthermore, the total amount of non-organic raw materials added to the synthetic substrate of the composition is ≤5%, which maximizes the natural safety of the raw materials and meets the high-quality requirements of infant food. The composition is prepared by a coupled biochemical process in which the enzymatic hydrolysis product is used as the fermentation substrate and the organic acid produced by fermentation regulates the rate of enzymatic hydrolysis reaction, realizing bidirectional synergy between enzymatic hydrolysis and fermentation, eliminating the need for a separate enzyme inactivation process, and ensuring the efficient synthesis of in-situ functional components.

[0011] Furthermore, the synthetic substrate does not contain stabilizers, flavoring agents, or acidity regulators, fully complying with the core requirements of simplified ingredients in infant formula, thus avoiding the food safety risks caused by unnecessary exogenous additives and ensuring the purity and safety of the product.

[0012] On the other hand, a method for preparing an infant-labeled fermented milk composition, the method comprising: S1. Preparation of synthetic substrates: Infant-suitable fruit and vegetable raw materials are washed, pulped, and sieved through an 80-mesh sieve to obtain fruit and vegetable substrates, removing coarse fiber and residue from fruits and vegetables, ensuring a delicate and smooth texture without any grainy feel, and suitable for infants' swallowing abilities; milk raw materials are processed in sequence through standardized treatment, pasteurization at 95℃ for 5 minutes, and cooling to 40℃ to obtain milk protein substrates, which fully kills harmful microorganisms in the raw materials while retaining the natural nutrients in milk to the greatest extent; S2. Construction of Coupled Biochemical System: Fruit and vegetable substrates, milk protein substrates, whey protein powder, and functional excipients are mixed in a sealed sterile reactor according to the specified ratio. At the same time, compound hydrolytic enzyme preparation and infant-specific fermentation strains are added to achieve simultaneous initiation of enzymatic hydrolysis and fermentation reactions, constructing a bidirectional synergistic reaction system and a coupled biochemical system in which enzymatic hydrolysis and microbial fermentation occur simultaneously. No separate enzyme inactivation treatment is performed during the reaction process, simplifying the preparation process and avoiding the destruction of fruit and vegetable nutrients by high-temperature enzyme inactivation. S3. Stepwise directional synthesis: First, low-temperature pre-fermentation is carried out to synthesize galactooligosaccharides, and then constant-temperature main fermentation is carried out to synthesize small molecule sensitizing and eliminating peptides and neutral homeostatic extracellular polysaccharides. The synthesis process of different functional components is precisely controlled in stages to ensure that the synthesis efficiency and content of each target component meet the standards. S4. Reaction Termination: The enzymatic and fermentation reactions are terminated by heat treatment at 58.5℃~59.5℃ for 14min~16min. This gentle termination of the reaction preserves the activity of the functional components synthesized in situ within the system and avoids the destruction of nutrients by high temperature, thus obtaining a fermented milk composition.

[0013] Furthermore, in step S2, the compound hydrolytic enzyme preparation is composed of pectinase, cellulase, and milk protein restriction endonuclease in a mass ratio of 2:1:1. Pectinase and cellulase can fully decompose the cell walls of fruits and vegetables, releasing natural pectin and nutrients. Milk protein restriction endonuclease can directionally hydrolyze milk-induced allergenic proteins, simultaneously achieving cell wall breaking of fruits and vegetables and desensitization of milk proteins. The total addition amount is 0.08%~0.15% of the total mass of the synthetic substrate. While ensuring enzymatic hydrolysis efficiency, it avoids excessive enzyme preparation causing the product to taste bitter and affecting the acceptance of infants and young children. The reaction conditions of the coupled biochemical system are as follows: temperature 39℃~41℃, which is adapted to the optimal activity temperature of the compound hydrolytic enzyme and the fermentation strain to ensure the synchronous and efficient enzymatic hydrolysis and fermentation reaction; vacuum degree 0.075MPa~0.085MPa to avoid oxidation and browning of materials during the reaction process, retain the natural color and flavor of the raw materials, and reduce the loss of nutrients; reaction time 22min~28min to ensure that the pre-reaction of enzymatic hydrolysis and fermentation is fully carried out, laying the foundation for subsequent stepwise directional synthesis.

