Bean curd yoghourt and preparation method thereof

Abstract

The invention provides bean curd yoghourt and a preparation method thereof. The hardness of the bean curd yoghourt is 127.10-196.33 g, and the viable count of the bean curd yoghourt is not less than 4.33 * 10 < 6 > CFU / mL. The bean curd yoghurt is rich in nutrition and balanced in nutrient variety, especially has relatively high viable count, and is beneficial to intestinal flora balance of a body; meanwhile, the bean curd yoghourt is moderate in hardness, uniform in texture, neat in tissue form and smooth, fine and mellow in taste.

Description

Technical Field

[0001] The invention relates to a bean curd yogurt, in particular to a bean curd yogurt and a preparation method thereof, belonging to the field of food. Background Art

[0002] Plant milk is gradually being integrated into mainstream products, especially products made from soybeans, which have attracted more and more attention from consumers. Soybeans contain a large amount of high-quality protein and the eight essential amino acids needed by the human body, making them one of the best sources of amino acids for humans. In addition, the bioactive ingredients contained in soybeans, such as oligosaccharides, unsaturated fatty acids, isoflavones, saponins, and sterols, play an important role in maintaining the normal functioning of the body, promoting intestinal health, and preventing chronic inflammation. Soybeans have a long history of cultivation. Due to their unique flavor and high nutritional value, they are often processed into different types of soy products. Tofu is one of the popular traditional foods.

[0003] The traditional tofu production process is to first make soybeans into soy milk, then heat the soy milk at high temperature, and the hot soy milk solidifies into a gel containing a large amount of water under the action of coagulants such as gypsum and brine, that is, tofu. However, traditional tofu has the disadvantages of poor water retention, rough taste, strong bean smell, lack of soybean flavor and cannot be stored for too long.

[0004] In recent years, with the improvement of people's living standards and health awareness, from a nutritional perspective, consumers have an increasing demand for foods with multiple nutritional and health attributes. For example, tofu yogurt is rich in animal protein and plant protein, which can reasonably balance the amino acid ratio and dietary structure and provide consumers with comprehensive nutrition. At present, although tofu yogurt made by traditional technology is rich in nutrition, it has low hardness, poor texture and chaotic organizational morphology. Summary of the invention

[0005] The invention provides a tofu yogurt, which has moderate hardness, uniform texture, neat tissue morphology, smooth, delicate and mellow taste, and high live bacteria count, and is beneficial to the balance of intestinal flora of the body.

[0006] The invention also provides a method for preparing tofu yogurt. The tofu yogurt obtained by the preparation method has moderate hardness, uniform texture, neat organizational morphology, smooth, delicate and mellow taste and high viable bacteria count.

[0007] The invention provides a tofu yogurt, wherein the tofu yogurt has a hardness of 127.10 g to 196.33 g and a viable bacterial count of not less than 4.33×10 6 CFU / mL.

[0008] The tofu yogurt as described above, wherein the whey precipitation rate of the tofu yogurt is 0.200-0.321.

[0009] The tofu yogurt as described above, wherein the raw materials of the tofu yogurt include, by weight percentage, 85%-90% raw milk, 5%-10% sweetener, 2%-5% bean source, 0.4%-0.8% salt coagulant, and 0.001%-0.005% fermentation bacteria;

[0010] Among them, the number of viable bacteria in the fermentation strain is (1-5)×10 6 CFU / g.

[0011] The tofu yogurt as described above, wherein the salt coagulant is a calcium salt.

[0012] The tofu yogurt as described above, wherein the calcium salt is calcium lactate.

[0013] The tofu yogurt as described above, wherein the tofu yogurt is prepared by a method comprising at least the following processes:

[0014] After adding salt coagulant and fermentation bacteria to the raw material system including bean source, sweetener and raw milk, fermentation treatment is carried out until the fermentation acidity reaches a certain level to obtain the tofu yogurt.

[0015] The present invention also provides a method for preparing the tofu yogurt described in any one of the above items, comprising the following steps:

[0016] 1) adding a first raw material including a bean source and a sweetening substance into raw milk to obtain a first material;

[0017] 2) adding a salt coagulant and a fermentation bacteria into the first material to obtain a second material;

[0018] 3) fermenting the second material, and terminating the fermentation when the fermentation acidity reaches 70°T to obtain the tofu yogurt.

[0019] In the preparation method as described above, in step 2), the salt coagulant is in a solution state.

[0020] The preparation method as described above, wherein, in step 2), the salt coagulant and the fermentation bacteria are sequentially added into the first material;

[0021] Wherein, the interval time between sequentially adding the salt coagulant and the fermentation bacteria is no longer than 2 minutes.

[0022] In the preparation method as described above, in step 2), the salt coagulant and the fermentation bacteria are added into the first material at the same time.

[0023] The tofu yogurt of the present invention is not only rich in nutrition and balanced in nutrient types, but can provide sufficient and comprehensive nutrition for the body, especially has a high number of viable bacteria, which is beneficial to the balance of the body's intestinal flora, and the tofu yogurt has moderate hardness, uniform texture, neat tissue morphology, smooth and delicate taste. Therefore, the tofu yogurt of the present invention not only enriches the diversity of fermented dairy products, but also can become the preferred fermented product of more consumers. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The first aspect of the present invention provides a tofu yogurt, wherein the hardness of the tofu yogurt is 127.10g-196.33g, and the number of viable bacteria is not less than 4.33×10 6 CFU / mL.

