Normal-temperature yoghourt and preparation method thereof

Abstract

The invention provides normal-temperature yoghourt and a preparation method thereof. The normal-temperature yoghurt comprises the following raw materials in percentage by mass: 3.5%-8.0% of heat-treated single cream, 5.0%-6.0% of concentrated milk protein powder, 1.5%-2.0% of modified whey protein powder, 100-500 u of a fermentation strain and the balance of 76.5%-82.5% of raw milk. The raw materials of the normal-temperature yoghurt are subjected to heat treatment of the single cream, the concentrated milk protein powder and the denatured whey protein powder to construct a stable system of the yoghurt, no food additive is included, and the normal-temperature yoghurt is long in storage time at normal temperature, fine and smooth in taste and high in stability.

Description

Technical Field

[0001] The invention relates to room temperature yogurt, in particular to room temperature yogurt and a preparation method thereof, and belongs to the field of food. Background Art

[0002] Compared with low-temperature yogurt, room-temperature yogurt requires the fermentation system to be sterilized again after fermentation to kill the lactic acid bacteria, thereby avoiding the continuous fermentation of lactic acid bacteria at room temperature, which leads to a decrease in product acidity and product deterioration.

[0003] In addition, commercially available ambient temperature yogurt also uses food additives to build a stable product system, so that the ambient temperature yogurt can have a stable taste and flavor during the shelf life, and the product state is stable. These food additives include citrus fiber, modified starch, pectin, gellan gum, agar, gelatin, etc.

[0004] With the increase of health awareness, consumers have very high requirements for not adding extra food additives to food. At the same time, the room temperature yogurt prepared with food additives has a rough taste and consumers have a poor experience.

[0005] Therefore, room temperature yogurt that is natural, healthy, free of food additives, has a delicate taste and high stability is expected to fill the market gap. Summary of the invention

[0006] The invention provides a room-temperature yogurt, which does not contain any food additives, has a delicate taste, uniform texture, high stability, and can be stably preserved for 6 months at room temperature.

[0007] The invention also provides a method for preparing room-temperature yogurt, which is simple to operate and suitable for industrial production.

[0008] The first aspect of the present invention provides a room temperature yogurt, wherein the raw materials of the room temperature yogurt include, by weight percentage: 3.5%-8.0% heat-treated cream, 5.0%-6.0% concentrated milk protein powder, 1.5%-2.0% denatured whey protein powder, 100u-500u fermentation bacteria, and the remainder is raw milk;

[0009] Wherein, the heat-treated cream is obtained by treating the cream at 121-139° C. for 4-60 seconds;

[0010] The denatured whey protein powder is obtained by heating and shearing natural whey protein;

[0011] The mass ratio of casein in the raw materials of the room temperature yogurt to the denatured whey protein powder is ≤1:1.

[0012] The room temperature yogurt as described above, wherein the raw materials of the room temperature yogurt include, in terms of mass percentage: 7% of the heat-treated cream, 5.7% of the concentrated milk protein powder, 1.8% of the denatured whey protein powder, 200u-400u of the fermentation bacteria, and the remainder being the raw milk.

[0013] The room temperature yogurt as described above, wherein the mass ratio of the casein to the denatured whey protein powder is 2:3.

[0014] The room temperature yogurt as described above, wherein the raw materials of the room temperature yogurt further include 7.5%-8.5% of sweetening substances according to the mass percentage.

[0015] The room temperature yogurt as described above, wherein the sweetening substance comprises white granulated sugar.

[0016] The room temperature yogurt as described above, wherein the fermentation bacteria include Lactobacillus delbrueckii bulgaricus and Streptococcus thermophilus.

[0017] The room temperature yogurt as described above, wherein the room temperature yogurt is prepared by a method comprising at least the following processes:

[0018] The fermentation bacteria are added to a raw material system including the raw milk, heat-treated cream, concentrated milk protein powder and denatured whey protein powder, and fermented until the fermentation acidity reaches a certain level, and then the fermentation system is sterilized to obtain the room temperature yogurt.