[0014] Furthermore, in step S3, the conditions for the low-temperature pre-fermentation are as follows: Bifidobacterium infantis and Lactobacillus rhamnosus are inoculated, both being native beneficial bacteria in the infant's gut, adapted to the infant's gut environment, and capable of efficiently synthesizing galactooligosaccharides; the total inoculation amount is 1.5 × 10⁻⁶. 6 CFU / g ~2.5×10 6 CFU / g ensures sufficient proliferation of the strain while avoiding excessive inoculation that could lead to excessive acidity in the product and affect the taste. Temperature is 32.5℃~33.5℃, time is 7.5h~8.5h. Under mild conditions, galactooligosaccharides are synthesized in a targeted manner, providing the best synthesis environment for the target strain and ensuring that the amount of galactooligosaccharides synthesized meets the standard. The conditions for the isothermal primary fermentation are as follows: inoculation with *Lactobacillus acidophilus* and *Lactobacillus fermentum*, which can directionally hydrolyze milk proteins to generate small-molecule sensitizing peptides to reduce the risk of product sensitization; and *Lactobacillus plantarum* mutagenesis strains that produce high levels of neutral extracellular polysaccharides, which can efficiently synthesize neutral, stable extracellular polysaccharides to provide long-term stability for the product. The total inoculation amount is 1.2 × 10⁻⁶. 6 CFU / g ~1.8×10 6 CFU / g, temperature 36.5℃~37℃, time 3.5h~4.5h, optimal activity conditions for the strain, to directionally synthesize small molecule sensitization-eliminating peptides and neutral homeostatic extracellular polysaccharides, simultaneously achieving desensitization of milk proteins and system stability, ensuring the efficient synthesis of target functional components; The Bifidobacterium infantis, Lactobacillus rhamnosus, Lactobacillus acidophilus, and Lactobacillus fermentum strains mentioned are all permitted strains for use in infant food, fully complying with the strain usage specifications for infant food, thus ensuring the food safety of the product from the source of the strains.

[0015] Compared with existing technologies, this infant-label fermented milk composition and its preparation method have the following beneficial effects: I. This invention solves the problems of separate, cumbersome, and non-synergistic enzymatic hydrolysis and fermentation in traditional infant formula fermented milk preparation by constructing a coupled biochemical synthesis system that simultaneously conducts biphasic targeted enzymatic hydrolysis and milk fermentation. In this system, enzymatic hydrolysis and fermentation occur simultaneously, eliminating the separate enzyme inactivation step, simplifying the preparation process, and reducing production control costs. Simultaneously, the reducing sugars and peptides generated by enzymatic hydrolysis can be directly used as carbon and nitrogen sources for the fermentation strains, and the organic acids produced during fermentation can precisely regulate the enzymatic hydrolysis reaction rate, forming a bidirectional synergistic closed-loop reaction mode. This allows for the in-situ synthesis of three functional components within the system: galacto-oligosaccharides, small-molecule sensitizing peptides, and neutral stable-state extracellular polysaccharides. No additional stabilizers, flavoring agents, acidity regulators, or other exogenous excipients are required, perfectly meeting the requirements for simplified ingredients in infant formula and improving the product's safety from the source of preparation.

[0016] II. This invention, through a stepwise, targeted biochemical synthesis process design, precisely controls reaction conditions and strain effects at each stage, solving the industry problems of high allergenicity risk, low nutrient digestibility, and poor long-term storage stability in traditional infant-label fermented milk products. By controlling the stages of low-temperature pre-fermentation and constant-temperature main fermentation, it can directionally generate nutrients adapted to the delicate digestive characteristics of infants. During synthesis, mild, restrictive modification of milk proteins is simultaneously completed, disrupting the antigenic epitopes of allergenic proteins in cow's milk, significantly reducing the product's allergenic risk, and simultaneously improving the in vitro digestibility and absorption rate of proteins. The in-situ synthesized neutral, stable extracellular polysaccharides can form a uniform three-dimensional network structure within the system, allowing the product to maintain a uniform texture during a 12-month storage period at room temperature without the need for exogenous stabilizers, thus solving the problems of easy stratification, water separation, and sedimentation in traditional products.

