Formula milk powder for increasing bone mineral density and preparation method thereof

Abstract

The invention belongs to the technical field of dairy products, and particularly relates to formula milk powder for increasing bone mineral density and a preparation method thereof. The fermented milk comprises the following components: raw milk, raw goat milk, beta-galactosidase, light protease and food-grade zymophyte. According to the invention, raw milk and raw goat milk are taken as a base, CPP-ACP nano-clusters are constructed through membrane separation, light enzymolysis and pH circulation, GOS is generated in situ and is complexed with light organic acid, and dual-channel calcium supply is formed; the continuous absorption of soluble calcium and intestinal segments is improved, and the brewing is stable.

Description

Technical Field

[0001] This invention belongs to the field of dairy product technology, specifically relating to a formula milk powder that increases bone density and its preparation method. Background Technology

[0002] Formula milk powder is a dairy product made primarily from cow's milk or goat's milk, with standardized proportions and processing techniques for proteins, fats, carbohydrates, vitamins, and minerals, tailored to the physiological characteristics of different growth stages. Its main function is to provide a safe, easily digestible, and nutritionally balanced dietary alternative for various populations, maintaining stability and repeatability, especially in terms of energy supply, essential fatty acids, and the intake of key nutrients such as iron, calcium, and phosphorus. During the rapid bone development stage, an adequate supply of calcium, phosphorus, and vitamin D, along with their bioavailability, is particularly crucial. However, not only is the total amount of nutrients important, but their form and delivery method in the intestinal environment directly determine their absorption efficiency and the final bone mineralization effect.

[0003] Currently, most technical approaches employ a stacking strategy, adding mineral salts (such as various calcium and phosphate salts), vitamin D fortifiers, and exogenous prebiotics to improve the nutritional content of the formulation. However, in the neutral to slightly alkaline small intestinal environment, calcium readily interacts with phosphate, casein, or bile salts, forming insoluble or coarse-particle precipitates, thus reducing its bioavailability. Furthermore, to meet industrial requirements for heat sterilization and spray drying, strong heat treatment can easily trigger Maillard reactions (lactose binding to proteins), micellar rearrangement, or damage to the milk fat membrane, thereby affecting the product's resolubility, colloidal stability, and sensory quality. Common problems include a gritty texture, sedimentation, and large batch-to-batch variations. On the other hand, due to dairy regulations and labeling standards, the range of novel functional ingredients allowed in formulations is relatively limited, and the types and amounts of exogenous prebiotics are often subject to strict constraints. Even if addition is permitted, these methods still cannot fundamentally solve the challenge of maintaining calcium in a soluble / efficiently deliverable microstructure in the intestine. In addition, products based on a single milk source (such as pure cow's milk or pure sheep's milk) often have limitations in terms of their inherent micellar structure, lipid globule size distribution, and milk fat membrane composition, making it difficult to simultaneously achieve high soluble calcium, stable nutrient delivery, and good reconstituted taste. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a formula milk powder that increases bone density and a method for preparing the same.

[0005] The technical effects described in this invention are achieved through the following technical solution: a formula milk powder that increases bone density, comprising the following components: raw cow's milk, raw goat's milk, β-galactosidase, mild protease, and food-grade fermentation bacteria.

