A method for inhibiting the precipitation of yogurt whey
By adding linoleic acid substrate to the production of sour milk, covalent cross-linking between milk protein molecules is solved, and the problem of precipitation of sour milk is achieved is achieved, which significantly reduces the amount of whey precipitation and increases the anti-cancer active ingredients. , and the process is simple and the cost is low.
Patent Information
- Application Number
- CN202211598523.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-12-14
- Publication Date
- 2025-02-14
- Estimated Expiration
- 2042-12-14
AI Technical Summary
Precipitation of sour milk whey is the main defect of sour milk products, affecting its appearance and taste, and shortening shelf life. The existing technology has failed to solve the problem from the root and has cost High and complex processes.
The linoleic acid substrate is added to the skimmed emulsion, and fermentation of lactic acid bacteria promotes covalent cross-linking between milk protein molecules and reduces the whey precipitation of sour milk.
Through this method, the whey precipitation amount of sour milk is reduced by more than 80% compared with sour milk without linoleic acid, and does not change the traditional sour milk production process, and almost no production cost is increased, and a rich anti-cancer active ingredient c9,t11 is obtained without changing the traditional sour milk production process. - Conjugated linoleic acid also significantly inhibits the precipitation of sour milk whey.
Smart Images
Figure CN115943994B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of food, and in particular relates to a method for inhibiting whey precipitation of yogurt. Background Art
[0002] Whey precipitation is one of the main product defects of coagulated yogurt, which not only affects its appearance and taste, but also significantly shortens the shelf life of the product. At present, the production adopts the addition of thickeners to prevent whey precipitation. Although this method can reduce whey precipitation, the addition of thickeners is being resisted by more and more consumers, and it has not solved the scientific problem of whey precipitation in yogurt from the root.
[0003] Yogurt is a protein gel product. Milk protein forms polymers through hydrogen bonds, ionic bonds, hydrophobic interactions, and covalent bonds. Covalent bonds are the most important force to maintain gel strength and water retention. Insufficient covalent cross-linking of milk protein is the main reason for the precipitation of whey in yogurt. Its covalent bonds are mainly disulfide bonds. Although some studies have achieved certain inhibitory effects by adding whey protein and promoting cross-linking between milk proteins through TG enzymes, these methods have not been applied in industry due to high production costs and complex processes.
[0004] Conjugated linoleic acid (CLA) is a general term for a group of 18-carbon conjugated diene acids, with up to 16 isomers, such as c9,t11-CLA and t10,c12-CLA isomers, and its physiological activity is isomer-specific, such as c9,t11-CLA isomers have anti-cancer physiological activity. In nature, CLA is mainly found in the fat of milk and meat of ruminants, mainly composed of c9,t11-CLA isomers, and the content is usually less than 1mg / g fat, which cannot meet the needs of health care and medical product production. Summary of the invention
[0005] The purpose of the present invention is to propose a new method for inhibiting whey precipitation of yogurt in view of the shortcomings of the prior art. A linoleic acid substrate is added to a skim emulsion, and the method is fermented by lactic acid bacteria to obtain yogurt rich in C9, T11-conjugated linoleic acid. At the same time, the covalent cross-linking between milk protein molecules is promoted by small molecular fatty acids, thereby reducing the whey precipitation of the yogurt. The whey precipitation amount of the yogurt is reduced by more than 80% compared with the yogurt without adding linoleic acid.
[0006] The present invention comprises the following steps
[0007] (1) Preparation of skim emulsion: antibiotic-free skim milk powder is mixed with water to prepare a skim emulsion with a mass percentage of 5-15%, preferably 9%, and 0-2% of oligosaccharides, preferably 0.5% of oligofructose, are added to the skim emulsion. After homogenization, the skim emulsion is pasteurized to obtain a skim emulsion for producing yogurt.
[0008] (2) Preparation of strains for production: The CGMCC1.1854 preserved strain of Lactobacillus acidophilus was inoculated into skim emulsion and cultured at 37°C for 24 h. After three-stage expansion culture, the strains for production were obtained.