[0026] The tofu yogurt of the present invention comprises bean components and milk components, is rich in animal protein and plant protein, is nutritious and has balanced nutrient types. The tofu yogurt has a stable hardness of 127.10g-196.33g during the shelf life (i.e., the shelf life), has moderate hardness, appropriate water content, uniform texture, neat organizational morphology, and a smooth, delicate and mellow taste.

[0027] The viable bacteria count of the tofu yogurt of the present invention is not less than 4.33×10 6 CFU / mL can not only regulate the balance of intestinal flora and maintain human health, but also enhance human immunity, promote intestinal peristalsis, help digestion, and promote the absorption of minerals, especially calcium.

[0028] The whey precipitation rate of the tofu yogurt is 0.200-0.321.

[0029] The whey precipitation rate indicates the degree of whey precipitation of tofu yogurt during the preparation and storage process, and characterizes the stability of the product. Among them, less whey precipitation proves that the product has high water retention and good stability, and more whey precipitation proves that the product has low water retention and poor stability. In a specific embodiment, the whey precipitation rate of the tofu yogurt of the present invention is maintained at 0.200-0.321 during the shelf life, which indicates that the tofu yogurt of the present invention has good water retention, and thus the hardness, texture and product state can remain stable, ultimately giving the product higher stability.

[0030] In a specific embodiment, the tofu yogurt raw materials include, by mass percentage, 85%-90% raw milk, 5%-10% sweetener, 2%-5% bean source, 0.4%-0.8% salt coagulant, and 0.001%-0.005% fermentation bacteria; wherein the number of viable bacteria of the fermentation bacteria is (1-5)×10 6 CFU / g.

[0031] The raw milk is the source of animal protein in the tofu yogurt of the present invention, contains a full range of essential amino acids for the human body, has high nutritional value, and is easy to digest, absorb and utilize. The present invention does not limit the type of raw milk, for example, it can be raw cow's milk, raw goat's milk, pure cow's milk, pure goat's milk, whole milk powder reconstituted milk, whole goat's milk powder reconstituted milk, skim milk powder reconstituted milk, skim goat's milk powder reconstituted milk, etc.

[0032] The bean source is the source of the vegetable protein in the tofu yogurt of the present invention, contains rich dietary fiber, can help improve the digestive function of the gastrointestinal tract, and also has antioxidant components, can delay aging, and does not contain cholesterol, which is healthier. The present invention does not limit the type of bean source, for example, it can be instant bean powder, soybean powder, etc.

[0033] Sweeteners can provide sweetness for the tofu yogurt of the present invention, and are also carbon sources that can be used by fermented bacteria, promoting the fermented bacteria to produce nutrients such as extracellular polysaccharides, enriching the nutrition in the tofu yogurt, and are closely related to the normal fermentation of the fermented bacteria and the tofu yogurt reaching the expected tissue state. The present invention does not limit the type of sweeteners, for example, at least one of white sugar, glucose, fructose syrup, xylitol, erythritol, maltitol, sucralose, steviol glycosides, and mogrosides can be selected.

[0034] Salt coagulants can coagulate and shrink proteins, thereby causing a coagulation reaction, and are a type of coagulant commonly used in preparing tofu. When using salt coagulants to make tofu, the protein coagulates quickly and the protein structure easily shrinks. It is generally used to make old tofu and dried tofu. The present invention does not limit the type of salt coagulant, for example, at least one of bittern, gypsum, calcium carbonate, calcium lactate, calcium citrate, and calcium sulfate can be selected.

[0035] Fermented bacteria can hydrolyze the raw materials of milk, soy sources and sweet substances into small molecules (such as galactose and lactic acid, small peptide chains and amino acids, etc.), making it easier for the human body to digest and absorb, thereby improving the utilization rate of various nutrients. At the same time, after fermentation, the extracellular polysaccharides, fatty acids, vitamins such as VB1, VB2, VB6, VB12, etc. in the product will increase, increasing the variety of nutrients, providing rich and comprehensive nutrition for the human body, and improving the viscosity of the product. In addition, fermented bacteria can also produce a large amount of enzymes and acids, which will also affect the coagulation and contraction of proteins in the raw materials.

[0036] The above-mentioned various components in the raw materials of tofu yogurt influence each other and work synergistically. When the raw material contains too much bean source and too little raw milk, the product has a strong bean smell, weak milk flavor, and poor flavor; when the bean source content is too little and the raw milk content is too much, the bean flavor is weak, the milk flavor is strong, and the flavor is poor. In addition, the content of bean source and raw milk will also affect the role of salt coagulants and fermentation bacteria. Similarly, the amount of sweeteners will not only affect the sweetness of the product, but also affect the vitality of the fermentation bacteria, and then have a certain impact on the utilization of bean sources, raw milk, and the role of salt coagulants. Both salt coagulants and fermentation bacteria have the function of coagulating proteins. If the proportion of salt coagulants is too high, it will not only affect the vitality of the fermentation bacteria, affect the utilization of bean sources, raw milk, and sweeteners, but also cause the protein in the raw materials to flocculate quickly, resulting in the inability to carry out the fermentation process. If the proportion of salt coagulants is too low, the protein in the raw materials will not be coagulated.