[0019] The second aspect of the present invention provides a method for preparing the room temperature yogurt according to the first aspect, comprising the following steps:

[0020] 1) sequentially homogenizing and sterilizing the raw material system including the raw milk, heat-treated cream, concentrated milk protein powder and denatured whey protein powder to obtain a first material;

[0021] 2) adding the fermentation bacteria to the first material and fermenting, and terminating the fermentation when the fermentation acidity is 72°T to 130°T to obtain a second material;

[0022] 3) subjecting the second material to a second sterilization treatment to obtain the room temperature yogurt.

[0023] In the preparation method as described above, the homogenization conditions in step 1) are a homogenization temperature of 60°C-65°C and a homogenization pressure of 30-50bar / 160-250bar, and the first sterilization treatment conditions are a sterilization temperature of 90°C-95°C and a sterilization time of 300s-600s.

[0024] As described above, in the preparation method, in step 3), the second sterilization treatment is carried out under the conditions of a sterilization temperature of 72°C-77°C and a sterilization time of 15s-25s.

[0025] The stabilization system of the room temperature yogurt of the present invention uses all food raw materials, avoids the use of food additives to construct the stabilization system, the label is cleaner, the product is more high-end, and it is natural, healthy and burden-free. Specifically, the room temperature yogurt of the present invention uses concentrated milk protein powder, denatured whey protein powder, and heat-treated cream to construct a yogurt stabilization system, and defines the mass ratio of casein and whey protein in the concentrated milk protein powder, thereby improving the stability of the room temperature yogurt and ensuring that it can be stably stored for 6 months. In addition, the room temperature yogurt has a delicate taste and uniform texture. DETAILED DESCRIPTION

[0026] 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.

[0027] The first aspect of the present invention provides a room temperature yogurt, wherein the raw materials of the room temperature yogurt include, by weight percentage: 3.5%-8.0% heat-treated cream, 5.0%-6.0% concentrated milk protein powder, 1.5%-2.0% denatured whey protein powder, 100u-500u fermentation bacteria, and the remainder is raw milk;

[0028] The heat-treated cream is obtained by treating the cream at 121-139° C. for 4-60 seconds.

[0029] The denatured whey protein powder is obtained by heating and shearing natural whey protein;

[0030] The mass ratio of casein in the raw materials of the above-mentioned room temperature yogurt to the above-mentioned denatured whey protein powder is ≤1:1.

[0031] The protein components in the concentrated milk protein powder, such as casein, provide a stable gel network structure foundation during the texture formation process of the above-mentioned room temperature yogurt, and at the same time can provide the above-mentioned room temperature yogurt with a delicate taste and rich creamy feel. In addition, the calcium ions in the concentrated milk protein powder can be combined with the above-mentioned network structure to make the network structure more stable.

[0032] Since the milk fat in the cream plays the role of a connecting point in the gel network structure of the above-mentioned room temperature yogurt, the cream is treated at 121-139°C for 4-60s to obtain heat-treated cream. Various enzymes in the above-mentioned heat-treated cream are destroyed, which not only prevents the above-mentioned enzymes from affecting the quality of the product, but also increases the binding sites of the milk fat in the heat-treated cream in the process of forming the stable system of the above-mentioned room temperature yogurt, which is beneficial to further enhance the stability of the gel network structure of the above-mentioned room temperature yogurt, thereby improving the stability of the product.

[0033] In addition, the heat-treated cream can also increase the viscosity of the product and improve the taste of the product.

[0034] Heating and shear denaturing whey protein can fully unfold its protein chains and fully cross-link it with heat-treated cream and milk protein to form a dense and stable network structure, which is conducive to the product obtaining higher stability and can also improve the taste of the product and make it more delicate.

[0035] The conditions of the above-mentioned heating and shear denaturation treatment are heating temperature 30-60°C and homogenization pressure 30-50bar / 150-200bar.

[0036] The present invention does not impose any particular limitation on the time of the above-mentioned heating and shear denaturation treatment, as long as the protein chains of the whey protein are fully unfolded, for example, the time may be 5-20 minutes.