[0017] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0019] Figure 1 This is a flowchart of the preparation method of the infant formula fermented milk composition of the present invention; Figure 2This is a schematic diagram of the synergistic mechanism of the enzymatic hydrolysis-fermentation coupled biochemical synthesis system of the present invention; Figure 3 This is a schematic diagram illustrating the stepwise directional synthesis of functional components and their in-situ efficacy in this invention. Detailed Implementation

[0020] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below. Example 1:

[0021] The fermented milk composition of this embodiment has a total feed amount of 1000 parts by weight, specifically consisting of: 580 parts fermented milk base, 380 parts strawberry fruit and vegetable raw materials, 20 parts whey protein powder, and 20 parts functional excipients; the sum of the weight parts of each raw material is 1000 parts.

[0022] The fermented milk base is made from whole milk fermented milk with a protein content of not less than 3.2g / 100g; the functional excipients are a mixture of citrus fiber and unmodified starch in a mass ratio of 1:1; no stabilizers, flavorings, or acidity regulators are added throughout the preparation process, and the total amount of non-organic raw materials added is less than 5%.

[0023] The overall preparation process of this embodiment is as follows: Figure 1 As shown, the specific preparation steps are as follows: S1. Preparation of synthetic substrate: Fresh strawberries were thoroughly washed with running water, the stems were removed, and the strawberries were pulped. The pulp was then passed through an 80-mesh sieve to obtain strawberry fruit and vegetable substrate. Milk raw materials were subjected to standardized treatment in sequence, pasteurized at 95℃ for 5 minutes, and cooled to 40℃ to obtain milk protein substrate.

[0024] S2. Construction of the Coupled Biochemical System: Strawberry fruit and vegetable substrate, milk protein substrate, whey protein powder, and functional excipients were added to a sealed sterile reactor according to the specified ratio and mixed thoroughly. Simultaneously, a compound hydrolytic enzyme preparation and an infant-specific fermentation strain were added to construct a coupled biochemical system in which enzymatic hydrolysis and microbial fermentation occur simultaneously. The compound hydrolytic enzyme preparation was composed of pectinase, cellulase, and milk protein restriction endonuclease in a mass ratio of 2:1:1, with a total addition amount of 0.12% of the total mass of the synthesized substrate. The reaction conditions for the coupled biochemical system were: temperature 40℃, vacuum 0.08MPa, and reaction time 25min. No separate enzyme inactivation treatment was performed during the reaction process. The synergistic mechanism of the coupled biochemical system in this step is as follows: Figure 2 As shown.

[0025] S3. Stepwise directional synthesis: First, low-temperature pre-fermentation is carried out, followed by inoculation with Bifidobacterium infantis and Lactobacillus rhamnosus, with a total inoculation amount of 2.0 × 10⁻⁶. 6In situ synthesis of galacto-oligosaccharides was achieved at CFU / g, 33℃, and 8 hours. Subsequent isothermal primary fermentation was carried out, inoculated with *Lactobacillus acidophilus*, *Lactobacillus fermentum*, and a *Lactobacillus plantarum* mutant strain that produces high levels of neutral extracellular polysaccharides, with a total inoculum of 1.5 × 10⁻⁶ CFU / g. 6 In situ synthesis of small molecule sensitizing elimination peptides and neutral homeostatic extracellular polysaccharides at CFU / g, temperature 36.5℃, and time 4h. The stepwise synthesis logic and in situ efficacy of this step are as follows: Figure 3 As shown.

[0026] S4. Reaction Termination: The enzymatic reaction and fermentation reaction are terminated simultaneously by heat treatment at 59℃ for 15 minutes to obtain the finished strawberry-flavored fermented milk composition.

[0027] Finished product performance testing: The finished product was tested for indicators, and the content of galactooligosaccharides was 7.2 g / L, the total residual amount of allergenic protein was 0.032 mg / kg, the in vitro digestibility of protein was 96.2%, and there was no stratification or water separation after 12 months of storage at room temperature. No exogenous additives were used.

