High-protein high-calcium yoghourt and preparation method thereof

Abstract

The invention relates to the field of dairy products, in particular to high-protein high-calcium yoghourt and a preparation method thereof. The invention provides a preparation method of high-protein high-calcium yoghurt, which comprises the following steps: 1) performing nanofiltration concentration on skimmed milk according to a concentration ratio of 1.6-2 to obtain concentrated milk; 2) mixing the concentrated milk and the single cream to obtain a mixture; and (3) inoculating a fermentation strain YO-MIX M01 and lactase into the mixture, and fermenting to obtain the high-protein and high-calcium yoghourt. The high-protein high-calcium yoghurt with the protein content of 5.5-6.3 wt%, the calcium content of 180-220 mg / 100 g and stable acidity can be prepared by a method of combining a formula and a process under the condition of not additionally adding any protein concentrate and calcium fortifying raw materials.

Description

Technical Field

[0001] The present application relates to the field of dairy products, and in particular to a high-protein and high-calcium yogurt and a preparation method thereof. Background Art

[0002] As a nutritious food, high-protein yogurt is favored for its rich protein content. Protein is an important nutrient for maintaining human health, and is especially beneficial for fitness enthusiasts, pregnant women, and people who need additional protein. It not only helps muscle recovery and growth, but also strengthens the immune system, while providing a lasting sense of fullness, which helps with weight management.

[0003] The high-protein yogurt commonly found on the market is mainly prepared through two processes: 1. Adding concentrated whey protein, isolated whey protein, etc. during the fermentation process to increase the protein content; 2. Separating whey from the fermented yogurt by centrifugation or membrane filtration to increase the protein content.

[0004] Although high-protein yogurt has many benefits, it also has some disadvantages. First, increasing the protein content by adding protein powder (process 1) may affect the natural taste and flavor of yogurt. Secondly, high-protein yogurt prepared by whey drainage (process 2) not only loses a large amount of whey protein during the whey drainage process, but also loses a large amount of native milk calcium. The product price is relatively high, and due to its high protein content, the product tastes strong and astringent. These factors jointly affect the overall quality of high-protein yogurt and consumer acceptance. Summary of the invention

[0005] The present application aims to solve the above-mentioned technical problems and produce a high-protein and high-calcium yogurt that not only maintains the natural flavor and taste of yogurt, but also increases the protein content and calcium content, and maintains stable acidity during the 31-day shelf life.

[0006] The present application optimizes the raw materials for preparing yogurt, concentration conditions, the ratio of concentrated milk and cream, the ratio of fermentation bacteria and lactase, etc., and can prepare high-protein and high-calcium yogurt with a high protein content of 5.5-6.3wt% and a high calcium content of 180mg-220mg / 100g without adding any additional protein concentrate and calcium-fortified raw materials. The yogurt has a sweet taste and little acidity change without the need for sweetening substances.

[0007] The first aspect of the present application provides a method for preparing a high-protein and high-calcium yogurt, comprising the following steps:

[0008] 1) Concentrating the skimmed milk by nanofiltration at a concentration ratio of 1.6 to 2 times to obtain concentrated milk;

[0009] 2) mixing condensed milk and cream to obtain a mixture;

[0010] 3) inoculating fermentation bacteria YO-MIX M01 and lactase into the mixture for fermentation to obtain the high-protein and high-calcium yogurt.

[0011] The skim milk has a protein content of 3.15-4.1 wt % and a fat content of <0.4 wt %.

[0012] When the concentrated milk and the light cream are mixed, the added amount of the concentrated milk is 91-94wt%; the fat content in the light cream is 35-40wt%, and the added amount of the light cream is such that the fat content in the final product is 3.0%-3.5wt%.

[0013] The inoculation amount of the fermentation strain YO-MIX M01 was 1×10 6 ~4×10 6 CFU / mL; and / or, the added amount of the lactase is 0.2-0.3wt%.

[0014] The second aspect of the present application provides a high-protein and high-calcium yogurt, which is prepared by the preparation method of the first aspect.

[0015] The beneficial effects of this application are:

[0016] The present application uses a method combining formula and process to prepare yogurt with both high protein and high calcium content without adding any additional protein concentrate and calcium fortified raw materials, with a protein content of 5.5-6.3wt% and a calcium content of 180mg-220mg / 100g. At the same time, the present application uses a method combining the optimization of a large number of strains and lactase, so that the product has a light natural sweetness without adding any sweet substances, obtains a suitable and higher acidity in a short preparation cycle, and has a small change in acidity during the shelf life (such as 31 days), and has a better taste than conventional high-protein yogurt or Greek yogurt on the market, and has a higher consumer acceptance. DETAILED DESCRIPTION

[0017] The following describes the implementation of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application.