[0037] The present invention limits the mass ratio of casein (mainly provided by concentrated milk protein) to denatured whey protein powder in the raw materials of yogurt to ≤1:1, which can further ensure that the room temperature yogurt can be stably stored at room temperature for 6 months.

[0038] Fermentation bacteria are used to ferment milk, forming the stringy texture of yogurt and giving the product a fermented flavor.

[0039] The present invention does not limit the type of the above-mentioned raw milk. For example, at least one of raw cow's milk, raw goat's milk, raw camel's milk, pure cow's milk, pure goat's milk, pure camel's milk, and reconstituted milk can be used as raw milk for preparing the above-mentioned room temperature yogurt.

[0040] The present invention reasonably compounds the above-mentioned heat-treated cream, denatured whey protein powder and concentrated milk protein powder, and limits the mass ratio of casein and denatured whey protein powder in the concentrated milk protein powder. Under the synergistic effect of the above-mentioned three raw materials, the casein, whey protein, milk fat, calcium and the like in the raw materials form a uniform and stable gel network structure of room-temperature yogurt, and constructs a stable system for the above-mentioned room-temperature yogurt, so that the room-temperature yogurt has a delicate taste, uniform texture, rich fermented flavor, high stability, does not contain any food additives, has a cleaner label, and is more natural and healthy.

[0041] Furthermore, when the raw materials of the above-mentioned room temperature yogurt include, in percentage by mass, 7% heat-treated cream, 5.7% concentrated milk protein powder, 1.8% denatured whey protein powder, 200u-400u fermentation bacteria, and the remainder is raw milk, the room temperature yogurt has a more delicate taste, a more uniform texture, higher stability, and a better fermentation flavor.

[0042] When the mass ratio of casein to denatured whey protein powder in the above-mentioned principle of room temperature yogurt is 2:3, the taste, texture, stability and flavor of the room temperature yogurt can be further improved.

[0043] The raw materials of the room temperature yogurt also include 7.5%-8.5% of sweet substances according to the mass percentage, which is beneficial to increase the sweetness of the product and make the taste richer.

[0044] The above-mentioned sweet substances include white sugar, which not only provides sweetness to the product, balances the lactic acid produced in the yogurt fermentation process, and achieves the sour-sweet balance of the product, but also provides soluble solids to the product, which is beneficial to increase the viscosity of the product and further improve the stability of the product.

[0045] In some embodiments, the fermentation strains include Lactobacillus delbrueckii and Streptococcus thermophilus. The yogurt obtained by fermenting with the above fermentation strains is easy to form a stringy texture and rich in fermentation flavor. In addition, the above fermentation strains have a high yield of extracellular polysaccharides with immune activity, which is beneficial to human health.

[0046] Furthermore, in the above yogurt, the amount of Lactobacillus delbrueckii bulgaricus is 10 4 -10 5 cfu / g, the above-mentioned thermophilic streptococcus is 10 9 -10 10 cfu / g, which can provide better fermentation flavor and texture for yogurt.

[0047] The room temperature yogurt is prepared by a method comprising at least the following steps:

[0048] Fermentation bacteria are added to a raw material system including raw milk, heat-treated cream, concentrated milk protein powder and denatured whey protein powder, and fermentation is carried out until the fermentation acidity reaches a certain level, and then the fermentation system is sterilized to obtain the above-mentioned room temperature yogurt.

[0049] It is understandable that in order to increase the activity of the fermentation bacteria and improve the fermentation quality, the temperature of the above raw material system can be preheated to 40-44°C in advance.

[0050] After adding the fermentation bacteria, it should be mixed evenly so that the fermentation bacteria are evenly dispersed in the above raw material system.

[0051] The fermentation temperature can be limited in combination with the type of fermentation bacteria, and generally, it can be 43±1°C.

[0052] The above fermentation acidity is generally 72-130°T. At this time, the acidity of the yogurt is appropriate, the sour feeling is better, and consumers prefer it.

