Fermented milk capable of promoting curdling and preparation method of fermented milk

Abstract

The invention discloses fermented milk for promoting curdling and a preparation method thereof, the fermented milk comprises the following raw materials: raw milk, a leavening agent, exopolysaccharide-producing lactic acid bacteria, anthocyanin and a carbon source, in the raw milk, the inoculation concentration of the leavening agent is 1 * 10 < 7 >-1 * 10 < 8 > CFU / mL, the initial concentration of the exopolysaccharide-producing lactic acid bacteria is 1 * 10 < 7 >-1 * 10 < 8 > CFU / mL, the inoculation amount is 2-4 Vol%, and the carbon source is a carbon source. The initial concentration of the anthocyanin is 10-20 mg / L, and the mass volume ratio of the carbon source to the raw milk is (4-10) g: 100 mL. According to the invention, lactic acid bacteria capable of producing exopolysaccharides at high yield are used for synergistic fermentation with traditional lactobacillus bulgaricus and streptococcus thermophilus, and meanwhile, natural anthocyanin is added, so that on one hand, the exopolysaccharides are promoted by the anthocyanin to improve the curding effect of the fermented milk, and on the other hand, the digestion stability of the anthocyanin is improved by the exopolysaccharides; therefore, the stability, sensory characteristics and functional components of the fermented dairy product are effectively improved, and a new strategy is provided for effectively improving the product quality.

Description

TECHNICAL FIELD

[0001] The present application relates to dairy products, in particular, to a fermented milk promoting curd and a preparation method thereof. BACKGROUND

[0002] Milk is rich in nutrients such as carbohydrates, lipids, proteins, water, vitamins, and minerals, and the colloidal stability of casein depends on the structure of casein micelles. Changes in physical and chemical conditions can affect the stability of casein, thereby affecting the curd process of fermented milk.

[0003] Milk coagulation is a necessary step in the production of cheese, milk cake, and yogurt, and coagulants play an important role in product development and quality improvement. The rapid development of the food industry, especially the cheese industry, has led to a shortage of coagulants, and it is imperative to develop new resources of coagulants.

[0004] However, due to the influence of raw material characteristics, process conditions, and microbial activity, the milk coagulation time is too long: (1) Influence of raw material characteristics: The protein composition and ionic environment of milk directly affect the coagulation efficiency. For example, milk with high κ-casein (κ-CN) content or β-lactoglobulin genotype AA coagulates faster and has stronger gel strength; on the contrary, high relative content of α-lactalbumin may inhibit gel formation, and low calcium ion concentration or abnormal pH value (such as less than 4.6) may slow down the acid production of lactic acid bacteria or enzyme activity, prolonging the coagulation time.

[0005] (2) Inappropriate process condition control: Temperature is a key factor. The optimal fermentation temperature of lactic acid bacteria (such as Lactobacillus bulgaricus and Streptococcus thermophilus) is 42-43°C. Low temperature will reduce enzyme activity, and high temperature may kill the bacteria. After heat sterilization, it needs to be cooled to an appropriate temperature before inoculation to avoid the decrease of pepsin activity or the occurrence of "lag phenomenon"; in addition, insufficient fermentation time (such as 6-8 hours for lactic acid bacteria) or too small inoculation amount will also prolong the coagulation.

[0006] (3) Microbial activity problems: Insufficient activity of bacteria is a common cause, including: using expired or improperly stored bacteria (such as inactivation due to improper storage); imbalance of bacterial population (such as improper ratio of Lactobacillus bulgaricus and Streptococcus thermophilus); and competition of miscellaneous bacteria in milk inhibiting the growth of lactic acid bacteria.