[0028] This embodiment uses strawberries as the fruit and vegetable raw material, combined with whole milk fermentation base, and adopts a preparation method that simultaneously carries out enzymatic hydrolysis and fermentation. It can generate a variety of functional substances in situ within the system. The overall ingredients are simplified, with no additional additives. It has a low content of allergenic proteins, and the protein is easily absorbed by infants and young children. After being stored at room temperature for 12 months, the texture remains uniform and there will be no separation or water separation. It is suitable as a complementary food for infants and young children. Example 2:

[0029] The fermented milk composition of this embodiment has a total feed amount of 1000 parts by weight, specifically consisting of: 660 parts organic A2 cow milk fermented milk base, 300 parts blueberry fruit and vegetable raw materials, 20 parts whey protein powder, and 20 parts functional excipients; the sum of the weight parts of each raw material is 1000 parts.

[0030] The fermented milk base material uses organic A2β-casein fermented milk, which accounts for no less than 65% of the total mass of the synthetic substrate; the functional excipients are a mixture of organic citrus fiber and organic unmodified starch in a mass ratio of 1:1; the total amount of non-organic raw materials added is 0, and no exogenous additives are added throughout the process.

[0031] The specific preparation steps are as follows: S1. Preparation of synthetic substrate: Organic blueberries were thoroughly washed with running water, the stems were removed, and the mixture was pulped. The pulp was then passed through an 80-mesh sieve to obtain blueberry fruit and vegetable substrate. Organic A2 milk raw materials were subjected to standardization treatment, pasteurized at 95℃ for 5 minutes, and cooled to 40℃ to obtain organic milk protein substrate.

[0032] S2. Construction of the Coupled Biochemical System: Blueberry fruit and vegetable substrate, organic milk protein substrate, whey protein powder, and functional excipients were added to a sealed sterile reactor according to the specified ratio and mixed evenly. Simultaneously, a compound hydrolytic enzyme preparation and an infant-specific fermentation strain were added to construct the coupled biochemical system. The compound hydrolytic enzyme preparation was composed of pectinase, cellulase, and milk protein restriction endonuclease in a mass ratio of 2:1:1, and the total amount added was 0.10% of the total mass of the synthesized substrate. The reaction conditions of the coupled biochemical system were a temperature of 41℃, a vacuum degree of 0.085MPa, and a reaction time of 22min. No separate enzyme inactivation treatment was performed during the reaction process.

[0033] S3. Stepwise directional synthesis: First, low-temperature pre-fermentation is carried out, followed by inoculation with Bifidobacterium infantis and Lactobacillus rhamnosus, with a total inoculation amount of 2.5 × 10⁻⁶. 6 In situ synthesis of galacto-oligosaccharides was achieved at CFU / g, temperature 33.5℃, and time 7.5h. Subsequent isothermal primary fermentation was carried out, inoculated with *Lactobacillus acidophilus*, *Lactobacillus fermentum*, and a *Lactobacillus plantarum* mutant strain that produces high levels of neutral extracellular polysaccharides, with a total inoculum of 1.2 × 10⁻⁶ CFU / g. 6 Small molecule sensitizing elimination peptides and neutral homeostatic extracellular polysaccharides were synthesized in situ at CFU / g, temperature 37℃, and time 3.5h.

[0034] S4. Reaction Termination: The enzymatic reaction and fermentation reaction are terminated simultaneously by heat treatment at 59.5℃ for 14 minutes to obtain the finished organic A2 blueberry flavored fermented milk composition.

[0035] Finished product performance testing: The finished product was tested for indicators, and the content of galactooligosaccharides was 7.6 g / L, the total residual amount of allergenic protein was 0.028 mg / kg, the in vitro digestibility of protein was 96.8%, and there was no stratification or water separation after 12 months of storage at room temperature. No exogenous additives were used.