[0037] The invention finds that when the raw materials of tofu yogurt include 85%-90% raw milk, 5%-10% sweetener, 2%-5% bean source, 0.4%-0.8% salt coagulant, and 0.001%-0.005% fermentation bacteria according to the mass percentage; wherein the number of live bacteria of the fermentation bacteria is (1-5)×10 6 CFU / g, the prepared tofu yogurt is rich in nutrition and the number of viable bacteria is not less than 4.33×10 6 CFU / mL, in a solid state, with uniform color, milky white or light yellow, moderate sourness and sweetness, prominent bean and milk flavor, weak bean smell, and harmonious odor.

[0038] Furthermore, the mass percentage of the bean source in the raw material is 3.5%-4%. At this time, the prepared tofu yogurt has a more prominent bean flavor, a weak bean smell, and a harmonious odor.

[0039] It is understandable that the above-mentioned fermented bacteria can use the commonly used bacteria in the art for preparing yogurt, for example, at least one of thermophilic Streptococcus, Lactobacillus casei, Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus delbrueckii subspecies bulgaricus, Lactobacillus rhamnosus, Lactobacillus helveticus, Lactobacillus paracasei, Lactobacillus salivarius, Lactobacillus gestatus, Lactobacillus fermentum, Lactobacillus reuteri, Bifidobacterium longum, Bifidobacterium lactis, Bifidobacterium animalis, Bifidobacterium infantis, Bifidobacterium breve, Bifidobacterium adolescentis, and Bifidobacterium bifidum can be selected.

[0040] In one embodiment, the fermentation bacteria are Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus.

[0041] The salt coagulant is a calcium salt, for example, at least one of calcium lactate, calcium carbonate, and calcium citrate. The addition of calcium salt can not only increase the calcium content of the tofu yogurt of the present invention, but also improve the water holding capacity of the product. At the same time, the calcium salt also has the effect of reducing the beany smell.

[0042] In a specific embodiment, the calcium salt is calcium lactate. The tofu yogurt prepared using calcium lactate has a high calcium content, suitable water holding capacity, prominent bean and milk flavors, weak bean smell, and harmonious odor.

[0043] The present invention does not limit the preparation method of the tofu yogurt having the above hardness and viable bacteria count. For example, the tofu yogurt is prepared by a method comprising the following steps:

[0044] After adding salt coagulants and fermentation bacteria to the raw material system including bean sources, sweeteners and raw milk, fermentation treatment is carried out until the fermentation acidity reaches a certain level to obtain the above-mentioned tofu yogurt.

[0045] The salt coagulant and the fermentation bacteria can be added to the raw material system separately or simultaneously. When added separately, the present invention does not limit the order of the two, but the time interval between the two additions should be controlled to be no longer than 2 minutes; when added simultaneously, it means that the two are added to the raw material system separately without mixing.

[0046] In the above preparation process, the salt coagulant and the fermentation bacteria are added into the raw material system at the same time and stirred. At this time, the salt coagulant and the fermentation bacteria will be evenly dispersed in the raw material system, and complete and thorough coagulation reaction and fermentation reaction will occur simultaneously. The tofu yogurt finally prepared has moderate hardness, uniform texture, neat organizational morphology, smooth, delicate and mellow taste, and low whey precipitation rate.

[0047] The present invention also provides a method for preparing any of the above-mentioned tofu yogurt, comprising:

[0048] 1) adding a first raw material including a bean source and a sweetening substance into raw milk to obtain a first material;

[0049] 2) adding a salt coagulant and a fermentation bacteria into the first material to obtain a second material;

[0050] 3) fermenting the second material, and terminating the fermentation when the fermentation acidity reaches 70°T to obtain the tofu yogurt.

[0051] The present invention does not limit the reaction site of the above step 1), and it can be, for example, a batching tank or a chemical tank.

[0052] It is understandable that in the above step 1), after adding the first raw material including bean source and sweetener into the raw milk, the mixture should be stirred evenly to make the first raw material including bean source and sweetener evenly dispersed in the raw milk to obtain the first material.

[0053] The existing method for preparing tofu yogurt is to first add fermentation strains to the raw materials for fermentation, and when the fermentation is completed, the fermented product has the characteristics of uniform texture and neat tissue morphology. Subsequently, a salt coagulant is added to the fermented product and stirred continuously to make the salt coagulant evenly dispersed in the raw materials, thereby ensuring that the coagulation reaction occurs thoroughly, and then obtaining tofu yogurt with uniform coagulation. However, stirring will destroy the uniform texture and neat tissue morphology of the fermented product, resulting in low hardness, poor texture, and chaotic tissue morphology of the prepared tofu yogurt. In the above step 2) of the preparation method of the present invention, the salt coagulant and the fermentation strain are added to the first material at the same time and stirred. At this time, the salt coagulant and the fermentation strain will be evenly dispersed in the first material, and a complete and thorough coagulation reaction and fermentation reaction will occur simultaneously. The tofu yogurt finally prepared has moderate hardness, uniform texture, neat tissue morphology, smooth and delicate taste, and low whey precipitation rate.