[0007] Anthocyanin is a kind of glycoside derivative with 2-phenylbenzopyryalium structure, which is a water-soluble pigment widely distributed in the plant kingdom. Modern research shows that anthocyanin has anti-inflammatory, antioxidant, prevention of cardiovascular disease and improvement of glycolipid metabolism and other various health promotion and disease prevention effects; at the same time, as a natural pigment, anthocyanin is safe, non-toxic, rich in resources and bright in color, and is a potential medical resource. Adding in milk can not only improve the flavor of milk, but also has a health care effect. However, direct addition can easily cause the instability of anthocyanin structure due to the increase of fermentation temperature in the preparation process of milk, resulting in low retention rate. SUMMARY

[0008] In view of the above problems, the application provides a fermented milk for promoting curd and a preparation method thereof, a strain with high exopolysaccharide yield and excellent sensory quality of fermentation product is screened from lactic acid bacteria derived from traditional fermented food, the strain is co-fermented with a starter, and anthocyanin is used for synergistic compounding to promote curd, improve the stability problems such as poor curd and whey separation commonly existing in fermented dairy products, and improve the bioavailability of exogenous anthocyanin in the product.

[0009] In order to achieve the above purpose, the application provides a fermented milk for promoting curd, which comprises the following raw materials: raw milk, a starter, exopolysaccharide-producing lactic acid bacteria, anthocyanin and a carbon source, wherein the inoculation concentration of the starter in the raw milk is 1×10 7 ~1×10 8 CFU / mL, the initial concentration of the exopolysaccharide-producing lactic acid bacteria is 1×10 7 ~1×10 8 CFU / mL, the inoculation amount is 2-4 Vol%, the initial concentration of the anthocyanin is 10-20 mg / L, and the mass-volume ratio of the carbon source to the raw milk is (4-10) g:100 mL.

[0010] In the above technical solution, the exopolysaccharide-producing lactic acid bacteria has the following effects on the curd of fermented milk: (1) Physical bridging and pre-thickening effect: Exopolysaccharide-producing lactic acid bacteria can produce exopolysaccharides (EPS), which are high-molecular-weight polymers. EPS can dissolve in milk in the early stage of fermentation (when the pH has not decreased significantly) to increase the viscosity and solid content of the system. These long-chain polysaccharide molecules can form "physical bridges" between casein micelles or fill the gaps between the protein network, starting to build a preliminary and weakened three-dimensional network before the acidity reaches the curd point. This is equivalent to building a "scaffold" in advance. When the traditional starter produces acid to reduce the pH to the isoelectric point, casein micelles are more likely to aggregate and cross-link on this pre-existing "scaffold", thereby accelerating the formation and strengthening of the gel structure, and macroscopically exhibiting faster and more solid coagulation.

[0011] (2) Improve the fermentation microenvironment and protect the starter: The mucilage layer formed around the bacterial cells or released into the substrate by EPS can have a buffering protective effect. This layer of polysaccharide can reduce the feedback inhibition of lactic acid accumulation on the bacteria themselves in the early stage of fermentation, maintaining higher activity of the bacteria; at the same time, it can also isolate other bacteria or inhibit substances to some extent. This makes the acid production process of traditional starters more stable and efficient. The thickening effect of EPS may change the rheological properties of the substrate, making the diffusion of acid and metabolites more uniform and avoiding local over-acidification, thereby allowing the overall coagulation to be more synchronized and faster.

[0012] (3) Multi-strain synergistic fermentation to improve fermentation efficiency and reduce costs: In a multi-strain system, the abilities of different strains can complement each other, such as some strains producing EPS and others producing acid, which can synergistically build a more stable texture system. EPS derived from lactic acid bacteria has functional properties such as probiotic and immune regulation, which cannot be achieved by adding chemically synthesized EPS. In addition, high-EPS-producing strains can produce acid and synthesize EPS in situ, directly forming a natural gel network, eliminating the need for reconstitution and homogenization processes required for adding exogenous EPS, simplifying the process flow, improving production continuity, reducing production steps, and reducing energy consumption and labor costs. This can simultaneously achieve texture construction and fermentation.