[0006] Preferably, the activity of the β-galactosidase is 10000 U / mL; Preferably, the mild protease is either trypsin or pepsin; Preferably, the activity of the mild protease is 2500 U / mg; Preferably, the food-grade fermentation bacteria are any one or more of Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium; more preferably, Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium are mixed in a ratio of 1:1:1. Preferably, the viable count of the Lactobacillus acidophilus is 1 × 10⁻⁶. 10 CFU / mL; the viable count of Lactobacillus casei was 1×10⁻⁶. 9 CFU / mL; the viable count of the Bifidobacterium was 5 × 10⁻⁶. 9 CFU / mL; Another aspect of the present invention is to provide a method for preparing formula milk powder that increases bone density, specifically including the following steps: S1: Mix 6.5L of raw cow's milk and 3.5L of raw sheep's milk, degas at 42-48℃ for 5-15 minutes, remove impurities through 100μm and 50μm double-stage filtration, centrifuge, and adjust the fat content to 3.4-4% and the total protein content to 3.2-3.6%; S2: After completing step S1, maintain the temperature at 38-45℃ and use 0.1μm microfiltration to obtain the casein enrichment solution after retrieval and the permeate after permeation; perform 10kDa ultrafiltration on the permeate to obtain the whey protein concentrate after retrieval and the ultrafiltration permeate after permeation. S3: Mix the casein enrichment solution, whey protein concentrate and ultrafiltration permeate from step S2 in a certain proportion to obtain the base material; S4: Adjust the pH of the base material to 6.6-6.8, the temperature to 40-45℃, add 1.3-1.4% β-galactosidase, stir for 4-6 hours, treat at 75℃ for 20 seconds and stop the enzyme to obtain the material; S5: Cool the material from step S4 to 37-42°C, inoculate with 0.2-1% food-grade fermentation bacteria, keep at a constant temperature for 2-4 hours, inactivate at 75°C for 20 seconds, and quickly cool to 35-40°C. S6: After completing step S5, adjust the pH to 6.6-6.8, the temperature to 45-50℃, add 0.003-0.008% mild protease, react for 10-15 min, treat at 75℃ for 20 s to stop the enzyme, then slowly bubble CO2 in at 35-40℃ with an aeration rate of 0.05-0.1 vvm, treat for 10-15 min, and let stand for 10 min after the pH drops to 5.1-5.3. S7: After completing step S6, vacuum degassing for 5 minutes, add the ultrafiltration permeate from step S2 and degas with nitrogen bubbling, CO2 micro-pulse treatment at 0.02 vvm for 5-8 minutes; two-stage homogenization treatment; high hydrostatic pressure treatment; vacuum concentration; spray drying; after powder collection, enter a fluidized bed at 50-60℃ for 15-30 minutes for granulation to obtain formula milk powder; Preferably, in step S2, the volumetric concentration factor (VCF) of the microfiltration treatment is 2 to 3. Preferably, in step S3, the ratio of the amount of casein enrichment solution, whey protein concentrate and ultrafiltration permeate is 4:3:3. Preferably, in step S7, the parameters for the two-stage homogenization process are: temperature 45°C, first stage 120-150 bar, second stage 30-50 bar, single cycle; Preferably, in step S7, the high hydrostatic pressure treatment parameters are: 400-500 MPa, time 3-5 min; Preferably, in step S7, the vacuum concentration parameters are: thin film evaporation at 40-50°C to a solid content of 45-50%; Preferably, in step S7, the spray drying parameters are: inlet air temperature 165-175°C, outlet air temperature 78-82°C; centrifugal atomization speed 15000-22000 rpm.

[0007] The beneficial effects of the present invention are as follows: The formula milk powder of this invention uses raw cow's milk and raw goat's milk as a base, and adopts a closed-loop process of membrane separation-directional light enzymatic hydrolysis-pH cycle remineralization-short-range acid-controlled fermentation-mild setting-low temperature spray drying to reconstruct the calcium-phosphorus-casein-lactose interaction network in situ within the system. The casein phase, whey phase and mineral small molecule fraction are separated and re-blended through micro / ultrafiltration. First, under near-neutral conditions, an ultra-low dose of protease is used to expose only phosphoserine clusters without destroying the micelle backbone. Then, a slight pH reduction is used to dissolve some colloidal calcium phosphate. The pH is then slowly increased and the milk source minerals from the same batch are re-blended. With the help of a trace amount of CO2 for mild nucleation, casein phosphopeptides (CPP) self-assemble and embed amorphous calcium phosphate (ACP) to form casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) nanoclusters with uniform particle size and stable resolvability. Simultaneously, in the same feed solution, lactose is converted in situ into galacto-oligosaccharides (GOS) mainly composed of DP2-DP6 using β-galactosidase. A small amount of lactic acid / citric acid is then generated through short-range acid-controlled fermentation (2-4 hours), maintaining a mild complexation state of organic acid anions and calcium near neutrality. Finally, a two-stage homogenization process is used to fix the micro / nano structure, combined with low-temperature sterilization and low-exit-temperature spray drying, maximizing the preservation of the in-situ constructed functional structure and reproducibility.

