Normal temperature milk and preparation method thereof

Abstract

This invention discloses a room-temperature milk and its preparation method. The room-temperature milk is characterized by the following raw materials: hyaluronic acid salts and raw milk; the content of the hyaluronic acid salts is 0.1‰-0.8‰; the ratio of hyaluronic acid salts: α-lactalbumin: β-lactoglobulin in the room-temperature milk is (1-8): (0.6-2.1): (0.8-3.6). This allows for a higher hyaluronic acid salt content within the range of 0.1‰-0.8‰, ensuring no quality issues such as fat floating, protein precipitation, or protein denaturation within a 6-month shelf life at room temperature, effectively achieving shelf-life stability.

Description

Technical Field

[0001] This invention relates to the field of milk, specifically to a room-temperature milk and its preparation method. Background Technology

[0002] Currently, improving skin hydration and enhancing the epidermal barrier function through dietary therapy has become a research hotspot. Hyaluronic acid, also known as hyaluronic acid or glass acid, is widely found in the skin, serum, and intercellular fluid of humans and animals, with the highest content in the dermis and synovial fluid of human joints. Hyaluronic acid is composed of D-glucuronic acid and N-acetylglucosamine linked by β-1,3 glycosidic bonds to form a disaccharide unit structure, which is then linked by β-1,4 glycosidic bonds to form a linear non-sulfated glycosaminoglycan. In nature, it mainly exists as hyaluronic acid salt (sodium hyaluronate). Hyaluronic acid has a special water-retention effect and is currently the best moisturizing substance found in nature. It is known as an ideal natural moisturizing factor. It can improve skin nutrition and metabolism, making the skin soft, smooth, wrinkle-free, more elastic, and preventing aging. While moisturizing, it is also a good transdermal absorption promoter. In September 2020, it was announced that sodium hyaluronate was listed as a new food ingredient that can be added to ordinary food for consumption, with a daily intake limit of ≤0.2g. Research literature has reported that daily intake of 120mg sodium hyaluronate for 45 consecutive days can significantly improve human skin moisture; at the same time, research literature has reported that daily intake of 150mg sodium hyaluronate is beneficial to bone and joint health.

[0003] Chinese patent document CN104397183A discloses a method for preparing hyaluronic acid milk, which includes a scheme for adding hyaluronic acid to milk. However, the hyaluronic acid content added to the milk described in the document is no higher than 0.1‰. According to the recommended daily milk intake of 300-500g in the "Chinese Dietary Guidelines 2022," the amount of hyaluronic acid ingested would be less than 50mg, far below the amount needed to improve skin hydration or bone and joint health. Furthermore, when hyaluronic acid is directly added to milk, the interaction of the multiple hydroxyl groups within the hyaluronic acid molecule forms a dense triple helix structure. This structure easily binds to milk proteins, causing instability issues. Therefore, simply increasing the sodium hyaluronate content in milk will significantly lead to the formation of a dense triple helix structure, resulting in clumping due to binding with milk proteins, ultimately affecting the shelf-life stability of the milk. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is how to improve the stability of room temperature milk by increasing the sodium hyaluronate content without adding any food thickeners.

[0005] Therefore, the present invention provides the following technical solution:

[0006] A room-temperature milk, comprising: hyaluronic acid salts and raw milk; wherein the content of the hyaluronic acid salts is 0.1‰-0.8‰; wherein the ratio of hyaluronic acid salts: α-lactalbumin: β-lactoglobulin in the room-temperature milk is (1-8): (0.6-2.1): (0.8-3.6).

[0007] The content of the hyaluronic acid salt is 0.1‰-0.7‰; the content ratio of β-lactoglobulin to α-lactalbumin is 0.8-2.5.

[0008] The raw materials of this invention also include N-acetylneuraminic acid, the content of which is less than 3‰.

[0009] The mass ratio of the hyaluronic acid salt to the N-acetylneuraminic acid is 1:(0-20), preferably 1:(0-10), and more preferably 1:(0.1-2).

[0010] The hyaluronic acid salt is sodium hyaluronate; preferably, the molecular weight of the sodium hyaluronate is 80,000 to 400,000 Da.

[0011] The ratio of hyaluronic acid salt to α-lactalbumin is greater than 2.

[0012] The raw milk content is 994.00 to 999.90‰, and the raw materials also include 0 to 1.2‰ of emulsifier and / or other functional raw materials not exceeding 5‰.

[0013] The emulsifier is at least one of glyceryl monostearate, mono- and diglyceryl fatty acid esters, sucrose fatty acid esters, polyglycerol fatty acid esters, and glyceryl citrate fatty acid esters.

[0014] Other functional ingredients include at least one of vitamin A, vitamin E, collagen peptides, Haematococcus pluvialis, nicotinamide, and glutathione.

[0015] The above-mentioned method for preparing room temperature milk includes: adding hyaluronic acid salts to raw milk heated to 60-75°C and mixing them evenly, and then carrying out subsequent sterilization processes;

[0016] The sterilization process includes pasteurization and ultra-high temperature instantaneous sterilization, and the sterilization parameters of the ultra-high temperature instantaneous sterilization are 137±3℃ and 4~6s.

[0017] The preparation method of the present invention includes:

[0018] Mixing: Heat a portion of the raw milk, then add other types of raw materials to the raw milk to dissolve and mix well to obtain a mixture liquid. Mix the remaining raw milk with the mixture liquid. When adding emulsifiers, the temperature of the raw milk is 40-50℃. When adding hyaluronic acid salts, the temperature of the raw milk is 60-75℃.

[0019] After undergoing a first homogenization, pasteurization, first cooling, second homogenization, ultra-high temperature instantaneous sterilization, and second cooling, the finished product is produced.