[0036] This embodiment uses organic blueberries and organic A2 milk fermentation base as the main raw materials. The preparation method of simultaneous enzymatic hydrolysis and fermentation preserves the nutritional components of the raw materials. No non-organic raw materials or exogenous excipients are added. Sufficient functional substances can be generated in the system. The product has low allergenicity and is stable when stored at room temperature for a long time, which meets the usage standards of organic infant complementary food. Example 3:

[0037] The fermented milk composition of this embodiment has a total feed amount of 1000 parts by weight, specifically consisting of: 620 parts fermented milk base, 340 parts apple and kiwi blended fruit and vegetable raw materials, 15 parts whey protein powder, and 25 parts functional excipients; the sum of the weight parts of each raw material is 1000 parts.

[0038] The compound fruit and vegetable raw materials are apples and kiwis in a 1:1 mass ratio; the fermented milk base is whole milk fermented milk with a protein content of not less than 3.2g / 100g; the functional excipients are a mixture of citrus fiber and unmodified starch in a 1:1 mass ratio; no stabilizers, flavorings, or acidity regulators are added throughout the preparation process, and the total amount of non-organic raw materials added is less than 5%.

[0039] The specific preparation steps are as follows: S1. Preparation of synthetic substrate: Fresh apples and kiwis are thoroughly washed with running water, and the peels and cores are removed. The mixture is then blended and pulped, and the pulp is passed through an 80-mesh sieve to obtain a compound fruit and vegetable substrate. The milk raw materials are then subjected to standardized treatment in sequence, pasteurized at 95℃ for 5 minutes, and cooled to 40℃ to obtain a milk protein substrate.

[0040] S2. Construction of the Coupled Biochemical System: The compound fruit and vegetable substrate, milk protein substrate, whey protein powder, and functional excipients were added to a closed sterile reactor according to the specified ratio and mixed evenly. At the same time, the compound hydrolytic enzyme preparation and infant-specific fermentation strain were added to construct the coupled biochemical system. The compound hydrolytic enzyme preparation was composed of pectinase, cellulase, and milk protein restriction endonuclease in a mass ratio of 2:1:1, and the total amount added was 0.14% of the total mass of the synthesized substrate. The reaction conditions of the coupled biochemical system were 39℃, 0.075MPa vacuum, and 28min reaction time. No separate enzyme inactivation treatment was performed during the reaction process.

[0041] S3. Stepwise directional synthesis: First, low-temperature pre-fermentation is carried out, followed by inoculation with Bifidobacterium infantis and Lactobacillus rhamnosus, with a total inoculum of 1.8 × 10⁻⁶. 6 In situ synthesis of galacto-oligosaccharides was achieved at CFU / g, temperature 32.5℃, and time 8.5h. Subsequent isothermal primary fermentation was carried out, inoculated with *Lactobacillus acidophilus*, *Lactobacillus fermentum*, and a *Lactobacillus plantarum* mutant strain that produces high levels of neutral extracellular polysaccharides, with a total inoculum of 1.8 × 10⁻⁶ CFU / g. 6 Small molecule sensitizing elimination peptides and neutral homeostatic extracellular polysaccharides were synthesized in situ at CFU / g, temperature 36℃, and time 4.5h.

[0042] S4. Reaction Termination: The enzymatic reaction and fermentation reaction are terminated simultaneously by heat treatment at 58.5℃ for 16 minutes to obtain the finished product of apple and kiwi flavored fermented milk composition.

[0043] Finished product performance testing: The finished product was tested for indicators, and the content of galactooligosaccharides was 6.9 g / L, the total residual amount of allergenic protein was 0.035 mg / kg, the in vitro digestibility of protein was 95.7%, and there was no stratification or water separation after 12 months of storage at room temperature. No exogenous additives were used.

[0044] In this embodiment, apples and kiwis are combined as fruit and vegetable raw materials, and whole milk is used as a fermentation base. The preparation method of simultaneous enzymatic hydrolysis and fermentation enriches the product's nutrition. The polysaccharides generated in situ within the system can stabilize the product's state, eliminating the need for added stabilizers. The product has a mild taste and balanced nutrition, which can meet the complementary food needs of infants and young children. Comparative Example 1:

[0045] The fermented milk composition of this comparative example has a total feed amount of 1000 parts by weight. The raw material composition is completely consistent with that of Example 1. It is prepared using only the industry-standard step-by-step process and forms a single variable comparison with the process of this invention.