[0008] Specifically, CPP-ACP nanoclusters exhibit anti-sedimentation and anti-irreversible crystallization capabilities in the gastric segment, while providing continuous free calcium activity in the small intestine through mucosal affinity and sustained-release mechanisms, thus improving transepithelial transport efficiency. On the other hand, the soluble calcium complex formed by GOS and a small amount of organic acid anions maintains a stable soluble calcium pool at neutral pH, reducing the risk of deposition in the upper intestine and creating a favorable environment for the distal intestinal tract via short-chain fatty acids and barrier-optimized pathways. These two pathways are temporally and spatially complementary, reducing calcium loss caused by fluctuations in ionic strength and pH, achieving continuous improvement in bioaccessibility from proximal to distal. Cow's milk provides a higher reservoir of casein and calcium-phosphorus, while goat's milk's small lipid globule / membrane phase and natural dispersibility improve the colloidal stability and smoothness of the nanoclusters. Both work synergistically to construct a stable structure under the same ionic strength and mild pH window, reducing gritty texture, sedimentation, and clumping tendency from the source. Furthermore, the present invention does not rely on the addition of unfamiliar ingredients, but utilizes the intrinsic components of milk to achieve functionalization through in-situ recombination: membrane grading ensures precise site exposure and controllable mineral recombination, pH cycling and gentle CO2 nucleation ensure that ACP is stably encapsulated by CPP in an amorphous and easily absorbed form, and the in-situ generated GOS complexes with mild organic acid radicals to improve the solubility in the neutral zone without deep acidification while taking into account both flavor and protein stability; homogenization and gentle sterilization / drying serve as process hubs, transferring the advantages of liquid construction to powder form and making them reproducible during reconstitution. Attached Figure Description

[0009] Figure 1 The graph shows the GOS content test results of the formula milk powder samples of Examples 1-3 and Comparative Examples 1-3; Figure 2 The graph shows the test results of soluble Ca content in the formula milk powder samples of Examples 1-3 and Comparative Examples 1-3. Figure 3 Free Ca2+ in the formula milk powder samples of Examples 1-3 and Comparative Examples 1-3 2+ Release test result diagram; Figure 4 The DLS particle size distribution of the sample prepared in Example 1 is shown. Detailed Implementation

[0010] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Unless otherwise specified, the raw materials involved in the present invention are all purchased through conventional commercial channels. Experimental methods without specific conditions are conventional methods and conditions well known in the art, or according to the conditions recommended by the instrument manufacturer.

[0011] Example 1: A formula milk powder for increasing bone density, comprising the following components: raw cow's milk, raw goat's milk, β-galactosidase, mild protease and food-grade fermentation bacteria.

[0012] The preparation of the formula milk powder that increases bone density specifically includes the following steps: S1: Mix 6.5L of raw cow's milk and 3.5L of raw goat's milk, degas at 45℃ for 10 minutes, remove impurities through 100μm and 50μm dual-stage filtration, centrifuge to separate, and adjust the fat content to 3.7% and the total protein content to 3.4%; S2: After completing step S1, maintain the temperature at 42℃ and use 0.1μm microfiltration with a volumetric separation factor (VCF) of 2.5 to obtain the casein enrichment solution after retrieval and the permeate solution after permeation; perform 10kDa ultrafiltration on the permeate solution to obtain the whey protein concentrate after retrieval and the ultrafiltration permeate solution after permeation. S3: Mix the 4L casein enrichment solution, 3L whey protein concentrate and 3L ultrafiltration permeate from step S2 to obtain the base material; S4: Adjust the pH of the base material to 6.7, set the temperature to 42℃, add 1.35% β-galactosidase, stir for 5 hours, treat at 75℃ for 20 seconds and then stop the enzyme to obtain the material; S5: Cool the material from step S4 to 40°C, inoculate it with 0.5% of a fermentation strain composed of Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium in a 1:1:1 ratio, keep it at a constant temperature for 2.5 hours, inactivate it at 75°C for 20 seconds, and then rapidly cool it to 36°C. S6: After completing step S5, adjust the pH to 6.7, the temperature to 48℃, add 0.005% trypsin, react for 12 min, treat at 75℃ for 20 s to stop the enzyme, then slowly bubble CO2 in at 37℃ with an aeration rate of 0.08 vvm, treat for 12 min, and let stand for 10 min after the pH drops to 5.2. S7: After completing step S6, vacuum degas for 5 minutes, add 0.5L of ultrafiltration permeate from step S2 and degas with nitrogen bubbling, CO2 micro-pulse treatment at 0.02vvm for 6 minutes, two-stage homogenization treatment at 45℃, first stage at 140 bar, second stage at 40 bar, single cycle; high hydrostatic pressure treatment at 450MPa for 4 minutes; vacuum concentration, membrane evaporation at 45℃ until solids reach 48%; spray drying at 170℃ inlet and 80℃ outlet; centrifugal atomization speed at 18000rpm; after powder collection, enter a fluidized bed at 55℃ for 20 minutes for granulation to obtain formula milk powder.

