A method for preparing a high probiotic activity yoghurt

Abstract

The application discloses a preparation method of high-probiotic-activity yoghurt and belongs to the technical field of functional food development, and comprises the following steps: white ginkgo starch and milk are treated by a dielectric barrier discharge low-temperature plasma (DBD) method respectively, the white ginkgo starch treated by the DBD method is added into the milk treated by the DBD method, white granulated sugar and a compound leavening agent are added according to a proportion, and the yoghurt is prepared by fermenting treatment for 8 h at 37 DEG C, and the gel property of the yoghurt and the probiotic quantity index are determined. The white ginkgo starch used in the application is low in price and widely sourced; the DBD treatment scheme is green, safe and simple to operate, can effectively improve the gel quality of the yoghurt and improve the stability of the yoghurt; in addition, the probiotic activity in the yoghurt is significantly enhanced after the DBD treatment, and the efficacy value of the yoghurt is effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional food development, and particularly relates to a preparation method of high-probiotic-activity yoghurt. BACKGROUND

[0002] Yogurt is one of the fermented products favored by consumers, and is rich in protein, calcium, probiotics and other functional ingredients, has rich taste and high nutritional value. However, during the production and storage and sale of yogurt, quality problems such as high whey separation rate, loose organization state and poor coagulation often occur, which seriously affects the sensory experience of consumers and the market acceptance of yogurt. Adding food thickeners is the simplest and most effective method to improve the gel properties of yogurt. At present, the commonly used thickeners in yogurt include xanthan gum, carrageenan and gum arabic. Compared with the commonly used food thickeners, starch has the advantages of low price, wide source, light flavor and stable properties. However, the poor water solubility and dispersion effect of starch seriously limit its application in the field of food processing. SUMMARY

[0003] The technical problem solved by the present application is to provide a preparation method of high-probiotic-activity yoghurt to improve the gel stability and functional activity of yogurt in view of the technical problems of food thickeners in the prior art during the preparation of yogurt.

[0004] The technical scheme of the present application is as follows:

[0005] Step 1: DBD is used to treat white gourd starch and milk respectively, and the treated products are stored at 4℃ for standby;

[0006] Step 2: The DBD-treated white gourd starch in step 1 is added to the DBD-treated milk, white sugar and a compound starter are added and uniformly mixed, and then the mixture is subjected to fermentation treatment at 37℃ for 8h to obtain yogurt, and the gel properties and the number of probiotics of the yogurt are determined.

[0007] Preferably, the specific steps for DBD treatment of white gourd starch in step 1 are as follows: 0.1-1g of white gourd starch is placed between two aluminum plate electrodes, the distance between the upper and lower medium barriers during treatment is 40mm, the treatment current is 1.5A, the high-voltage discharge frequency is 145Hz, the voltage is adjusted to 30kV, and five groups of white gourd starch samples are prepared by treating for 10s, 20s, 30s, 40s and 50s respectively, and the samples are stored at 4℃ for standby.

[0008] Preferably, the specific steps of DBD treatment of milk in step 1 are as follows: 5-20 mL of milk is measured and placed in a thin plastic box, the plastic box is placed between two aluminum plate electrodes, the distance between the upper and lower medium barriers during treatment is 40 mm, the treatment current is 1.5 A, the high-voltage discharge frequency is 145 Hz, the voltage is adjusted to 30 kV, and five groups of milk samples are prepared by treating for 10 s, 20 s, 30 s, 40 s and 50 s respectively, and stored at 4°C for standby.

[0009] Preferably, in step 2, the ratio of white ginkgo starch to milk is 1:(20-50); the addition ratio of white granulated sugar to milk is 1:10; and the addition ratio of composite starter culture to milk is 1:500.

[0010] Preferably, in step 2, the composite starter culture is one or a combination of Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium lactis, Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus casei and Lactobacillus rhamnosus.

