Milk skin flavored yoghurt and preparation method thereof

Abstract

The invention discloses milk skin flavored yogurt and a preparation method thereof, and belongs to the technical field of fermented milk. The milk skin flavored yogurt comprises the following raw materials in parts by mass: fresh milk, white granulated sugar, single cream powder, sweetened condensed milk and the like. The preparation method comprises the following steps: heating the raw milk to 50-60 DEG C, adding the white granulated sugar and the like, stirring, adding the single cream and the like, and mixing to obtain a fermentation base material; carrying out homogenization treatment on the fermentation base material accounting for 45%-55%, and mixing the homogenized fermentation base material and the non-homogenized fermentation base material; activating the strain of lactic acid bacteria, inoculating the activated lactic acid bacteria into the cooled fermentation base material, and stirring; and heating the inoculated material to 40-45 DEG C, carrying out filling treatment after heating, and fermenting the filled base material at 41-45 DEG C to obtain the milk skin flavored yogurt. The milk skin of the milk skin flavored yoghurt disclosed by the invention is moderate in thickness and fine and smooth in mouth feel.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fermented milk, in particular to a milk skin flavored yogurt and a preparation method thereof. BACKGROUND

[0002] With the upgrading of China's dairy industry and the diversification of consumer demand, the yogurt market continues to show a high-end and characteristic development trend. The competition in the yogurt industry is becoming increasingly fierce. Consumers not only pay attention to the quality and nutritional value of yogurt, but also pay attention to the other values brought by various sensory experiences in the consumption process. Under the background of consumption upgrading, more and more segmented consumer demands such as health, functionality and scene of yogurt products are emerging. At present, the innovation iteration speed of the yogurt market is accelerating, and especially new product categories of low-temperature yogurt are emerging. In recent years, "milk skin yogurt" has gradually become a new product category that consumers pay attention to.

[0003] Milk skin is a traditional dairy product, mainly popular in the nomadic areas of northern China. It is made of cow's milk, goat's milk or mare's milk after heating, standing, cooling, and a layer of thin film rich in fat naturally coagulated on the surface. It is named because it looks like "milk skin". The reason why "milk skin yogurt" is so named is that the surface of the yogurt has a slightly yellow layer of "milk skin", and its formation process is similar to that of traditional milk skin, which is a "fat protein layer". The essence of milk skin yogurt is that a layer of "milk skin" is added to the surface of the set yogurt "old yogurt". "Milk skin yogurt" has a unique taste, combining the dense milk skin and the smooth yogurt to form a "one spoon to the bottom" level of feeling; it is rich in nutrients and meets the needs of healthy diet, especially popular among fitness and health groups. Through travel consumption and the spread of young groups, "milk skin yogurt" has become a single product for restaurant diversion, triggering a check-in craze.

[0004] The existing milk skin yogurt process has the following defects when preparing milk skin yogurt:

[0005] (1) When producing and preparing milk skin yogurt, in order to make the fat float to form a protein fat layer "milk skin", no homogenization process is adopted, resulting in a rough and not delicate taste of the milk skin layer and the yogurt layer;

[0006] (2) In order to form the upper layer of milk skin, additional separately sterilized thin cream is separately added during filling after the base mixture is inoculated to participate in co-fermentation, which requires additional energy consumption and additional equipment;

[0007] (3) Flavor imbalance, too thick milk skin leading to greasy feeling, or too thin losing characteristics;

[0008] (4) The fermentation aroma of the selected fermentation strain is insufficient, the taste is consistent with traditional old yogurt, and the natural milk skin flavor is not preserved;

[0009] (5) poor layered stability, loose yogurt structure, easy to form fragmented yogurt skin, water holding capacity of yogurt layer decreases during shelf life, and yogurt skin layer and yogurt layer are easy to be fused;

[0010] (6) some yogurt with yogurt skin on the market is made by traditional manual method, and there is no industrialized continuous production, and the scientific production technology is lack, and the taste and flavor of the finished product are greatly different. SUMMARY

[0011] The purpose of the present application is to overcome the above technical deficiencies, provide a yogurt with yogurt skin flavor and a preparation method thereof, solve the technical problems of the prior art that the thickness of the yogurt skin is not moderate and the taste is rough and not delicate.