[0018] Before further describing the specific implementation methods of the present application, it should be understood that the scope of protection of the present application is not limited to the specific specific implementation methods described below; it should also be understood that the terms used in the examples of the present application are for describing specific specific implementation methods rather than for limiting the scope of protection of the present application; in the specification and claims of the present application, unless otherwise expressly stated herein, the singular forms "a", "an" and "the" include plural forms.

[0019] When the embodiments give numerical ranges, it should be understood that, unless otherwise specified in the present application, the two endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as those generally understood by those skilled in the art. In addition to the specific methods, equipment, and materials used in the embodiments, according to the grasp of the prior art by those skilled in the art and the record of the present application, any method, equipment, and material of the prior art similar or equivalent to the methods, equipment, and materials described in the embodiments of the present application can also be used to realize the present application.

[0020] The present application first provides a method for preparing high-protein and high-calcium yogurt, comprising the following steps:

[0021] 1) Concentrating the skimmed milk by nanofiltration at a concentration ratio of 1.6 to 2 times to obtain concentrated milk;

[0022] 2) mixing condensed milk and cream to obtain a mixture;

[0023] 3) inoculating fermentation bacteria YO-MIX M01 and lactase into the mixture for fermentation to obtain the high-protein and high-calcium yogurt.

[0024] In the present application, the high calcium refers to that the calcium content of the high-protein and high-calcium yogurt prepared in the present application is 180mg-220mg / 100g, that is, every 100g of high-protein and high-calcium yogurt contains 180mg-220mg of calcium.

[0025] In the present application, the high protein refers to the high-protein and high-calcium yogurt prepared in the present application, whose protein content is 5.5-6.3wt%, that is, based on the total weight of the high-protein and high-calcium yogurt as 100%, the weight of the protein in the high-protein and high-calcium yogurt accounts for 5.5-6.3wt% of the total weight of the high-protein and high-calcium yogurt.

[0026] In the present application, the yogurt may be flavored yogurt.

[0027] In a specific embodiment of the present application, the starting material for preparing the high-protein and high-calcium yogurt is skim milk. Through screening, the present application found that using skim milk as the starting material for high-protein and high-calcium yogurt makes the high-protein and high-calcium yogurt prepared in the present application have a higher degree of milk flavor without adding sweet substances.

[0028] The protein content of the skim milk is 3.15-4.1wt%, that is, the weight of the protein in the skim milk accounts for the percentage of the total weight of the skim milk, for example, it can be 3.15-3.2wt%, 3.2-3.3wt%, 3.3-3.4wt%, 3.4-3.5wt%, 3.5-3.6wt%, 3.6-3.7wt%, 3.7-3.8wt%, 3.8-3.9wt%, 3.9-4.0wt%, 4.0-4.1wt%.

[0029] The fat content of the skim milk is ≤0.4wt%, that is, the weight of the fat in the skim milk accounts for the percentage of the total weight of the skim milk, for example, it can be 0.01-0.4wt%, 0.01-0.05wt%, 0.05-0.1wt%, 0.1-0.15wt%, 0.15-0.2wt%, 0.2-0.25wt%, 0.25-0.3wt%, 0.3-0.35wt%, 0.35-0.4wt%.

[0030] The concentration ratio of nanofiltration concentration refers to the mass ratio of the solution before concentration to the retentate after concentration per unit time. In the specific implementation of the present application, the concentration ratio of nanofiltration concentration is 1.6 to 2 times, for example, it can be 1.6 to 1.7 times, 1.7 to 1.8 times, 1.8 to 1.9 times, 1.9 to 2 times. In the present application, the nanofiltration process is creatively used for concentration, and the concentration ratio of nanofiltration concentration is optimized. Compared with the traditional whey discharge process, the nanofiltration process used in the present application can retain the calcium in the raw materials and avoid the loss of calcium during the concentration process, thereby increasing the calcium content of the product; when the concentration ratio is too high (greater than 2 times), it will affect the smoothness, powdery and astringent taste of the product. When the concentration ratio is too low (less than 1.6 times), the protein content is low and the required high protein content cannot be achieved.

