Milk for assisting in reducing blood sugar and preparation method thereof

Abstract

The invention relates to the technical field of dairy products, in particular to milk for assisting in reducing blood sugar and a preparation method thereof. According to the milk preparation method provided by the invention, the problems of shelf life stability, functional active substance stability and sense organ of the liquid milk with the function of assisting in reducing blood sugar and added with the mulberry leaf extract are effectively solved, and under the condition that food additives such as a thickening agent, an emulsifying agent, an acidity regulator and food essence are not added, the milk can be prepared into milk with the function of assisting in reducing blood sugar. The product is stable in system within the shelf life of 6 months at normal temperature, free of fat floating and precipitation and good in color, luster, taste and smell, and the stability and the retention rate of the blood sugar reducing active ingredients are relatively high; the milk product provided by the invention is a low-GI food, can effectively relieve postprandial blood sugar rise and fluctuation, can effectively stabilize postprandial blood sugar when being used along with food, and achieves the effect of assisting in reducing blood sugar.

Description

Technical Field

[0001] This invention relates to the field of dairy technology, and in particular to a milk that helps lower blood sugar and its preparation method. Background Technology

[0002] With changing lifestyles and dietary habits, as well as an aging population, the prevalence of diabetes and prediabetes is rising annually, becoming a serious global health problem. Complications of diabetes, such as cardiovascular disease and osteoporosis, also severely impact patients' quality of life. However, existing diabetes management methods have significant limitations, such as the potential for hypoglycemia with traditional hypoglycemic drugs and low adherence rates, and technological bottlenecks and supply gaps in the market for related medical foods. Therefore, developing functional foods that meet the daily dietary needs of patients with diabetes and prediabetes while also having a supplementary hypoglycemic effect is of great significance.

[0003] Patients with diabetes and prediabetes need to pay close attention to their carbohydrate intake. After carbohydrates are ingested, they are eventually digested into monosaccharides by salivary amylase in the mouth, intestinal amylase (mainly α-amylase from pancreatic juice), and α-glucosidase at the brush border of the small intestine, with glucose being the largest component. Postprandial blood glucose represents the blood glucose level after a glucose load and is an important indicator for the early diagnosis of diabetes. Choosing foods with a low glycemic index (low GI, i.e., GI value ≤ 55), which can slow down sugar absorption and increase satiety, can effectively control postprandial blood glucose, thereby achieving the goal of early intervention and reducing the incidence of diabetes.

[0004] Currently, most functional foods that assist in lowering blood sugar are in solid dosage form, such as meal replacement powders and formula milk powder. Their retention of nutrients, absorption efficiency, and taste are inferior to liquid dosage forms, especially for children and the elderly with weaker digestive and absorption functions, for whom liquid foods are a better choice. Furthermore, reported liquid dosage forms for assisting in lowering blood sugar contain various excipients (such as stabilizers) in addition to the active ingredients. In particular, current liquid dairy product formulas with added blood sugar-lowering functional substances contain large amounts of thickeners, emulsifiers, acidity regulators, and other stabilizers to ensure product stability within a 6-month shelf life and prevent phenomena such as fat floating and protein denaturation precipitation. However, this fails to meet consumer and market demands for green, healthy, and clean labeling. Simultaneously, the active ingredients in the ingredients can give the product a noticeable herbal taste, bitterness, and other unpleasant sensory experience, making it difficult for consumers to develop a drinking habit and thus failing to have a sustained impact on consumer health. In addition, most liquid dairy products that have added substances that help lower blood sugar have not undergone human trials to verify the clinical efficacy of their formulas, such as measuring the glycemic index of the products or conducting studies on the immediate blood glucose response with meals (the impact on postprandial blood glucose levels), so as to provide drinking guidance for people with diabetes and prediabetes.

[0005] Dairy products are recommended for daily consumption by diabetic patients, providing high-quality protein. Milk itself is also a low-sugar, low-GI food, which will not burden blood sugar levels. Developing functional milk products with blood sugar stabilizing effects, based on milk and incorporating functional ingredients, offers advantages in nutrition, health, efficacy, and portability. However, due to the inherent composition and properties of milk, adding blood sugar-lowering functional substances can easily reduce the stability of the milk system, its taste, and the stability of its active blood sugar-lowering components, thus affecting the overall stability and efficacy of the product. Summary of the Invention

[0006] This invention provides a milk that helps lower blood sugar and a method for preparing the same.

[0007] This invention, through screening, compounding, and optimization of hypoglycemic active ingredients, identified mulberry leaf extract and resistant dextrin as the optimal hypoglycemic components. However, when these active ingredients are mixed with milk to prepare functional milk, the stability of the product system and the stability of the hypoglycemic active ingredients are low, and the product's color and taste are also significantly affected. It is difficult to maintain product system stability, efficacy stability, and good sensory qualities without adding stabilizers (thickeners, emulsifiers, etc.) and flavor modifiers (flavorings, sweeteners, etc.). The product stability, active ingredient stability, and sensory problems discovered during the research and development process are specifically manifested in the following aspects: 1. Product stability: (1) System stability: The functional substance mulberry leaf extract contains polyphenols and flavonoids. Appropriate amounts of polyphenols and flavonoids can act as natural antioxidants to delay the oxidative rancidity of milk fat. However, excessive amounts may bind to casein and whey protein in milk through hydrophobic interactions or hydrogen bonds, forming polyphenol / flavonoid-protein complexes. This increases the particle size, and after pasteurization and ultra-high temperature sterilization, it exacerbates aggregation and undermines system stability. In addition, the polysaccharides in mulberry leaf extract have large molecular weights and are hydrophilic. Appropriate amounts of polysaccharides can play a positive role in system stability by increasing viscosity. However, excessive amounts may affect the stability of the milk protein system through steric exclusion effect and competitive hydration, leading to uneven texture or precipitation. Furthermore, some insoluble fiber components in the extract cannot be completely dissolved in the milk system and may also precipitate during the shelf life.

[0008] (2) Stability of active substances: The main active ingredient of mulberry leaf extract, 1-deoxynojirimycin (DNJ), has poor thermal stability. The activity of DNJ is significantly destroyed in solution or under long-term high temperature environment. Therefore, the application of functional substances such as mulberry leaf extract in room temperature dairy products that need to be sterilized by ultra-high temperature is limited. In order to ensure the functional stability of the product throughout its shelf life, it is necessary to solve the problems of active substance retention rate and shelf-life decay during processing.

[0009] 2. Product sensory characteristics: (1) Color: Mulberry leaf extract is a yellow-green, yellow-brown to dark brown powder. Due to the different contents of pigments such as chlorophyll, it presents different shades of color. Adding it to milk will affect the color of the product and thus affect the consumer experience.

[0010] (2) Taste: Mulberry leaf extract has a bitter and herbal taste due to the presence of volatile substances such as polyphenols, flavonoids and aldehydes. Adding it to milk will affect the taste of the product and thus affect the consumer experience.

[0011] This invention also reveals that due to differences in mulberry leaf varieties and extraction methods, different mulberry leaf extracts exhibit significant variations in components such as polyphenols, polysaccharides, flavonoids, pigments, and alkaloids. Adding these to milk can lead to differences in color, taste, stability, and efficacy, thus affecting the final product's characteristics. Existing technologies primarily focus on the content of alkaloids, the main active ingredient in mulberry leaf extracts, while paying less attention to the stability and sensory impact of polyphenols, polysaccharides, flavonoids, and pigments on the milk system.