[0009] (3) Preparation of yogurt: 5% by weight of the production strain of step (2) is inoculated into skim milk, and 0.05-0.2% by weight of linoleic acid substrate is added to the skim milk, mixed and fermented at 30-45°C for 12-36 hours, preferably 0.12% by weight of linoleic acid, mixed and fermented at 37°C for 24 hours to obtain yogurt rich in C9, T11-conjugated linoleic acid, the content of C9, T11-conjugated linoleic acid in the yogurt is as high as more than 0.1%, and the amount of whey precipitation is reduced by more than 80% compared with yogurt without linoleic acid.
[0010] The lactic acid bacteria used in the present invention is Lactobacillus acidophilus, which is stored in the China General Microbiological Culture Collection Center with a number of CGMCC 1.1854.
[0011] Compared with the prior art, the present invention has the following advantages
[0012] At present, in order to reduce the whey precipitation of yogurt, gelatin, agar, starch and other thickeners are often added in production to prevent it. Although this method can reduce the whey precipitation, the addition of thickeners is being resisted by more and more consumers, and it has not solved the scientific problem of whey precipitation in yogurt from the root. Other studies have added whey protein and promoted cross-linking between milk proteins through TG enzyme. Although these methods have a certain effect of inhibiting whey precipitation, the production cost is high and the process is complicated, and they have not been applied industrially.
[0013] The present invention proposes a new method for inhibiting whey precipitation of yogurt, wherein linoleic acid substrate is added to skim emulsion, and through lactic acid bacteria fermentation, yogurt rich in C9, T11-conjugated linoleic acid is obtained, and covalent cross-linking between milk protein molecules is promoted through small molecular fatty acids, thereby reducing whey precipitation of yogurt, and the amount of whey precipitation of yogurt is reduced by more than 80% compared with yogurt without thickener. The method does not change the traditional yogurt production process, and almost does not increase the production cost. While obtaining C9, T11-conjugated linoleic acid rich in anti-cancer active ingredients, it achieves the effect of significantly inhibiting whey precipitation of yogurt. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 This is a graph showing the effect of the amount of linoleic acid added on the whey precipitation of yogurt in Example 1.
[0015] Figure 2 This is the electrophoresis diagram of the cross-linking between small molecule fatty acid lactogenic protein molecules in Example 1.
[0016] Figure 3 This is a scanning electron micrograph of the c9, t11-conjugated linoleic acid-rich yogurt and the control group in Example 1. DETAILED DESCRIPTION
[0017] The present invention is further illustrated by the following examples.
[0018] Example 1
[0019] The antibiotic-free skim milk powder was prepared with water into a skim emulsion with a mass percentage of 9%, and 0.5% of oligofructose was added to the skim emulsion. After high-pressure homogenization, the skim emulsion for producing yogurt was obtained by pasteurization at 85°C. The CGMCC 1.1854 preserved strain of Lactobacillus acidophilus was inoculated into the sterilized skim emulsion, cultured at 37°C for 24 hours, and obtained the strain for production after three-stage expansion culture. 5% by weight of the Lactobacillus acidophilus CGMCC 1.1854 strain of step (2) is introduced into the sterilized skim milk, and 0.12% by weight of linoleic acid is added to the skim milk. After mixing, the mixture is fermented and cultured at 37° C. for 24 hours to obtain yogurt rich in c9,t11-conjugated linoleic acid. The content of c9,t11-conjugated linoleic acid in the yogurt is 0.11%, and the amount of whey precipitation is reduced by 85.5% compared with yogurt without linoleic acid.