[0031] In a specific embodiment of the present application, in step 1), the concentration temperature is 40-50°C, for example, 40-41°C, 41-42°C, 42-43°C, 43-44°C, 44-45°C, 45-46°C, 46-47°C, 47-48°C, 48-49°C, 49-50°C.

[0032] In a specific embodiment of the present application, the protein content of the concentrated milk obtained after the above-mentioned nanofiltration concentration is 5.4-6.6wt%, for example, it can be 5.4-5.5wt%, 5.5-5.6wt%, 5.6-5.7wt%, 5.7-5.8wt%, 5.8-5.9wt%, 5.9-6.0wt%, 6.0-6.1wt%, 6.1-6.2wt%, 6.2-6.3wt%, 6.3-6.4wt%, 6.4-6.5wt%, 6.5-6.6wt%.

[0033] In a specific embodiment of the present application, the lactose content of the concentrated milk obtained after the above-mentioned nanofiltration concentration is 7.0-9.2wt%, for example, it can be 7.0-7.2wt%, 7.2-7.4wt%, 7.4-7.6wt%, 7.6-7.8wt%, 7.8-8.

[0034] 0wt%, 8.0~8.2wt%, 8.2~8.4wt%, 8.4~8.6wt%, 8.6~8.8wt%, 8.8~9.0wt%, 9.0~9.2wt%.

[0035] In a specific embodiment of the present application, in step 2), when the concentrated milk and the light cream are mixed, the amount of the concentrated milk added is 91-94wt%, that is, the amount of the concentrated milk added is 91-94wt% of the total weight of the mixture after mixing, for example, it can be 91-91.5wt%, 91.5-92wt%, 92-92.5wt%, 92.5-93wt%, 93-93.5wt%, 93.5-94wt%.

[0036] In a specific embodiment of the present application, in step 2), the fat content of the cream is 35-40wt%, that is, the weight of the fat in the cream accounts for 35-40wt% of the total weight of the cream, for example, it can be 35-35.5wt%, 35.5-36wt%, 36-36.5wt%, 36.5-37wt%, 37-37.5wt%, 37.5-38wt%, 38-38.5wt%, 38.5-39wt%, 39-39.5wt%, 39.5-40wt%.

[0037] In a specific embodiment of the present application, in step 2), the amount of the cream added is such that the fat content in the final product is 3.0%-3.5wt%, that is, the fat content in the prepared high-protein and high-calcium yogurt product is controlled to be 3.0%-3.5wt% by controlling the amount of the cream added. For example, the fat content in the high-protein and high-calcium yogurt product may be 3.0%-3.1wt%, 3.1%-3.2wt%, 3.2%-3.3wt%, 3.3%-3.4wt%, 3.4%-3.5wt%. Specifically, in certain embodiments of the present application, the amount of the cream added is 6-9wt%, that is, the amount of the cream added is such that the weight of the cream is 6-9wt% of the total weight of the mixed mixture, for example, it may be 6-6.5wt%, 6.5-7wt%, 7-7.5wt%, 7.5-8wt%, 8-8.5wt%, 8.5-9wt%.

[0038] In a specific embodiment of the present application, in step 2), the mixing includes mixing the concentrated milk and the cream.

[0039] In a specific embodiment of the present application, step 2) also includes homogenizing and sterilizing the mixture.

[0040] In a specific embodiment of the present application, the homogenization includes primary homogenization and secondary homogenization. The pressure of the primary homogenization is 16 to 20 MPa, for example, 16 to 16.5 MPa, 16.5 to 17 MPa, 17 to 17.5 MPa, 17.5 to 18 MPa, 18 to 18.5 MPa, 18.5 to 19 MPa, 19 to 19.5 MPa, 19.5 to 20 MPa; the pressure of the secondary homogenization is 2 to 5 MPa, for example, 2 to 2.5 MPa, 2.5 to 3 MPa, 3 to 3.5 MPa, 3.5 to 4 MPa, 4 to 4.5 MPa, 4.5 to 5 MPa.

[0041] In a specific embodiment of the present application, the homogenization temperature is 55-65°C, for example, it can be 55-56°C, 56-57°C, 57-58°C, 58-59°C, 59-60°C, 60-61°C, 61-62°C, 62-63°C, 63-64°C, 64-65°C.