[0012] In summary, ensuring the shelf-life stability and sensory quality of room-temperature milk products containing mulberry leaf extract and resistant dextrin, while also maintaining good efficacy, without the use of any thickeners, emulsifiers, acidity regulators, or other stabilizers and flavor modifiers, presents significant technical challenges.

[0013] This invention solves the aforementioned problems of product stability, sensory properties, and efficacy by optimizing the product's raw material system and preparation process.

[0014] Specifically, the present invention provides the following technical solutions.

[0015] This invention provides a method for preparing milk, wherein the milk comprises raw milk and resistant dextrin and mulberry leaf extract in a mass ratio of (8-20):(1-4); The mulberry leaf extract contains chlorophyll content <3.0 mg / g, total polyphenol content of 10.0-20.0 mg / g, total flavonoid content of 3.0-5.0 mg / g, crude polysaccharide content of 7.0-10.0 mg / g, and (E)-2-hexenal content <800.00 μg / kg. The preparation method includes: first, mixing all mulberry leaf extracts with resistant dextrin accounting for 40%-60% of the total amount of resistant dextrin added to obtain a preliminary mixture; then, mixing the remaining resistant dextrin with the preliminary mixture to obtain a premix; and finally, mixing the premix with raw milk.

[0016] The main concept of the milk raw material system and preparation method provided by this invention is to use resistant dextrin and mulberry leaf extract with specific key component contents (chlorophyll <3.0 mg / g, total polyphenols 10.0-20.0 mg / g, total flavonoids 3.0-5.0 mg / g, crude polysaccharides 7.0-10.0 mg / g, (E)-2-hexenal <800.00 μg / kg). The resistant dextrin and mulberry leaf extract powder are premixed using a stepwise method, and then mixed evenly before being combined with raw milk. Regarding system stability, by controlling the content of total polyphenols, total flavonoids, and crude polysaccharides in the mulberry leaf extract raw material within a certain range, the positive effects of these components are maximized while minimizing their destructive impact on the stability of the milk system. Furthermore, by adding resistant dextrin and mulberry leaf extract in specific proportions and using a specific premixing process, the resistant dextrin, containing a large number of glycosidic bonds, forms highly branched glucan chains, providing abundant binding sites. The hydroxyl groups (-OH) on its glucose units can form hydrogen bond networks with the phenolic hydroxyl groups and carboxyl groups of polyphenols. At the same time, the partially branched structure of resistant dextrin can form hydrophobic cavities, encapsulating nonpolar polyphenol molecules (such as the benzene rings of flavonoids), thereby blocking the hydrophobic interactions or hydrogen bonding between polyphenols and flavonoids and proteins in milk through steric hindrance, solving the problem of polyphenol or flavonoid-protein complex precipitation. In addition, the resistant dextrin used, with its small molecule and high solubility, can encapsulate mulberry leaf extract particles, creating a stable aqueous environment for them and inhibiting the steric exclusion and competitive hydration of proteins in the milk system by the large molecule polysaccharides. Meanwhile, resistant dextrin also has a certain viscosity, and its addition to neutral milk can thicken it to a certain extent. It can stabilize some insoluble components such as fiber in mulberry leaf extract by increasing the viscosity of the system and forming a certain spatial network structure, thus preventing precipitation during shelf life. Regarding the stability of active substances, the hydroxyl groups (-OH) on the glucose units of resistant dextrin can form a hydrogen bond network with the amino groups (-NH) of DNJ, or encapsulate the non-polar parts of DNJ through hydrophobic cavity interactions, thereby forming a physical barrier to protect active ingredients such as DNJ in functional substances, reducing their direct exposure to the UHT high-temperature environment, thereby reducing the risk of thermal decomposition and improving the retention rate of active substances. In terms of color, chlorophyll is a key pigment affecting the color of mulberry leaf extract. This invention has explored a suitable range of chlorophyll content, and using this mulberry leaf extract can give milk a good and stable color. At the same time, the off-white color of resistant dextrin can neutralize the brownish tone of mulberry leaf extract. Adding resistant dextrin and mulberry leaf extract in the specific ratio provided by this invention can make the overall color of the raw materials closer to the milk base, balancing the product color.In terms of taste, polyphenols and flavonoids are important sources of the bitterness of mulberry leaf extract, while aldehydes (represented by (E)-2-hexenal) are important sources of its herbal flavor. Controlling the content of total polyphenols, total flavonoids, and (E)-2-hexenal within the aforementioned ranges ensures efficacy and stability while also imparting a good and stable taste to milk. Furthermore, resistant dextrin has a slightly sweet taste and a certain viscosity, which can balance the bitterness of mulberry leaf extract to some extent, achieving a balanced product taste. Regarding its hypoglycemic effect, this invention has been verified through human trials that resistant dextrin can more effectively reduce the product's GI value and stabilize postprandial blood sugar. Simultaneously, the combined use of resistant dextrin and mulberry leaf extract within the specific ratio range of this invention can exert a synergistic effect by delaying carbohydrate digestion and absorption, regulating insulin sensitivity, and improving intestinal metabolism, thereby achieving the best auxiliary hypoglycemic effect. Replacing part of the staple food or using it as an extra food can maximize the smoothness of postprandial blood sugar fluctuations.

[0017] Through the above-mentioned optimization of raw materials and processes, while ensuring good auxiliary blood sugar lowering effects, the stability and sensory issues of functional liquid milk products within a 6-month shelf life at room temperature under the condition of no food additives such as stabilizers, flavorings, and sweeteners have been effectively solved. This has enabled the development of auxiliary blood sugar lowering functional milk without stabilizers and with clean labels, ensuring the stability of the milk system, the stability of the functional substances, and good sensory effects within the shelf life.

[0018] In the above method, the premix is ​​preferably a dry powder premix, that is, the resistant dextrin and mulberry leaf extract are mixed evenly in a dry powder state.

[0019] Preferably, the mulberry leaf extract contains 0.5-2.5 mg / g of chlorophyll (more preferably 1.5-2.5 mg / g), 10.0-20.0 mg / g of total polyphenols, 3.0-5.0 mg / g of total flavonoids, 7.0-9.2 mg / g of crude polysaccharides, and 300-700 μg / kg of (E)-2-hexenal (more preferably 600-700 μg / kg).

[0020] Preferably, the milk comprises the following components in parts by weight: 950-995 parts raw milk, 8-20 parts resistant dextrin, and 1-4 parts mulberry leaf extract.

[0021] More preferably, the milk comprises the following components in parts by weight: 965-992 parts raw milk, 8-20 parts resistant dextrin, and 1-4 parts mulberry leaf extract.

[0022] In this invention, the mulberry leaf extract is prepared from mulberry leaves through processes such as water extraction, membrane concentration, and spray drying. The preparation method of the mulberry leaf extract is a known conventional method and is substantially equivalent to that of mulberry leaves. The main active ingredients in mulberry leaves that exert their hypoglycemic effect include 1-deoxynojirimycin (DNJ) and mulberry leaf polysaccharides. DNJ is a substance unique to mulberry leaves, and its main function is to competitively inhibit the activity of α-glucosidase in the small intestine, precisely blocking the final step of carbohydrate digestion (disaccharide digestion into monosaccharide), thus reducing postprandial blood glucose peaks. Simultaneously, DNJ can also synergistically improve insulin sensitivity and regulate glucose metabolism in conjunction with polysaccharides and flavonoids in mulberry leaves. The DNJ content of the mulberry leaf extract is ≥1% (e.g., 1%-2%).