[0054] The fermentation process of the present invention takes the fermentation end point when the fermentation acidity reaches 70°T, and the tofu yogurt of the present invention can be prepared after the fermentation ends.

[0055] Since the fermentation bacteria need to maintain good growth, reproduction and fermentation speed at the optimal temperature, the present invention does not limit the fermentation temperature, and the optimal fermentation temperature can be determined according to the characteristics of the fermentation bacteria. For example, in one embodiment, the fermentation bacteria are thermophilic Streptococcus and Lactobacillus delbrueckii subspecies bulgaricus, and the fermentation temperature is set to 41-44°C.

[0056] The tofu yogurt prepared by the preparation method has moderate hardness, uniform texture, neat organizational morphology, smooth and delicate taste, low whey precipitation rate and good stability.

[0057] In order to keep the first material in a uniform and stable liquid phase, the first material needs to be homogenized. The present invention does not limit the homogenization conditions, for example, the homogenization temperature is 50°C-60°C, the first homogenization pressure is 177-182 bar, and the second homogenization pressure is 38-42 bar.

[0058] It is understandable that the first material needs to be sterilized. The present invention does not limit the sterilization method and conditions. For example, the sterilization method can be high-temperature sterilization, the sterilization temperature is 90°C-125°C, and the sterilization time is 1min-10min. When the bean source is a raw bean source, the above sterilization should be high-temperature sterilization, which can play a sterilization role on the one hand, and can ripen the raw bean source on the other hand, so as to facilitate the subsequent coagulation.

[0059] Because the temperature of the first material after high temperature sterilization is too high, which is not conducive to the survival of the fermentation bacteria, the first material needs to be cooled before step 2) to reduce the temperature of the first material. The present invention does not limit the cooling method and cooling temperature, but the temperature of the first material after cooling should be conducive to the growth and reproduction of the fermentation bacteria. Therefore, the appropriate cooling temperature can be determined according to the type of fermentation bacteria. For example, the cooling method is natural cooling. When the fermentation bacteria are thermophilic Streptococcus and Lactobacillus delbrueckii subspecies bulgaricus, the cooling temperature is 40°C-45°C.

[0060] In order to accelerate the dispersion of the salt coagulant, ensure uniform curdling, and thus improve the quality of the final product, the present invention adds the salt coagulant in solution to the first material to make it evenly dispersed, which is beneficial to the normal coagulation and fermentation and ensures the quality of the final product.

[0061] The above-mentioned solution state refers to an aqueous solution of a salt coagulant. In the preparation process of tofu yogurt, the amount of the aqueous solution of the salt coagulant is determined according to the amount of the salt coagulant added. In one embodiment, the salt coagulant is calcium lactate, and 20 g of calcium lactate is weighed and completely dissolved in 100 mL of distilled water to prepare a calcium lactate aqueous solution with a mass concentration of 20%.

[0062] It is understandable that in order to avoid contamination by miscellaneous bacteria, the solution state of the above-mentioned salt coagulant should be sterilized.

[0063] In one embodiment, a salt coagulant and a fermentation bacteria are sequentially added to the first material;

[0064] Among them, the interval time between adding salt coagulant and fermentation bacteria shall not be longer than 2 minutes.

[0065] The present invention does not restrict the order of adding the salt coagulant and the fermentation bacteria, but in order to ensure that the coagulation reaction and the fermentation reaction are carried out simultaneously, the present invention controls the interval time of adding the two to be no longer than 2 minutes. Such operation can not only avoid the possible contamination of miscellaneous bacteria caused by adding the two in sequence, but also make the prepared tofu yogurt have moderate hardness, maintain uniform texture and neat organizational morphology, and have a delicate and mellow taste.

[0066] In one embodiment, the salt coagulant and the fermentation bacteria are added to the first material at the same time. In order to prevent the salt coagulant from affecting the activity of the fermentation bacteria, the two are added separately and simultaneously, and cannot be mixed together.

[0067] Hereinafter, the tofu yogurt and the preparation method of the tofu yogurt of the present invention will be described in more detail through specific examples.

[0068] The specific sources of some raw materials in the following preparation process are:

[0069] Instant soybean powder (food grade): Heilongjiang Bingquan Industrial Co., Ltd.

[0070] Calcium lactate (food grade): Puhui Ruixin Nutrition Technology Co., Ltd.;

[0071] Calcium carbonate (food grade): Puhui Ruixin Nutrition Technology Co., Ltd.;

[0072] Calcium citrate (food grade): Nantong Licheng Bioengineering Co., Ltd.;

[0073] The fermentation bacteria are Streptococcus thermophilus and Lactobacillus delbrueckii subspecies bulgaricus, among which the mass ratio of Streptococcus thermophilus and Lactobacillus delbrueckii subspecies bulgaricus in the fermentation bacteria is 1:2:Danisco (China) Co., Ltd.