[0042] In a specific embodiment of the present application, the temperature of the sterilization treatment is 90-95°C, for example, it can be 90-91°C, 91-92°C, 92-93°C, 93-94°C, 94-95°C.

[0043] In a specific embodiment of the present application, the sterilization treatment time is 5 to 7 minutes, for example, it can be 5 to 5.5 minutes, 5.5 to 6 minutes, 6 to 6.5 minutes, or 6.5 to 7 minutes.

[0044] In a specific embodiment of the present application, the fermentation strain is YO-MIX M01; through screening and optimization of a large number of strains, the present application found that the fermentation strain YO-MIX M01 can have a higher acidity than other strains (such as representative fermentation strains YO-MIXPRIME 800LYO and Quark-plus) under the same fermentation conditions (such as fermentation time), thereby being able to obtain a higher product acidity within a suitable acidity range at a shorter fermentation time.

[0045] In a specific embodiment of the present application, in step 3), the inoculation amount of the fermentation strain YO-MIX M01 is 1×10 6 ~4×10 6 CFU / mL, for example, can be 1×10 6 ~1.5×106 CFU / mL, 1.5×10 6 ~2×10 6 CFU / mL, 2×10 6 ~2.5×10 6 CFU / mL, 2.5×10 6 ~3×10 6 CFU / mL, 3×10 6 ~3.5×10 6 CFU / mL, 3.5×10 6 ~4×10 6 CFU / mL.

[0046] In a specific embodiment of the present application, in step 3), the amount of lactase added is 0.2-0.3wt%, that is, the amount of lactase added is 0.2-0.3wt% of the total weight of the total system after addition, for example, it can be 0.2-0.21wt%, 0.21-0.22wt%, 0.22-0.23wt%, 0.23-0.24wt%, 0.24-0.25wt%, 0.25-0.26wt%, 0.26-0.27wt%, 0.27-0.28wt%, 0.28-0.29wt%, 0.29-0.3wt%. If the amount of lactase added is less than 0.2%, it will lead to incomplete hydrolysis of lactose and insufficient sweetness, because the sweetness of lactose is lower than the sweetness of glucose. The present application hydrolyzes lactose into one molecule of glucose and one molecule of galactose through lactase, which can effectively improve the sweetness of the yogurt base, thereby improving the taste. Adding lactase in an amount exceeding 0.3% results in waste and increases production costs.

[0047] In a specific embodiment of the present application, in step 3), the fermentation temperature is 40-44°C, for example, 40-41°C, 41-42°C, 42-43°C, 43-44°C.

[0048] In a specific embodiment of the present application, in step 3), the end point of the fermentation is pH 4.4-4.6, which means that the pH in the fermentation system is measured after fermentation, and the fermentation product is harvested when the pH reaches 4.4-4.6, for example, it can be 4.4-4.5, 4.5-4.6.

[0049] In a specific embodiment of the present application, step 3) further includes subjecting the fermentation product obtained by the fermentation to demulsification, cooling, and post-ripening treatment to obtain the high-protein and high-calcium yogurt.

[0050] Demulsification refers to the process in which small droplets of dispersed phase of the emulsion aggregate into large droplets, and finally separate the oil-water phases. The present application does not limit the demulsification method, for example, it can be cooling demulsification, stirring demulsification, homogenization demulsification, automatic demulsification device, chemical demulsification method, physical demulsification method, biological demulsifier method, membrane demulsification method.

[0051] In a specific embodiment of the present application, the demulsification is carried out by stirring, and the stirring time is 2 to 3 minutes, for example, 2 to 2.2 minutes, 2.2 to 2.4 minutes, 2.4 to 2.6 minutes, 2.6 to 2.8 minutes, 2.8 to 3.0 minutes; the stirring speed is 20 to 30 r / min, for example, 20 to 22 r / min, 22 to 24 r / min, 24 to 26 r / min, 26 to 28 r / min, 28 to 30 r / min.

[0052] In a specific embodiment of the present application, the cooling is cooling to 2-8°C, for example, 2-3°C, 3-4°C, 4-5°C, 5-6°C, 6-7°C, 7-8°C.

[0053] The post-ripening treatment refers to the process of cooling and leaving the yogurt for a period of time after the yogurt fermentation is completed to further improve its taste, flavor and stability.