[0023] In some embodiments of the present invention, the preparation method of the mulberry leaf extract includes: pulverizing mulberry leaves and decocting them in boiling water 1-3 times (preferably, the material-to-liquid ratio is 7-11 times, the decoction temperature is preferably 95-100℃, and the time is preferably 1.5-2.5h); concentrating the extract by membrane filtration (preferably, the concentration temperature is 75-80℃, and the vacuum degree is preferably -0.06~-0.08MPa); and spray drying the resulting concentrated paste (preferably, the inlet air temperature is 175-185℃, and the tower temperature is 95-99℃). Preferably, the mulberry leaf variety is Qiangsang No. 1 or Nongsang No. 14.

[0024] In this invention, the resistant dextrin has an average molecular weight of 1800-2000 Da. Preferably, the total dietary fiber content (on a dry basis) of the resistant dextrin is ≥90%.

[0025] In this invention, the raw milk is preferably raw cow's milk.

[0026] The milk provided by this invention may also contain other functional ingredients and / or other raw materials, wherein the other functional ingredients include one or more selected from kudzu root powder, inulin, white kidney bean extract, tagatose, L-arabinose, corn silk powder, glucan, bitter melon extract, artificially cultivated ginseng, wolfberry, astragalus, and monk fruit; the other raw materials include lactase.

[0027] Preferably, the milk comprises the following components in parts by weight: 950-995 parts raw milk, 8-20 parts resistant dextrin, 1-4 parts mulberry leaf extract, 0-3 parts other functional ingredients, and 0-1 parts other raw materials.

[0028] In some embodiments of the present invention, the milk comprises the following components in parts by weight: 965-992 parts raw milk, 8-20 parts resistant dextrin, 1-4 parts mulberry leaf extract, 0.01-3 parts other active ingredients (preferably 0.1-3 parts), and 0.01-1 parts lactase (preferably 0.2-1 parts). The other active ingredients are preferably kudzu root powder.

[0029] Preferably, the total weight of the milk is 1000 parts.

[0030] The milk described in this invention does not contain at least one ingredient selected from stabilizers, acidity regulators, flavorings, and sweeteners. The stabilizers include thickeners or emulsifiers.

[0031] Preferably, the milk does not contain stabilizers (including thickeners and emulsifiers), acidity regulators, flavorings, or sweeteners.

[0032] In the above preparation method, the mixing of the remaining resistant dextrin with the initial mixture is preferably carried out in two steps. Specifically, 40%-60% of the remaining resistant dextrin is first mixed with the initial mixture, and then the resulting mixture is mixed with the final remaining resistant dextrin.

[0033] In the above preparation method, the mixing of the premix with the raw milk includes: first, dissolving the premix with a portion of the raw milk at 40-50°C, and then mixing the resulting solution with the remaining raw milk. Dissolving at 40-50°C better ensures that all raw materials are uniformly and fully dissolved and dispersed in the raw milk. If other active ingredients or raw materials are added, they should also be added during the dissolving process.

[0034] Preferably, the chemical mixing is carried out using a high-efficiency online mixer with a flow rate of ≥25000L / h.

[0035] Preferably, during the mixing process, the feeding rate of the premixed material is controlled to be ≤1 kg / min. Controlling the feeding rate can achieve the optimal mixing effect.

[0036] Preferably, the raw milk used in the chemical treatment is 10-30 times the mass of the raw material to be treated.

[0037] In some embodiments of the present invention, a portion of the raw material emulsion is used for the chemical treatment, wherein the portion of the raw material emulsion is 10-30 times the mass of the raw material to be treated. After the chemical treatment is completed, the remaining raw material emulsion is mixed with the chemically treated mixture.

[0038] Preferably, the reaction time is 10-15 minutes.

[0039] In the above preparation method, after mixing the premix with the raw milk, the steps of homogenization, pasteurization, secondary homogenization and ultra-high temperature sterilization are also included in sequence.

[0040] Preferably, the conditions for the first homogenization are as follows: homogenization temperature 50~80℃ (preferably 65~75℃); total homogenization pressure 150~170 bar (secondary pressure 30~40 bar).

[0041] Preferably, the pasteurization conditions are as follows: temperature 75±2℃, time 15~20s.

[0042] Preferably, the conditions for secondary homogenization are as follows: temperature 60~90℃, preferably 65~75℃, total pressure 220~240 bar, secondary pressure 40~50 bar.

[0043] Preferably, the ultra-high temperature sterilization conditions are as follows: 137±2℃, 4~6s.

[0044] In some embodiments of the present invention, the method for preparing the milk includes the following steps: (1) Premixing: First, premix all the mulberry leaf extract with 45%-55% of the total amount of resistant dextrin to obtain a preliminary mixture. Then, add the remaining resistant dextrin to the preliminary mixture in two batches, each time adding 45%-55% of the remaining resistant dextrin. After each batch is mixed evenly, add the remaining resistant dextrin. After mixing, the premix is ​​obtained. (2) Premixing: Use 10 to 30 times the total mass of raw milk to be premixed at 40 to 50°C to premix the raw materials. Control the flow rate of the high-efficiency online mixer to be ≥25000L / h. Add the premix from step (1) to the high-efficiency online mixer (if other functional substances or other raw materials are added, add them in this step as well). Stir for 10 to 15 minutes. The stirring time should be sufficient to ensure that all raw materials are completely dissolved and uniformly, so as to obtain a mixed liquid. (3) Online mixing: Mix the remaining raw milk with the mixture from step (2).

[0045] (4) Pasteurization: Preheating temperature 50~80℃; homogenization temperature 50~80℃ (preferably 65~75℃). Homogenization total pressure 150~170 bar (secondary pressure 30~40 bar); pasteurization temperature 75±2℃, time 15~20s, cooling to 1~7℃; (5) Volume adjustment: Adjust the volume of the cooled liquid from step (4); (6) Sterilization: After preheating (temperature 60~90℃), homogenization (temperature 60~90℃, preferably 65~75℃, total pressure 220~240bar, secondary pressure 40~50bar), ultra-high temperature sterilization (137±2℃, 4~6s) is carried out, and then cooled to 15~30℃.

[0046] The present invention also provides milk prepared using the preparation method described above.

[0047] Preferably, the milk has the effect of helping to lower blood sugar and / or stabilize postprandial blood sugar; Preferably, the milk is room temperature milk. More preferably, it is a neutral room temperature modified milk product.

[0048] Preferably, the milk contains ≥3.2g / 100mL of native protein and ≥100mg / 100mL of native calcium.