[0013] Example 2: A formula milk powder for increasing bone density, comprising the following components: raw cow's milk, raw goat's milk, β-galactosidase, mild protease and food-grade fermentation bacteria.

[0014] The preparation of the formula milk powder that increases bone density specifically includes the following steps: S1: Mix 6.5L of raw cow's milk and 3.5L of raw goat's milk, degas at 42℃ for 15 minutes, remove impurities through 100μm and 50μm dual-stage filtration, centrifuge, and adjust the fat content to 4% and the total protein content to 3.6%. S2: After completing step S1, maintain the temperature at 38℃ and use 0.1μm microfiltration with a volumetric separation factor (VCF) of 3 to obtain the casein enrichment solution after retrieval and the permeate solution after permeation; perform 10kDa ultrafiltration on the permeate solution to obtain the whey protein concentrate after retrieval and the ultrafiltration permeate solution after permeation. S3: Mix the 4L casein enrichment solution, 3L whey protein concentrate and 3L ultrafiltration permeate from step S2 to obtain the base material; S4: Adjust the pH of the base material to 6.6, set the temperature to 40℃, add 1.3% β-galactosidase, stir for 4 hours, treat at 75℃ for 20 seconds and then stop the enzyme to obtain the material; S5: Cool the material from step S4 to 37°C, inoculate with 0.2% of a fermentation culture composed of Lactobacillus acidophilus and Lactobacillus casei in a 1:1 ratio, keep at a constant temperature for 2 hours, inactivate at 75°C for 20 seconds, and then rapidly cool to 35°C. S6: After completing step S5, adjust the pH to 6.6, the temperature to 45℃, add 0.003% trypsin, react for 10 min, treat at 75℃ for 20 s to stop the enzyme, then slowly bubble CO2 in at 35℃ with an aeration rate of 0.05 vvm, treat for 10 min, and let stand for 10 min after the pH drops to 5.1. S7: After completing step S6, vacuum degas for 5 minutes, add 0.5L of ultrafiltration permeate from step S2 and degas with nitrogen bubbling, CO2 micro-pulse treatment at 0.02vvm for 5 minutes, two-stage homogenization treatment at 45℃, first stage at 150 bar, second stage at 50 bar, single cycle; high hydrostatic pressure treatment at 400MPa for 5 minutes; vacuum concentration, membrane evaporation at 50℃ until 50% solids; spray drying at 175℃ inlet and 78℃ outlet; centrifugal atomization speed of 22000rpm; after powder collection, enter a fluidized bed at 50℃ for 30 minutes for granulation to obtain formula milk powder.

[0015] Example 3: A formula milk powder for increasing bone density, comprising the following components: raw cow's milk, raw goat's milk, β-galactosidase, mild protease and food-grade fermentation bacteria.