[0074] Example 1

[0075] A tofu yogurt of the present embodiment includes the following raw materials (the total amount of raw materials is calculated based on 1000g):

[0076] Raw milk 895.99g, white sugar 80g, instant soy powder 20g, calcium lactate 4g, fermentation bacteria 0.01g;

[0077] The method for preparing the tofu yogurt comprises the following steps:

[0078] 1) adding a first raw material including instant bean powder and white sugar into raw milk, stirring evenly, homogenizing and sterilizing to obtain a first material;

[0079] 2) lowering the temperature of the first material to 40° C.-45° C., then sequentially adding calcium lactate and fermentation bacteria into the first material at intervals of no longer than 2 minutes, stirring evenly, to obtain a second material;

[0080] 3) fermenting the second material at 41-44°C, and terminating the fermentation when the fermentation acidity reaches 70°T to obtain the tofu yogurt.

[0081] Example 2

[0082] A tofu yogurt of the present embodiment includes the following raw materials (the total amount of raw materials is calculated based on 1000g):

[0083] Raw milk 877.48g, white sugar 80g, instant soy powder 38.5g, calcium lactate 4g, fermentation bacteria 0.02g;

[0084] The preparation method of the tofu yogurt is the same as that of Example 1.

[0085] Example 3

[0086] A tofu yogurt of the present embodiment includes the following raw materials (the total amount of raw materials is calculated based on 1000g):

[0087] Raw milk 875.48g, white sugar 80g, instant soy powder 38.5g, calcium lactate 6g, fermentation bacteria 0.02g;

[0088] The preparation method of the tofu yogurt is the same as that of Example 1.

[0089] Example 4

[0090] A tofu yogurt of the present embodiment includes the following raw materials (the total amount of raw materials is calculated based on 1000g):

[0091] Raw milk 873.48g, white sugar 80g, instant soy powder 38.5g, calcium lactate 8g, fermentation bacteria 0.02g;

[0092] The preparation method of the tofu yogurt is the same as that of Example 1.

[0093] Example 5

[0094] A tofu yogurt of the present embodiment includes the following raw materials (the total amount of raw materials is calculated based on 1000g):

[0095] Raw milk 861.95g, white sugar 80g, instant soybean powder 50g, calcium lactate 8g, fermentation bacteria 0.05g;

[0096] The preparation method of the tofu yogurt is the same as that of Example 1.

[0097] Example 6

[0098] This embodiment is basically the same as embodiment 3, except that calcium carbonate is used instead of calcium lactate in embodiment 3.

[0099] Example 7

[0100] This embodiment is basically the same as embodiment 3, except that calcium citrate is used instead of calcium lactate in embodiment 3.

[0101] Example 8

[0102] This embodiment is basically the same as embodiment 3, except that before step 2) of the preparation method, 20 g of calcium lactate is completely dissolved in 100 mL of distilled water to prepare a calcium lactate aqueous solution with a mass concentration of 20% and sterilized, and then in step 2) 30 mL of the sterilized calcium lactate aqueous solution and the fermentation bacteria are sequentially added to the first material.

[0103] Example 9

[0104] This embodiment is basically the same as embodiment 3, except that in step 2) of the preparation method, calcium lactate and the fermentation bacteria are added to the first material at the same time.

[0105] Comparative Example 1

[0106] A yogurt of this comparative example includes the following raw materials (the total amount of raw materials is calculated based on 1000g):

[0107] Raw milk 913.98g, white sugar 80g, calcium lactate 6g, fermentation bacteria 0.02g;

[0108] The method for preparing the yogurt comprises the following steps:

[0109] 1) adding a first raw material including white sugar into raw milk, stirring evenly, homogenizing and sterilizing to obtain a first material;

[0110] 2) lowering the temperature of the first material to 40° C.-45° C., then sequentially adding calcium lactate and fermentation bacteria into the first material at intervals of no longer than 2 minutes, stirring evenly, to obtain a second material;

[0111] 3) fermenting the second material at 41-44° C., and terminating the fermentation when the fermentation acidity reaches 70° T to obtain the yogurt.

[0112] Comparative Example 2

[0113] A tofu yogurt of this comparative example includes the following raw materials (the total amount of raw materials is calculated based on 1000g):

[0114] Raw milk 881.48g, white sugar 80g, instant soy powder 38.5g, fermentation bacteria 0.02g;

[0115] The method for preparing the tofu yogurt comprises the following steps:

[0116] 1) adding a first raw material including instant bean powder and white sugar into raw milk, stirring evenly, homogenizing and sterilizing to obtain a first material;

[0117] 2) lowering the temperature of the first material to 40° C.-45° C., then adding the fermentation bacteria into the first material, stirring evenly, to obtain the second material;

[0118] 3) fermenting the second material at 41-44°C, and terminating the fermentation when the fermentation acidity reaches 70°T to obtain the tofu yogurt.