[0013] Anthocyanins are easily degraded during processing and storage, mainly affected by pH, temperature, light, oxidation, and metal ions. The present invention provides protection for them from multiple aspects: (1) "Microcapsule" and embedding effect of EPS: The viscous network formed by EPS can physically embed and fix anthocyanin molecules. This limits the free movement of anthocyanin molecules and their contact area with water and oxygen, equivalent to wrapping them in a "microcapsule" composed of a polysaccharide matrix. This can effectively slow down the oxidation reaction and thermal degradation.

[0014] (2) Low oxygen and acidic environment created by fermentation system: Lactic acid bacteria fermentation is an anaerobic process, which can consume oxygen in the system and create a low oxygen environment, greatly inhibiting the oxidative degradation of anthocyanins. Anthocyanins are most stable under acidic conditions (pH < 3.5). Although the final product pH of fermented milk (~ 4.2-4.6) is slightly higher than the optimum point, it is still in the acidic range, which is much more conducive to the preservation of anthocyanins than neutral milk (pH ~ 6.7). The fermentation process itself changes the environment of cow's milk from "not conducive to anthocyanins" to "relatively conducive".

[0015] (3) Non-covalent interactions (such as hydrogen bonds, hydrophobic interactions) may occur between anthocyanins (flavonoids) and EPS (polysaccharides) or casein degradation products. This interaction can change the electronic distribution of anthocyanins, improve their stability, or "anchor" them on the gel network to prevent migration and loss.

[0016] (4) Shorten the heat treatment time: Due to the shortening of the curd time, the entire fermentation process can be completed faster, which means that the total time of anthocyanins exposed to fermentation temperature (~ 42°C) is reduced, thereby reducing the loss of thermal degradation.

[0017] Preferably, the ratio of viable counts of Lactobacillus bulgaricus and Streptococcus thermophilus in the starter culture is 1: (1.5-3).

[0018] Specifically, the exopolysaccharide-producing lactic acid bacteria are Paracasei, Fermentum, and Rhamnosus.

[0019] Preferably, the carbon source is one or more of sucrose, glucose, and oligosaccharides.

[0020] Preferably, the fermented milk is yogurt or cheese.

[0021] The second aspect of the present application provides a method for preparing the above-mentioned fermented milk, which comprises the following steps: adding a starter culture, exopolysaccharide-producing lactic acid bacteria, anthocyanins, and a carbon source to raw milk, and fermenting at a temperature of 39-41°C until the protein curd is formed. The fermented milk after fermentation is placed at 0-10°C for 4-24 h to obtain the fermented milk.

[0022] Through the above technical solution, the following beneficial effects are achieved: The present application utilizes high exopolysaccharide-producing lactic acid bacteria to co-ferment with traditional Lactobacillus bulgaricus and Streptococcus thermophilus, and adds natural anthocyanins, which on the one hand promotes the exopolysaccharide to improve the curd effect of fermented milk by anthocyanins, and on the other hand, the exopolysaccharide improves the digestion stability of anthocyanins, thereby effectively improving the stability, sensory properties, and functional ingredients of fermented dairy products, providing a new strategy for effectively improving product quality. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 are microstructures in different milk fermentation processes in Example 5 of the present application. DETAILED DESCRIPTION

[0024] The specific embodiments of the present application are described in detail below with reference to the accompanying examples. It should be understood that the detailed description is only intended to illustrate and explain the present application, and is not intended to limit the present application.

[0025] In the following examples, the performance tests were carried out using the following methods, respectively: Extracellular polysaccharide content determination: phenol-sulfuric acid method was used to determine the extracellular polysaccharide yield. After fermentation, centrifugation was carried out at 4500 rpm for 15 min at 4 ℃ to obtain cell-free supernatant. Then, trichloroacetic acid (TCA, 80%) was added to the supernatant to a concentration of 4%. Anhydrous ethanol was added to the supernatant, and it was stored overnight at 4 ℃. The supernatant was centrifuged (4500 rpm / min, 4 ℃, 15 min), and the precipitate was redissolved in distilled water. The absorbance was measured at a wavelength of 490 nm. The corresponding sugar content was found on the standard curve, and the extracellular polysaccharide content was obtained.