[0012] To achieve the above technical purpose, the technical scheme of the present application provides a yogurt with yogurt skin flavor, the raw materials are calculated by mass fraction, including: raw milk 776-800 parts, white granulated sugar 65-70 parts, light cream 100-120 parts, sweet condensed milk 50-55 parts, whey protein powder 3-5 parts, cheese powder 3-5 parts and gelatin 4-6 parts; the inoculation amount of lactic acid bacteria is 0.01-0.015 UC / kg of raw materials.

[0013] In any embodiment, it further includes 0.03-0.05 parts of beta-carotene.

[0014] In any embodiment, the lactic acid bacteria includes Streptococcus salivarius subsp. thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Lactococcus lactis subsp. lactis and Lactococcus cremoris; and / or, the use amount ratio of the Streptococcus salivarius subsp. thermophilus, the Lactobacillus delbrueckii subsp. bulgaricus, the Lactococcus lactis subsp. lactis and the Lactococcus cremoris is 1:(0.5-0.6):(0.5-0.6):(0.5-0.6).

[0015] In any embodiment, the thickness of the yogurt skin layer is 1-2 mm.

[0016] In addition, the present application also proposes a preparation method of the above-mentioned yogurt with yogurt skin flavor, comprising the following steps:

[0017] S1, the raw milk is heated to 50-60 DEG C, then white granulated sugar, whey protein powder, cheese powder and gelatin are added and stirred, then light cream and sweet condensed milk are added and mixed to obtain a fermentation base;

[0018] S2, 45%-55% of the fermentation base is subjected to homogenization treatment, and the remaining fermentation base is not subjected to homogenization treatment, and the homogenized and non-homogenized fermentation bases are mixed;

[0019] S3, sterilize the mixed fermentation base, cool the sterilized fermentation base to 1-6 DEG C, activate the lactic acid bacteria, inoculate the activated lactic acid bacteria into the cooled fermentation base and stir, warm the inoculated material to 40-45 DEG C, after warming, perform filling treatment, the filling temperature is kept at 39-42 DEG C, ferment the filled base at 41-45 DEG C to obtain the milk skin flavor yogurt.

[0020] In any embodiment, in step S1, before stirring, beta-carotene is also added.

[0021] In any embodiment, in step S2, 50% of the fermentation base is subjected to homogenization treatment.

[0022] In any embodiment, in step S2, the pressure of the homogenization treatment is 18-20 MPa, and the temperature of the homogenization treatment is 50-65 DEG C.

[0023] In any embodiment, in step S3, during the warming process, stirring is performed for 3-5 minutes per hour.

[0024] In any embodiment, in step S3, the fermentation time is 5-7 hours, the acidity of the milk skin flavor yogurt reaches 70-80 DEG T, and the fermentation is completed, and / or in step S3, after fermentation, the milk skin flavor yogurt is subjected to low-temperature ripening at 1-6 DEG C for 12-24 hours.

[0025] Compared with the prior art, the beneficial effects of the present application include: the milk skin flavor yogurt of the present application is prepared from raw milk, whipping cream, white granulated sugar, sweet condensed milk, concentrated whey protein powder, cheese powder, gelatin, beta-carotene and lactic acid bacteria, through homogenization treatment of 40%-55% of the base, and the remaining base is not subjected to homogenization treatment, and is mixed with the compound bacteria for fermentation, so that the fat globules with moderate thickness can be suspended in the surface layer of the set-type fermented milk, thereby obtaining a milk skin flavor yogurt with excellent texture and flavor, and ensuring that the milk skin has moderate thickness and delicate taste.

[0026] The preparation method of the present application is simple, can be realized on a large scale by using the original fermentation milk production line for step-by-step filling, and reduces the cost increase caused by the transformation of the production line. No special equipment is required throughout the process, and the existing yogurt filling line can be directly used for production.

[0027] The homogenization of the half base and the non-homogenization of the half base not only retain the upper layer of fat protein layer "milk skin", but also make the lower layer of yogurt taste delicate and smooth.

[0028] The Streptococcus salivarius subsp. thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Lactococcus lactis subsp. lactis and Lactococcus cremoris are compounded to ferment, the milk skin flavor is obvious, the cheese powder has a little cheese fragrance, and the natural milk skin flavor is reserved.

[0029] The gelatin system is added, the yogurt structure is stable, the yogurt layer is stable in water retention force in the shelf life, the appropriate addition amount of the whipped cream guarantees the thickness of the milk skin of 1-2mm, and the addition of the beta-carotene enables the yogurt to be naturally colored and has antioxidant property. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a flowchart of the preparation method of the milk skin flavored yogurt of the embodiment 1 of the present application.