[0049] The beneficial effects of this invention include at least the following: The milk preparation method provided by this invention effectively solves the problems of shelf-life stability, stability of functional active substances, and sensory characteristics of liquid milk with added mulberry leaf extract for auxiliary blood sugar reduction. Without adding any thickeners, emulsifiers, acidity regulators, food flavorings, or other food additives, the product achieves system stability within a 6-month shelf life at room temperature, with no fat floating or sedimentation, good color and taste, and high stability and retention rate of blood sugar-reducing active ingredients. The milk product provided by this invention is itself a low-GI food, which can effectively alleviate postprandial blood sugar rise and fluctuations. Consuming it with meals can effectively stabilize postprandial blood sugar and achieve the effect of auxiliary blood sugar reduction. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0051] The raw milk used in the following examples and comparative examples conforms to the requirements of GB 19301. In the following examples and comparative examples, the mulberry leaf extract was prepared from mulberry leaves through a process of pulverization, hot water extraction, membrane filtration concentration, and spray drying. All mulberry leaf extracts used in the examples and comparative examples were prepared according to the above process. However, due to differences in mulberry leaf varieties and specific extraction process parameters, the contents of chlorophyll, total polyphenols, total flavonoids, crude polysaccharides, and (E)-2-hexenal varied. The detection methods for the contents of key components in the mulberry leaf extract are as follows: Chlorophyll content: determined according to the method in NY / T 3082-2017; Total polyphenol content: determined according to T / AHFIA. The following parameters were determined according to method 005-2018: Total flavonoid content: Method 1 of Chapter 15 of the Technical Guidelines for the Testing and Evaluation of Physicochemical and Hygienic Indicators of Health Food (2020 Edition); Crude polysaccharide content: Part 1 of Chapter 3 of the "Detection Methods for Efficacy Components of Health Food" published by China Traditional Chinese Medicine Press in 2011; (E)-2-hexenal content: determined by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), and quantitative analysis was performed using the internal standard method; DNJ content: determined according to method GB / T 40642-2021.

[0052] Example 1 This embodiment provides a milk supplement for lowering blood sugar, comprising the following components by weight: 988.00 parts raw milk, 8 parts resistant dextrin, and 4 parts mulberry leaf extract. The mulberry leaf extract is made from mulberry leaves of Qiangsang No. 1 harvested from Zhejiang Province. The leaves are pulverized and boiled twice in boiling water (9 times the amount of water added, boiling temperature 97℃, time 2.0h). The extract is then concentrated by membrane filtration (concentration temperature 77℃, vacuum degree -0.07MPa). The resulting concentrated paste is then spray-dried (inlet air temperature 181℃, tower temperature 99℃). The chlorophyll content is 1.7mg / g, the total polyphenol content is 19.5mg / g, the total flavonoid content is 3.8mg / g, the crude polysaccharide content is 9.1mg / g, the (E)-2-hexenal content is 651.23μg / kg, and the DNJ content is 1.02%.

[0053] The above-mentioned method for preparing milk includes the following steps: (1) Weighing / Premixing: Weigh raw milk, resistant dextrin, and mulberry leaf extract according to the formula. Premix the resistant dextrin and mulberry leaf extract. The specific premixing steps are as follows: First, premix all the mulberry leaf extract with 50% of the total amount of resistant dextrin to obtain a preliminary mixture. Then, add the remaining resistant dextrin to the above preliminary mixture in two batches. Each addition is 25% of the total amount of resistant dextrin. After each batch is mixed evenly, add the remaining resistant dextrin to obtain the final premix. (2) Mixing: Add raw milk to the mixing tank (the amount of raw milk should be 10 times the total mass of the raw materials and should not be lower than the stirring level), turn on the stirring, and turn on the high-efficiency online mixer after heating to 40°C. Control the flow rate to 25000L / h. In the circulation state, slowly add the premixed material in step (1) to the high-efficiency online mixer and stir at a constant temperature for 10 minutes to ensure that the raw materials are completely dissolved and uniform. Take an appropriate amount of liquid and place it in a steel basin. Observe it under natural light or lamp light. The liquid should have a uniform color and no particles in its texture. (3) Online mixing: Mix the remaining raw milk with the mixture from step (2) online, and then transfer it into the pasteurization system for pasteurization (the mixture in the milk tank or feed tank needs to be added before the pasteurization is completed). (4) Pasteurization: Preheating temperature 63.2℃. The parameters of the flash (falling film) equipment are adjusted according to the physicochemical properties of the corresponding semi-finished products. Homogenization temperature 65.5℃. Homogenization total pressure 150.5 bar (secondary pressure 30.3 bar). Pasteurization temperature 73.2℃, time 15s, cooling to 2.8℃; (5) Volume adjustment: Pump the pasteurized liquid into the semi-finished product tank and adjust the volume in the semi-finished product tank; (6) Sterilization: Preheated by plate heat exchanger (63.2℃), homogenized (65.5℃, total pressure 220.5 bar, secondary pressure 40.3 bar), and then subjected to ultra-high temperature sterilization (135.8℃, 4s). After sterilization, it was cooled to 16.8℃. (7) Aseptic filling: The liquid is cooled to 15℃~30℃ for filling and nitrogen is added (the pressure setting parameter is 0.5 bar) to prevent fat from floating during shelf life; (8) Finished product: The product is packaged in light-blocking and oxygen-blocking paper packaging.

[0054] Example 2 This embodiment provides a milk supplement for lowering blood sugar, comprising the following components by weight: 980.70 parts raw milk, 17 parts resistant dextrin, 2 parts mulberry leaf extract, 0.10 parts kudzu root powder, and 0.20 parts lactase. The mulberry leaf extract is made from mulberry leaves of variety Nongsang 14 from Zhejiang Province. The leaves are pulverized and boiled twice in boiling water (9 times the amount of water added, boiling temperature 96℃, time 2.0h). The extract is then concentrated by membrane filtration (concentration temperature 75℃, vacuum degree -0.07MPa). The resulting concentrated paste is then spray-dried (inlet air temperature 179℃, tower temperature 97℃). The chlorophyll content is 2.1 mg / g, the total polyphenol content is 12.6 mg / g, the total flavonoid content is 4.1 mg / g, the crude polysaccharide content is 9.0 mg / g, the (E)-2-hexenal content is 639.59 μg / kg, and the DNJ content is 1.01%.

[0055] The above-mentioned method for preparing milk includes the following steps: (1) Weighing / Premixing: Weigh raw milk, resistant dextrin, and mulberry leaf extract according to the formula. Premix the resistant dextrin and mulberry leaf extract. The specific premixing steps are as follows: First, premix all the mulberry leaf extract with 50% of the total amount of resistant dextrin to obtain a preliminary mixture. Then, add the remaining resistant dextrin to the above preliminary mixture in two batches. Each addition is 25% of the total amount of resistant dextrin. After each batch is mixed evenly, add the remaining resistant dextrin to obtain the final premix. (2) Mixing raw milk: Add raw milk to the mixing tank (the amount of raw milk is 15 times the total mass of the raw materials and should not be lower than the stirring liquid level), turn on the stirring, and turn on the high-efficiency online mixer after heating to 45°C. Control the flow rate to 25000L / h. In the circulation state, slowly add the premixed material, kudzu root powder and lactase from step (1) to the high-efficiency online mixer in sequence, and stir at a constant temperature for 15 minutes to ensure that all raw materials are completely dissolved and uniform. Take an appropriate amount of liquid and place it in a steel basin. Observe it under natural light or lamp light. The liquid should have a uniform color and no particles in its texture. (3) Online mixing: Mix the remaining raw milk with the mixture from step (2) online, and then transfer it into the pasteurization system for pasteurization (the mixture in the milk tank or feed tank needs to be added before the pasteurization is completed). (4) Pasteurization: Preheating temperature 68.7℃. The parameters of the flash (falling film) equipment are adjusted according to the physicochemical properties of the corresponding semi-finished products. Homogenization temperature 70.3℃. Homogenization total pressure 161.2 bar (secondary pressure 35.3 bar). Pasteurization temperature 75.5℃, time 15s, cooling to 4.3℃; (5) Volume adjustment: Pump the pasteurized liquid into the semi-finished product tank and adjust the volume in the semi-finished product tank; (6) Sterilization: Preheated by plate heat exchanger (68.7℃), homogenized (70.3℃, total pressure 231.2 bar, secondary pressure 45.1 bar), and then subjected to ultra-high temperature sterilization (137.2℃, 5s). After sterilization, it was cooled to 21.1℃. (7) Aseptic filling: The liquid is cooled to 15℃~30℃ for filling and nitrogen is added (the pressure setting parameter is 0.5 bar) to prevent fat from floating during shelf life; (8) Finished product: The product is packaged in light-blocking and oxygen-blocking paper packaging.