[0026] pH determination: measured with a pH meter.

[0027] Water holding capacity determination: the sample was weighed as W0, centrifuged at 4500 rpm for 15 min at 4 ℃, and the precipitate in the test tube was weighed as W1. The water holding capacity was calculated as follows: Water holding capacity (WHC) = W1 / W0 x 100% Viable cell count determination: dilution plate pouring method was used to determine the change of viable cell count in the sample. 0.85% sterile physiological saline was prepared for gradient dilution of the sample, and 1 mL of the diluent was taken in a sterile culture dish, followed by pouring with MRS solid medium, 37 ℃ inverted culture for 48 h, and calculation of the viable cell count in the sample.

[0028] Microstructure observation: the sample was dried, fixed, and sputter coated with gold, and the microstructure of the sample was observed using a scanning electron microscope.

[0029] Establishment of in vitro digestion models: Simulated gastric juice contained pepsin, 3.1 mg / mL NaCl, 1.1 mg / mL KCl, and 0.6 mg / mL NaHCO3; simulated intestinal juice contained trypsin, 2.7 mg / mL NaCl, 0.31 mg / mL KCl, and 20 mg / mL porcine bile salts. Pepsin solution and simulated gastric juice were added to the sample, and the pH was adjusted to 2 with 4 mol / L HCl. The reaction was carried out at 37°C in the dark for 1 h to simulate gastric digestion; this process was labeled G2. Trypsin was dissolved in 0.1 mol / L NaHCO3, and trypsin solution and simulated intestinal juice were added to the sample. The pH was adjusted to 7 with 4 mol / L NaOH, and the reaction was carried out at 37°C in the dark for 2 h to simulate intestinal digestion; this process was labeled I2. At each stage, the protease inhibitor AEBSF was immediately added to the sample solution at a final concentration of 1 mmol / L to terminate each digestion stage. Undigested processes were labeled UD.

[0030] Anthocyanin content determination: The total anthocyanin content was determined using the pH differential method. 1 mL of sample solution was pipetted and 6 mL of pH 1.0 hydrochloric acid-potassium chloride buffer or 6 mL of pH 4.5 acetate-sodium acetate buffer was added. The mixture was thoroughly mixed, and the absorbance values ​​at 520 nm and 700 nm were measured and recorded as A. The path length of the cuvette was 1 cm. Distilled water was used as a blank control instead of the sample solution. The total anthocyanin content was calculated using the following formula, and the result was expressed as a multiple.

[0031] C = ΔA × M × f / ε In the formula, C is the total anthocyanin concentration, mg / mL; ΔA is the absorbance value, ΔA = (A520nm - A700nm)pH1.0 - (A520nm - A700nm)pH4.5; M is cyanidin-3- O - The relative molecular mass of glucoside is 449.2 g / mol; f is the dilution factor of the sample solution; ε is cyanidin-3- O - The molar extinction coefficient of glucoside is 26900 L / (mol·cm).

[0032] Example 1 Sterilize fresh milk at 108 °C for 15 min and set aside. Activate NM-8 lactic acid bacteria that produce extracellular polysaccharides, centrifuge at 8000 rpm for 10 min, discard the supernatant, wash three times with sterile water, and resuspend in an equal volume of milk. Inoculate the milk with 1×10⁻⁶ cells / day. 8 The starter culture was prepared at a concentration of CFU / mL, with Lactobacillus bulgaricus and Streptococcus thermophilus in a 1:3 ratio, and the subsequent inoculation concentration was 5 × 10⁻⁶. 7The exopolysaccharide-producing lactic acid bacteria NM-8 was inoculated at a concentration of 4%, 6% sucrose was added, 20 mg / L anthocyanin extract was added, and the mixture was fermented at 39°C until curd was formed. The fermented milk was then placed at 4°C for 24 h.