[0031] Figure 2 is a photo of the milk skin flavored yogurt prepared in the group 1A of the embodiment 1 of the present application.

[0032] Figure 3 is a photo of the milk skin flavored yogurt prepared in the group 1B of the embodiment 1 of the present application.

[0033] Figure 4 is a photo of the milk skin flavored yogurt prepared in the group 1C of the embodiment 1 of the present application.

[0034] Figure 5 is a photo of the milk skin flavored yogurt prepared in the group 1D of the embodiment 1 of the present application.

[0035] Figure 6 is a photo of the milk skin flavored yogurt prepared in the group 1E of the embodiment 1 of the present application.

[0036] Figure 7 is a photo of the milk skin flavored yogurt prepared in the comparative example 1 of the present application.

[0037] Figure 8 is a photo of a certain milk skin flavored yogurt on the market. DETAILED DESCRIPTION

[0038] "ranges" recited in the specification are inclusive of the endpoints and are presented as shorthand for describing a range of values. A range of values includes the endpoint values unless specifically indicated otherwise. For example, a range of "60-120" and a range of "80-110" are considered to be synonymous, with the range of "60-110" and the range of "80-120" being equivalent. Additionally, a range of values includes all values between (and including) the minimum and maximum range values, as is understood by one of ordinary skill in the art. For example, a numerical range of "1-5" means that data between (and including) the values of 1 and 5, i.e. 1, 2, 3, 4, and 5.

[0039] The terms "comprise" (and any grammatical variations thereof, such as "comprises" and "comprising"), when used in the specification and / or claims, can mean "includes," "includes," or "including" but not limited to, and the terms "comprised of" and / or "comprising of, when used in the specification and / or claims, can mean "includes," "includes," or "including" but not limited to.

[0040] The term "or," in its various forms, as used in the specification and / or claims includes any one and both of the items that it conjoins. For example, the phrase "A or B" includes any one of A, B, or both A and B. More specifically, any one of the following conditions fulfills the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0041] The specific embodiment provides a milk skin flavor yogurt, the raw materials include, by mass fraction: raw milk 776-800 parts, white granulated sugar 65-70 parts, light cream 100-120 parts, sweet condensed milk 50-55 parts, whey protein powder 3-5 parts, cheese powder 3-5 parts and gelatin 4-6 parts; the inoculation amount of lactic acid bacteria is 0.01-0.015 UC / kg of raw materials. The whey protein powder is preferably concentrated whey protein powder.

[0042] In some embodiments, 0.03-0.05 parts of beta-carotene are also included.

[0043] In some embodiments, the lactic acid bacteria include Streptococcus thermophilus, Lactobacillus delbrueckii bulgaricus, Lactococcus lactis lactis, and Lactococcus cremoris, and the use ratio of the Streptococcus thermophilus, the Lactobacillus delbrueckii bulgaricus, the Lactococcus lactis lactis, and the Lactococcus cremoris is 1:(0.5-0.6):(0.5-0.6):(0.5-0.6).

[0044] In some embodiments, the thickness of the milk skin layer is 1-2 mm.

[0045] In addition, the present specific embodiment also proposes a preparation method of the above-mentioned milk skin flavored yogurt, which comprises the following steps:

[0046] S1, the raw milk is heated to 50-60℃, then white granulated sugar, whey protein powder, cheese powder and gelatin are added and stirred, then light cream and sweetened condensed milk are added and mixed to obtain a fermentation base;

[0047] S2, 45%-55% of the fermentation base is subjected to homogenization treatment, and the remaining fermentation base is not subjected to homogenization treatment, and the homogenized and non-homogenized fermentation bases are mixed;

[0048] S3, the mixed fermentation base is subjected to sterilization treatment, and the sterilized fermentation base is cooled to 1-6℃; the strain of lactic acid bacteria is activated, and the activated lactic acid bacteria are inoculated into the cooled fermentation base and stirred; the inoculated material is heated to 40-45℃, and stirring is performed for 3-5 min every hour during the heating process; after heating, filling treatment is performed, the filling temperature is maintained at 39-42℃, and the filled base is fermented at 41-45℃ for 5-7 h; the acidity of the milk skin flavored yogurt reaches 70-80°T, and the fermentation is completed, then the milk skin flavored yogurt is subjected to low-temperature ripening at 1-6℃ for 12-24 h.