[0056] Example 3 This embodiment provides a milk supplement for lowering blood sugar, comprising the following components by weight: 978.70 parts raw milk, 20 parts resistant dextrin, 1 part mulberry leaf extract, 0.10 parts kudzu root powder, and 0.20 parts lactase. The mulberry leaf extract is made from mulberry leaves of variety Nongsang 14 from Sichuan Province. The leaves are pulverized and boiled twice in boiling water (9 times the amount of water added, boiling temperature 95℃, time 2.0h). The extract is then concentrated by membrane filtration (concentration temperature 76℃, vacuum degree -0.07MPa). The resulting concentrated paste is then spray-dried (inlet air temperature 178℃, tower temperature 96℃). The chlorophyll content is 2.0 mg / g, the total polyphenol content is 13.1 mg / g, the total flavonoid content is 4.9 mg / g, the crude polysaccharide content is 7.3 mg / g, the (E)-2-hexenal content is 617.21 μg / kg, and the DNJ content is 1.02%.

[0057] The above-mentioned method for preparing milk includes the following steps: (1) Weighing / Premixing: Weigh raw milk, resistant dextrin, and mulberry leaf extract according to the formula. Premix the resistant dextrin and mulberry leaf extract. The specific premixing steps are as follows: First, premix all the mulberry leaf extract with 45% of the total amount of resistant dextrin to obtain a preliminary mixture. Then, add the remaining resistant dextrin to the above preliminary mixture in two batches. Each addition is 27.5% of the total amount of resistant dextrin. After each batch is mixed evenly, add the remaining resistant dextrin to obtain the final premix. (2) Mixing raw milk: Add raw milk to the mixing tank (the amount of raw milk should be 30 times the total mass of the raw materials and should not be lower than the stirring level), turn on the stirring, and turn on the high-efficiency online mixer after heating to 50°C. Control the flow rate to 30000L / h. In the circulation state, slowly add the premixed material, kudzu root powder and lactase from step (1) to the high-efficiency online mixer in sequence, and stir at a constant temperature for 15 minutes to ensure that all raw materials are completely dissolved and uniform. Take an appropriate amount of liquid and place it in a steel basin. Observe it under natural light or lamp light. The liquid should have a uniform color and no particles in its texture. (3) Online mixing: Mix the remaining raw milk with the mixture from step (2) online, and then transfer it into the pasteurization system for pasteurization (the mixture in the milk tank or feed tank needs to be added before the pasteurization is completed). (4) Pasteurization: Preheating temperature 72.9℃. The parameters of the flash (falling film) equipment are adjusted according to the physicochemical properties of the corresponding semi-finished products. Homogenization temperature 74.8℃. Homogenization total pressure 169.9 bar (secondary pressure 39.8 bar). Pasteurization temperature 76.8℃, time 20s, cooling to 6.2℃; (5) Volume adjustment: Pump the pasteurized liquid into the semi-finished product tank and adjust the volume in the semi-finished product tank; (6) Sterilization: Preheated by plate heat exchanger (72.9℃), homogenized (74.8℃, total pressure 239.7 bar, secondary pressure 49.6 bar), and then subjected to ultra-high temperature sterilization (138.5℃, 6s). After sterilization, it was cooled to 26.3℃. (7) Aseptic filling: The liquid is cooled to 15℃~30℃ for filling and nitrogen is added (the pressure setting parameter is 0.5 bar) to prevent fat from floating during shelf life; (8) Finished product: The product is packaged in light-blocking and oxygen-blocking paper packaging.

[0058] Comparative Example 1 This comparative example provides a type of milk, namely New Nutrition lactose-free milk (whole milk), as a standard control sample.

[0059] Comparative Example 2 This comparative example provides a milk that helps lower blood sugar. The only difference between this milk and the milk in Example 1 is the mulberry leaf extract used. Specifically, the mulberry leaf extract is made from mulberry leaves of the Anhui No. 1 variety, which are crushed and boiled twice in boiling water (9 times the amount of water, boiling temperature of 90°C, time of 2.0h). The extract is then concentrated by membrane filtration (concentration temperature of 76°C, vacuum degree of -0.08MPa). The resulting concentrated paste is then spray-dried (inlet air temperature of 175°C, tower temperature of 97°C). The chlorophyll content is 9.3mg / g, the total polyphenol content is 5.6mg / g, the total flavonoid content is 2.0mg / g, the crude polysaccharide content is 8.0mg / g, the (E)-2-hexenal content is 958.29μg / kg, and the DNJ content is 1.03%.

[0060] The method for preparing the milk described above is the same as in Example 1.

[0061] In this comparative example, the milk contained higher levels of chlorophyll and (E)-2-hexenal from mulberry leaf extract, resulting in a darker color and a stronger herbal flavor; the content of polyphenols and flavonoids was lower, and the milk underwent significant oxidation and fat floating after storage at 45°C.

[0062] Comparative Example 3 This comparative example provides a blood sugar-lowering milk, which differs from the milk in Example 1 only in that the mulberry leaf extract used is different. Specifically, the mulberry leaf extract is made from mulberry leaves from Vietnam harvested in Guangdong. The leaves are crushed and boiled twice in boiling water (9 times the amount of water, boiling temperature 90°C, time 1.5h). The extract is then concentrated by membrane filtration (concentration temperature 76°C, vacuum degree -0.06MPa). The resulting concentrated paste is then spray-dried (inlet air temperature 170°C, tower temperature 90°C). The chlorophyll content is 2.5mg / g, the total polyphenol content is 106.8mg / g, the total flavonoid content is 23.7mg / g, the crude polysaccharide content is 5.2mg / g, the (E)-2-hexenal content is 712.33μg / kg, and the DNJ content is 1.01%.

[0063] The method for preparing the milk described above is the same as in Example 1.

[0064] The milk in this comparative example had excessively high levels of polyphenols and flavonoids from mulberry leaf extract, and low levels of polysaccharides. After UHT sterilization, the product underwent protein denaturation and precipitation, making sensory and stability tests impossible.

[0065] Comparative Example 4 This comparative example provides a milk that helps lower blood sugar. The only difference between this milk and the milk in Example 1 is the mulberry leaf extract used. Specifically, the mulberry leaf extract is made from mulberry leaves of the Husang 197 variety from Sichuan Province. The leaves are crushed and boiled twice in boiling water (9 times the amount of water, boiling temperature 93°C, time 2.0h). The extract is then concentrated by membrane filtration (concentration temperature 75°C, vacuum degree -0.07MPa). The resulting concentrated paste is then spray-dried (inlet air temperature 173°C, tower temperature 92°C). The chlorophyll content is 23.1mg / g, the total polyphenol content is 14.9mg / g, the total flavonoid content is 1.7mg / g, the crude polysaccharide content is 5.6mg / g, the (E)-2-hexenal content is 1278.9μg / kg, and the DNJ content is 1.02%.