[0033] Example 2 The other conditions were the same as in Example 1, and the effect of different exopolysaccharide-producing lactic acid bacteria on the content of exopolysaccharide was verified.

[0034]

[0035] Note: Different lowercase letters indicate significant differences between groups P <0.05); the same letter means not significant.

[0036] According to the table, 45 strains of lactic acid bacteria isolated from food in the early stage were used to screen lactic acid bacteria with high exopolysaccharide production. It can be seen that there are significant differences in exopolysaccharide production between different strains, which is due to the influence of many factors on the content of lactic acid bacteria exopolysaccharide, such as species characteristics, strain source, medium composition and conditions, etc. According to Table 1, the exopolysaccharide production of 45 strains was 0.01~0.24 g / L, among which the content of Paracasei TM-31, KM-10 and NM-12 was significantly higher than that of other groups, which was 0.20~0.24 g / L, followed by Paracasei TM-26, TM-27, KM-7 and NM-8, Lactobacillus rhamnosus AM-3 and AM-10, and Lactobacillus fermentum PC11, with an exopolysaccharide content of 0.12~0.17 g / L.

[0037] Example 2 The other conditions were the same as in Example 1, and the effect of different amounts of starter on the quality of fermented milk was verified.

[0038]

[0039] Example 3 The other conditions were the same as in Example 1, and the effect of different amounts of lactic acid bacteria NM-8 on the quality of fermented milk was verified.

[0040]

[0041] The results showed that the pH, water holding capacity and viable count of fermented milk were constantly changing. When the inoculum of strain NM-8 was 4%, the pH was lower, and the water holding capacity and viable count were significantly higher than those of other groups, being 73.51 ± 2.27% and 9.54 ± 0.04 log CFU / mL, respectively. When the inoculum was greater than 4% (5%), the viable count did not differ significantly, and only when the inoculum was 6% did the viable count increase, while the water holding capacity of fermented milk decreased significantly. Therefore, when the inoculum of strain NM-8 was 2% to 4%, the overall quality of fermented milk was better. A lower inoculum might lead to insufficient acid production, and a higher inoculum might exacerbate acidification and rough texture.

[0042] Example 4 Other conditions were the same as in Example 1, and the effect of different carbon source addition amounts on the quality of fermented milk was verified.

[0043]

[0044] The addition of carbon sources in fermented milk is not only crucial for sweetness, but also important for improving properties such as water holding capacity. Adding an appropriate amount of carbon source is beneficial to improve the taste, making the product have a suitable sweet-sour ratio and good mouthfeel. At the same time, carbon sources can also serve as carbon sources for lactic acid bacteria fermentation, promoting fermentation and the formation of metabolic products. As can be seen from Table 6, the water holding capacity and viable count of fermented milk prepared with different carbon source addition amounts were significantly different. With the increase of carbon source addition amount, the water holding capacity first increased rapidly and then slowly, and the viable count first increased and then decreased. When the addition amount was 6%, the water holding capacity was 70.61 ± 0.51%, which was significantly higher than that when the addition amount was 2% to 4%, and the viable count was 9.72 ± 0.01 log CFU / mL, which was significantly higher than that when the addition amount was 2% to 4% and 6% to 10%. When the sugar addition amount was 6% to 10%, the higher the carbon source addition amount, the lower the viable count, which was due to the lack of sufficient substrate for lactic acid bacteria. Carbon sources had a greater impact on the quality of fermented milk. When the addition amount was 6%, the product had a suitable sweet-sour ratio and the best quality, and too much sugar addition would result in a too smooth mouthfeel and higher cost.