[0020] The temperature of the first homogenization is 50–80°C, and the total pressure is 150–270 bar;

[0021] The pasteurization temperature is 72±2℃ and the time is 15s;

[0022] The temperature of the first cooling is 1–7°C;

[0023] The temperature of the second homogenization is 60–90°C, and the total pressure is 220–240 bar.

[0024] The temperature of the second cooling is 15–30°C.

[0025] In the mixing step, the mass of the raw milk used to dissolve other types of raw materials is 100-120 times the weight of the other types of raw materials.

[0026] The feeding rate of the hyaluronic acid salt is ≤1 kg / min; when the hyaluronic acid salt is mixed with N-acetylneuraminic acid, the feeding rate of the mixture is ≤1 kg / min.

[0027] The feeding rate of the emulsifier is ≤5 kg / min.

[0028] The technical solution of this invention has the following advantages:

[0029] 1. This invention provides a room-temperature milk, which, by controlling the mass ratio of hyaluronic acid to α-lactalbumin and β-lactoglobulin in the room-temperature milk to (1-8):(0.6-2.1):(0.8-3.6), achieves a hyaluronic acid content within a higher range of 0.1‰-0.8‰, with an absolute value of Δclarification index (sample stored at room temperature for 6 months - sample removed from shelf life), Δparticle size distribution (sample stored at room temperature for 6 months - sample removed from shelf life), ≤0.1 μm, and Δcentrifugation sedimentation rate (sample stored at room temperature for 6 months - sample removed from shelf life), ≤1.0%. Therefore, under these conditions, no quality problems such as fat floating, protein precipitation, or protein denaturation can be achieved within a 6-month shelf life at room temperature, effectively achieving stability during the shelf life; and good stability can still be achieved even with a higher hyaluronic acid content. That is, compared with the milk with hyaluronic acid salts at a concentration of 0.1‰ prepared by the method disclosed in the existing CN104397183A document, it not only achieves the superior efficacy of hyaluronic acid salts themselves, but also has significantly better stability, and the effect is very remarkable.

[0030] 2. The present invention provides a room-temperature milk with further optimized composition. Specifically, the present invention adds N-acetylneuraminic acid in addition to hyaluronic acid salt. N-acetylneuraminic acid is acidic, and hyaluronic acid salt is weakly basic. The acid-base reaction between the two raw materials will change the triple helix structure of sodium hyaluronate, forming a hydrophilic carrier, further solving the solubility problem of sodium hyaluronate in liquid milk and improving the degree of chemical reaction of sodium hyaluronate. At the same time, the N-acetylneuraminic acid molecule carries a negative charge, and the linear structure of sodium hyaluronate can encapsulate N-acetylneuraminic acid to form a water film, solving the problem of protein denaturation caused by local over-acidity when N-acetylneuraminic acid is added alone in liquid milk. The two cooperate with each other through molecular cross-linking to form a stable network structure, further improving stability.

[0031] Furthermore, by combining hyaluronic acid salts with N-acetylneuraminic acid in a specific ratio of 1:(0-20), and when the ratio of β-lactoglobulin to α-lactalbumin is 0.8-2.5, the effective rate of significantly improving skin moisture in subjects can reach over 75%; and when the content of hyaluronic acid salts is 0.2‰-0.8‰, and the ratio of hyaluronic acid salts to α-lactalbumin is greater than 2, the effective rate of improving skin moisture can reach over 80%.

[0032] Furthermore, when the ratio of hyaluronic acid to N-acetylneuraminic acid is further optimized to 1:(0.1-2), the product not only significantly improves skin hydration, but also, through the water-retaining properties of hyaluronic acid, enhances the immune efficacy of N-acetylneuraminic acid, thereby increasing the product's effect on the activity of immune cells. This is superior to using N-acetylneuraminic acid alone to enhance immunity. Therefore, N-acetylneuraminic acid and hyaluronic acid achieve a synergistic effect in terms of immune efficacy.

[0033] 3. This invention further optimizes the content of the hyaluronic acid salt. When the content is preferably in the range of 0.1‰-0.7‰ and the ratio of β-lactoglobulin to α-lactalbumin is 0.8-2.5, it can effectively ensure that the product has a clarity index ≤0.030, a particle size median ≤0.30μm, and a centrifugal sedimentation rate ≤2.5% upon production. At the same time, there are no quality problems such as fat floating, protein precipitation, or protein denaturation within a shelf life of 6 months at room temperature, achieving stability during the shelf life.

[0034] Furthermore, when the mass ratio of hyaluronic acid to N-acetylneuraminic acid is 1:(0-10), even better sensory results can be obtained.

[0035] 4. In the preparation process of this invention, the stability is effectively improved by coordinating the parameters of the material preparation temperature and the ultra-high temperature instantaneous sterilization. Specifically, at a material preparation temperature of 60-75°C, the structures of α-lactalbumin and β-lactoglobulin unfold and decompose into monomers, exposing hydrophobic residues. At the same time, the added sodium hyaluronate allows its linear non-sulfated structure to attach to the hydrophobic residues of the milk proteins, forming a hydrophilic carrier that allows sodium hyaluronate to dissolve in liquid milk, improving solubility. Simultaneously, the formed hydrophilic carrier can effectively protect the denaturation of milk proteins caused by heat processing, thereby effectively ensuring that under the subsequent ultra-high temperature instantaneous sterilization parameters, the optimal mass ratio of hyaluronic acid salt: α-lactalbumin: β-lactoglobulin is (1-8): (0.6-2.1): (0.8-3.6), and the optimal mass ratio of hyaluronic acid salt to α-lactalbumin and β-lactoglobulin is 2.6:1:1.02, ensuring heat processing stability.