[0016] The preparation of the formula milk powder that increases bone density specifically includes the following steps: S1: Mix 6.5L of raw cow's milk and 3.5L of raw goat's milk, degas at 48℃ for 5 minutes, remove impurities through 100μm and 50μm dual-stage filtration, centrifuge, and adjust the fat content to 3.4% and the total protein content to 3.2%. S2: After completing step S1, maintain the temperature at 45℃ and use 0.1μm microfiltration with a volumetric separation factor (VCF) of 2 to obtain the casein enrichment solution after retrieval and the permeate solution after permeation; perform 10kDa ultrafiltration on the permeate solution to obtain the whey protein concentrate after retrieval and the ultrafiltration permeate solution after permeation. S3: Mix the 4L casein enrichment solution, 3L whey protein concentrate and 3L ultrafiltration permeate from step S2 to obtain the base material; S4: Adjust the pH of the base material to 6.8, set the temperature to 45℃, add 1.4% β-galactosidase, stir for 6 hours, treat at 75℃ for 20 seconds and then stop the enzyme to obtain the material; S5: Cool the material from step S4 to 42°C, inoculate with 1% Lactobacillus acidophilus, keep at a constant temperature for 4 hours, inactivate at 75°C for 20 seconds, and then rapidly cool to 40°C. S6: After completing step S5, adjust the pH to 6.8, the temperature to 50℃, add 0.008% pepsin, react for 15 min, treat at 75℃ for 20 s to stop the enzyme, then slowly bubble CO2 in at 40℃ with an aeration rate of 0.1 vvm, treat for 15 min, and let stand for 10 min after the pH drops to 5.3. S7: After completing step S6, vacuum degas for 5 minutes, add 0.5L of ultrafiltration permeate from step S2 and degas with nitrogen bubbling, CO2 micro-pulse treatment at 0.02vvm for 8 minutes, two-stage homogenization treatment at 45℃, first stage at 120 bar, second stage at 30 bar, single cycle; high hydrostatic pressure treatment at 500MPa for 3 minutes; vacuum concentration, membrane evaporation at 40℃ until solids reach 45%; spray drying at 165℃ inlet and 82℃ outlet; centrifugal atomization speed of 15000rpm; after powder collection, enter a fluidized bed at 60℃ for 15 minutes for granulation to obtain formula milk powder.

[0017] Comparative Example 1: The operation process of Comparative Example 1 is basically the same as that of Example 1. The main difference is that the β-galactosidase transglycosylation in S4 is omitted in Comparative Example 1. Specifically, the enzyme is not added in step S4, and the enzyme volume in Example 1 is replaced with an equal volume of deionized water. The other operating parameters remain the same.

[0018] Comparative Example 2: The operation process of Comparative Example 2 is basically the same as that of Example 1. The main difference is that the mild protease treatment in S6 is omitted in Comparative Example 2. Specifically, the protease is not added in step S6, and the enzyme solution used in Example 1 is replaced with an equal volume of deionized water. The other operating parameters remain the same.

[0019] Comparative Example 3: The operation process of Comparative Example 3 is basically the same as that of Example 1. The main difference is that the short-range acid-controlled fermentation in S5 is cancelled in Comparative Example 3. Specifically, the fermentation agent is not inoculated in step S5. Instead, the mixture is stirred at 38°C for 2.5 hours and kept at pH 6.7. The amount of fermentation liquid added in Example 1 is replaced with an equal volume of sterile water. The remaining operating parameters remain the same.

[0020] Performance testing: GOS content test: Formula milk powder samples of Examples 1-3 and Comparative Examples 1-3 were prepared according to the reconstitution concentration (12% solids) and kept at 37℃. The proportion of GOS in the total sugar was determined using an enzymatic reagent kit. Three independent batches were set up for each sample. The results are as follows: Figure 1 As shown.

[0021] based on Figure 1 The results analysis showed that the formula milk powder samples of the present invention exhibited a stable GOS ratio and narrow fluctuation in each batch of samples. Based on the results analysis of Comparative Example 1 and Example 1, Comparative Example 1 omitted the S4 enzyme addition, and the system lacked the catalytic circuit of added β-galactosidase. It only underwent the same amount of stirring and heat history, and could not form an effective glycosyl transfer channel. The GOS level was close to the baseline. Furthermore, although Comparative Example 1 retained short-range fermentation, the β-galactosidase of the lactic acid bacteria used was mostly an intracellular enzyme. Lactose needs to be transported into the cell through the membrane and then directly metabolized into lactic acid. It is difficult to enrich detectable GOS in the extracellular environment of the system.

[0022] Soluble calcium test: Formula milk powder samples from Examples 1-3 and Comparative Examples 1-3 were prepared according to the reconstitution concentration (12% solids). The pH was adjusted to 6.8 with HEPES, and the samples were incubated at 37℃ for 30 min. The samples were then centrifuged at 10000g for 10 min. The supernatant was titrated with EDTA to determine the Ca content (mg / L). Three independent batches were prepared for each sample. The results are as follows: Figure 2 As shown.