[0054] In a specific embodiment of the present application, the temperature of the post-ripening treatment is 2 to 8°C, for example, 2 to 3°C, 3 to 4°C, 4 to 5°C, 5 to 6°C, 6 to 7°C, 7 to 8°C; the time of the post-ripening treatment is 10 to 24h, for example, 10 to 12h, 12 to 14h, 14 to 16h, 16 to 18h, 18 to 20h, 20 to 22h, 22 to 24h.

[0055] The present application also provides a high-protein and high-calcium yogurt, which is prepared by the above-mentioned preparation method.

[0056] The high-protein and high-calcium yogurt has a protein content of 5.5-6.3 wt %, a calcium content of 180 mg-220 mg / 100 g, a small change in acidity during the shelf life (such as 31 days), and stable quality.

[0057] The present application is further described below by specific examples. When the examples give numerical ranges, it should be understood that, unless otherwise specified in the present application, the two endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as those generally understood by those skilled in the art. In addition to the specific methods, equipment, and materials used in the examples, according to the technical personnel in the art's grasp of the prior art and the records of the present application, any methods, equipment, and materials of the prior art similar or equivalent to the methods, equipment, and materials described in the examples of the present application can also be used to implement the present application. Unless otherwise specified, the instruments, reagents, and materials used in the examples can be obtained by conventional means, such as commercially available.

[0058] The sources of raw materials used in the examples are:

[0059] Raw milk: Bright Dairy Co., Ltd.

[0060] Lactic acid bacteria YO-MIX M01: Danisco (China) Co., Ltd.

[0061] Lactase: Chr. Hansen

[0062] Example 1

[0063] This embodiment provides a high-protein and high-calcium yogurt, and the preparation method is as follows:

[0064] (1) Preparation of fermentation product: skim milk (protein content 3.28wt%, fat content 0.4wt%) was concentrated by nanofiltration at a concentration ratio of 1.8 times at 40°C to obtain concentrated milk, in which the lactose content was 8.5wt% and the protein content was 5.4%. 93.3% concentrated milk and 6.7% (fat content 35%) cream were fully mixed. After homogenization and sterilization, the starter YO-MIX M01 was inoculated at an inoculum size of 1×10 6 CFU / mL and 0.2wt% lactase were fermented until the pH value of the fermentation end point was 4.4 to obtain a fermentation product.

[0065] The homogenization temperature is 60°C, the first-stage homogenization pressure is 20MPa, and the second-stage homogenization pressure is 5MPa. The sterilization temperature is 90°C for 7 minutes. The fermentation conditions are 40°C.

[0066] (2) The fermentation product is subjected to demulsification, cooling, and post-ripening to obtain the high-protein and high-calcium yogurt.

[0067] Among them, the demulsification conditions are: stirring for 3 minutes, the stirring speed is 25r / min. The cooling temperature is 5°C. The ripening conditions are: refrigerated ripening in a 5°C environment for 24 hours.

[0068] The prepared high-protein and high-calcium yogurt has a protein content of 5.5% and a fat content of 3.0%.

[0069] Example 2

[0070] This embodiment provides a high-protein and high-calcium yogurt, and the preparation method is as follows:

[0071] (1) Preparation of fermentation product: skim milk (protein content 3.15wt%, fat content 0.2wt%) was concentrated by nanofiltration at a concentration ratio of 2 times at 50°C to obtain concentrated milk, in which the lactose content was 9.2wt% and the protein content was 6.3%. 91.73% concentrated milk and 8.3% (fat content 40%) cream were fully mixed. Then, after homogenization and sterilization, the starter YO-MIX M01 was inoculated at an inoculum size of 4×10 6 CFU / mL and 0.3 wt% lactase were fermented until the pH value at the fermentation end point was 4.6 to obtain a fermentation product.

[0072] The homogenization temperature is 62°C, the first-stage homogenization pressure is 18MPa, and the second-stage homogenization pressure is 3MPa. The sterilization temperature is 92°C for 6 minutes. The fermentation conditions are 42°C.

[0073] (2) The fermentation product is subjected to demulsification, cooling, and post-ripening to obtain the high-protein and high-calcium yogurt.

[0074] Among them, the demulsification conditions are: stirring for 2.5 minutes, the stirring speed is 25r / min. The cooling temperature is 6°C. The ripening conditions are: refrigerated ripening in a 6°C environment for 16 hours.

[0075] The prepared high-protein and high-calcium yogurt has a protein content of 5.7% and a fat content of 3.5%.