[0011] Beneficial effects: Compared with the prior art, the present application has at least the following advantages:

[0012] 1. In the yogurt preparation method of the present application, white ginkgo starch is used as a thickening agent, and ginkgo is a food resource with medicinal and edible properties, which has a long history of planting, eating and medicinal use in China. It has multiple effects such as delaying aging, anti-fatigue and antibacterial. White ginkgo, as the kernel of ginkgo, is rich in various nutrients, with a starch content of more than 70%. White ginkgo starch has higher stability and viscosity than other starches, and can effectively improve the texture and taste of yogurt as a food thickening agent. The white ginkgo starch is inexpensive and widely available.

[0013] 2. The yogurt preparation method uses a dielectric barrier discharge low-temperature plasma DBD treatment method. Compared with high-temperature plasma, low-temperature plasma has relatively simple working conditions and is more gentle. It has a wider application in the sterilization of heat-sensitive raw materials and food preservation. Low-temperature plasma can produce active oxygen, active nitrogen, singlet oxygen and ozone, etc. Active particles have a strong destructive effect on microbial activity, which can maximize the safety of the materials being treated. In addition, active particles have a certain erosive effect on starch particles and a certain depolymerization effect on starch chains, which significantly reduces the digestibility of starch. Using air dielectric barrier discharge plasma to treat white ginkgo starch can significantly improve the fluidity of starch paste. In addition, these active particles can also interact with proteins, leading to oxidation, deamidation, nitration, sulfuration and other processes during the treatment of amino acids. Proteins may form some intramolecular or intermolecular bonds, leading to aggregation, polymerization and unfolding, thereby changing the structure. This green and safe method is simple to operate and can effectively improve the gel quality and stability of yogurt.

[0014] 3. The DBD treatment method further sterilizes milk, reduces the growth of miscellaneous bacteria, and strongly promotes the growth and reproduction of lactic acid bacteria. After fermentation, the ginkgo starch and milk treated with DBD significantly enhance the reproduction of probiotics. In particular, after 20 seconds of DBD treatment, the number of streptococci, bifidobacteria, and lactobacilli increased by 370.4%, 164.3%, and 721.9%, respectively, effectively enhancing the efficacy and value of yogurt. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the yogurt preparation process of the present invention;

[0016] Figure 2 This is a bar chart showing the total number of lactic acid bacteria in the yogurts prepared in Examples 1-5 and Comparative Examples 1-3 of the present invention;

[0017] Figure 3 This is a bar chart showing the number of streptococci in the yogurts prepared in Examples 1-5 and Comparative Examples 1-3 of the present invention;

[0018] Figure 4 This is a bar chart showing the number of Bifidobacteria in the yogurts prepared in Examples 1-5 and Comparative Examples 1-3 of the present invention;

[0019] Figure 5 The bar chart shows the number of lactobacilli in the yogurts prepared in Examples 1-5 and Comparative Examples 1-3 of this invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will be described in conjunction with the accompanying drawings of the embodiments of the present invention. Figures 1-5 The technical solutions of the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0021] like Figure 1 As shown, a method for preparing a high-probiotic active yogurt according to the present invention includes the following steps:

[0022] Step 1: white ginkgo starch and milk were treated by DBD respectively, and stored at 4℃ for standby. The specific treatment steps of white ginkgo starch were as follows: 0.1-1g of white ginkgo starch was placed between two aluminum plate electrodes, the distance between the upper and lower dielectric barriers was 40mm, the treatment current was 1.5A, the high-voltage discharge frequency was 145Hz, the regulated voltage was 30kV, and five groups of white ginkgo starch samples were prepared by treating for 10s, 20s, 30s, 40s and 50s respectively, and stored at 4℃ for standby. The specific treatment steps of milk were as follows: 5-20mL of milk was placed in a light and thin plastic box, the plastic box was placed between two aluminum plate electrodes, the distance between the upper and lower dielectric barriers was 40mm, the treatment current was 1.5A, the high-voltage discharge frequency was 145Hz, the regulated voltage was 30kV, and five groups of milk samples were prepared by treating for 10s, 20s, 30s, 40s and 50s respectively, and stored at 4℃ for standby.