[0066] The method for preparing the milk described above is the same as in Example 1.

[0067] In this comparative example, the milk contained excessive amounts of chlorophyll and (E)-2-hexenal from mulberry leaf extract, resulting in a dark color and a strong herbal flavor; low flavonoid content, and significant oxidation and fat floating after storage at 45℃; and low crude polysaccharide content, resulting in significant precipitation after storage at 45℃.

[0068] Comparative Example 5 This comparative example provides a milk that helps lower blood sugar. The only difference between this milk and the milk in Example 1 is the mulberry leaf extract used. Specifically, the mulberry leaf extract is made from mulberry leaves of Jiading 204 from Zhejiang Province. The leaves are crushed and boiled twice in boiling water (9 times the amount of water, boiling temperature 98°C, time 2.0h). The extract is then concentrated by membrane filtration (concentration temperature 80°C, vacuum degree -0.08MPa). The resulting concentrated paste is then spray-dried (inlet air temperature 183°C, tower temperature 100°C). The chlorophyll content is 2.3mg / g, the total polyphenol content is 7.2mg / g, the total flavonoid content is 3.6mg / g, the crude polysaccharide content is 11.9mg / g, the (E)-2-hexenal content is 692.1μg / kg, and the DNJ content is 1.04%.

[0069] The method for preparing the milk described above is the same as in Example 1.

[0070] In this comparative example, the milk contained normal levels of chlorophyll and (E)-2-hexenal from mulberry leaf extract, and its color and herbal flavor were normal. However, the polyphenol content was low, and oxidation and fat floating were severe after storage at 45°C. The crude polysaccharide content was high, and precipitation was severe after storage at 45°C.

[0071] Comparative Example 6 This comparative example provides a blood sugar-lowering milk, which differs from the milk in Example 1 only in that the mulberry leaf extract used is different. Specifically, the mulberry leaf extract is made from mulberry leaves of Sichuan 99 variety, which are crushed and boiled twice in boiling water (9 times the amount of water, boiling temperature of 96°C, time of 1.5h). The extract is then concentrated by membrane filtration (concentration temperature of 73°C, vacuum degree of -0.06MPa). The resulting concentrated paste is then spray-dried (inlet air temperature of 175°C, tower temperature of 98°C). The chlorophyll content is 2.7mg / g, the total polyphenol content is 24.7mg / g, the total flavonoid content is 4.0mg / g, the crude polysaccharide content is 9.2mg / g, the (E)-2-hexenal content is 682.8μg / kg, and the DNJ content is 1.03%.

[0072] The method for preparing the milk described above is the same as in Example 1.

[0073] In this comparative example, the milk contained normal levels of chlorophyll and (E)-2-hexenal from mulberry leaf extract, and its color and herbal flavor were normal; however, it had a high polyphenol content, and significant precipitation occurred after storage at 45°C.

[0074] Comparative Example 7 This comparative example provides a blood sugar-lowering milk, which differs from the milk in Example 1 only in that the mulberry leaf extract used is different. Specifically, the mulberry leaf extract is made from mulberry leaves of Sichuan 98-1 variety, which are crushed and boiled twice in boiling water (9 times the amount of water, boiling temperature of 95°C, time of 2.0h). The extract is then concentrated by membrane filtration (concentration temperature of 78°C, vacuum degree of -0.06MPa). The resulting concentrated paste is then spray-dried (inlet air temperature of 180°C, tower temperature of 95°C). The chlorophyll content is 2.8mg / g, the total polyphenol content is 15.4mg / g, the total flavonoid content is 5.8mg / g, the crude polysaccharide content is 8.1mg / g, the (E)-2-hexenal content is 782.9μg / kg, and the DNJ content is 1.03%.

[0075] The method for preparing the milk described above is the same as in Example 1.

[0076] In this comparative example, the milk contained normal levels of chlorophyll and (E)-2-hexenal from mulberry leaf extract, and its color and herbal flavor were normal; however, it had high flavonoid content, and significant precipitation occurred after storage at 45°C.

[0077] Comparative Example 8 This comparative example provides an adjunctive hypoglycemic preparation comprising the following components in parts by weight: 980.9 parts water, 17 parts resistant dextrin, 2 parts mulberry leaf extract, and 0.10 parts kudzu root powder; wherein the mulberry leaf extract is the same as that in Example 2.

[0078] The difference between the preparation method of the above preparation and the preparation method of Example 2 is that the premixing in step (1) is omitted, and the resistant dextrin, mulberry leaf extract and kudzu root powder are directly added to the feed for processing, and water is used instead of raw milk.

[0079] Comparative Example 9 This comparative example provides a milk that helps lower blood sugar, comprising the following components in parts by weight: 997.7 parts raw milk, 2 parts mulberry leaf extract, 0.10 parts kudzu root powder, and 0.20 parts lactase; wherein the mulberry leaf extract is the same as in Example 2.

[0080] The difference between the above-mentioned milk preparation method and the preparation method of Example 2 is that: resistant dextrin is not added, the premixing in step (1) is omitted, and mulberry leaf extract and lactase are directly added to the feed for processing.

[0081] Comparative Example 10 This comparative example provides a milk that helps lower blood sugar. Its formula is the same as that of the milk in Example 2. The only difference is that step (1) of the preparation method is: weigh raw milk, resistant dextrin, and mulberry leaf extract according to the formula, and premix all the resistant dextrin and mulberry leaf extract at one time.

[0082] Comparative Example 11 This comparative example provides a milk that helps lower blood sugar, comprising the following components in parts by weight: 980.70 parts raw milk, 12 parts resistant dextrin, 7 parts mulberry leaf extract, 0.10 parts kudzu root powder, and 0.20 parts lactase; wherein the mulberry leaf extract is the same as in Example 2.

[0083] The method for preparing the milk described above is the same as in Example 2.

[0084] Comparative Example 12 This comparative example provides a milk for assisting in lowering blood sugar, comprising the following components in parts by weight: 980.70 parts raw milk, 18.5 parts resistant dextrin, 0.5 parts mulberry leaf extract, 0.10 parts kudzu root powder, and 0.20 parts lactase; wherein the mulberry leaf extract is the same as in Example 2.

[0085] The method for preparing the milk described above is the same as in Example 2.

[0086] Experimental Example 1 Sensory and stability tests were conducted on the milk from Example 1 and Comparative Examples 1-2 and 4-7. The specific test methods, index controls, and test results are as follows.

[0087] 1. Detection Method Sensory descriptive testing: A quantitative descriptive profile (QDP) was established according to the method of GB / T 39625-2020 / ISO 13299:2016 to describe the sensory characteristics of the product and quantify their intensity. The results were statistically analyzed using analysis of variance (ANOVA).

[0088] Clarity index: using a LUMiSizer X65 stability analyzer, light factor 1.00, rotation speed 4000 rpm, temperature 25℃, profile 300, time interval 10s.

[0089] 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%.

[0090] Centrifugal sedimentation rate (%): Weigh 50g of sample into a centrifuge tube, centrifuge at 4000rpm for 15min, remove the supernatant, and dry the tube in a 37℃ oven for 2min. Calculate the sedimentation amount xg. Centrifugal sedimentation rate = x / 50 100%.