[0053] Because the fermentation bacteria in the fermentation system still have high activity after the fermentation is completed, in order to avoid the above-mentioned fermentation bacteria continuing to ferment and produce lactic acid during the shelf life, thereby reducing the acidity of the product and causing the product to deteriorate, the fermentation system should be sterilized to inactivate the fermentation bacteria in the fermentation system, thereby ensuring that the acidity of the product will not continue to decrease during the shelf life and allowing the product to be stored for a long time at room temperature.

[0054] The room temperature yogurt can be stably stored at room temperature for 6 months, and has a delicate taste, uniform texture, and rich fermented flavor.

[0055] The second aspect of the present invention provides a method for preparing the room temperature yogurt of the first aspect, comprising the following steps:

[0056] 1) sequentially homogenizing and sterilizing a raw material system including raw milk, heat-treated cream, concentrated milk protein powder and denatured whey protein powder to obtain a first material;

[0057] 2) adding the fermentation bacteria to the first material and fermenting, and terminating the fermentation when the fermentation acidity is 72°T to 130°T to obtain the second material;

[0058] 3) subjecting the second material to a second sterilization treatment to obtain the above-mentioned room temperature yogurt.

[0059] The above homogenization is a routine operation in this field. On the one hand, it enables the raw materials to be fully dispersed and improves their dispersion effect. On the other hand, it can break the fat globules in the raw material system to prevent the fat from floating up, so that the milk fat in the raw milk is evenly distributed in the above raw material system, which is beneficial to maintaining the delicate taste of the product, easy digestion and absorption, and can also improve the milk flavor of the product.

[0060] The purpose of the first sterilization treatment is to kill the miscellaneous bacteria in the raw material system and avoid miscellaneous bacteria contamination during the fermentation process.

[0061] It is understandable that in order to improve the activity of the fermentation bacteria and improve the fermentation quality, the temperature of the first material can be maintained at 40-44°C in advance, because the optimal fermentation temperature of most conventional fermentation bacteria is 40-44°C.

[0062] After adding the fermentation bacteria, the mixture should be mixed evenly so that the fermentation bacteria are evenly dispersed in the first material.

[0063] The fermentation temperature can be limited in combination with the type of fermentation bacteria, and generally, it can be 43±1°C.

[0064] The acidity of the fermentation system can be tested 6 hours after fermentation, and tested every half an hour. When the fermentation acidity reaches 72-130°T, the fermentation is terminated. At this time, the acidity of the yogurt is appropriate and the sourness is good, which consumers prefer.

[0065] Although fermentation is over, the fermentation bacteria in the second material still have high activity. In order to prevent the fermentation bacteria from continuing to ferment during room temperature storage, producing too much lactic acid, reducing the acidity of the product and causing the product to deteriorate, the second material needs to be subjected to a second sterilization treatment to inactivate the fermentation bacteria in the second material, thereby ensuring that the acidity of the product remains stable during room temperature storage and ensuring the quality of the product.

[0066] The preparation method is simple to operate and is suitable for industrial production. The preparation method first forms a protein gel in the first material through homogenization and a first sterilization treatment, and then under the fermentation action of the fermentation bacteria, the casein, whey protein, milk fat and calcium in the first material cooperate and interact with each other to form a uniform and stable gel network of the second material. Finally, after the fermentation bacteria in the second material are killed through a second sterilization treatment, a room-temperature yogurt is obtained which can be stably stored at room temperature for 6 months and has a delicate taste, uniform texture and rich fermentation flavor.

[0067] The above raw material system can generally be prepared by a method including at least the following process: adding concentrated milk protein powder and denatured whey protein powder to raw milk for mixing, and then adding heat-treated cream to obtain the above raw material system.

[0068] In order to promote the concentrated milk protein powder and the denatured whey protein powder to be fully mixed with the raw milk, part of the raw milk can be preheated to 50-55°C, and the concentrated milk protein powder and the denatured whey protein powder can be added and dissolved for 10 minutes before adding the heat-treated cream; in order to make the heat-treated cream fully dispersed and fully react with its raw materials, the heat-treated cream can be added and dissolved for 15-20 minutes, and then the remaining raw milk can be used to make up the volume to the ingredient amount, thereby obtaining the above-mentioned raw material system.