[0020] Comparison of whey precipitation in yogurt with different amounts of linoleic acid added, such as Figure 1The results show that when 0.12% or more of linoleic acid is added to skim milk, the amount of whey precipitation is reduced by more than 85%. However, as the concentration of linoleic acid continues to increase, the production of c9,t11-CLA no longer continues to increase, but instead shows a downward trend, mainly due to the inhibition of bacterial growth. The results of reducing and non-reducing SDS-PAGE electrophoresis of acidified milk protein gel are shown in Figure 1. Figure 2 As shown in the figure, lane 1 is the reduction treatment group, and lane 2 is the non-reduction treatment group. It was found that small molecular fatty acids promoted the sulfhydryl cross-linking between β-Lg and milk protein. The yogurt gel was observed by scanning electron microscopy. The results are shown in Figure 3 As shown in the figure, a is a scanning electron micrograph of yogurt with linoleic acid added, and b is a scanning electron micrograph of yogurt without linoleic acid added. It is found that the pores of the yogurt gel become smaller and denser after adding linoleic acid ( Figure 3 ), further proving that small molecule fatty acids promote molecular cross-linking between yogurt milk proteins.
[0021] Example 2
[0022] The antibiotic-free skim milk powder is prepared with water into a skim emulsion with a mass percentage of 10%, and 0.5% of oligofructose and 5.0% of strawberry juice are added to the skim emulsion, and after high-pressure homogenization, the strawberry skim emulsion for producing yogurt is obtained by pasteurization at 85°C. The Lactobacillus acidophilus CGMCC 1.1854 deposited strain is inoculated into the sterilized strawberry skim emulsion, cultured at 37°C for 24 hours, and after three-stage expansion culture, the strain for production is obtained. 5% by weight of the Lactobacillus acidophilus CGMCC 1.1854 strain of step (2) is introduced into the sterilized strawberry skim lotion, and 0.12% by weight of linoleic acid is added at the same time, and the mixture is mixed and fermented at 37° C. for 24 hours to obtain strawberry yogurt rich in c9, t11-conjugated linoleic acid, wherein the content of c9, t11-conjugated linoleic acid in the strawberry yogurt is 0.1%, and the amount of whey precipitation is reduced by 81.2% compared with the strawberry yogurt without adding linoleic acid.
Claims
1. A method for inhibiting whey precipitation of yogurt, characterized in that: Linoleic acid substrate is added to skim milk, and lactic acid bacteria fermentation is performed to obtain yogurt rich in C9, T11-conjugated linoleic acid, and small molecular fatty acids are used to promote covalent cross-linking between milk protein molecules, thereby reducing the precipitation of yogurt whey, including the following steps: (1) Preparation of skim emulsion: preparing a skim emulsion with a mass percentage of 5-15% by weight of antibiotic-free skim milk powder and water, adding 0.5% by weight of oligofructose to the skim emulsion, homogenizing, and pasteurizing to obtain a skim emulsion for producing yogurt; (2) Preparation of bacterial strains for production: Lactobacillus acidophilus ( Lactobacillus acidophilus )CGMCC 1.1854 deposited strain was inoculated into skim emulsion and cultured at 37℃ for 24h. After three-level expansion culture, the strain for production was obtained; (3) Preparation of yogurt: 5% by weight of the production strain of step (2) is inoculated into skim milk, and 0.12-0.2% by weight of linoleic acid substrate is added to the skim milk. After mixing, the mixture is fermented at 30-45° C. for 12-36 hours to obtain yogurt rich in C9,T11-conjugated linoleic acid.
2. A method for inhibiting whey precipitation of yogurt according to claim 1, characterized in that: In the step (1), a skim emulsion with a mass percentage of 9% is prepared.
3. The method for inhibiting whey precipitation of yogurt according to claim 1, characterized in that: In the step (3), 0.12% linoleic acid by weight of the skim emulsion is added, mixed and fermented at 37° C. for 24 hours.
4. The method for inhibiting whey precipitation of yogurt according to claim 1, characterized in that: The content of c9,t11-conjugated linoleic acid in the yogurt prepared in step (3) is as high as more than 0.1%.
5. The method for inhibiting whey precipitation of yogurt according to claim 1, characterized in that: The whey precipitation amount of the yogurt prepared in the step (3) is reduced by more than 80% compared with the yogurt without adding linoleic acid.