[0091] 2. Control of qualified indicators Sensory descriptive tests: For the milk samples of Example 1 and Comparative Examples 1-2 and 4-7, the indicators characterizing their color, taste and odor were either better or not significantly different from those of Xinyangdao lactose-free milk (whole milk) stored under the same conditions (p>0.05).

[0092] Stability indicators (lower limits): For milk samples from Example 1 and Comparative Examples 1-2 and 4-7, the clarification index is ≤0.050, the median particle size is ≤0.30μm, and the centrifugal sedimentation rate is ≤2.5%.

[0093] Stability indicators (stored at 45℃ for 7 days): For milk samples of Example 1 and Comparative Examples 1-2 and 4-7, Δ Clarification Index (samples stored at 45℃ for 7 days - samples below the cutoff line, absolute value) ≤ 0.02, Δ Particle Size (samples stored at 45℃ for 7 days - samples below the cutoff line, absolute value) ≤ 0.1 μm, and Δ Sedimentation Rate (samples stored at 45℃ for 7 days - samples below the cutoff line, absolute value) ≤ 1.0%.

[0094] 3. Test Results The sensory descriptive test results of the milk samples from Example 1 and Comparative Examples 1-2 and 4-7 are shown in Tables 1 and 2. The stability test results are shown in Table 3.

[0095] Table 1 Results of offline sensory descriptive testing

[0096] In Table 1, the analysis of variance of each index in each embodiment and comparative example shows that for the same index, different letters indicate significant differences between groups (p<0.05).

[0097] Table 2. Sensory descriptive test results after 7 days of storage at 45℃

[0098] In Table 2, the variance analysis of each indicator in each embodiment and comparative example shows that for the same indicator, different letters indicate significant differences between groups (p<0.05).

[0099] Table 3 Stability test results

[0100] The above results indicate that, compared with the mulberry leaf extract used in Comparative Examples 2 and 4-7, the mulberry leaf extract used in Example 1 has a significantly better match for the milk system in terms of the content of chlorophyll, polyphenols, flavonoids, polysaccharides, and aldehydes (represented by (E)-2-hexenal), resulting in better sensory and stability performance of the milk. Adding it to a lactose-free milk base does not significantly affect its sensory and stability characteristics.

[0101] Experiment Example 2 The stability, sensory properties, and hypoglycemic efficacy of the milk prepared by the methods of the above embodiments and comparative examples (comparative example 8 is a formulation) were tested. The testing methods, index control, and test results are as follows.

[0102] 1. Detection Method Clarity index: using a LUMiSizer X65 stability analyzer, light factor 1.00, rotation speed 4000 rpm, temperature 25℃, profile 300, time interval 10s.

[0103] 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%.

[0104] Centrifugal sedimentation rate (%): Weigh 50g of sample into a centrifuge tube, centrifuge at 4000rpm for 15min, remove the supernatant, and dry the tube in a 37℃ oven for 2min. Calculate the sedimentation amount xg. Centrifugal sedimentation rate = x / 50 100%.

[0105] Microbiological determination (commercial sterility): One sample from each batch is stored at 2-5℃ as a control. The remaining samples are incubated at 36±1℃ for 10 days, followed by sensory evaluation, pH testing, and microscopic examination of stained smears. If no signs of microbial growth are found, the sample is considered commercially sterile. For detailed testing methods, please refer to GB 4789.26.

[0106] DNJ content: determined according to GB / T 40642-2021 method.

[0107] Sensory evaluation: 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 evaluation of products that have reached commercial sterility. The full score is 100 points. The evaluation criteria are shown in Table 4. The final score is the average value.

[0108] Table 4 Sensory Evaluation Standards for Products

[0109] Glycemic Index (GI) Determination: A population-based trial was conducted, referencing WS / T 652-2019 "Methods for Determining the Glycemic Index of Foods." The study investigated the changes in blood glucose levels of subjects consuming the test substance to obtain its GI value and assess its impact on blood glucose in healthy individuals. Specific methods: Fifteen healthy subjects were selected. After measuring their fasting blood glucose levels, they consumed either glucose containing 25.0g of available carbohydrates or the test substance. Blood glucose levels were measured at different time points within 2 hours postprandial, and the changes in the glycemic response curve of the test substance were observed. Specific methods: A uniform dinner was arranged the day before the trial, avoiding the intake of high-sugar and high-fiber foods. Subjects fasted for 10 hours before the trial and avoided strenuous exercise, smoking, and alcohol consumption. On the morning of the experiment, participants walked to the laboratory and sat quietly in a chair for at least 10 minutes. Fasting venous blood was drawn, followed by either a reference food glucose sample or the test sample, which was consumed within 5-10 minutes. The start time of eating was recorded as 0 minutes. At subsequent minutes of 15, 30, 45, 60, 90, and 120 minutes, 3 mL of blood was drawn venously. The blood samples were allowed to stand for 30 minutes, then centrifuged at 3000 rpm for 5 minutes to separate the serum, and serum glucose was measured. Participants completed a gastrointestinal reaction record form on the day of each blood draw. The above procedure was repeated every 7 days. GI value = 100. Increase in area under the curve of postprandial blood glucose of test substance / increase in area under the curve of postprandial blood glucose of glucose.

[0110] Immediate Blood Glucose Response Study with Meals: A population trial, referencing WS / T652-2019 "Methods for Determining the Glycemic Index of Foods," investigated changes in blood glucose and insulin levels in subjects after consuming a test substance or a rice combination, comparing and evaluating the effect of the test substance on postprandial blood glucose levels in healthy individuals. Specific methods: Twenty-one healthy subjects were recruited and consumed different masses of rice containing 50g of available carbohydrates, along with the same volume of purified water or the test substance. The study investigated postprandial blood glucose changes from different food combinations containing 50g of available carbohydrates. The study also investigated the effect of adding the test substance on postprandial blood glucose after consuming the same mass of rice (50g carbohydrates) and the same volume of purified water or the test substance. A uniform dinner was arranged the day before the trial, avoiding high-sugar and high-fiber foods. Participants fasted for 14 hours before the trial and avoided strenuous exercise, smoking, and alcohol consumption. On the morning of the experiment, participants walked to the laboratory, sat quietly in a chair for at least 10 minutes, and had fasting venous blood drawn. They then consumed the test sample, finishing their meal within 5-10 minutes, recording the start of eating as 0 min. At subsequent minutes of 15, 30, 45, 60, 90, and 120 minutes, 3 mL of blood was drawn venously. The blood samples were allowed to stand for 30 minutes, then centrifuged at 3000 rpm for 5 minutes to separate the serum, and serum glucose was measured. The elution period for each experiment was set at 7 days.

[0111] 2. Control of qualified indicators Stability indicators (lower limits): Clarity index ≤ 0.050, median particle size ≤ 0.30 μm, centrifugal sedimentation rate ≤ 2.5%.

[0112] Stability indicators (shelf life of 6 months at room temperature): Δ Clarity index (samples stored at room temperature for 6 months - samples taken offline, absolute value) ≤ 0.02, Δ Particle size (samples stored at room temperature for 6 months - samples taken offline, absolute value) ≤ 0.1 μm, Δ Centrifugal sedimentation rate (samples stored at room temperature for 6 months - samples taken offline, absolute value) ≤ 1.0%.

[0113] Microbiological: Commercially sterile.

[0114] Sensory evaluation: Sensory score ≥ 90 points.