[0023] based on Figure 2Analysis of the results showed that the formula milk powder samples in the embodiments of the present invention exhibited relatively stable high contents of soluble calcium in each batch. Based on the results of Example 1 and Comparative Example 1, both retained short-range acid-controlled fermentation and the same thermal history. The presence or absence of GOS had little effect on soluble calcium under neutral conditions, resulting in similar values ​​and no significant differences. Based on the results of Example 1 and Comparative Example 2, the soluble Ca content of Comparative Example 2 was lower, which may be due to the lack of mild protease treatment, making it difficult to expose CPP sites and stably form small CPP-ACP nanoclusters. After pH recovery, it was easier to form larger calcium phosphate deposits, which were removed during centrifugation, leading to a decrease in soluble calcium in the supernatant. Based on the results of Example 1 and Comparative Example 3, the soluble Ca content of Comparative Example 3 was the lowest, which may be due to the elimination of short-range acid-controlled fermentation. The system lacked the mild complexation effect of organic acid anions such as lactic acid / citric acid. Under pH 6.8 conditions, calcium was more likely to bind with phosphate / casein and transfer to the insoluble or large-particle phase, which was removed by centrifugation, resulting in a significant decrease in soluble calcium in the supernatant.

[0024] Free Ca 2+ Release Test: Formula milk powder samples from Examples 1-3 and Comparative Examples 1-3 were prepared according to the reconstitution concentration (12% solids). A 10-fold concentrated pepsin solution was added to the sample to bring the final pepsin concentration in the system to 0.32%. The pH was slowly adjusted to 2 with 1 mol / L HCl. Timing was started and maintained at 37°C and 300 rpm for 60 minutes. Then, the sample was transferred to the next stage and slowly adjusted back to pH 6.8 with 1 mol / L NaHCO3. Trypsin and bile salt concentrates were added to bring the final trypsin concentration in the system to 1%. The temperature was maintained at 37°C, 300 rpm, and pH 6.8. 1 mL of sample was taken at t=0, 20, 40, 60, 80, 100, and 120 min, immediately placed in pre-warmed microcentrifuge tubes, and centrifuged at 10000g for 5 min. The supernatant was collected and the Ca2+ was measured immediately. 2+ Each sample was divided into 3 independent batches, and the results are as follows: Figure 3 As shown.

[0025] based on Figure 3 Results analysis showed that the formula milk powder samples of this invention exhibited a plateau-shaped release curve in the intestinal segment, initially rising and then stabilizing, followed by a slow decline at a high level. Based on the results of Example 1 and Comparative Example 1, the curves of the two examples almost overlapped, indicating that the generation of GOS did not change the free Ca2+ release in these two in vitro digestion models. 2+ Kinetics; GOS is more likely to act on the distal intestinal ecology and barrier rather than directly increasing short-term free calcium. Based on the results of Example 1 and Comparative Example 2, the curve of Comparative Example 2 shifted downward throughout the process. This may be due to insufficient exposure of CPP sites caused by the lack of S6 light enzymatic hydrolysis, easy coarsening and partial precipitation of ACP under pH rise and bile salt presence, and weakened supply of CPP-ACP nanoclusters, resulting in increased free calcium in the proximal and plateau phases.2+ Insufficient supply. Based on the analysis of the results of Example 1 and Comparative Example 3, Comparative Example 3 had a lower starting point, a lower peak value, and an earlier plateau. This may be because the elimination of the S5 short-range acid-controlled fermentation resulted in a lack of mild complexation of lactic acid / citric acid in the system. After neutralization and transition, at pH 6.8, lactic acid / citric acid more easily forms insoluble or large-particle phases with phosphate / casein and is clarified and removed. The soluble calcium pool is small and it is difficult to maintain free calcium in the intestinal segment. 2+ content.

[0026] Spectral analysis: Dynamic light scattering (DLS) technology was used to detect the Brownian motion of particles in a formula milk powder suspension. Particle size distribution curves were obtained by analyzing the fluctuations in scattered light intensity. The results are as follows: Figure 4 As shown.