[0036] 5. Macroscopically, this invention locks in the heat-sensitive protein whey protein in neutral milk, forming a stable hydrophilic carrier structure. Simultaneously, sodium hyaluronate can selectively form stable neutral small units with N-acetylneuraminic acid, a raw material that induces localized over-acidification. This allows room-temperature sodium hyaluronate milk, free of any thickeners or stabilizers, to maintain a good texture within a 6-month shelf life, while exhibiting no oxidation or non-enzymatic browning under 37°C conditions. Detailed Implementation

[0037] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0038] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0039] The raw milk used in the following examples conforms to GB 19301 standard; sodium hyaluronate: molecular weight 80,000~400,000 Da, purity ≥95%, meets the requirements for new resource food; N-acetylneuraminic acid: purity ≥98%, meets the requirements for new resource food.

[0040] Example 1:

[0041] This embodiment provides a room-temperature milk, the raw materials of which include: hyaluronic acid salt and raw milk. The hyaluronic acid salt is sodium hyaluronate with a molecular weight of 200,000 Da, the content of sodium hyaluronate is 0.1 kg, and the content of raw milk is 999.9 kg.

[0042] A method for preparing room temperature milk, the specific process of which is as follows:

[0043] Add 100 times the total weight of hyaluronic acid salts to the raw milk in the mixing tank (pot), i.e., 10 kg of raw milk. Start stirring: After heating the raw milk to 60°C, slowly add sodium hyaluronate to the heated raw milk at a rate of ≤1 kg / min. After the addition is complete, continue stirring for 15 minutes to ensure that the raw materials are completely dissolved and uniform.

[0044] The remaining 989.9 kg of raw milk was transferred to the pasteurization system. The prepared feed solution was then added online to the raw milk for the first homogenization, pasteurization, and first cooling. Specifically, the feed solution was preheated to 70°C via a plate heat exchanger, and then homogenized at 70°C with a total pressure of 200 bar. After the first homogenization, pasteurization was performed at 72±2°C for 15 seconds, followed by a first cooling to 5°C.

[0045] The cooled liquid was preheated to 80°C using a plate heat exchanger and then homogenized a second time at 80°C. The total pressure of the second homogenization was 230 bar. After the second homogenization, the liquid was sterilized at 135°C for 6 seconds.

[0046] The liquid material can be cooled to 25°C and then filled using an aseptic tank filling machine.

[0047] The product's indicators were tested, confirming that the protein content in the finished product was 3.30 g / 100 mL, the pH of the finished product was 6.70, and the mass ratio of hyaluronic acid, α-lactalbumin and β-lactoglobulin in the finished product was 1:1.03:2.51.

[0048] Example 2:

[0049] This embodiment provides a room-temperature milk, the raw materials of which include: hyaluronic acid salt, N-acetylneuraminic acid, emulsifier, and raw milk. Specifically, the hyaluronic acid salt is sodium hyaluronate with a molecular weight of 90,000 Da, the emulsifier is 1.0 kg of glyceryl monostearate, the content of sodium hyaluronate is 0.125 kg, the content of N-acetylneuraminic acid is 0.187 kg, and the content of raw milk is 998.688 kg.

[0050] A method for preparing room temperature milk, the specific process of which is as follows:

[0051] In a mixing tank (pot), add 131.2 kg of raw milk (100 times the total weight of hyaluronic acid, N-acetylneuraminic acid, and emulsifier) ​​and start stirring. Heat the raw milk to 45°C, and slowly add the emulsifier to the heated raw milk at a rate ≤5 kg / min. After complete addition, stir at a constant temperature for 5 minutes to ensure that the emulsifier is completely dissolved. Then, heat the mixture to 68°C and slowly add the mixture of sodium hyaluronate and N-acetylneuraminic acid to the heated raw milk at a rate ≤1 kg / min. Continue stirring for 15 minutes to ensure that the raw materials are completely and evenly dissolved.

[0052] The remaining 867.488 kg of raw milk was transferred to the pasteurization system. The prepared feed solution was then added online to the raw milk for the first homogenization, pasteurization, and first cooling. Specifically, the feed solution was preheated to 70°C via a plate heat exchanger, and then homogenized at 70°C with a total pressure of 200 bar. After the first homogenization, pasteurization was performed at 72±2°C for 15 seconds, followed by a first cooling to 5°C.

[0053] The cooled liquid was preheated to 80°C using a plate heat exchanger and then homogenized a second time at 80°C. The total pressure of the second homogenization was 230 bar. After the second homogenization, the liquid was sterilized at 136°C for 5 seconds.

[0054] The liquid material can be cooled to 25°C and then filled using an aseptic tank filling machine.

[0055] The product's indicators were tested, confirming that the protein content in the finished product was 3.25 g / 100 mL, the pH of the finished product was 6.56, and the mass ratio of hyaluronic acid, α-lactalbumin and β-lactoglobulin in the finished product was 1.25:1.74:2.83.

[0056] Example 3:

[0057] This embodiment provides a room-temperature milk, the raw materials of which include: hyaluronic acid salt, N-acetylneuraminic acid, emulsifier, and raw milk. The hyaluronic acid salt is sodium hyaluronate with a molecular weight of 100,000 Da, the emulsifier is 0.25 kg of glyceryl stearate and 0.25 kg of sucrose fatty acid ester, the content of sodium hyaluronate is 0.12 kg, the content of N-acetylneuraminic acid is 2 kg, and the content of raw milk is 997.38 kg.

