Application of nisin in inhibiting plasmin activity and improving quality of milk and / or dairy products
By adding nisin to milk and dairy products and subjecting them to heat sterilization, the problem of dairy quality deterioration caused by fibrinolytic enzymes is solved, achieving a high level of quality improvement and safety inhibition, and is suitable for dairy processing.
Patent Information
- Application Number
- CN202610114131.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-28
- Publication Date
- 2026-02-27
AI Technical Summary
Existing technologies are insufficient to effectively inhibit plasmin activity, leading to problems such as deterioration in texture, flavor defects, nutrient loss, and shortened shelf life of milk and dairy products during storage and sales. Furthermore, traditional methods such as high-intensity heat sterilization and chemical inhibitors have limitations.
Nisin is used as a food additive. By adding it to raw milk and subjecting it to heat sterilization treatment, including UHT and pasteurization treatment, the activity of fibrinolytic enzyme is significantly inhibited. The addition amount is 0.1~100mg/kg, the mixing pressure is 10~30MPa, and the temperature and time are adjusted according to different sterilization methods.
It effectively inhibits fibrinolytic enzyme activity, avoids the cooked taste and browning caused by excessive heat treatment, maintains the original flavor and nutritional value of dairy products, extends shelf life, and is suitable for large-scale industrial production.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of food technology, specifically relating to the application of nisin in inhibiting plasmin activity and improving the quality of milk and / or dairy products. Background Technology
[0002] Fibrinolytic enzymes are an important component of the plasmin system and a key factor affecting the quality stability of milk and dairy products. Fibrinolytic enzymes are highly heat-stable proteases that maintain high activity even at pasteurization temperatures (e.g., 72-85°C), especially in heat-sterilized milk such as ESL (Extended Shelf Life Pasteurized Milk) and UHT (Ultra-High Temperature Sterilized Milk). Even under UHT treatment (135-150°C, for several seconds), some proenzymes may be activated, or proenzymes from spore-forming bacteria may be activated during storage, forming active plasmin.
[0003] During the storage and sale of dairy products, residual fibrinolytic enzymes continue to hydrolyze casein, especially αs-casein and β-casein, leading to a series of serious product quality problems. These include: ① Deterioration of product texture: causing gelation, thickening, or sedimentation in milk. ② Flavor defects: producing bitter peptides, resulting in an unpleasant bitter taste. ③ Nutritional loss: damaging protein integrity and reducing nutritional value. ④ Shortened shelf life: the above changes severely limit the commercial shelf life of the product, causing economic losses.
[0004] Currently, traditional methods for controlling plasmin activity in the industry have many limitations. For example, ① High-intensity heat sterilization: Increasing the intensity of heat treatment (such as extending the holding time) can more thoroughly inactivate plasmin, but this method exacerbates the Maillard reaction in milk, producing a cooked flavor and browning, and destroying heat-sensitive vitamins, leading to significant deterioration in nutrition and flavor. ② Adding chemical protease inhibitors: For example, some plant-based (such as soybean trypsin inhibitors) or synthetic inhibitors have shown effectiveness in laboratory studies, but their application in food is strictly limited by food safety regulations, consumer demands for "clean labels," and the potential introduction of foreign odors; moreover, many highly effective inhibitors (such as ε-aminocaproic acid) are pharmaceutical ingredients and are not permitted for addition to food. Therefore, there is an urgent need to provide a safer substance that can inhibit plasmin activity. Summary of the Invention
[0005] The purpose of this invention is to provide the application of nisin in inhibiting plasmin activity and improving the quality of milk and / or dairy products, wherein the nisin can significantly inhibit plasmin activity.
[0006] This invention provides the application of nisin in inhibiting plasmin activity.
[0007] As a preferred embodiment, the source of the fibrinolytic enzyme includes milk and / or dairy products.
[0008] This invention provides the application of nisin in improving the quality of milk and / or dairy products.
[0009] As a preferred embodiment, the milk and / or dairy products include: milk and / or dairy products that have undergone heat sterilization.
[0010] As a preferred embodiment, the temperature for heat sterilization is 60~150℃.