[0045] Example 5 Other conditions were the same as in Example 1, and the effect of different carbon source addition amounts on the quality of fermented milk was verified.

[0046]

[0047] As shown in the above table, compared with traditional starter fermented milk, inoculation of strain NM-8 can make the pH of milk decrease faster. In 0-4 h, the pH of two kinds of milk decreased from 6.62 ± 0.01 to 5.25 ± 0.01 and 6.61 ± 0.01 to 4.77 ± 0.01, respectively. The pH of NM-8 treatment group decreased to the vicinity of isoelectric point at 5 h of fermentation, reaching 4.56 ± 0.01, while the pH of the control group decreased to 4.63 ± 0.01 at 6 h of fermentation. According to the known, the isoelectric point of casein in milk is pH 4.5. Under this condition, the protein denatures, the casein bundle aggregates, and the protein coagulates. At the same time, the coagulation time of fermented milk was monitored, and it was found that the coagulation time of the control group was 5 h 59 min (359 min), and that of the NM-8 treatment group was 5 h 12 min (312 min). This result is consistent with the pH change, indicating that the high-yield exopolysaccharide lactic acid bacteria can promote the coagulation of milk protein, and the coagulation time of fermented milk is shortened by 13.09%. Water holding capacity is also an important indicator reflecting the coagulation characteristics of fermented milk. Therefore, the change of water holding capacity of the two groups of milk during fermentation was determined, and the results showed that the control group showed a certain water holding capacity at 5 h-6 h of fermentation, which was 67.29 ± 1.10%-69.43 ± 1.93%, and the water holding capacity of the NM-8 treatment group was 67.88 ± 0.34% after 4 h of fermentation, and increased to 71.28 ± 1.53% at 6 h. Therefore, through the synergistic fermentation of exopolysaccharide-producing lactic acid bacteria, the coagulation process of milk can be effectively promoted, and the texture stability of fermented milk can be improved.

[0048] Figure 1 The scanning electron micrographs (×200) of the control group and the NM-8 treatment group during the fermentation of milk are shown in the figure. As can be seen from the figure, for the control group, at 5 h of fermentation, the microstructure of milk is a kind of reticular structure with large pores. There are countless irregular pores in this reticular structure. With the fermentation of milk, at about 6 h of coagulation time, the voids of milk decrease obviously. The milk of the treatment group forms relatively dense voids at 5 h, because with the extension of fermentation time, casein denatures, aggregates, and coagulation gradually forms. Compared with the fermented milk added with strain NM-8, the microstructure of the control group is rough and irregular with relatively large pore size, and the structure is more loose. While the addition of exopolysaccharide-producing strain for co-fermentation, the reticular structure of milk protein is more compact, the pore size is smaller, and the surface is more smooth and flexible. This result is consistent with the quality change of different milk during fermentation, indicating that the coagulation time of milk of the NM-8 treatment group is shorter, the gel structure formed after coagulation is more stable, and the texture of fermented milk is also more stable.

[0049] Example 6 Other conditions are the same as example 1, verify the influence of different anthocyanin addition amount on fermented milk.

[0050]

[0051] As shown in the above table, different anthocyanin addition amount can cause the pH, water holding capacity and viable count of fermented milk product to change. When the anthocyanin addition amount is 10-20 mg / L, the water holding capacity of fermented milk is 68.09 ± 0.19%-69.57 ± 0.55%, which is significantly higher than that of fermented milk without adding anthocyanin (67.36 ± 0.25%). With the increase of anthocyanin addition amount from 20 mg / L to 30-40 mg / L, the water holding capacity of fermented milk decreases rapidly, showing poor texture, which may be related to the high degree of cross-linking between casein and anthocyanin caused by high concentration of anthocyanin. In addition, a certain concentration of anthocyanin (10-30 mg / L) can provide nutrients for microbial growth and promote the reproduction of lactic acid bacteria. When the anthocyanin addition amount is 20 mg / L, the viable count of fermented milk is the highest, reaching 8.86 ± 0.01 lg CFU / mL.