[0119] Comparative Example 3

[0120] A tofu yogurt of this comparative example includes the following raw materials (the total amount of raw materials is calculated based on 1000g):

[0121] Raw milk 875.48g, white sugar 80g, instant soy powder 38.5g, calcium lactate 6g, fermentation bacteria 0.02g;

[0122] The method for preparing the tofu yogurt comprises the following steps:

[0123] 1) adding a first raw material including instant bean powder and white sugar into raw milk, stirring evenly, homogenizing and sterilizing to obtain a first material;

[0124] 2) lowering the temperature of the first material to 40° C.-45° C., then adding the fermentation bacteria into the first material, stirring evenly, to obtain the second material;

[0125] 3) fermenting the second material at 41-44°C, and terminating the fermentation when the fermentation acidity reaches 70°T. The fermentation time is generally not less than 4 hours, and then adding calcium lactate, stirring evenly and standing for 15 minutes to obtain the tofu yogurt.

[0126] Comparative Example 4

[0127] A tofu yogurt of this comparative example includes the following raw materials (the total amount of raw materials is calculated based on 1000g):

[0128] Raw milk 875.48g, white sugar 80g, instant soy powder 38.5g, calcium lactate 6g, fermentation bacteria 0.02g;

[0129] The method for preparing the tofu yogurt comprises the following steps:

[0130] 1) adding a first raw material including instant bean powder and white sugar into raw milk, stirring evenly, homogenizing and sterilizing to obtain a first material;

[0131] 2) lowering the temperature of the first material to 40° C.-45° C., then adding calcium lactate to the first material, stirring evenly, letting it stand for 15 minutes, then adding the fermentation bacteria, stirring evenly to obtain the second material;

[0132] 3) fermenting the second material at 41-44°C, and terminating the fermentation when the fermentation acidity reaches 70°T to obtain the tofu yogurt.

[0133] Comparative Example 5

[0134] This comparative example is basically the same as comparative example 2, except that soy protein powder is used to replace the instant soy powder in comparative example 2.

[0135] Comparative Example 6

[0136] A tofu yogurt of the present embodiment includes the following raw materials (the total amount of raw materials is calculated based on 1000g):

[0137] Raw milk 870.48g, white sugar 80g, instant soy powder 38.5g, calcium lactate 11g, fermentation bacteria 0.02g;

[0138] The preparation method of the tofu yogurt is the same as that of Example 1.

[0139] Comparative Example 7

[0140] A tofu yogurt of the present embodiment includes the following raw materials (the total amount of raw materials is calculated based on 1000g):

[0141] Raw milk 879.48g, white sugar 80g, instant soy powder 38.5g, calcium lactate 2g, fermentation bacteria 0.02g;

[0142] The preparation method of the tofu yogurt is the same as that of Example 1.

[0143] Test example

[0144] 1. The following parameters of the above embodiments and comparative examples were tested:

[0145] 1) Hardness: The hardness was measured using a BROOKFIELD texture analyzer with the following parameters set: pre-test speed: 1.00 mm / s; test speed: 1.00 mm / s; post-test speed: 1.00 mm / s; punching depth: 10.000 mm; time: 10.00 s; trigger force: 0.1 g; hardness tests were performed at 0 days, 7 days, 14 days, 21 days, and 25 days of shelf life, and each sample was tested three times. The average value was taken to obtain the hardness test results shown in Table 1.

[0146] 2) Viable bacteria count: The viable bacteria count test was carried out in accordance with GB 4789.35-2016 National Food Safety Standard Food Microbiology Examination Lactic Acid Bacteria Test. The viable bacteria count test was carried out at 0 days, 7 days, 14 days, 21 days and 25 days of shelf life. Each sample was tested three times and the average value was taken. The specific results are shown in Table 1.

[0147] 3) Whey precipitation rate: a certain amount of sample was placed in a centrifuge tube, centrifuged at 3500 rpm for 10 min at 20°C, the mass of the supernatant was weighed, and the percentage of the supernatant mass to the sample mass was the whey precipitation rate. The whey precipitation rate was tested at 0 day, 7 days, 14 days, 21 days, and 25 days of shelf life. Each sample was tested three times and the average value was taken. The specific results are shown in Table 2.

[0148] 4) Sensory evaluation: 60 professional evaluators (male to female ratio of 1:1) were randomly selected to evaluate the tofu yogurt on the first day of shelf life based on its texture, taste and smell. The full score for each indicator was 10 points. Each sample was tested three times and the average value was taken. The sensory evaluation standards are shown in Table 3 and the evaluation results are shown in Table 4.

[0149] 5) Fermentation time: The fermentation process was timed. The specific results are shown in Table 5.