[0049] In some embodiments, in step S1, β-carotene is also added before stirring.

[0050] In some embodiments, in step S2, preferably 50% of the fermentation base is subjected to homogenization treatment.

[0051] In some embodiments, in step S2, the pressure of the homogenization treatment is 18-20 MPa, and the temperature of the homogenization treatment is 50-65℃.

[0052] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0053] In the present application, "some embodiments", "the present embodiments" and the like are described, which describe a subset of all possible embodiments, but it can be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments, and can be combined with each other without conflict.

[0054] If similar descriptions of "first / second" appear in the application file, the following description is added, in the following description, the terms "first\second\third" involved only distinguish similar objects, and do not represent the specific order of the objects, and it can be understood that "first\second\third" can be interchanged in specific order or sequence as allowed, so that the embodiments described here can be implemented in an order other than that illustrated or described here.

[0055] In the present embodiment, the term "and / or" only describes the association relationship of the associated objects, which means that there can be three relationships, for example, object A and / or object B, which can mean that object A exists alone, object A and object B exist together, and object B exists alone.

[0056] Hereinafter, the embodiments of the present application are described. The embodiments described below are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application. If the specific technology or condition is not specified in the embodiments, it is carried out according to the technology or condition described in the literature in the art or according to the product instruction. If the reagent or instrument used is not specified by the manufacturer, it is a conventional product that can be obtained by purchase.

[0057] Embodiment 1

[0058] The milk pie flavor yogurt of the present embodiment is prepared from raw materials including fresh milk 776 kg, white granulated sugar 65 kg, light cream 110 kg, sweet condensed milk 50 kg, concentrated whey protein powder 3 kg, cheese powder 3 kg, gelatin 5 kg, and β-carotene 0.03 kg, in terms of mass fraction. The inoculation amount of lactic acid bacteria is 0.0148 UC / kg of raw materials. The lactic acid bacteria in the present embodiment include Streptococcus salivarius subsp. thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Lactococcus lactis subsp. lactis, and Lactococcus cremoris. The use amount ratio of the Streptococcus salivarius subsp. thermophilus, the Lactobacillus delbrueckii subsp. bulgaricus, the Lactococcus lactis subsp. lactis, and the Lactococcus cremoris is 1:0.5:0.6:0.5.

[0059] The present embodiment provides a preparation method of milk pie flavor yogurt, which comprises the following steps:

[0060] S0, the raw milk is accepted, and the raw milk is evaluated for odor, organization state, color, fat, protein, non-fat milk solids, acidity, impurity degree, microbial index detection, and the raw milk is qualified for quality inspection. The milk temperature in the factory is 6℃; the raw milk is filtered and cleaned, and the filter hole diameter of the two-stage filtration is 1.5mm when filtering, and the temperature of the cleaned milk is 6℃;

[0061] S1, the raw milk is standardized; 776kg of raw milk (i.e. fresh milk) is heated to 60℃, and then white granulated sugar 65kg, concentrated whey protein powder 3kg, cheese powder 3kg, gelatin 5kg and β-carotene 0.03kg are added in turn, stirred for 10min, and then light cream 110kg and sweet condensed milk 50kg are added and mixed uniformly to obtain a fermentation base;

[0062] S2, 500kg of the fermentation base is subjected to homogenization treatment, the homogenization pressure is 20MPa, and the homogenization temperature is 60℃; the remaining 512.03kg of the base is not subjected to homogenization treatment, and finally the two parts of the fermentation base are mixed uniformly;

[0063] S3, the mixed fermentation base is subjected to pasteurization treatment, the sterilization temperature is 95℃, and the sterilization time is 300s; the fermentation base after pasteurization is cooled to 6℃; the strain is activated, and 15UC of the activated lactic acid bacteria is inoculated into the cooled fermentation base, stirred for 10min and mixed uniformly with the fermentation base; the inoculated material is heated to 45℃, and every 1h of the heating process is opened for 5min of stirring to prevent the fat from floating and causing uneven indicators; after heating, the material is subjected to filling treatment, and the filling temperature is 42℃; the filled material is placed in a fermentation room for fermentation treatment, the fermentation temperature is 42℃, and the fermentation time is 6h; the acidity of the milk skin yogurt reaches 75°T, and after fermentation, the yogurt is rapidly cooled to 6℃ to terminate the fermentation; the fermented yogurt is placed in a cold storage, the cold storage temperature is 6℃, and the yogurt is subjected to low-temperature ripening for 12h to obtain the finished milk skin yogurt; the milk skin yogurt is subjected to inspection and screening, and the sensory indicators, physicochemical indicators and microbial indicators are evaluated; the qualified milk skin yogurt is delivered.