[0023] Step 2: the white ginkgo starch treated by DBD in step 1 was added to the milk treated by DBD according to the ratio of 1:(20-50), white granulated sugar was added according to the ratio of 1:10, and composite starter was added according to the ratio of 1:500, the composite starter was one or a combination of Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium lactis, Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus casei and Lactobacillus rhamnosus; after mixing uniformly, the yogurt was prepared by fermentation treatment at 37℃ for 8h, and the gel property and the number of probiotics of the yogurt were determined.

[0024] Example 1: a preparation method of a high-probiotic-activity yogurt according to the application, comprising the following steps:

[0025] Step 1: 0.7g of white ginkgo starch was placed between two aluminum plate electrodes, the distance between the upper and lower dielectric barriers was 40mm, the treatment current was 1.5A, the high-voltage discharge frequency was 145Hz, the regulated voltage was 30kV, and the white ginkgo starch sample was prepared by treating for 10s, and stored at 4℃ for standby.

[0026] 20mL of milk was placed in a light and thin plastic box, the plastic box was placed between two aluminum plate electrodes, the distance between the upper and lower dielectric barriers was 40mm, the treatment current was 1.5A, the high-voltage discharge frequency was 145Hz, the regulated voltage was 30kV, and the milk sample was prepared by treating for 10s, and stored at 4℃ for standby.

[0027] Step 2: Add the ginkgo starch treated by DBD in step 1 to the DBD-treated milk, add white sugar according to the addition ratio of white sugar to milk of 1:10, and add a composite starter according to the addition ratio of the composite starter to milk of 1:500, the composite starter being one or a combination of Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium lactis, Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus rhamnosus; after being mixed uniformly, ferment at 37°C for 8h to obtain yogurt, and determine the gel property and the number of probiotics of the yogurt.

[0028] Example 2: A preparation method of a high-probiotic-activity yogurt according to the application, comprising the following steps:

[0029] Step 1: Place 0.7g of ginkgo starch between two aluminum plate electrodes, the distance between the upper and lower medium barriers is 40mm, the treatment current is 1.5A, the high-voltage discharge frequency is 145Hz, and the regulated voltage is 30kV, and the ginkgo starch sample is treated for 20s and stored at 4°C for standby.

[0030] Step 1: Place 0.7g of ginkgo starch between two aluminum plate electrodes, the distance between the upper and lower medium barriers is 40mm, the treatment current is 1.5A, the high-voltage discharge frequency is 145Hz, and the regulated voltage is 30kV, and the ginkgo starch sample is treated for 20s and stored at 4°C for standby.

[0031] Step 2: Add the ginkgo starch treated by DBD in step 1 to the DBD-treated milk, add white sugar according to the addition ratio of white sugar to milk of 1:10, and add a composite starter according to the addition ratio of the composite starter to milk of 1:500, the composite starter being one or a combination of Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium lactis, Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus rhamnosus; after being mixed uniformly, ferment at 37°C for 8h to obtain yogurt, and determine the gel property and the number of probiotics of the yogurt.

[0032] Example 3: A preparation method of a high-probiotic-activity yogurt according to the application, comprising the following steps:

[0033] Step 1: Place 0.7g of ginkgo starch between two aluminum plate electrodes, the distance between the upper and lower medium barriers is 40mm, the treatment current is 1.5A, the high-voltage discharge frequency is 145Hz, and the regulated voltage is 30kV, and the ginkgo starch sample is treated for 20s and stored at 4°C for standby.

[0034] Take 20 mL of milk and place it in a light and thin plastic box. Place the plastic box between two aluminum plate electrodes. The distance between the upper and lower medium barriers during processing is 40 mm, the processing current is 1.5 A, the high-voltage discharge frequency is 145 Hz, the adjusted voltage is 30 kV, and the processing time is 30 s. The milk sample is prepared and stored at 4℃ for later use.