[0058] A method for preparing room temperature milk, the specific process of which is as follows:

[0059] In a mixing tank (pot), add 262 kg of raw milk (100 times the total weight of hyaluronic acid, N-acetylneuraminic acid, and emulsifier) ​​and start stirring. Heat the raw milk to 45°C, and slowly add the emulsifier to the heated raw milk at a rate ≤5 kg / min. After complete addition, stir at a constant temperature for 5 minutes to ensure that the emulsifier is completely dissolved. Then, heat the mixture to 70°C and slowly add the mixture of sodium hyaluronate and N-acetylneuraminic acid to the heated raw milk at a rate ≤1 kg / min. Continue stirring for 15 minutes to ensure that the raw materials are completely and evenly dissolved.

[0060] The remaining 735.38 kg of raw milk was transferred to the pasteurization system. The prepared feed solution was then added online to the raw milk for the first homogenization, pasteurization, and first cooling. Specifically, the feed solution was preheated to 70°C via a plate heat exchanger, and then homogenized at 70°C with a total pressure of 200 bar. After the first homogenization, pasteurization was performed at 72±2°C for 15 seconds, followed by a first cooling to 5°C.

[0061] The cooled liquid was preheated to 80°C using a plate heat exchanger and then homogenized a second time at 80°C. The total pressure of the second homogenization was 230 bar. After the second homogenization, the liquid was sterilized at 139°C for 4 seconds.

[0062] The liquid material can be cooled to 25°C and then filled using an aseptic tank filling machine.

[0063] The product's indicators were tested, confirming that the protein content in the finished product was 3.32 g / 100 mL, the pH of the finished product was 6.70, and the mass ratio of hyaluronic acid, α-lactalbumin and β-lactoglobulin in the finished product was 1.2:0.67:0.82.

[0064] Example 4:

[0065] This embodiment provides a room-temperature milk, the raw materials of which include: hyaluronic acid salt, N-acetylneuraminic acid, emulsifier, and raw milk. The hyaluronic acid salt is sodium hyaluronate with a molecular weight of 400,000 Da, the emulsifier consists of 0.2 kg of phospholipid, 0.5 kg of polyglycerol fatty acid ester, and 0.5 kg of propylene glycol alginate, the content of sodium hyaluronate is 0.8 kg, the content of N-acetylneuraminic acid is 1.2 kg, the content of emulsifier is 1.2 kg, and the content of raw milk is 996.8 kg.

[0066] A method for preparing room temperature milk, the specific process of which is as follows:

[0067] In a mixing tank (pot), add 320 kg of raw milk, which is 100 times the total weight of hyaluronic acid, N-acetylneuraminic acid, and emulsifier. Start stirring: heat the raw milk to 45°C, and slowly add the emulsifier to the heated raw milk at a rate of ≤5 kg / min. After the emulsifier is completely added, stir at a constant temperature for 5 minutes to ensure that the emulsifier is completely dissolved. Then heat the mixture to 75°C and slowly add the mixture of sodium hyaluronate and N-acetylneuraminic acid to the heated raw milk at a rate of ≤1 kg / min. Continue stirring for 15 minutes to ensure that the raw materials are completely and evenly dissolved.

[0068] The remaining 676.8 kg of raw milk was transferred to the pasteurization system. The prepared feed solution was then added online to the raw milk for the first homogenization, pasteurization, and first cooling. Specifically, the feed solution was preheated to 70°C via a plate heat exchanger, and then homogenized at 70°C with a total pressure of 200 bar. After the first homogenization, pasteurization was performed at 72±2°C for 15 seconds, followed by a first cooling to 5°C.

[0069] The cooled liquid was preheated to 80°C using a plate heat exchanger and then homogenized a second time at 80°C. The total pressure of the second homogenization was 230 bar. After the second homogenization, the liquid was sterilized at 138°C for 6 seconds.

[0070] The liquid material can be cooled to 25°C and then filled using an aseptic tank filling machine.

[0071] The product's indicators were tested, confirming that the protein content in the finished product was 3.36 g / 100 mL, the pH of the finished product was 6.72, and the mass ratio of hyaluronic acid, α-lactalbumin and β-lactoglobulin in the finished product was 8:2.03:3.51.

[0072] Example 5:

[0073] This embodiment provides a room-temperature milk, the raw materials of which include: hyaluronic acid salt, emulsifier, other functional ingredients, and raw milk. The hyaluronic acid salt is sodium hyaluronate with a molecular weight of 80,000 Da; the emulsifier consists of 0.25 kg of propylene glycol fatty acid ester, 0.25 kg of polyoxyethylene (20) sorbitan monooleate, and 0.5 kg of mono- and diglyceride fatty acid esters; the other functional ingredients include 0.01 kg of collagen peptides and 0.002 kg of vitamin E; the content of sodium hyaluronate is 0.2 kg; the content of emulsifier is 1 kg; the content of other functional ingredients is 0.012 kg; and the content of raw milk is 998.788 kg.

[0074] A method for preparing room temperature milk, the specific process of which is as follows:

[0075] In a mixing tank (pot), add 121.2 kg of raw milk, which is 100 times the total weight of hyaluronic acid salts, other functional ingredients, and emulsifier. Start stirring. Heat the raw milk to 45°C. Slowly add the emulsifier, collagen peptides, and vitamin E to the heated raw milk at a rate ≤5 kg / min. After complete addition, stir at a constant temperature for 5 minutes to ensure that the emulsifier is completely dissolved. Then heat to 65°C and slowly add sodium hyaluronate to the heated raw milk at a rate ≤1 kg / min. Continue stirring for 15 minutes to ensure that all ingredients are completely and evenly dissolved.

[0076] The remaining 877.588 kg of raw milk was transferred to the pasteurization system. The prepared feed solution was then added online to the raw milk for the first homogenization, pasteurization, and first cooling. Specifically, the feed solution was preheated to 70°C via a plate heat exchanger, and then homogenized at 70°C with a total pressure of 200 bar. After the first homogenization, pasteurization was performed at 72±2°C for 15 seconds, followed by a first cooling to 5°C.