[0076] Example 3

[0077] This embodiment provides a high-protein and high-calcium yogurt, and the preparation method is as follows:

[0078] (1) Preparation of fermentation product: skim milk (protein content 4.1wt%, fat content 0.1wt%) was concentrated by nanofiltration at a concentration ratio of 1.6 times at 45°C to obtain concentrated milk, in which the lactose content was 7.0wt% and the protein content was 6.6%. 92% concentrated milk and 8.0% (fat content 38%) cream were fully mixed. After homogenization and sterilization, the starter YO-MIX M01 was inoculated at an inoculum size of 2×10 6 CFU / mL and 0.25 wt% lactase were fermented until the pH value of the fermentation end point was 4.5 to obtain a fermentation product.

[0079] The homogenization temperature is 65°C, the first-stage homogenization pressure is 16MPa, and the second-stage homogenization pressure is 2MPa. The sterilization temperature is 95°C for 5 minutes. The fermentation conditions are 44°C.

[0080] (2) The fermentation product is subjected to demulsification, cooling, and post-ripening to obtain the high-protein and high-calcium yogurt.

[0081] Among them, the demulsification conditions are: stirring for 2 minutes, the stirring speed is 30r / min. The cooling temperature is 2°C. The ripening conditions are: refrigerated ripening in a 2°C environment for 10 hours.

[0082] The prepared high-protein and high-calcium yogurt has a protein content of 6.0% and a fat content of 3.1%.

[0083] Comparative Example 1

[0084] This comparative example is a comparative example of Example 3, except that the skim milk is changed into whole milk, and the fat in the final product is supplemented with cream.

[0085] Comparative Example 2

[0086] This comparative example is a comparative example of Example 3, except that the strain is replaced with the representative strain YO-MIXPRIME 800LYO (Danisco).

[0087] Comparative Example 3

[0088] This comparative example is a comparative example of Example 3, except that the bacterial species is replaced with the representative bacterial species Quark-plus (Chr. Hansen).

[0089] Comparative Example 4

[0090] It is the commercially available Yoplait Icelandic-style high-protein yogurt, and the concentration is concentrated using a whey removal process.

[0091] Comparative Example 5

[0092] This comparative example is the comparative example of Example 3, except that the concentration ratio is 2.2 times, so that the lactose content of the concentrated milk is 10.12% and the protein content is 9%.

[0093] Example 6 Taste Test

[0094] The high-protein and high-calcium yogurts prepared in Examples 1 to 3 and Comparative Examples 1 to 5 were subjected to taste tests, and the products of the examples were subjected to tasting tests. The number of testers was 38, of which 38 were effective tests. Tasting method: Tasting was conducted in an anonymous scoring manner; the smoothness, powdery astringency, milky aroma, etc. of the samples of the examples were scored separately, and the full score for each item was 20 points. The total score was calculated and the average score was calculated; the higher the average score, the better the effect. The statistical results are recorded in Table 1.

[0095] Table 1 Example product tasting results data table

[0096] index Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Milky 18 19 18.5 14.5 18.3 15.5 14 18.2 sour 18 17.8 18.3 17.8 16.3 16.4 10 18 Sweetness 17.8 18.9 17.5 17.3 16.5 16.3 12 17 Smoothness 19 18.5 18.7 18.5 17.2 16.2 13 14 Pinky feeling 18 18.3 17.8 17.5 17.1 15.2 12 15

[0097] The calcium content of Example 3 and Comparative Example 4 was tested respectively, and the calcium content of Example 3 was 180 mg / 100 g, and the calcium content of Comparative Example 4 was 100 mg / 100 g. Since Comparative Example 4 used a whey removal process, calcium would be lost with the whey in the whey removal process, and the present application used a nanofiltration process, and calcium could be retained in the retentate, so the high-protein and high-calcium yogurt prepared by the process of the present application had a higher calcium content than the yogurt of the comparative example.

[0098] It can be seen from Comparative Example 1 that when the raw skim milk used in this application is changed to whole milk and then cream is added to the final product, the milk flavor of the prepared product will be greatly reduced. It can be seen from Comparative Examples 2 and 3 that when the fermentation strain YO-MIX M01 in this application is changed to other strains such as YO-MIXPRIME 800LYO and Quark-plus, the acidity of the product is significantly reduced under the same fermentation conditions. Only by using the fermentation strain YO-MIX M01 of this application can a suitable and higher product acidity be achieved in a shorter process cycle. It can be seen from Comparative Example 5 that only under the nanofiltration concentration ratio of this application can the product have the best smoothness and powdery astringency. When the conditions are higher than those of this application, the taste of the product will be seriously affected.