[0069] The above-mentioned part of raw milk may be raw milk accounting for 55% of the total amount of raw milk in the formula.

[0070] When the above raw material system also includes sweeteners, such as white sugar, it can be added together with the heat-treated cream.

[0071] It is understandable that the above preparation method also includes demulsifying the second material obtained after the fermentation is completed, and then performing a second sterilization treatment after the demulsification treatment, which is beneficial to improving the effect of the second sterilization treatment and improving the taste, flavor and other qualities of the product.

[0072] The above demulsification conditions are a stirring speed of 20-30 rpm and a stirring time of 5 min.

[0073] The above fermentation endpoint may also be when the pH reaches below 4.45, that is, the pH of the fermentation system is detected starting 6 hours after fermentation, and is detected every half hour. When the pH reaches below 4.45, the fermentation is terminated. At this time, the acidity of the yogurt is appropriate and the sourness is better.

[0074] Generally, the fermentation time needs to be controlled within 8-16 hours, for example, 12 hours.

[0075] After the second sterilization treatment is completed in the above step 3), the sterilized material is also bottled at 20-30°C.

[0076] Furthermore, the homogenization conditions are 60°C-65°C, 30-50bar / 160-250bar, and the first sterilization conditions are 90°C-95°C, 300s-600s. This is conducive to ensuring the effects of the homogenization and the first sterilization, promoting the formation of protein gel in the first material, and forming a more uniform and stable gel network under the action of the fermentation bacteria for casein, whey protein, milk fat, and calcium in the second material, thereby improving the taste, flavor, and stability of the product.

[0077] Preferably, the homogenization pressure may also be 50 / 200 bar. A suitable homogenization pressure is beneficial to improving the homogenization effect.

[0078] In step 3) of the above preparation method, the second sterilization treatment is carried out at a sterilization temperature of 72°C-77°C and a sterilization time of 15s-25s. Under such conditions, the fermentation bacteria in the second material can be effectively killed, and the acidity of the product can be prevented from continuously decreasing during the storage period at room temperature, thereby ensuring the quality of the product and improving the stability of the product, so that it can be stored at room temperature for 6 months.

[0079] Furthermore, the sterilization temperature may also be 75° C., which is conducive to more convenient control of the sterilization temperature and improved process convenience.

[0080] Hereinafter, the room temperature yogurt and the preparation method thereof of the present invention will be described in more detail through specific examples.

[0081] The specific sources of some raw materials in the following preparation process are:

[0082] Concentrated milk protein powder: Fonterra, Arla;

[0083] Cream: Yili Company, Nestle Company;

[0084] Whey protein powder: Fonterra, Arla;

[0085] White sugar: COFCO;

[0086] Raw milk: Yili Company;

[0087] Milk: Yili Company;

[0088] Fermentation bacteria: including Lactobacillus delbrueckii and Streptococcus thermophilus.

[0089] Example 1

[0090] A room temperature yogurt of this embodiment includes the following raw materials:

[0091] Heat-treated cream 50kg, concentrated milk protein powder 55kg, denatured whey protein powder 16kg, fermentation bacteria 100u, white sugar 85kg, raw milk 800kg, milk to make up to 1000kg;

[0092] Among them, the mass ratio of casein to denatured whey protein powder is 7:10;

[0093] The method for preparing the room temperature yogurt comprises the following steps:

[0094] 1) treating the cream at 121-139° C. for 4-60 seconds to obtain heat-treated cream; heating and shearing the natural whey protein at 60° C. and 30 bar / 150 bar to obtain denatured whey protein powder;

[0095] 2) adding concentrated milk protein powder and denatured whey protein powder to raw milk preheated to 50-55° C., blending for 10 minutes, then adding heat-treated cream and white sugar, blending for 15-20 minutes, and diluting to 1000 kg with milk to obtain a raw material system;