[0077] The cooled liquid was preheated to 80°C using a plate heat exchanger and then homogenized a second time at 80°C. The total pressure of the second homogenization was 230 bar. After the second homogenization, the liquid was sterilized at 137°C for 4 seconds.

[0078] The liquid material can be cooled to 25°C and then filled using an aseptic tank filling machine.

[0079] The product's indicators were tested, confirming that the protein content in the finished product was 3.41 g / 100 mL, the pH of the finished product was 6.80, and the mass ratio of hyaluronic acid, α-lactalbumin and β-lactoglobulin in the finished product was 2.6:1.02:1.

[0080] Example 6:

[0081] This embodiment provides a room-temperature milk, the raw materials of which include: hyaluronic acid salt, N-acetylneuraminic acid, other functional ingredients, and raw milk. The hyaluronic acid salt is sodium hyaluronate with a molecular weight of 500,000 Da. The other functional ingredients are 1.2 kg of skipjack tuna active protein, 1.5 kg of konjac ceramide, 1.8 kg of collagen peptides, and 0.5 kg of Haematococcus pluvialis. The content of sodium hyaluronate is 0.65 kg, the content of N-acetylneuraminic acid is 0.08 kg, the content of other functional ingredients is 5 kg, and the content of raw milk is 994.27 kg.

[0082] A method for preparing room temperature milk, the specific process of which is as follows:

[0083] In a mixing tank (pot), add 537 kg of raw milk, which is 100 times the total weight of hyaluronic acid, N-acetylneuraminic acid, and emulsifier. Start stirring. Heat the raw milk to 45°C. Slowly add other functional ingredients, such as bonito active protein, konjac ceramide, collagen peptides, and Haematococcus pluvialis, to the heated raw milk at a rate ≤5 kg / min. After complete addition, stir at a constant temperature for 5 minutes to ensure that all functional ingredients, such as bonito active protein, konjac ceramide, collagen peptides, and Haematococcus pluvialis, are completely dissolved. Then, heat the mixture to 60°C and slowly add the mixture of sodium hyaluronate and N-acetylneuraminic acid to the heated raw milk at a rate ≤1 kg / min. Continue stirring for 15 minutes to ensure that all ingredients are completely and evenly dissolved.

[0084] The remaining 457.27 kg of raw milk was transferred to the pasteurization system. The prepared feed solution was then added online to the raw milk for the first homogenization, pasteurization, and first cooling. Specifically, the feed solution was preheated to 70°C via a plate heat exchanger, and then homogenized at 70°C with a total pressure of 200 bar. After the first homogenization, pasteurization was performed at 72±2°C for 15 seconds, followed by a first cooling to 5°C.

[0085] The cooled liquid was preheated to 80°C using a plate heat exchanger and then homogenized a second time at 80°C. The total pressure of the second homogenization was 230 bar. After the second homogenization, the liquid was sterilized at 137°C for 4 seconds.

[0086] The liquid material can be cooled to 25°C and then filled using an aseptic tank filling machine.

[0087] The product's indicators were tested, confirming that the protein content in the finished product was 3.60 g / 100 mL, the pH of the finished product was 6.78, and the mass ratio of hyaluronic acid, α-lactalbumin and β-lactoglobulin in the finished product was 6.5:0.96:1.84.

[0088] Example 7:

[0089] This comparative example provides a room-temperature milk, the raw materials of which include: hyaluronic acid salt, N-acetylneuraminic acid, emulsifier, and raw milk. Specifically, the hyaluronic acid salt is sodium hyaluronate with a molecular weight of 95000 Da, the emulsifier consists of 0.5 kg of sodium stearoyl lactylate and 0.5 kg of mono- and diglycerides of fatty acids, the total content of sodium hyaluronate is 0.32 kg, the content of N-acetylneuraminic acid is 0.1 kg, the content of emulsifier is 1 kg, and the content of raw milk is 998.58 kg.

[0090] A method for preparing room temperature milk, the specific process of which is as follows:

[0091] In a mixing tank (pot), add approximately 100 times the total weight of hyaluronic acid, N-acetylneuraminic acid, and emulsifier to raw milk, i.e., 142 kg of raw milk. Start stirring: heat the raw milk to 45°C, and slowly add the emulsifier to the heated raw milk at a rate ≤ 5 kg / min. After complete addition, maintain the temperature and stir for 5 minutes to ensure that the emulsifier is completely dissolved. Then heat to 80°C, and slowly add the mixture of sodium hyaluronate and N-acetylneuraminic acid to the heated raw milk at a rate ≤ 1 kg / min. Continue stirring for 15 minutes to ensure that the raw materials are completely and evenly dissolved.

[0092] The remaining 856.58 kg of raw milk was filtered through nanofiltration and ultrafiltration membrane processes to adjust the ratio of β-lactoglobulin to α-lactalbumin to 2:1 (i.e., α-lactalbumin content of 0.0987 mg / L and β-lactoglobulin content of 0.1899 mg / L). The membrane-filtered raw milk was then transferred to a pasteurization system. Subsequently, the prepared feed solution was added online to the raw milk for the first homogenization, pasteurization, and first cooling. Specifically, the feed solution was preheated to 70°C via a plate heat exchanger, and the first homogenization was performed at 70°C under a total pressure of 200 bar. After the first homogenization, pasteurization was carried out at 72±2°C for 15 seconds, followed by a first cooling to 5°C.

[0093] The cooled liquid was preheated to 80°C using a plate heat exchanger and then homogenized a second time at 80°C. The total pressure of the second homogenization was 230 bar. After the second homogenization, the liquid was sterilized at 140°C for 4 seconds.

[0094] The liquid material can be cooled to 25°C and then filled using an aseptic tank filling machine.