[0150] 2. Test results

[0151] Table 1 Hardness and viable count

[0152]

[0153] The hardness results in Table 1 show that the hardness of the samples in each embodiment is moderate, generally better than that of the comparative examples; among them, in Embodiment 3, Embodiment 6 and Embodiment 7, the hardness of the products with the addition of calcium carbonate and calcium citrate salt coagulants is slightly higher than that of the products with the addition of calcium lactate, and the products with the addition of calcium lactate have a more moderate hardness, more delicate and mellow taste; in Embodiment 8 (adding calcium lactate aqueous solution), the hardness of the product is improved to a certain extent during the storage period of the shelf life, and the hardness of the product reaches 178.59g at the highest, but its hardness is still relatively moderate. In addition, because the calcium lactate is prepared as a solution in Embodiment 8, the hardness of the product is relatively moderate. Adding it to the fermentation system avoids the situation that the direct addition of powder may cause incomplete dissolution. At the same time, after the calcium lactate solution of appropriate concentration is added to the fermentation system, it will have a certain buffering effect on the fermentation system, and exert the synergistic effect of calcium lactate and fermentation bacteria, so as to ensure that the fermentation system is fermented slowly for a long time, while calcium ions are combined with bean source protein in the fermentation system, so that the obtained product is more delicate and thick, and the hardness is kept moderate; Comparative Example 1 has a higher hardness; Comparative Example 2 (without calcium lactate) has a higher hardness, which may be because the fermentation system without calcium lactate does not have a salt coagulant (such as The above advantages brought by the synergistic effect of calcium lactate) and the fermentation bacteria make the final product have a higher hardness; in Comparative Example 3, the fermentation bacteria are first added to the fermentation base to complete the fermentation, and then calcium lactate is added. Since the product is in a solidified state after the fermentation, in order to ensure that the calcium lactate added later can be mixed evenly, the product after the fermentation needs to be stirred, which destroys the organizational state of the product and its organizational state cannot be restored. Therefore, the hardness of the obtained product is low; the hardness of Comparative Example 4 increases greatly during the shelf life, and the stability of the hardness is poor; in Comparative Examples 2, 5 and 7, the hardness is close to , which are all relatively high; the hardness of Comparative Example 6 (adding too high a concentration of calcium lactate) is only 101.64g at the highest, which may be because, to a certain extent, the excessively high concentration of calcium lactate inhibits the fermentation of the fermentation bacteria, which is not conducive to the formation of a coagulated state of the final product, resulting in a low hardness of the product; in addition, the various components of the tofu yogurt raw materials influence and synergize with each other, and the different amounts of instant soy powder added will affect the function of other components, and ultimately make the hardness of the obtained product different; the increase in the amount of salt coagulant added will also affect the function of other components, and ultimately make the hardness of the product show a downward trend.

[0154] The results of viable bacterial counts in Table 1 show that the viable bacterial counts of the final products obtained by adding different proportions of fermentation agents are quite different. Adding a high proportion of fermentation agents can ensure that the strains reach the logarithmic growth phase in a short time, utilize the nutrients in the base material to produce extracellular polysaccharides, etc., so that the product solidifies. The viable bacterial count of the final product obtained in Example 1 (the addition ratio of fermentation strains is small) is relatively low, and the highest still reaches 4.35×10 8 CFU / mL; During the entire shelf life, the viable count of the sample was not less than 4.33×106 CFU / mL.

[0155] Table 2 whey precipitation rate

[0156]

[0157]

[0158] The whey precipitation rate results in Table 2 show that the whey precipitation rate of each embodiment is not higher than 0.321 during the shelf life, which indicates that the product of each embodiment has high stability. This may be due to the good stability of calcium salt in the soybean-milk fermentation system, especially calcium lactate has better stability in the soybean-milk fermentation system, and the addition of calcium salt increases the water holding capacity of the soybean-milk base, thereby improving the product stability. Compared with calcium carbonate and calcium citrate, the whey precipitation rate of the sample obtained by adding calcium lactate during the shelf life is relatively low, and the stability is relatively higher. The whey precipitation rate of the sample of Example 8 during the shelf life is only 0.293, and the stability is higher. This is because after calcium lactate is dissolved, it is added to the fermentation base in a solution state, which ensures that calcium lactate is evenly mixed in the fermentation base, thereby better playing a role. In Comparative Example 6, a high concentration of calcium lactate is added, which not only inhibits the fermentation of the strain and affects the fermentation effect, but also causes the fermentation base to flocculate in a relatively short time, generating a large amount of water precipitation, and the whey precipitation rate is high, and the stability is low.

[0159] Table 3 Sensory evaluation standards

[0160]

[0161]

[0162] Table 4 Sensory evaluation results

[0163] sample Organization Status taste odor Example 1 8.19 7.66 7.84 Example 2 8.22 7.85 8.34 Example 3 8.25 8.21 8.73 Example 4 7.86 8.09 7.68 Example 5 8.14 7.58 7.31 Example 6 8.17 7.29 8.22 Example 7 8.23 7.56 8.18 Example 8 8.33 8.36 8.75 Example 9 8.26 8.17 8.68 Comparative Example 1 8.01 6.88 3.75 Comparative Example 2 8.15 5.25 2.87 Comparative Example 3 3.78 3.29 5.10 Comparative Example 4 7.05 6.99 7.55 Comparative Example 5 7.98 7.58 6.71 Comparative Example 6 2.84 4.82 5.21 Comparative Example 7 8.08 6.21 6.05