[0046] The specific preparation steps are as follows: S1. Substrate preparation: Fresh strawberries are washed, pulped, and passed through an 80-mesh sieve to obtain fruit and vegetable substrates. The fruit and vegetable substrates are enzymatically hydrolyzed separately. After enzymatic hydrolysis, the temperature is raised to 95℃ and kept at that temperature for 5 minutes to inactivate the enzymes. The substrates are then cooled to room temperature for later use.

[0047] S2. Milk Fermentation: After standardized treatment and pasteurization, milk raw materials are individually inoculated with a fermentation strain for constant temperature fermentation. After fermentation, the raw materials are cooled to room temperature for later use.

[0048] S3. Physical mixing: The enzyme-inactivated fruit and vegetable substrates and fermented milk are physically mixed according to the ratio in Example 1, and additional stabilizers and flavorings are added to adjust the texture and taste of the product.

[0049] S4. Sterilization Termination: The reaction is terminated by high-temperature heat treatment at 95℃ for 5 minutes to obtain the finished fermented milk composition.

[0050] Finished product performance testing: The finished product was tested for indicators. It was found that galactooligosaccharides were not detected, the total residual amount of allergenic proteins was 0.216 mg / kg, the in vitro digestibility of protein was 72.3%, and the product showed stratification and water separation after being left at room temperature for 12 months, indicating that exogenous additives were used.

[0051] This comparative example uses a conventional method of separately enzymatically hydrolyzing and inactivating enzymes in fruits and vegetables, separately fermenting milk, and then physically mixing the products. The enzymatic hydrolysis and fermentation processes are independent and cannot be coordinated. Functional substances cannot be synthesized in situ within the system, and exogenous excipients need to be added to maintain the product's state. The content of allergenic proteins is relatively high, the protein absorption effect is average, and long-term storage at room temperature is prone to stratification, water separation, and uneven texture.

[0052] Comparison table of core performance between the examples and comparative examples:

[0053] The finished product testing data shows that all three examples, prepared using a simultaneous enzymatic hydrolysis and fermentation process, can synthesize sufficient galacto-oligosaccharides in situ. The total residual amount of allergenic proteins is controlled below 0.035 mg / kg, and the in vitro protein digestibility is above 95%. The systems remain stable for 12 months at room temperature without the use of any exogenous additives, fully meeting the requirements of simplified, low-allergenicity, and high-nutrition ingredients for infant formula. Comparative Example 1, using a conventional step-by-step process, cannot synthesize functional substances in situ. The residual amount of allergenic proteins is more than 6 times higher than in the examples, the protein digestibility is low, exogenous additives are required, and long-term storage stability is poor. The data directly demonstrate the actual improvement brought by the process of this invention, making it more suitable for the needs of infant complementary foods.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A fermented milk composition for infant formula, characterized in that, The fermented milk composition, by mass percentage, consists of 55%–68% fermented milk base, 25%–40% infant-appropriate fruit and vegetable ingredients, 1%–2.5% whey protein powder, and 0.5%–1.5% functional excipients. The composition contains 6.0 g / L to 8.0 g / L of in-situ biochemically synthesized galactooligosaccharides, 2.5 g / 100 g to 3.5 g / 100 g of small molecule sensitizing and eliminating peptides, and ≥6.0 g / L of neutral homeostatic extracellular polysaccharides; The functional excipient is a mixture of citrus fiber and unmodified starch in a mass ratio of 1:

1.

2. The infant formula fermented milk composition according to claim 1, characterized in that, The fermented milk base is whole milk fermented milk with a protein content of ≥3.2g / 100g, or organic A2β-casein milk fermented milk with a mass percentage of ≥65% in the synthetic substrate.

3. The infant formula fermented milk composition according to claim 1, characterized in that, The infant-appropriate fruit and vegetable ingredients are one of strawberries, blueberries, apples, and kiwis, or a mixture of two or more of them in a mass ratio of 1:1 to 3:

1.