[0096] 3) The raw material system is subjected to a homogenization first sterilization treatment in sequence, and the first material is obtained after being cooled to 40-44° C., wherein the homogenization temperature is 60° C.-65° C., the homogenization pressure is 40 / 200 bar, and the conditions of the first sterilization treatment are a sterilization temperature of 90° C.-95° C. and a sterilization time of 300s-600s;

[0097] 4) adding the fermentation bacteria to the first material and fermenting at a temperature of 43±1°C, terminating the fermentation when the fermentation acidity is 72°T to 130°T, breaking the emulsion at a stirring speed of 20-30 rpm and a stirring time of 5 min to obtain a second material;

[0098] 5) subjecting the second material to a second sterilization treatment and filling at 25° C. to obtain the above-mentioned room temperature yogurt, wherein the conditions of the second sterilization treatment are a sterilization temperature of 75° C. and a sterilization time of 25 seconds.

[0099] Example 2

[0100] A room temperature yogurt of this embodiment includes the following raw materials:

[0101] Heat-treated cream 35kg, concentrated milk protein powder 50kg, denatured whey protein powder 15kg, fermentation bacteria 100u, white sugar 75kg, raw milk 800kg, milk to make up to 1000kg;

[0102] Among them, the mass ratio of casein to denatured whey protein powder is 1:2;

[0103] The preparation method of the above-mentioned room temperature yogurt is basically the same as that of Example 1, except that:

[0104] Replace 60℃, 30bar / 150bar with 30℃-60℃, 50bar / 200bar.

[0105] Example 3

[0106] A room temperature yogurt of this embodiment includes the following raw materials:

[0107] Heat-treated cream 80kg, concentrated milk protein powder 60kg, denatured whey protein powder 20kg, fermentation bacteria 500u, white sugar 80kg, raw milk 800kg, milk to make up to 1000kg;

[0108] Among them, the mass ratio of casein to denatured whey protein powder is 6.5:10;

[0109] The preparation method of the room temperature yogurt is the same as that of Example 1.

[0110] Example 4

[0111] A room temperature yogurt of this embodiment includes the following raw materials:

[0112] Heat-treated cream 70kg, concentrated milk protein powder 57kg, denatured whey protein powder 18kg, fermentation bacteria 400u, white sugar 85kg, raw milk 800kg, milk to make up to 1000kg;

[0113] Among them, the mass ratio of casein to denatured whey protein powder is 7.3:10;

[0114] The preparation method of the room temperature yogurt is the same as that of Example 1.

[0115] Example 5

[0116] A room temperature yogurt of this embodiment includes the following raw materials:

[0117] Heat-treated cream 80kg, concentrated milk protein powder 56kg, denatured whey protein powder 17kg, fermentation bacteria 200u, white sugar 80kg, raw milk 800kg, milk to make up to 1000kg;

[0118] The mass ratio of casein to denatured whey protein powder is 2:3;

[0119] The preparation method of the above-mentioned room temperature yogurt is the same as that of Example 1.

[0120] Comparative Example 1

[0121] A room temperature yogurt of this comparative example comprises the following raw materials of the following quality:

[0122] 40kg light cream, 50.8kg concentrated milk protein powder, 12kg modified starch, 1kg pectin, 0.8kg agar, 0.25kg gellan gum, 0.6kg diacetyl tartaric acid mono- and diglycerides, 100u fermentation bacteria, and make up the amount of raw milk to 1000kg.

[0123] The method for preparing the room temperature yogurt comprises the following steps:

[0124] 1) adding concentrated milk protein powder, modified starch, pectin, agar, gellan gum, and diacetyl tartaric acid mono- and diglycerides to raw milk preheated to 50-55° C., accounting for 55% of the ingredients, and blending for 10 minutes, then adding cream and white sugar, blending for 15-20 minutes, and adjusting the volume to 1000 kg with the remaining raw milk to obtain a raw material system;