[0064] All other conditions such as formula, raw material, fermentation and post-fermentation process are kept completely consistent, only the weight ratio (W / W) of the homogenized part of the base in the total fermentation base is changed, and the following five experimental groups are set:

[0065] A group: 0% homogenization (i.e. traditional process, all base is not homogenized)

[0066] B group: 30% homogenization (homogenized part accounts for 30%, non-homogenized part accounts for 70%)

[0067] C group: 50% homogenization (homogenized part accounts for 50%, non-homogenized part accounts for 50%)

[0068] Group D: 70% homogenized (70% homogenized part, 30% non-homogenized part)

[0069] Group E: 100% homogenized (i.e. conventional yogurt process, all base homogenized)

[0070] 2. Evaluation method and index:

[0071] (1) Cream layer evaluation:

[0072] Thickness (mm): After fermentation is completed, the average thickness of the cream layer is measured using a digital caliper.

[0073] Morphology: Observe whether the cream layer is complete, continuous, and fragmented.

[0074] Combination with yogurt layer: Gently touch the cream layer with a spoon back and observe whether it is easy to separate from the lower layer of yogurt.

[0075] (2) Yogurt body evaluation:

[0076] Taste fineness: Blind test and score by trained sensory evaluation personnel (at least 5 people) (1-10 points, 10 points represent extremely fine and smooth).

[0077] Viscosity / firmness: Measure gel strength using a texture analyzer.

[0078] (3) Overall stability evaluation:

[0079] Whey separation rate: After 21 days of cold storage at 4°C, measure the change in whey separation rate (%).

[0080] Flavor: Sensory evaluation personnel conduct descriptive evaluation on "cream flavor intensity", "greasy feeling", and "sweet and sour balance".

[0081] Experimental results and data analysis are shown in Table 1.

[0082] Table 1

[0083]

[0084] Combined Figures 2-6 , this example proves the necessity of the "semi-homogenized" ratio: the experimental data clearly shows that the change of homogenization ratio from 0% to 100% has a continuous and nonlinear effect on product characteristics. Neither completely non-homogeneous (Group A) nor completely homogeneous (Group E) can obtain ideal double-layer structure cream yogurt, which proves the correctness and necessity of the "partial homogenization" idea adopted in this invention.

[0085] Highlighting the excellence and non-obviousness of the homogenization "50%" ratio:

[0086] (1) Synergistic effect: The preferred 50% ratio (Group C) of the present application is not a simple compromise between the two extremes (0% and 100%), but a "golden section" that achieves the best balance of taste and structure. It cleverly uses the homogeneous part to provide a delicate taste and a stable system, and the non-homogeneous part to provide sufficient and morphologically perfect fat floating, and the combination of the two produces a "1+1>2" synergistic effect.

[0087] (2) Unexpected technical effect:

[0088] In combination Figures 2-6 In terms of cream layer: Group C forms a cream layer with moderate thickness (1.5 mm) and dense and complete structure, perfectly solving the problems of Group A (too thick and loose) and Group D (too thin and fragmented). Moreover, the whey separation rate is as low as 1.2% after 21 days of storage.

[0089] (3) In combination Figures 2-6 In terms of yogurt taste: the delicacy of the lower layer of yogurt in Group C (8.5 points) is much better than that of Group A (4.5 points) and Group B (6.8 points), and compared with the high scores of Groups D and E, its delicacy is achieved on the premise of successfully maintaining a significant cream layer, which is one of the core contributions of the present application.

[0090] Example 2

[0091] This example is to further investigate the quantitative effects of the addition amount of whipped cream and the addition amount of gelatin, two key variables under the core process of "half base homogeneous", on the thickness of the cream layer, the whey separation rate and the sensory quality of the creamed yogurt, so as to determine the optimal formula combination and provide solid data support for the claims of the present application. The basic formula and process are as follows:

[0092] Except for the variables to be investigated, the amounts of the remaining components (fresh milk, white sugar, etc.) and the preparation process (especially "half homogeneous, half non-homogeneous") are consistent with those of the present application.