[0095] The product's indicators were tested, confirming that the protein content in the finished product was 3.18 g / 100 mL, the pH of the finished product was 6.68, and the mass ratio of hyaluronic acid, α-lactalbumin and β-lactoglobulin in the finished product was 3:2:1.

[0096] Comparative Example 1:

[0097] The difference between this comparative example and Example 1 is that this comparative example uses the method disclosed in Example 1 of CN104397183A to prepare milk with a hyaluronic acid concentration of 0.1‰; the specific process is as follows:

[0098] Dissolve 0.1 kg of sodium hyaluronate with a molecular weight of 200,000 Da in 10 times the amount of water to obtain a sodium hyaluronate solution.

[0099] 989.9 kg of raw milk was mixed with sodium hyaluronate solution.

[0100] The feed liquid is preheated to 65°C by a plate heat exchanger and homogenized at 65°C with a total pressure of 180 bar. After homogenization, it is sterilized at 110°C for 6 seconds and then refrigerated at 6°C.

[0101] The product's indicators were tested, confirming that the protein content in the finished product was 3.15g / 100mL, the pH of the finished product was 6.68, and the mass ratio of hyaluronic acid, α-lactalbumin and β-lactoglobulin in the finished product was 1:9:32.

[0102] Comparative Example 2:

[0103] This comparative example provides a room-temperature milk, the raw materials of which include: hyaluronic acid salt, N-acetylneuraminic acid, emulsifier, and raw milk. Specifically, the hyaluronic acid salt is sodium hyaluronate with a molecular weight of 500,000 Da; the emulsifier consists of 0.5 kg of glyceryl monostearate and 0.5 kg of sucrose fatty acid ester; the content of sodium hyaluronate is 0.25 kg; the content of N-acetylneuraminic acid is 3 kg; the ratio of sodium hyaluronate to N-acetylneuraminic acid is 1:12; the content of emulsifier is 1 kg; and the content of raw milk is 995.75 kg.

[0104] A method for preparing room temperature milk, the specific process of which is as follows:

[0105] In a mixing tank (pot), add 425 kg of raw milk, which is 100 times the total weight of hyaluronic acid, N-acetylneuraminic acid, and emulsifier. Start stirring: heat the raw milk to 45°C, and slowly add the emulsifier to the heated raw milk at a rate of ≤5 kg / min. After the emulsifier is completely added, stir at a constant temperature for 5 minutes to ensure that the emulsifier is completely dissolved. Then heat the mixture to 68°C and slowly add the mixture of sodium hyaluronate and N-acetylneuraminic acid to the heated raw milk at a rate of ≤1 kg / min. Continue stirring for 15 minutes to ensure that the raw materials are completely and evenly dissolved.

[0106] The remaining 538.48 kg of raw milk was transferred to the pasteurization system. The prepared feed solution was then added online to the raw milk for the first homogenization, pasteurization, and first cooling. Specifically, the feed solution was preheated to 70°C via a plate heat exchanger, and then homogenized at 70°C with a total pressure of 200 bar. After the first homogenization, pasteurization was performed at 72±2°C for 15 seconds, followed by a first cooling to 5°C.

[0107] The cooled liquid is preheated to 80°C using a plate heat exchanger and then homogenized a second time at 80°C. The total pressure of the second homogenization is 230 bar. After the second homogenization, ultra-high temperature sterilization is performed at 137°C. During the sterilization process, the tubes become mushy and the product cannot be formed.

[0108] Comparative Example 3:

[0109] This comparative example provides a room-temperature milk, the raw materials of which include: N-acetylneuraminic acid, emulsifier, stabilizer, and raw milk. The emulsifier consists of 0.5 kg of glyceryl monostearate, 1.0 kg of sodium carboxymethyl cellulose, and 0.5 kg of sodium alginate; the stabilizer consists of 1.0 kg of microcrystalline cellulose and 0.2 kg of gellan gum; the content of N-acetylneuraminic acid is 0.5 kg; the content of emulsifier is 2 kg; the content of stabilizer is 1.2 kg (this comparative example requires the addition of stabilizer to protect the milk protein from local denaturation caused by N-acetylneuraminic acid, thereby meeting its stability requirements); and the content of raw milk is 996.3 kg.

[0110] A method for preparing room temperature milk, the specific process of which is as follows:

[0111] Add 370 kg of raw milk (100 times its total weight of N-acetylneuraminic acid, emulsifier, and stabilizer) to a mixing tank (pot). Start stirring. Heat the raw milk to 45°C. Slowly add the emulsifier to the heated raw milk at a rate ≤ 5 kg / min. After complete addition, stir at a constant temperature for 5 minutes to ensure the emulsifier is completely dissolved. Then heat to 60°C and slowly add N-acetylneuraminic acid to the heated raw milk at a rate ≤ 1 kg / min. Continue stirring for 15 minutes to ensure the raw materials are completely and evenly dissolved.

[0112] The remaining 627.3 kg of raw milk was transferred to the pasteurization system. The prepared feed solution was then added online to the raw milk for the first homogenization, pasteurization, and first cooling. Specifically, the feed solution was preheated to 70°C via a plate heat exchanger, and then homogenized at 70°C with a total pressure of 200 bar. After the first homogenization, pasteurization was performed at 72±2°C for 15 seconds, followed by a first cooling to 5°C.

[0113] The cooled liquid was preheated to 80°C using a plate heat exchanger and then homogenized a second time at 80°C. The total pressure of the second homogenization was 230 bar. After the second homogenization, the liquid was sterilized at 137°C for 6 seconds.

[0114] The liquid material can be cooled to 25°C and then filled using an aseptic tank filling machine.

[0115] The product's indicators were tested, confirming that the protein content in the finished product was 3.26g / 100mL and the pH of the finished product was 6.72.