[0052] Example 7 Other conditions are the same as example 1, verify the coagulation time of different fermented milk.

[0053]

[0054] As shown in the table, compared with fermented milk only added with traditional starter, NM-8 alone and anthocyanin alone respectively promote the coagulation process of milk, making the coagulation time shortened by 10% and 4%; while NM-8 and anthocyanin are used together, the coagulation time of milk can be further shortened, and the coagulation efficiency is increased by 15.1%. Therefore, on the basis of high yield of exopolysaccharide of NM-8, the addition of anthocyanin can synergistically promote coagulation. Compared with traditional starter combined with NM-8, anthocyanin can shorten the coagulation time of milk by 15.1%, from 5.00 ± 0.05 h to 4.67 ± 0.12 h.

[0055] Example 8 Other conditions are the same as example 1, verify the retention rate of anthocyanin in different fermented milk.

[0056]

[0057] According to the table, compared with the anthocyanin alone and the traditional starter fermented milk, the NM-8 combined with the anthocyanin and the traditional starter fermented milk can preferentially improve the stability of the anthocyanin in the product, especially the retention rate of the anthocyanin during the in vitro gastrointestinal digestion. After the gastric digestion, the exopolysaccharide produced by the NM-8 significantly improves the retention rate of the anthocyanin, which is increased from 30.11 ± 0.35% to 43.15 ± 0.22%; after the intestinal digestion, the retention rate of the anthocyanin is improved more obviously, which is increased from 5.19 ± 0.16% to 17.76 ± 0.56%. Therefore, the lactic acid bacteria NM-8 with high exopolysaccharide production combined with the anthocyanin can not only further promote the coagulation process of the fermented milk and improve the texture stability of the product, but also effectively retain the digestion stability of the functional component of the anthocyanin, so that the product has more significant functional activity.

[0058] The above describes the preferred embodiments of the present application in detail, but the present application is not limited to the specific details in the above embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0059] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present application will not further describe various possible combination manners.

[0060] In addition, various different embodiments of the present application can also be combined in any manner, as long as it does not deviate from the idea of the present application, and it should be considered as the disclosed content of the present application.

Claims

1. A fermented milk for promoting curdling, characterized by, The raw milk, the starter, the exopolysaccharide-producing lactic acid bacteria, the anthocyanin and the carbon source are included, wherein the inoculation concentration of the starter in the raw milk is 1×10 7 ~1×10 8 CFU / mL, the initial concentration of the exopolysaccharide-producing lactic acid bacteria is 1×10 7 ~1×10 8 CFU / mL, the inoculation amount is 2~4 Vol%, the initial concentration of the anthocyanin is 10~20 mg / L, and the mass-volume ratio of the carbon source to the raw milk is (4~10) g:100 mL.

2. The fermented cow's milk for promoting curdling according to claim 1, characterized by, The ratio of viable cell number of Lactobacillus bulgaricus and Streptococcus thermophilus in the fermenting agent is 1: (1.5-3).

3. The fermented milk for promoting curdling according to claim 1, characterized by, The exopolysaccharide-producing lactic acid bacteria are Paracaseolovis casei, Lactobacillus fermentum and Lactobacillus rhamnosus.

4. The fermented milk for promoting curdling according to claim 1, characterized by, The carbon source is one or more of sucrose, glucose and oligosaccharide.

5. The fermented cow's milk for promoting curdling according to any one of claims 1 to 4, characterized by, The fermented milk is yogurt or cheese.

6. The method of producing a fermented milk according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: The raw milk is fermented at a temperature of 39-41 DEG C until protein curd is formed by adding the fermenting agent, the exopolysaccharide-producing lactic acid bacteria, the anthocyanin and the carbon source, and the fermented milk is then placed at a temperature of 0-10 DEG C for 4-24 hours.

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