[0011] As a preferred embodiment, the use of the lactic acid nisin includes inhibiting plasmin activity.
[0012] This invention provides a method for improving the quality of milk and / or dairy products, comprising the following steps: adding nisin to raw milk, mixing and then subjecting it to heat sterilization.
[0013] As a preferred embodiment, the amount of nisin added is 0.1~100 mg / kg.
[0014] As a preferred embodiment, the heat sterilization includes: UHT sterilization and / or pasteurization.
[0015] As a preferred embodiment, the UHT sterilization temperature is 135~150℃ and the time is 2~8s; the pasteurization temperature is 70~85℃ and the time is 12~30s.
[0016] Beneficial Effects: This invention provides the application of nisin in inhibiting plasmin activity. The nisin described in this invention can significantly inhibit plasmin activity. The nisin described in this invention is a permitted food additive, INS number 234, and has high safety.
[0017] This invention provides the application of nisin in improving the quality of milk and / or dairy products. Fibrinolytic enzymes are key enzymes leading to the deterioration of milk and its quality. The nisin described in this invention improves the quality of milk and / or dairy products at its source by inhibiting the activity of fibrinolytic enzymes.
[0018] This invention provides a method for improving the quality of milk and / or dairy products, comprising the following steps: adding nisin to raw milk, mixing, and then subjecting it to heat sterilization. The method of this invention does not require excessively high heat sterilization intensity and can still inhibit fibrinolytic enzyme activity, thereby effectively avoiding the "cooked taste," browning, and nutrient loss caused by excessive heat treatment, and better preserving the original flavor and nutritional value of the milk. The method of this invention is simple and low-cost, requiring only the addition of a mixing step to the existing conventional dairy processing flow, without the need for additional complex equipment. Furthermore, the amount of nisin added is low, and the cost is controllable, making it very suitable for large-scale industrial production. Detailed Implementation
[0019] This invention provides the application of nisin in inhibiting plasmin activity.
[0020] The nisin described in this invention can significantly inhibit plasmin activity. The nisin described in this invention is a permitted food additive (INS number 234) and has high safety. This invention does not have special requirements regarding the source of the nisin; commercially available products that are well-known to those skilled in the art and comply with GB1886.231—2023 "National Food Safety Standard for Food Additives - Nisin" are acceptable. As a preferred embodiment, the plasmin source of this invention includes milk and / or dairy products. The nisin described in this invention is a plasmin activity inhibitor.
[0021] This invention provides the application of nisin in improving the quality of milk and / or dairy products. As a preferred embodiment, the milk and / or dairy products include: milk and / or dairy products that have undergone heat sterilization. The heat sterilization temperature of this invention can be any value within the range of 60~150°C, for example, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, or 150°C. This invention can be used to improve the quality of heat-treated milk and / or dairy products. As a preferred embodiment, the use of nisin in this invention includes: inhibiting plasmin activity. Plasmin is a key enzyme leading to the deterioration of milk and milk quality, and it has extremely high thermal stability. The nisin described in this invention improves the quality of milk and / or dairy products from the source by inhibiting the activity of plasmin, and delays the formation of protein hydrolysis, gelation, bitterness and precipitation caused by plasmin.