[0164] The sensory evaluation results in Table 4 show that the sensory evaluation indicators such as the texture, taste, and smell of each embodiment are all in a moderate range, and the overall scores are high; the addition of calcium lactate in different proportions has a significant difference in the texture and taste of the product. Adding calcium lactate in an appropriate proportion can buffer the fermentation system, ensuring that the sample is fermented slowly for a long time. At the same time, the released calcium ions act as a bridge between the carboxyl and imidazole groups of the denatured soy protein molecules in the system, giving the product a bean flavor and delicate taste, while reducing the generation of bean smell; while the addition of salt coagulants at an excessively high concentration ratio inhibits the fermentation of the fermentation bacteria, thereby affecting the texture and flavor of the product. Among them, the sample using 0.6% calcium lactate has uniform color, delicate and mellow taste, obvious bean flavor and milk flavor, and the bean smell is not obvious, which is weaker than the bean smell of the sample made with soy protein powder in Comparative Example 5; while the sample adding 0.8% calcium lactate has slightly weaker bean flavor and milk flavor; 1.1% calcium lactate was added in Comparative Example 6, and the tissue state of the obtained product was poor and the astringency was obvious; at the same time, the addition method of calcium lactate and the addition of different types of calcium salts also have a certain effect on the sensory flavor of the product; in Example 8, calcium lactate was dissolved and added to the base material, and calcium lactate was mixed evenly in the base material, and the sensory scores of each dimension were the highest. In addition, the proportion of soybean powder added was low, and the product had a weak bean flavor; the proportion of soybean powder added was high, the milk flavor was weakly perceived, and it had a certain bean smell. The components of the product raw materials interacted with each other and synergized, and the optimal combination and ratio could only be determined by carrying out a lot of research and development work. The sample obtained in Comparative Example 2 did not add salt coagulants, the fermentation time was short, the obtained sample had a heavy bean smell, and the product texture was hard. Comparative Example 3 adopts the method of fermentation first and then salt coagulation. The product has poor tissue state, is relatively loose, has a slight astringent feeling, and has no obvious flavor.

[0165] Table 5 Fermentation time

[0166] sample Fermentation time / h sample Fermentation time / h Example 1 6 Example 9 7 Example 2 6 Comparative Example 1 6 Example 3 7 Comparative Example 2 5 Example 4 9 Comparative Example 3 5 Example 5 10 Comparative Example 4 8 Example 6 8 Comparative Example 5 5 Example 7 8 Comparative Example 6 12 Example 8 7 Comparative Example 7 6

[0167] From Table 5, it can be found that the addition of different types and proportions of salt coagulants significantly affects the fermentation time of the product, thereby having a certain impact on the texture, tissue state, flavor and taste of the product. As the content of calcium lactate increases, the fermentation time of the product is prolonged. In Comparative Example 6, 1.1% calcium lactate was added, and the fermentation time reached 12h. The addition of a higher concentration of calcium lactate inhibited the fermentation of the strain to a certain extent, thereby prolonging the fermentation time. The product obtained by adding 0.6% calcium lactate was fermented slowly for a long time, and the fermentation time was 7h. The product had a uniform color and a delicate taste, which was a suitable addition ratio.

[0168] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A tofu yogurt, characterized in that: The hardness of the tofu yogurt is 127.10g-196.33g, and the number of viable bacteria is not less than 4.33×10 6 CFU / mL.

2. The tofu yogurt according to claim 1, characterized in that The whey precipitation rate of the tofu yogurt is 0.200-0.

321.

3. The tofu yogurt according to claim 1 or 2, characterized in that: The raw materials of the tofu yogurt include, by mass percentage, 85%-90% of raw milk, 5%-10% of sweetener, 2%-5% of bean source, 0.4%-0.8% of salt coagulant, and 0.001%-0.005% of fermentation bacteria; Among them, the number of viable bacteria in the fermentation strain is (1-5)×10 6 CFU / g.

4. The tofu yogurt according to claim 3, characterized in that The salt coagulant is a calcium salt.

5. The tofu yogurt according to claim 4, characterized in that The calcium salt is calcium lactate.

6. The tofu yogurt according to claim 5, characterized in that: The tofu yogurt is prepared by a method comprising at least the following steps: After adding salt coagulant and fermentation bacteria to the raw material system including bean source, sweetener and raw milk, fermentation treatment is carried out until the fermentation acidity reaches a certain level to obtain the tofu yogurt.

7. A method for preparing the tofu yogurt according to any one of claims 1 to 6, characterized in that: include: 1) adding a first raw material including a bean source and a sweetening substance into raw milk to obtain a first material; 2) adding a salt coagulant and a fermentation bacteria into the first material to obtain a second material; 3) fermenting the second material, and terminating the fermentation when the fermentation acidity reaches 70°T to obtain the tofu yogurt.

8. The preparation method according to claim 7, characterized in that: In step 2), the salt coagulant is in solution.

9. The preparation method according to claim 8, characterized in that: In step 2), the salt coagulant and the fermentation bacteria are sequentially added into the first material; Wherein, the interval time between sequentially adding the salt coagulant and the fermentation bacteria is no longer than 2 minutes.

10. The preparation method according to any one of claims 7 to 9, characterized in that: In the step, the salt coagulant and the fermentation bacteria are added into the first material at the same time.

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