[0125] 3) The raw material system is subjected to a homogenization first sterilization treatment in sequence, and the first material is obtained after being cooled to 43° C., wherein the homogenization temperature is 60° C., the homogenization pressure is 30 / 160 bar, and the conditions of the first sterilization treatment are a sterilization temperature of 95° C. and a sterilization time of 300 s;

[0126] 4) adding the fermentation bacteria to the first material and fermenting at a temperature of 43±1°C, terminating the fermentation when the fermentation acidity is 72°T to 80°T, breaking the emulsion at a stirring speed of 20-30 rpm and a stirring time of 5 min to obtain a second material;

[0127] 5) subjecting the second material to a second sterilization treatment and filling at 20-30° C. to obtain the above-mentioned room temperature yogurt, wherein the conditions of the second sterilization treatment are a sterilization temperature of 72° C.-75° C. and a sterilization time of 25 seconds.

[0128] Comparative Example 2

[0129] This comparative example is basically the same as Example 1, except that:

[0130] No heat-treated cream is added, and the remainder is made up with milk.

[0131] Comparative Example 3

[0132] This comparative example is basically the same as Example 1, except that:

[0133] 16 kg of concentrated milk protein powder is used to replace 16 kg of denatured whey protein powder.

[0134] Comparative Example 4

[0135] This comparative example is basically the same as Example 1, except that:

[0136] 57 kg of denatured whey protein powder is used to replace 57 kg of concentrated milk protein powder.

[0137] Comparative Example 5

[0138] This comparative example is basically the same as Example 1, except that:

[0139] 1) Ordinary cream is used to replace heat-treated cream;

[0140] 2) In step 1 of the preparation method, it is modified to heat and shear natural whey protein at 30°C - 60°C and 50 bar / 200 bar to obtain denatured whey protein powder.

[0141] Comparative Example 6

[0142] This comparative example is basically the same as Example 1, except that:

[0143] 1) Ordinary concentrated whey protein powder is used to replace denatured whey protein powder.

[0144] 2) In step 1 of the preparation method, it is modified to treat cream at 121 - 139°C for 4 - 60 s to obtain heat-treated cream.

[0145] Comparative Example 7

[0146] This comparative example is basically the same as Example 1, except that:

[0147] The casein content in the concentrated milk protein powder is 60%.

[0148] Comparative Example 8

[0149] This comparative example is basically the same as Example 1, except that:

[0150] The second sterilization treatment is not included in the preparation method.

[0151] 1. The following parameters of the products in the above examples and comparative examples are detected:

[0152] 1) Sensory evaluation: The products of each embodiment and comparative example were evaluated from the aspects of flavor, taste, color, nutritional value, etc., with a full score of 10 for each item. The higher the score, the better the item effect. A total of 200 evaluators (100 males and 100 females aged 18-28) were selected. An anonymous scoring system was adopted. The score of each item was expressed as the average score of all evaluators, and the sum of the scores of the above items was taken as the total score. At the same time, the products were evaluated according to the degree of liking the products, including liking, good, and general, and the number of people corresponding to each degree was counted. The sensory evaluation results of the products are shown in Table 1;

[0153] 2) Stability study: The product was placed at room temperature (about 25°C), and the organizational state of the product, including fat floating, protein precipitation and water precipitation, was observed several times at fixed intervals during the shelf life. The fat floating was observed by visual inspection and measurement of fat thickness. The floating fat was taken out to determine the mass of the floating fat, and the percentage of the mass of the floating fat in the mass of the yogurt was the fat floating rate. A certain amount of the product was centrifuged and the protein precipitation amount was directly measured by the difference method. The percentage of the protein precipitation amount in the mass of the yogurt was the protein precipitation rate. At the same time, the water precipitation of the product was analyzed in combination with visual observation and protein precipitation. The above indicators can reflect the stability of the product. The specific results are shown in Table 2.

[0154] 3) Particle size: Take a certain amount of sample and observe it under a microscope to measure the particle size. The results are shown in Table 3.

[0155] 2. Test results

[0156] Table 1 Sensory evaluation results of products

[0157]

[0158]

[0159] It can be seen from Table 1 that the taste and flavor of the room temperature yogurt provided by Examples 1-5 of the present invention are better than those of the room temperature yogurt provided by Comparative Examples 1-8.