[0022] This invention provides a method for improving the quality of milk and / or dairy products, comprising the following steps: adding nisin to raw milk, mixing, and then subjecting the mixture to heat sterilization. The amount of nisin added according to this invention, based on the mass of the raw milk, can be any value within the range of 0.1~100 mg / kg, for example, 0.1, 0.2, 0.5, 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 mg / kg. The low amount of nisin added results in controllable costs, making it very suitable for large-scale industrial production. The nisin described in this invention is a permitted food additive, and its addition amount complies with the requirements of GB2760—2024 "National Food Safety Standard for the Use of Food Additives," namely, a maximum usage of 0.5 g / kg in milk and dairy products. In a preferred embodiment, the mixing described in this invention includes: high-pressure homogenization mixing; the pressure of the high-pressure homogenization mixing can be any value within the range of 10~30 MPa, for example, 10, 20, or 30 MPa; high-pressure homogenization can make the mixing more uniform. In a preferred embodiment, the heat sterilization includes: UHT sterilization and / or pasteurization. The temperature of the UHT sterilization described in this invention can be any value within the range of 135~150℃, for example, 135, 140, 143, 147, or 150℃; the time can be any value within the range of 2~8s, for example, 2, 4, 6, or 8s. Preheating treatment can also be performed before the UHT sterilization described in this invention; the preheating temperature can be any value within the range of 60~70℃, for example, 60, 65, or 70℃; the time can be any value within the range of 20~30min, for example, 20, 25, or 30min. The pasteurization temperature described in this invention can be any value within the range of 70~85℃, for example, 70, 80, or 85℃; the time can be any value within the range of 12~30s, for example, 12, 16, 20, 25, or 30s. The method described in this invention does not require excessively increasing the heat sterilization intensity, thus avoiding the "cooked taste," browning, and nutrient loss caused by excessive heat treatment, and better preserving the original flavor and nutritional value of the milk. As a preferred embodiment, after heat sterilization, this invention further includes: cooling before filling or preparing dairy products according to conventional methods before packaging. The cooling temperature described in this invention can be any value within the range of ≤25℃, for example, 4, 10, 15, 20, or 25℃. The method described in this invention is simple in process and low in cost, requiring only the addition of a mixing step to the existing conventional dairy processing flow, without the need for additional complex equipment.
[0023] To further illustrate the present invention, the application of nisin provided by the present invention in inhibiting plasmin activity and improving the quality of milk and / or dairy products is described in detail below with reference to embodiments, but these should not be construed as limiting the scope of protection of the present invention.
[0024] Reagent: Nisin (Z type), brand name: Aladdin, CAS number: 137061-46-2.
[0025] Example 1 Add 250mg of nisin to 50kg of milk, homogenize under high pressure at 20MPa, preheat to 65℃ and maintain for about 20min, then perform indirect (in a container) ultra-high temperature heating treatment (135℃, 4s), aseptically cool to room temperature (23±2℃), and then aseptically package in aseptic bags.
[0026] Example 2 Add 50mg of nisin to 50kg of milk, homogenize under high pressure at 20MPa, preheat to 65℃ and maintain for about 20min, then perform indirect ultra-high temperature heating (135℃, 4s), aseptically cool to room temperature (23±2℃), and then aseptically package in sterile bags.
[0027] Example 3 Add 25mg of nisin to 50kg of milk, homogenize under high pressure at 20MPa, preheat to 65℃ and maintain for about 20min, then perform indirect ultra-high temperature heating (135℃, 4s), aseptically cool to room temperature (23±2℃), and then aseptically package in sterile bags.
[0028] Example 4 Add 10 mg of nisin to 50 kg of milk, homogenize under high pressure at 20 MPa, preheat to 65 °C and maintain for about 20 min, then perform indirect ultra-high temperature heating (135 °C, 4 s), aseptically cool to room temperature (23 ± 2 °C), and then aseptically package in aseptic bags.
[0029] Example 5 Add 10 mg of nisin to 50 kg of milk, homogenize under high pressure at 20 MPa, preheat to 65 °C and maintain for about 20 min, then perform indirect ultra-high temperature heating (147 °C, 4 s), aseptically cool to room temperature (23 ± 2 °C), and then aseptically package in sterile bags.
[0030] Example 6 Add 5 mg of nisin to 50 kg of milk, homogenize under high pressure at 20 MPa, preheat to 65°C and maintain for about 20 min, then perform indirect ultra-high temperature heating (147°C, 4 s), aseptically cool to room temperature (23±2°C), and then aseptically package in sterile bags.
[0031] Example 7 Add 5 mg of nisin and 100 g of sodium citrate (stabilizer) to 50 kg of goat milk, perform high-pressure homogenization at 20 MPa, then preheat to 65 °C and maintain for about 20 min, then perform indirect ultra-high temperature heating treatment (135 °C, 4 s), aseptically cool to room temperature (23 ± 2 °C), and then aseptically package in aseptic bags.
[0032] Comparative Example 1 The procedure was carried out in accordance with Example 1, except that the amount of nisin added was replaced with 0.