[0115] DNJ Retention Rate (Offline Indicator): DNJ Retention Rate (100%) (Theoretical content - Actual content) / Theoretical content, absolute value. Theoretical content refers to the DNJ content of the mulberry leaf extract raw material. (Amount added) ≥90.0%.

[0116] DNJ retention rate (6-month shelf life at room temperature): DNJ retention rate (100%) (Theoretical content - content of sample stored at room temperature for 6 months) / theoretical content, absolute value. The theoretical content is the DNJ content of mulberry leaf extract raw material. (Amount added) ≥85.0%.

[0117] Glycemic index determination: In a population trial, glucose GI was set at 100 as a reference, and foods with GI ≤ 55 were considered low-GI foods.

[0118] Studies on immediate blood glucose response during meals: In human trials, replacing part of rice or adding it as a side dish can smooth out postprandial blood glucose fluctuations.

[0119] 3. Test Results The sensory evaluation results of the products of Examples 1-3 and Comparative Examples 8-12 are shown in Table 5.

[0120] Table 5. Sensory evaluation results of products

[0121] The stability test results of the products of Examples 1-3 and Comparative Examples 8-12 are shown in Table 6.

[0122] Table 6 Results of Product Stability Tests

[0123] The above results indicate that the milk products of Examples 1-3 have good sensory properties, high system stability, and active substance stability, while the sensory performance, system stability, and active substance stability of Comparative Examples 8-12 are significantly worse than those of the Examples. Due to stability issues, the products of Comparative Examples 8-12 were not included in the functional verification tests for the following population groups.

[0124] The glycemic index results of the milk products in Examples 1-3 are shown in Table 7.

[0125] Table 7 Results of Glycemic Index Measurement

[0126] The results of the increase in the area under the blood glucose curve after consuming different foods containing a total of 50g of available carbohydrates (including rice + an equal volume of test substance) are shown in Table 8.

[0127] Table 8. Results of the increase in area under the blood glucose curve after consuming different foods with a total available carbohydrate content of 50g.

[0128] The results of the increase in the area under the blood glucose curve after consuming 50g of rice with a total available carbohydrate content and the same volume of different test substances are shown in Table 9.

[0129] Table 9. Results of the increase in area under the blood glucose curve after consuming 50g of rice (containing a total of available carbohydrates) and equal volumes of different test substances.

[0130] The experimental conditions corresponding to the results in Table 8 are a total intake of 50g of available carbohydrates, i.e., a total intake of 50g of carbohydrates from rice and milk products, simulating a scenario where milk products serve as a partial meal replacement. The experimental conditions corresponding to the results in Table 9 are a intake of 50g of available carbohydrates from rice plus an equal volume of milk products, simulating a scenario where milk products are consumed alone with meals. The combined results of Tables 8 and 9 show that, in the embodiments of the present invention, milk products can moderate postprandial blood glucose fluctuations when replacing part of the rice or as an extra food outside of meals.

[0131] In summary, the milk and its preparation method of the present invention solve the stability and sensory problems of adding mulberry leaf extract to liquid milk, while ensuring the hypoglycemic effect. It achieves stability of the milk product within a 6-month shelf life without the addition of stabilizers or other food additives, resulting in a clean-label, stable hypoglycemic liquid milk product. Specifically, by selecting resistant dextrin and mulberry leaf extract with specific component contents (chlorophyll <3.0 mg / g, total polyphenols 10.0-20.0 mg / g, total flavonoids 3.0-5.0 mg / g, crude polysaccharides 7.0-10.0 mg / g, (E)-2-hexenal <800.00 μg / kg), the negative impact of the mulberry leaf extract's own components on the product's sensory and stability is minimized, while maximizing its positive effects; the optimized ratio of resistant dextrin to mulberry leaf extract is (8~20):( (1-4) The dry powders are premixed stepwise in proportion, allowing resistant dextrin to form a stable encapsulation and support structure for polyphenols, flavonoids, polysaccharides, functional active substances, and a small number of insoluble components in mulberry leaf extract through hydrogen bonding and hydrophobic interactions. This avoids cross-linking with milk proteins during processing and shelf life, preventing sedimentation, loss or attenuation of functional active ingredients, and balancing the color and taste differences caused by functional ingredients, ensuring a good taste in the final product and achieving system, active substance, and sensory stability within a 6-month shelf life. Further human trials have verified that within the ratio range of this invention, resistant dextrin and mulberry leaf extract can exert a synergistic effect in delaying carbohydrate digestion and absorption, regulating insulin sensitivity, and improving intestinal metabolism, thereby achieving a better auxiliary hypoglycemic effect. Replacing part of rice or as an extra food can maximize the smoothing of postprandial blood glucose fluctuations.

[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of preparing milk, characterized in that, The milk comprises raw milk and resistant dextrin and mulberry leaf extract in a mass ratio of (8-20):(1-4); The mulberry leaf extract contains chlorophyll content <3.0 mg / g, total polyphenol content of 10.0-20.0 mg / g, total flavonoid content of 3.0-5.0 mg / g, crude polysaccharide content of 7.0-10.0 mg / g, and (E)-2-hexenal content <800.00 μg / kg. The preparation method includes: first, mixing all mulberry leaf extracts with resistant dextrin accounting for 40%-60% of the total amount of resistant dextrin added to obtain a preliminary mixture; then, mixing the remaining resistant dextrin with the preliminary mixture to obtain a premix; and finally, mixing the premix with raw milk.

2. The method of claim 1, wherein The milk comprises the following components in parts by weight: 950-995 parts raw milk, 8-20 parts resistant dextrin, and 1-4 parts mulberry leaf extract.

3. The method for preparing milk according to claim 1, characterized in that, The milk also contains other functional ingredients and / or other raw materials; The other active ingredients include one or more selected from kudzu root powder, inulin, white kidney bean extract, tagatose, L-arabinose, corn silk powder, glucan, bitter melon extract, artificially cultivated ginseng, wolfberry, astragalus, and monk fruit; The other ingredients include lactase.

4. The method for preparing milk according to claim 3, characterized in that, The milk comprises the following components in parts by weight: 950-995 parts raw milk, 8-20 parts resistant dextrin, 1-4 parts mulberry leaf extract, 0-3 parts other functional ingredients, and 0-1 parts other raw materials.

5. The method for preparing milk according to any one of claims 1 to 4, characterized in that, The milk does not contain at least one of the following: stabilizers, acidity regulators, flavorings, and sweeteners.

6. The method for preparing milk according to any one of claims 1 to 4, characterized in that, The process of mixing the remaining resistant dextrin with the initial mixture involves first mixing 40%-60% of the remaining resistant dextrin with the initial mixture, and then mixing the resulting mixture with the final remaining resistant dextrin.

7. The method for preparing milk according to any one of claims 1 to 4, characterized in that, Mixing the premix with the raw milk includes: first, dissolving the premix with a portion of the raw milk at 40-50°C, and then mixing the resulting liquid with the remaining raw milk.

8. The method for preparing milk according to any one of claims 1 to 4, characterized in that, After mixing the premix with the raw milk, the method further includes, in sequence: primary homogenization, pasteurization, secondary homogenization, and ultra-high temperature sterilization.

9. Milk prepared by the method according to any one of claims 1 to 8.

10. The milk according to claim 9, characterized in that, The milk has the effect of helping to lower blood sugar and / or stabilize postprandial blood sugar; And / or, the milk is room temperature milk.

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