[0035] Step 2: Add the DBD-treated ginkgo starch in step 1 to the DBD-treated milk. Add white sugar according to the addition ratio of 1:10 of white sugar to milk. Add a composite starter according to the addition ratio of 1:500 of the composite starter to milk. The composite starter is one or a combination of Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium lactis, Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus rhamnosus. After thorough mixing, ferment the mixture at 37℃ for 8 h to obtain yogurt. Measure the gel properties and the number of probiotics in the yogurt.

[0036] Example 4: A method for preparing a high-probiotic-activity yogurt according to the present application, comprising the following steps:

[0037] Step 1: Take 0.7 g of ginkgo starch and place it between two aluminum plate electrodes. The distance between the upper and lower medium barriers during processing is 40 mm, the processing current is 1.5 A, the high-voltage discharge frequency is 145 Hz, the adjusted voltage is 30 kV, and the processing time is 40 s. The ginkgo starch sample is prepared and stored at 4℃ for later use.

[0038] Take 20 mL of milk and place it in a light and thin plastic box. Place the plastic box between two aluminum plate electrodes. The distance between the upper and lower medium barriers during processing is 40 mm, the processing current is 1.5 A, the high-voltage discharge frequency is 145 Hz, the adjusted voltage is 30 kV, and the processing time is 40 s. The milk sample is prepared and stored at 4℃ for later use.

[0039] Step 2: Add the DBD-treated ginkgo starch in step 1 to the DBD-treated milk. Add white sugar according to the addition ratio of 1:10 of white sugar to milk. Add a composite starter according to the addition ratio of 1:500 of the composite starter to milk. The composite starter is one or a combination of Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium lactis, Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus rhamnosus. After thorough mixing, ferment the mixture at 37℃ for 8 h to obtain yogurt. Measure the gel properties and the number of probiotics in the yogurt.

[0040] Example 5: A method for preparing a high-probiotic-activity yogurt according to the present application, comprising the following steps:

[0041] Step 1: 0.7g of white ginkgo starch was weighed and laid between two aluminum plate electrodes, the distance between the upper and lower medium barriers was 40mm, the treatment current was 1.5A, the high-voltage discharge frequency was 145Hz, the adjusting voltage was 30kV, and the white ginkgo starch sample was prepared by treating for 50s and stored at 4℃ for standby.

[0042] 20mL of milk was measured and placed in a light and thin plastic box, and the plastic box was placed between two aluminum plate electrodes, the distance between the upper and lower medium barriers was 40mm, the treatment current was 1.5A, the high-voltage discharge frequency was 145Hz, the adjusting voltage was 30kV, and the milk sample was prepared by treating for 50s and stored at 4℃ for standby.

[0043] Step 2: The DBD-treated white ginkgo starch in step 1 was added to the DBD-treated milk, white sugar was added according to the addition ratio of 1:10, and composite starter was added according to the addition ratio of 1:500, and the composite starter was one or a combination of Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium lactis, Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus rhamnosus; After mixing evenly, the yogurt was prepared by fermenting at 37℃ for 8h, and the gel property and the number of probiotics of the yogurt were determined.

[0044] Example 6: A method for preparing a high-probiotic-activity yogurt according to the present application, comprising the following steps:

[0045] Step 1: 0.1g of white ginkgo starch was weighed and laid between two aluminum plate electrodes, the distance between the upper and lower medium barriers was 40mm, the treatment current was 1.5A, the high-voltage discharge frequency was 145Hz, the adjusting voltage was 30kV, and the white ginkgo starch sample was prepared by treating for 20s and stored at 4℃ for standby.

[0046] 5mL of milk was measured and placed in a light and thin plastic box, and the plastic box was placed between two aluminum plate electrodes, the distance between the upper and lower medium barriers was 40mm, the treatment current was 1.5A, the high-voltage discharge frequency was 145Hz, the adjusting voltage was 30kV, and the milk sample was prepared by treating for 20s and stored at 4℃ for standby.