[0033] Comparative Example 2 The procedure was carried out in accordance with Example 7, except that the amount of nisin added was replaced with 0.
[0034] Test Example 1 After aseptically packaged samples from Examples 1-7 and Comparative Examples 1-2 were stored at 37°C for 90 days, the following tests were performed, and the results of the plasmin activity in the samples are shown in Table 1.
[0035] Casein dissociation: Add 250 μL of 0.4 M trisodium citrate buffer (pH 8.9) to 1 mL of sample and mix for 15 min. Centrifuge at room temperature for 1 h at 10000 g to remove the upper fat layer and collect the supernatant for later use.
[0036] Plasmin isolation: The supernatant was diluted 1:1 (v / v) with a detection buffer containing 0.1M Tris-HCl, 4 mg / mL gelatin, 8 mM EACA (monoaminocarboxylic acid), 0.4 M NaCl, and pH 8. The mixture was stirred for 15 min to separate plasmin from casein, resulting in a sample solution containing plasmin.
[0037] Fibrinolytic activity assay: Fibrinolytic activity was determined by measuring the hydrolysis rate of the plasminogen chromogenic substrate S-2251. Substrate S-2251 was dissolved in 0.1M Tris-HCl buffer at pH 8 to a concentration of 4mM. 75 μL of the plasmin-containing sample solution and 75 μL of the substrate solution were mixed, and 100 μL was added to a 96-well microplate. The plate was sealed in a resealable bag and placed in a 37°C water bath for 120 min. Absorbance was measured at 405 nm and 490 nm every 20 min. To correct for turbidity, the absorbance at 490 nm was subtracted from the absorbance at 405 nm. A linear curve was plotted with time on the x-axis and absorbance on the y-axis, and the slope was calculated to obtain a standard curve (y = -0.00001786x + 0.09264286). Enzyme activity was calculated based on the standard curve.
[0038] Sensory evaluation: Ten evaluators who had conducted sensory evaluations of liquid dairy products evaluated the cooked flavor of the obtained samples. A scoring system was used to assess the intensity of the cooked flavor, ranging from 1 to 10 points. The higher the score, the stronger the cooked flavor.
[0039] Table 1. Results of plasmin activity and sensory evaluation.
[0040] As shown in Table 1, Examples 1-7 significantly inhibited plasmin activity by adding nisin, effectively avoiding the "cooked taste" caused by excessive heat treatment, and delaying protein hydrolysis and gelation caused by plasmin. The resulting products had no bitter taste or precipitation. In contrast, Comparative Examples 1 and 2, without the addition of nisin, showed significantly increased plasmin activity, produced a large amount of precipitation, and exhibited a bitter taste. Therefore, nisin can significantly inhibit plasmin activity.
[0041] Therefore, plasmin is a key enzyme leading to the deterioration of milk and milk quality, and it has extremely high thermal stability. The nisin described in this invention improves the quality of milk and / or dairy products from the source by inhibiting plasmin activity.
[0042] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.
Claims
1. Application of nisin in inhibiting plasmin activity.
2. The application according to claim 1, characterized in that, The sources of the fibrinolytic enzyme include milk and / or dairy products.
3. Application of nisin in improving the quality of milk and / or dairy products.
4. The application according to claim 3, characterized in that, The milk and / or dairy products include: milk and / or dairy products that have undergone heat sterilization.
5. The application according to claim 4, characterized in that, The temperature for heat sterilization is 60~150℃.
6. The application according to claim 5, characterized in that, The uses of the lactic acid nisin include inhibiting plasmin activity.
7. A method for improving the quality of milk and / or dairy products, characterized in that, Includes the following steps: Nisin is added to the raw milk, and the mixture is then subjected to heat sterilization.
8. The method according to claim 7, characterized in that, The amount of nisin added is 0.1~100mg / kg.
9. The method according to claim 7, characterized in that, The heat sterilization includes: UHT sterilization and / or pasteurization.
10. The method according to claim 9, characterized in that, The UHT sterilization temperature is 135~150℃ and the time is 2~8s; the pasteurization temperature is 70~85℃ and the time is 12~30s.