[0116] Experiment 1 - Stability Index Detection

[0117] 1. The clarification index was tested using a LUMiSizer X65 stability analyzer with the following parameters: light factor 1.00, rotation speed 4000 rpm, temperature 25℃, profile 300, and time interval 10s.

[0118] 2. Particle size analysis: Median diameter (μm): The median diameter was obtained using an LA 960 laser particle size analyzer with a transmittance of 70%–90%.

[0119] 3. Centrifugal sedimentation rate (%): Weigh 50g of sample and place it in a centrifuge tube. Centrifuge at 3500rpm for 15min. Place the centrifuge tube with the supernatant removed in a 37℃ oven to dry for 2min. Calculate the amount of sediment xg. Centrifugal sedimentation rate = x / 50*100%.

[0120] The stability indicators for a 6-month shelf life should meet the following requirements: Δ Clarity Index (6-month sample - off-line sample, absolute value) ≤ 0.1, Δ Particle Size (6-month sample - off-line sample, absolute value) ≤ 0.1 μm, and Δ Centrifugal Sedimentation Rate (6-month sample - off-line sample, absolute value) ≤ 1.0%.

[0121] Examples 1-7 and Comparative Examples 2-3 were stored at room temperature (25°C), while Comparative Example 1 was refrigerated at 6°C. The products from the examples and comparative examples were tested using the above-described testing methods, and the results are shown in Table 1.

[0122] Table 1

[0123]

[0124] The results from Examples 1-7 in Table 1 show that by optimizing the mass ratio of hyaluronic acid to α-lactalbumin and β-lactoglobulin in the room-temperature milk to (1-8):(0.6-2.1):(0.8-3.6), good stability can be achieved even within a higher hyaluronic acid content range of 0.1‰-0.8‰. This results in an absolute value of Δclarification index (sample stored at room temperature for 6 months - sample removed from shelf life), Δparticle size distribution (sample stored at room temperature for 6 months - sample removed from shelf life), ≤0.1 μm, and Δcentrifugation sedimentation rate (sample stored at room temperature for 6 months - sample removed from shelf life), ≤1.0%. Therefore, under these conditions, there are no quality problems such as fat floating, protein precipitation, or protein denaturation within a 6-month shelf life at room temperature, effectively achieving shelf-life stability. Compared to the method disclosed in the existing CN104397183A document, the 0.1‰ concentration of hyaluronic acid in milk prepared by this method not only achieves superior efficacy but also exhibits significantly better stability, demonstrating remarkable effects.

[0125] Furthermore, a comparison of Examples 1-3 and 5-6 with Examples 4 and 7 shows that when the hyaluronic acid content is preferably in the range of 0.1‰-0.7‰, and the ratio of β-lactoglobulin to α-lactalbumin is in the range of 0.8-2.5, it can effectively ensure that the product's clarity index is ≤0.030, the particle size distribution is ≤0.30μm, and the centrifugal sedimentation rate is ≤2.5% upon completion, further improving product stability.

[0126] Experimental Example 2 - Microbial Determination (Commercially Sterile)

[0127] One sample from each batch was stored at 2℃~5℃ as a control. The remaining samples were incubated at 36℃±1℃ for 10 days, followed by sensory evaluation, pH testing, and microscopic examination of stained smears. Samples deemed commercially sterile were those showing no signs of microbial growth. The testing methods are detailed in GB 4789.26. The test results are shown in Table 2 below.

[0128] Table 2

[0129]

[0130] As shown in Table 2, Comparative Example 1 only meets the total bacterial count requirement for pasteurized milk, but does not meet the commercial sterility standard, and therefore cannot meet the sterility requirements for room temperature milk.

[0131] Experiment Example 3 - Sensory Evaluation

[0132] Organize personnel (n≥30 people) who have received professional sensory training, are in good health and do not have lactose intolerance, and have a habit of drinking milk to conduct sensory evaluations on commercially sterile products. The full score is 100 points, and the evaluation criteria are shown in Table 3. The final score is the average value.

[0133] Table 3 Sensory Evaluation Standards for Products

[0134]

[0135]

[0136] The products of the embodiments and comparative examples were evaluated using the above sensory evaluation criteria, and the evaluation results are shown in Table 4 below.

[0137] Table 4

[0138]

[0139] The sensory evaluation results above show that when the mass ratio of hyaluronic acid to N-acetylneuraminic acid is 1:(0-10), and the content ratio of β-lactoglobulin to α-lactalbumin is 0.8-2.5, even better sensory results can be obtained, with a sensory score of over 90.

[0140] Experimental Example 4 - Skin Moisture Content Measurement

[0141] The recruitment criteria for volunteers are that they are in good physical condition and do not have lactose intolerance, and have a habit of drinking milk. The male-to-female ratio is 1:1. In order to ensure the statistical sample size (N≥30) and to avoid the subjects dropping out due to special circumstances, the sample size is increased by 10%, which is 33 people, including 16 men and 17 women.

[0142] Except for Examples 4 and 6, the dosage of the products in the other examples is two packets daily, one in the morning and one in the evening, with an interval of 10 ± 2 hours. For Examples 4 and 6, one packet daily is consumed; each packet contains 250 mL. After 30 days of consumption, the effect of the product of this invention on skin moisture is tested.

[0143] The analyzer used was the German SHP88 skin analyzer, which measured the moisture content of the stratum corneum before and after the food test. The test site was the central cheek area. The testing environment required a spacious, well-ventilated space with a temperature of 23±2℃ and an air humidity of 25%–35%. Subjects entered the testing room 30 minutes before the test and were in a quiet state. The test results are shown in Table 5 below. A significant improvement in skin moisture (p<0.05) was considered valid; no significant improvement (p>0.05) was considered invalid.