[0047] Step 2: The DBD-treated white ginkgo starch in step 1 was added to the DBD-treated milk, white sugar was added according to the addition ratio of 1:10, and composite starter was added according to the addition ratio of 1:500, and the composite starter was one or a combination of Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium lactis, Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus rhamnosus; After mixing evenly, the yogurt was prepared by fermenting at 37℃ for 8h, and the gel property and the number of probiotics of the yogurt were determined.

[0048] Example 7: A method for preparing a high probiotic activity yogurt of the present application, comprising the following steps:

[0049] Step 1: 1 g of white ginkgo starch was weighed and laid between two aluminum plate electrodes, and the distance between the upper and lower medium barriers was 40 mm during treatment, the treatment current was 1.5 A, the high-voltage discharge frequency was 145 Hz, the adjusted voltage was 30 kV, and the white ginkgo starch sample was treated for 20 s and stored at 4°C for standby.

[0050] 20 mL of milk was measured and placed in a light and thin plastic box, and the plastic box was placed between two aluminum plate electrodes, and the distance between the upper and lower medium barriers was 40 mm during treatment, the treatment current was 1.5 A, the high-voltage discharge frequency was 145 Hz, the adjusted voltage was 30 kV, and the milk sample was treated for 20 s and stored at 4°C for standby.

[0051] Step 2: The white ginkgo starch treated by DBD in step 1 was added to the DBD-treated milk, white granulated sugar was added according to the addition ratio of 1:10, and composite starter was added according to the addition ratio of 1:500, and the composite starter was one or a combination of Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium lactis, Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus rhamnosus; After mixing evenly, the yogurt was fermented at 37°C for 8 h to prepare the yogurt, and the gel property and probiotic quantity indicators of the yogurt were determined.

[0052] Comparative Example 1: 0.7 g of white ginkgo starch was weighed and added to 20 mL of milk, white granulated sugar was added according to the addition ratio of 1:10, and composite starter was added according to the addition ratio of 1:500, and the composite starter was one or a combination of Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium lactis, Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus rhamnosus; After mixing evenly, the yogurt was fermented at 37°C for 8 h to prepare the yogurt, and the gel property and probiotic quantity indicators of the yogurt were determined.

[0053] Comparative Example 2: Step 1: 0.7 g of white ginkgo starch was weighed and laid between two aluminum plate electrodes, and the distance between the upper and lower medium barriers was 40 mm during treatment, the treatment current was 1.5 A, the high-voltage discharge frequency was 145 Hz, the adjusted voltage was 30 kV, and the white ginkgo starch sample was treated for 30 s and stored at 4°C for standby.

[0054] Step 2: The ginkgo starch treated by DBD in step 1 was added to 20 mL of milk, white sugar was added according to the addition ratio of white sugar to milk of 1:10, and composite starter was added according to the addition ratio of composite starter to milk of 1:500, the composite starter being one or a combination of Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium lactis, Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus rhamnosus; after being mixed uniformly, the yogurt was prepared by fermentation treatment at 37℃ for 8h, and the gel property and the number of probiotics of the yogurt were determined.

[0055] Comparative Example 3: Step 1: 20 mL of milk was measured and placed in a thin plastic box, and the plastic box was placed between two aluminum plate electrodes, the distance between the upper and lower medium barriers during treatment was 40 mm, the treatment current was 1.5 A, the high-voltage discharge frequency was 145 Hz, the voltage was adjusted to 30 kV, and the milk sample was prepared by treatment for 30 s, and stored at 4℃ for standby.

[0056] Step 2: 0.7 g of ginkgo starch was weighed and added to the DBD-treated milk, white sugar was added according to the addition ratio of white sugar to milk of 1:10, and composite starter was added according to the addition ratio of composite starter to milk of 1:500, the composite starter being one or a combination of Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium lactis, Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus rhamnosus; after being mixed uniformly, the yogurt was prepared by fermentation treatment at 37℃ for 8h, and the gel property and the number of probiotics of the yogurt were determined.