[0160] Table 2 Product stability study (25°C)

[0161]

[0162]

[0163]

[0164]

[0165] As can be seen from Table 2, the room temperature yogurt provided by Examples 1-5 of the present invention can be stored at room temperature for more than 6 months without unacceptable fat floating and protein precipitation, and has a long shelf life, which is conducive to product promotion and sales. However, the products of Comparative Examples 1-8 showed serious fat floating, water separation and precipitation in the observation results of 150 days and 180 days, which was more obvious than that of the products of Examples 1-5 and was in an unacceptable range.

[0166] Table 3 Particle size

[0167]

[0168]

[0169] It can be seen from Table 3 that the particle size of the yogurt provided by Examples 1-5 of the present invention is better than that of the yogurt provided by Comparative Examples 1-8, which further illustrates the effect of yogurt particle size distribution on taste, which is consistent with the sensory evaluation results in Table 1.

[0170] 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 room temperature yogurt, It is characterized in that The raw materials of the room temperature yogurt include, by weight percentage, 3.5%-8.0% heat-treated cream, 5.0%-6.0% concentrated milk protein powder, 1.5%-2.0% denatured whey protein powder, 100u-500u fermentation bacteria, and the remainder raw milk; Wherein, the heat-treated cream is obtained by treating the cream at 121-139° C. for 4-60 seconds; The denatured whey protein powder is obtained by heating and shearing natural whey protein; The mass ratio of casein in the raw materials of the room temperature yogurt to the denatured whey protein powder is ≤1:

1.

2. The room temperature yogurt according to claim 1, It is characterized in that The raw materials of the room temperature yogurt include, in terms of mass percentage, 7% of the heat-treated cream, 5.7% of the concentrated milk protein powder, 1.8% of the denatured whey protein powder, 200u-400u of the fermentation bacteria, and the remainder being the raw milk.

3. The room temperature yogurt according to claim 2, It is characterized in that The mass ratio of the casein to the denatured whey protein powder is 2:

3.

4. The room temperature yogurt according to any one of claims 1 to 3, It is characterized in that The raw materials of the room temperature yogurt also include 7.5%-8.5% of sweet substances according to the mass percentage.

5. The room temperature yogurt according to claim 4, It is characterized in that The sweetener includes white sugar.

6. The room temperature yogurt according to any one of claims 1 to 5, It is characterized in that The fermentation bacteria include Lactobacillus delbrueckii and Streptococcus thermophilus.

7. The room temperature yogurt according to any one of claims 1 to 6, It is characterized in that The room temperature yogurt is prepared by a method comprising at least the following processes: The fermentation bacteria are added to a raw material system including the raw milk, heat-treated cream, concentrated milk protein powder and denatured whey protein powder, and fermented until the fermentation acidity reaches a certain level, and then the fermentation system is sterilized to obtain the room temperature yogurt.

8. A method for preparing the room temperature yogurt according to any one of claims 1 to 7, It is characterized in that The following steps are involved: 1) sequentially homogenizing and sterilizing the raw material system including the raw milk, heat-treated cream, concentrated milk protein powder and denatured whey protein powder to obtain a first material; 2) adding the fermentation bacteria to the first material and fermenting, and terminating the fermentation when the fermentation acidity is 72°T to 130°T to obtain a second material; 3) subjecting the second material to a second sterilization treatment to obtain the room temperature yogurt.

9. The preparation method according to claim 8, It is characterized in that The homogenization conditions in step 1) are a homogenization temperature of 60°C-65°C and a homogenization pressure of 30-50bar / 160-250bar, and the first sterilization treatment conditions are a sterilization temperature of 90°C-95°C and a sterilization time of 300s-600s.

10. The preparation method according to claim 8 or 9, It is characterized in that In step 3), the second sterilization treatment is carried out under the conditions of a sterilization temperature of 72° C.-77° C. and a sterilization time of 15 s-25 s.

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