[0144] Table 5

[0145]

[0146] The data in Table 5 above shows that when the hyaluronic acid content is 0.1‰-0.8‰, the mass ratio of hyaluronic acid to N-acetylneuraminic acid is 1:(0-20), and the ratio of β-lactoglobulin to α-lactalbumin is 0.8-2.5, the effective rate of significantly improving skin moisture in subjects reaches over 75%, demonstrating a significant effect. Furthermore, when the hyaluronic acid content is 0.2‰-0.8‰, and the ratio of hyaluronic acid to α-lactalbumin is greater than 2, the effective rate of improving skin moisture reaches over 80%, demonstrating an even more significant effect.

[0147] Experimental Example 5 - Evaluation of Immune Function

[0148] Immunological function was evaluated in four aspects: cellular immune function (mouse spleen lymphocyte transformation experiment, delayed-type hypersensitivity experiment), humoral immune function (antibody-producing cell detection, serum hemolysin assay), monocyte-macrophage function (mouse carbon clearance experiment, mouse peritoneal macrophage phagocytosis of chicken red blood cells experiment), and NK cell activity. A positive result in any two of these aspects indicates that the test sample has an immune-enhancing effect. The immunological function evaluation methods refer to the "Draft for Comments on Methods for Functional Testing and Evaluation of Health Foods (2020 Edition)," and the evaluation results are shown in Table 6 below.

[0149] Table 6

[0150]

[0151] As shown in Table 6 above, only when the mass ratio of hyaluronic acid to N-acetylneuraminic acid is 1:(0.1-2), combined with the mass ratio of hyaluronic acid to α-lactalbumin and β-lactoglobulin being (1-8):(0.6-2.1):(0.8-3.6) and the content ratio of β-lactoglobulin to α-lactalbumin being 0.8-2.5, can the synergistic effect of enhancing immunity be effectively achieved.

[0152] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A type of room-temperature milk, characterized in that, Raw materials include: Hyaluronic acid salts and raw milk; the mass fraction of the hyaluronic acid salts is 0.1‰-0.8‰; The mass ratio of hyaluronic acid salts to α-lactalbumin to β-lactoglobulin in the room-temperature milk is (1~8):(0.6~2.1):(0.8~3.6). The hyaluronic acid salt is sodium hyaluronate; the molecular weight of sodium hyaluronate is 80,000~400,000 Da; Hyaluronic acid salts are added to raw milk heated to 60-75°C and mixed thoroughly before subsequent sterilization to obtain room temperature milk.

2. The room-temperature milk according to claim 1, characterized in that, The content of the hyaluronic acid salt is 0.1‰-0.7‰; The ratio of β-lactoglobulin to α-lactalbumin is 0.8-2.

5.

3. The room-temperature milk according to claim 1, characterized in that, The ratio of hyaluronic acid salt: α-lactalbumin: β-lactoglobulin is (1~8): (0.8~2.1): (1~3.6).

4. A room-temperature milk according to any one of claims 1-3, characterized in that, The raw materials also include N-acetylneuraminic acid, the content of which is less than 3‰.

5. The room-temperature milk according to claim 4, characterized in that, The mass ratio of the hyaluronic acid salt to the N-acetylneuraminic acid is 1:(0~20). The ratio of hyaluronic acid salt to α-lactalbumin is greater than 2.

6. The room-temperature milk according to claim 5, characterized in that, The mass ratio of the hyaluronic acid salt to the N-acetylneuraminic acid is 1:(0~10).

7. The room-temperature milk according to claim 6, characterized in that, The mass ratio of the hyaluronic acid salt to the N-acetylneuraminic acid is 1:(0.1~2).

8. A room-temperature milk according to any one of claims 1-3, characterized in that, The raw milk content is 994.00~999.90‰, and the raw materials also include emulsifiers at a rate not exceeding 1.2‰ and / or other functional raw materials at a rate not exceeding 5‰.

9. A method for preparing room-temperature milk according to any one of claims 1-8, characterized in that, include: Hyaluronic acid salts are added to raw milk heated to 60-75°C and mixed thoroughly before proceeding with the subsequent sterilization process. The sterilization process includes pasteurization and ultra-high temperature instantaneous sterilization, and the sterilization parameters of the ultra-high temperature instantaneous sterilization are 137±3℃ and 4~6s.

10. The preparation method according to claim 9, characterized in that, include: Mixing: Heat a portion of the raw milk, then add other types of raw materials to the raw milk to dissolve and mix well to obtain a mixture liquid. Mix the remaining raw milk with the mixture liquid. When adding emulsifiers, the temperature of the raw milk is 40-50℃. When adding hyaluronic acid salts, the temperature of the raw milk is 60-75℃. After undergoing a first homogenization, pasteurization, first cooling, second homogenization, ultra-high temperature instantaneous sterilization, and second cooling, the finished product is produced.

11. The preparation method according to claim 10, characterized in that, The temperature of the first homogenization is 50~80℃, and the total pressure is 150~270 bar; The pasteurization temperature is 72±2℃ and the time is 15s; The temperature of the first cooling is 1~7℃; The temperature of the second homogenization is 60~90℃, and the total pressure is 220~240 bar; The temperature of the second cooling is 15~30℃.

12. The preparation method according to claim 10 or 11, characterized in that, In the mixing step, the mass of the raw milk used to dissolve other types of raw materials is 100-120 times the weight of the other types of raw materials.

13. The preparation method according to claim 10 or 11, characterized in that, The feeding rate of the hyaluronic acid salt is ≤1 kg / min; when the hyaluronic acid salt is mixed with N-acetylneuraminic acid, the feeding rate of the mixture is ≤1 kg / min. The feeding rate of the emulsifier is ≤5 kg / min.

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