4. The infant formula fermented milk composition according to claim 1, characterized in that, The molecular weight of the small molecule sensitizing and eliminating peptide is 1000 Da to 3000 Da, and the total residual amount of β-lactoglobulin and α-lactalbumin in the composition is ≤0.05 mg / kg.

5. The infant formula fermented milk composition according to claim 1, characterized in that, The molecular weight of the neutral, stable extracellular polysaccharide is 200,000 Da to 500,000 Da; the pH value of the composition is 4.22 to 4.28, the total acid content is 0.53 g / 100 g to 0.57 g / 100 g, the protein content is ≥3.2 g / 100 g, and the sodium content is ≤1.0 mg / 100 g.

6. The infant formula fermented milk composition according to claim 1, characterized in that, The total amount of non-organic raw materials added to the synthesis substrate of the composition is ≤5%; the composition is prepared by a coupled biochemical process in which the enzymatic hydrolysis product is used as the fermentation substrate and the organic acid produced by fermentation regulates the rate of enzymatic hydrolysis reaction.

7. The infant formula fermented milk composition according to claim 1, characterized in that, The synthetic substrate does not contain stabilizers, flavoring agents, or acidity regulators.

8. A method for preparing an infant-labeled fermented milk composition, the method being used to prepare the infant-labeled fermented milk composition according to any one of claims 1-7, characterized in that, The preparation method includes: S1. Preparation of synthetic substrates: Infant-suitable fruit and vegetable raw materials are washed, pulped, and sieved through an 80-mesh sieve to obtain fruit and vegetable substrates; milk raw materials are standardized, pasteurized at 95℃ for 5 min, and cooled to 40℃ to obtain milk protein substrates. S2. Construction of Coupled Biochemical System: Fruit and vegetable substrates, milk protein substrates, whey protein powder, and functional excipients are added to a closed sterile reactor according to the specified ratio and mixed. At the same time, compound hydrolytic enzyme preparations and infant-specific fermentation strains are added to construct a coupled biochemical system in which enzymatic hydrolysis and microbial fermentation occur simultaneously. No separate enzyme inactivation treatment is performed during the reaction process. S3. Stepwise directional synthesis: First, low-temperature pre-fermentation is carried out to synthesize galactooligosaccharides, and then isothermal primary fermentation is carried out to synthesize small molecule sensitizing and eliminating peptides and neutral homeostatic extracellular polysaccharides. S4. Reaction Termination: The enzymatic and fermentation reactions are terminated by heat treatment at 58.5℃~59.5℃ for 14min~16min to obtain the fermented milk composition.

9. The method for preparing an infant formula fermented milk composition according to claim 8, characterized in that, In step S2, the compound hydrolytic enzyme preparation is composed of pectinase, cellulase, and milk protein restriction endonuclease in a mass ratio of 2:1:1, and the total amount added is 0.08%~0.15% of the total mass of the synthetic substrate. The reaction conditions of the coupled biochemical system are: temperature 39℃~41℃, vacuum degree 0.075MPa~0.085MPa, and reaction time 22min~28min.

10. The method for preparing an infant formula fermented milk composition according to claim 8, characterized in that, In step S3, the conditions for the low-temperature pre-fermentation are: inoculation with Bifidobacterium infantis and Lactobacillus rhamnosus, with a total inoculation amount of 1.5 × 10⁻⁶. 6 CFU / g ~2.5×10 6 CFU / g, temperature 32.5℃~33.5℃, time 7.5h~8.5h; The isothermal primary fermentation conditions were as follows: inoculation with *Lactobacillus acidophilus*, *Lactobacillus fermentum*, and a *Lactobacillus plantarum* mutant strain that produces high levels of neutral extracellular polysaccharides, with a total inoculum size of 1.2 × 10⁻⁶. 6 CFU / g ~1.8×10 6 CFU / g, temperature 36.5℃~37℃, time 3.5h~4.5h; The aforementioned Bifidobacterium infantis, Lactobacillus rhamnosus, Lactobacillus acidophilus, and Lactobacillus fermentum are all strains permitted for use in infant food.

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