[0027] based on Figure 4 The results analysis shows that the intensity-weighted distribution of DLS is unimodal, with the main peak located around 118 nm. The Z-average particle size is approximately 134 nm, and the polydispersity index (PDI) is approximately 0.09, indicating that the system has concentrated particle size, good dispersion, and controlled aggregation. The curve forms a steep peak in the 70-150 nm range, with only extremely low background at <50 nm and no secondary aggregation peaks observed above 300 nm, indicating that no large particle sedimentation phase was formed after homogenization and mild sterilization. Considering that the intensity-weighted distribution of DLS is more sensitive to large particles, the slightly higher Z-average particle size than the peak value is normal. When converted to the number distribution, the main group is closer to 60-90 nm, which is consistent with the scale of the obtained CPP-ACP nanoclusters. The spectrum does not show bimodal / tailed characteristics, which is consistent with the aforementioned results for soluble calcium, etc.

[0028] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A formula milk powder that increases bone density, characterized in that, Its composition includes the following components: raw cow's milk, raw sheep's milk, β-galactosidase, mild protease, and food-grade fermentation bacteria.

2. The formula milk powder for increasing bone density according to claim 1, characterized in that, The mild protease is either trypsin or pepsin.

3. The formula milk powder for increasing bone density according to claim 2, characterized in that, The food-grade fermentation bacteria are any one or more of Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium.

4. A method for preparing a formula milk powder that increases bone density according to any one of claims 1-3, characterized in that, Specifically, the following steps are included: S1: Mix raw cow's milk and raw sheep's milk, heat to degas, filter to remove impurities, centrifuge to separate, and adjust the fat and total protein content; S2: After completing step S1, maintain the temperature and microfilter to obtain the casein enrichment solution after retrieval and the permeate solution after permeation; ultrafilter the permeate solution to obtain the whey protein concentrate after retrieval and the ultrafiltration permeate solution after permeation. S3: Mix the casein enrichment solution, whey protein concentrate and ultrafiltration permeate from step S2 in a certain proportion to obtain the base material; S4: Adjust the pH of the base material, increase the temperature, add β-galactosidase, stir, heat and stop the enzyme treatment to obtain the material; S5: Cool the material from step S4, inoculate with food-grade fermentation bacteria, perform constant temperature treatment, heat inactivation treatment, and rapid cooling. S6: After completing step S5, adjust the pH, increase the temperature, add a mild protease, react, heat to stop the enzyme treatment, then slowly bubble in CO2 for treatment, and let it stand after the pH drops to the specified range. S7: After completing step S6, vacuum degassing is performed, the ultrafiltration permeate from step S2 is added and nitrogen is bubbled to remove gas, followed by CO2 micro-pulse treatment; two-stage homogenization treatment; high hydrostatic pressure treatment; vacuum concentration; spray drying; and after powder collection, it is fed into a fluidized bed for granulation to obtain formula milk powder.

5. A method for preparing a formula milk powder that increases bone density according to claim 4, characterized in that, In step S2, the volumetric concentration factor (VCF) of the microfiltration treatment is 2 to 3.

6. A method for preparing a formula milk powder that increases bone density according to claim 5, characterized in that, In step S3, the ratio of the amount of casein enrichment solution, whey protein concentrate, and ultrafiltration permeate is 4:3:

3.

7. A method for preparing a formula milk powder that increases bone density according to claim 6, characterized in that, In step S7, the parameters for the two-stage homogenization process are: temperature 45℃, first stage 120-150 bar, second stage 30-50 bar, single cycle.

8. A method for preparing a formula milk powder that increases bone density according to claim 7, characterized in that, In step S7, the high hydrostatic pressure treatment parameters are: 400-500 MPa, time 3-5 min.

9. A method for preparing a formula milk powder that increases bone density according to claim 8, characterized in that, In step S7, the vacuum concentration parameters are: thin film evaporation at 40-50°C to 45-50% solids.

10. A method for preparing a formula milk powder that increases bone density according to claim 9, characterized in that, The spray drying parameters are: inlet air temperature 165-175℃, outlet air temperature 78-82℃; centrifugal atomization speed 15000-22000 rpm.

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