[0099] Example 7 Acidity Detection

[0100] In this example, the acidity of the high-protein and high-calcium yogurt prepared in Examples 1 to 3 and Comparative Examples 2 and 3 was tested.

[0101] The acidity detection method refers to the third method of GB 5009.239-2016.

[0102] The acidity test results are shown in Table 2 below.

[0103] Table 2 Acidity changes of the products of the examples

[0104] sample Day 2 Acidity Acidity on Day 7 Day 14 Acidity Day 21 Acidity Example 1 125 128 132 135 Example 2 120 128 135 140 Example 3 130 135 138 142 Comparative Example 2 131 138 140 149 Comparative Example 3 125 140 145 153

[0105] As can be seen from Table 2, the acidity of the products prepared in Examples 1 to 3 remained basically stable within 21 days, and the acidity change was less than that of the products prepared in Comparative Examples 2 and 3, indicating that the acidity of the expected product changed little within the 31-day shelf life and the quality of the product could be maintained.

[0106] In summary, only by combining the preparation conditions of the present application can a yogurt with both high protein and high calcium content be obtained, with a protein content of 5.5-6.3wt%, a calcium content of 180mg-220mg / 100g, a suitable and higher acidity in a shorter preparation cycle, an optimal taste with a combination of milk flavor, acidity, sweetness, smoothness, and powdery astringency, and a high-protein, high-calcium yogurt with little acidity change and stable quality during the shelf life.

[0107] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall still be covered by the claims of the present application.

Claims

1. A method for preparing high-protein and high-calcium yogurt, comprising the following steps: 1) Concentrating the skimmed milk by nanofiltration at a concentration ratio of 1.6 to 2 times to obtain concentrated milk; 2) mixing condensed milk and cream to obtain a mixture; 3) inoculating fermentation bacteria YO-MIX M01 and lactase into the mixture for fermentation to obtain the high-protein and high-calcium yogurt.

2. The preparation method according to claim 1, characterized in that: In step 1), the skim milk has a protein content of 3.15-4.1 wt% and a fat content of ≤0.4 wt%; And / or, the temperature of the nanofiltration concentration is 40-50°C.

3. The preparation method according to claim 1, characterized in that: In step 2), when the concentrated milk and the cream are mixed, the amount of the concentrated milk added is 91-94 wt %; And / or, the fat content of the cream is 35-40wt%, and the amount of the cream added is such that the fat content of the final product is 3.0%-3.5wt%; Preferably, the added amount of the cream is 6-9wt%.

4. The preparation method according to claim 1, characterized in that: In step 3), the inoculation amount of the fermentation strain YO-MIX M01 is 1×10 6 ~4×10 6 CFU / mL; and / or, the added amount of the lactase is 0.2-0.3wt%.

5. The preparation method according to claim 1, characterized in that: In step 3), the fermentation temperature is 40-44°C; And / or, the end point of the fermentation is pH 4.4-4.

6.

6. The method according to claim 1, characterized in that Step 2) also includes homogenizing and sterilizing the mixture.

7. The preparation method according to claim 6, characterized in that: The homogenization includes primary homogenization and secondary homogenization, and the temperature of the homogenization is 55-65° C.; preferably, the pressure of the primary homogenization is 16-20 MPa, and the pressure of the secondary homogenization is 2-5 MPa. And / or, the sterilization treatment conditions are: the sterilization treatment temperature is 90-95° C., and the sterilization treatment time is 5-7 minutes.

8. The preparation method according to claim 1, characterized in that: Step 3) further comprises subjecting the fermentation product obtained by the fermentation to demulsification, cooling, and post-ripening treatment to obtain the high-protein and high-calcium yogurt.

9. The preparation method according to claim 8, characterized in that: The demulsification is carried out by stirring; preferably, the stirring time is 2 to 3 minutes, and the stirring speed is 20 to 30 r / min; And / or, the cooling is cooling to 2-8°C; And / or, the conditions of the post-ripening treatment are: the temperature of the post-ripening treatment is 2 to 8° C., and the time of the post-ripening treatment is 10 to 24 hours.

10. A high-protein and high-calcium yogurt prepared by the preparation method according to any one of claims 1 to 9.