[0057] The whey separation rates of the yogurts prepared in Examples 1-5 and Comparative Examples 1-3 were detected to obtain the effects of different conditions on the whey separation rate of fermented yogurt, and the results are shown in Table 1:

[0058]

[0059] As shown in Table 1, the whey separation rates of Example 2 and Example 4 were significantly reduced by 19.34% and 44.12% respectively compared with Comparative Example 1, indicating that the ginkgo starch and milk treated by DBD for 20s and 40s can obtain more stable yogurt products, and longer or lower treatment time can significantly increase the whey separation amount of yogurt.

[0060] Figures 2-5The total number of lactic acid bacteria, the number of streptococci, the number of bifidobacteria and the number of lactobacilli in the yoghurt prepared by Comparative Examples 1-3 and Examples 1-5 are shown in the graphs. The blank group is the yoghurt prepared by fermenting the white ginkgo starch and the milk without DBD treatment; the milk treatment group is the yoghurt prepared by fermenting the milk subjected to DBD treatment for 30 s; the white ginkgo starch treatment group is the yoghurt prepared by fermenting the white ginkgo starch subjected to DBD treatment for 30 s; DBD-10 s, DBD-20 s, DBD-30 s, DBD-40 s and DBD-50 s are the yoghurt prepared by fermenting the milk and the white ginkgo starch subjected to DBD treatment for 10 s, 20 s, 30 s, 40 s and 50 s, respectively. It can be seen from the graphs that the total number of lactic acid bacteria, the number of streptococci, the number of bifidobacteria and the number of lactobacilli in the yoghurt prepared by fermenting the milk and the white ginkgo starch subjected to DBD treatment for 20 s are all high. Figures 2-5

[0061] The above is the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, can also make a number of improvements and refinements, these improvements and refinements should also be considered within the scope of the present application.​

Claims

1. A method for the preparation of a high probiotic activity yoghurt, characterized in that, Comprising the following steps: Step 1: DBD is used to treat white ginkgo starch and milk respectively, and they are stored at 4℃ for standby; The specific steps for DBD treatment of white ginkgo starch are as follows: 0.1-1g of white ginkgo starch is weighed and laid flat between two aluminum plate electrodes, the distance between the upper and lower dielectric barriers is 40mm during treatment, the treatment current is 1.5A, the high-voltage discharge frequency is 145Hz, the regulated voltage is 30kV, the white ginkgo starch sample is prepared by treating for 20s, and it is stored at 4℃ for standby; The specific steps for DBD treatment of milk are as follows: 5-20mL of milk is measured and placed in a light and thin plastic box, the plastic box is placed between two aluminum plate electrodes, the distance between the upper and lower dielectric barriers is 40mm during treatment, the treatment current is 1.5A, the high-voltage discharge frequency is 145Hz, the regulated voltage is 30kV, the milk sample is prepared by treating for 20s, and it is stored at 4℃ for standby; Step 2: The white ginkgo starch treated by DBD in step 1 is added to the milk treated by DBD, the ratio of white ginkgo starch to milk is 1:(20-50); after adding white granulated sugar and composite starter and mixing uniformly, the yogurt is prepared by fermenting at 37℃ for 8h, and the gel property of the yogurt and the number of probiotics are determined.

2. The method of preparing a high probiotic activity yoghurt according to claim 1, characterized in that, The addition ratio of white granulated sugar to milk in step 2 is 1:10; the addition ratio of composite starter to milk is 1:

500.

3. The method of preparing a high probiotic activity yoghurt according to claim 1, characterized in that, The composite starter in step 2 is one or a combination of Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium lactis, Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus rhamnosus. The composite starter in step 2 is one or a combination of Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium lactis, Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus rhamnosus.

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