[0093] Whipped cream addition amount single factor experiment:

[0094] Fix the addition amount of gelatin at 5 g / kg, set four gradients of the addition amount of whipped cream, and the addition amounts of other raw materials and the process conditions are the same as those of Example 1:

[0095] Group F: 90 g / kg

[0096] Group G: 110 g / kg

[0097] Group H: 130 g / kg

[0098] Group I: 150 g / kg

[0099] Gelatin addition amount single factor experiment:

[0100] The fixed amount of whipping cream was 110 g / kg, and four gradient amounts of gelatin were set. The amounts of other raw materials and process conditions were the same as in Example 1:

[0101] Group 1: 3 g / kg

[0102] Group 2: 5 g / kg

[0103] Group 3: 7 g / kg

[0104] Group 4: 9 g / kg

[0105] Evaluation index and method:

[0106] Cream layer thickness (mm): measured on the day of post-ripening (day 1).

[0107] Whey separation rate (%): measured on day 1 and day 21 to investigate the stability during the shelf life.

[0108] Sensory score (points): evaluated by 5 trained evaluators on day 1 for the shape of the cream layer, greasy feeling, and overall acceptability (10-point scale).

[0109] The experimental results and data analysis are shown in Tables 2 and 3.

[0110] Table 2

[0111]

[0112] Conclusion 1: The amount of whipping cream directly determines the thickness and flavor intensity of the cream layer. When the amount is less than 110 g / kg, it is not possible to form a clear cream layer with product characteristics. When the amount is more than 110 g / kg, although a thicker cream layer can be formed, it will bring an undesirable greasy feeling, and the excessively thick fat layer may damage the system stability to some extent. Therefore, 110 g / kg is the optimal choice that takes into account product characteristics, taste, and stability.

[0113] Table 3: Effect of different gelatin amounts on product quality (whipping cream fixed at 110 g / kg)

[0114]

[0115] Conclusion 2: The amount of gelatin added is the key to control the stability and texture of the product. When the amount is less than 5 g / kg, the gel network is not strong enough to effectively bind water, resulting in severe whey separation and structure collapse during the shelf life; when the amount is more than 5 g / kg, although the stability is further enhanced, it will bring a strong gelatinous feeling, sacrificing the smooth and natural taste of yogurt. Therefore, the addition of 5 g / kg of gelatin can ensure the stability of the 21-day shelf life while providing the most pleasant taste.

[0116] 1. This experiment, combined with the previous semi-matrix ratio experiment, fully proves that the inventiveness of the present application does not come from a single process or a single formula change, but is the result of the synergistic effect of the "semi-matrix homogenization" core process, the specific amount of whipped cream (110 g / kg) and the specific amount of gelatin (5 g / kg).

[0117] 2. By controlling the amount of whipped cream to 110 g / kg and combining it with 5 g / kg of gelatin and the semi-homogenization process, the present application unexpectedly achieves three difficult-to-achieve goals at the same time: forming a characteristic milk skin with moderate thickness (1.5 mm) and perfect shape. Obtaining a smooth and pleasant taste without greasy feeling. Ensuring that the product has a very low whey separation rate (1.2%) and stable shape within 21 days of shelf life.

[0118] In summary, the amount of 110 g / kg of whipped cream and 5 g / kg of gelatin is the best synergistic combination verified by a large number of creative experiments.

[0119] Comparative Example 1

[0120] Replace the gelatin in the scheme of group C in Example 1 with an equal amount of milk base powder, and the amounts of other raw materials and process steps are the same as those of group C in Example 1. The photo of the yogurt with milk skin prepared is shown in Figure 7 It can be seen that there is almost no milk skin layer.

[0121] Figure 8 are photos of two kinds of yogurt with milk skin on the market. The milk skin in the figure is yellow, thick and slightly hard, the yogurt is white and has a powdery feeling, the taste is delicate and has a gelatinous texture structure, and the normal yogurt flavor.

[0122] The specific embodiments of the present application described above do not constitute a limitation on the scope of protection of the present application. Any various other corresponding changes and modifications made in accordance with the technical concept of the present application shall be included in the scope of protection of the claims of the present application.

Claims

1. A milk skin-flavored yogurt, characterized in that, The raw materials, calculated by weight, include: 776-800 parts raw milk, 65-70 parts white sugar, 100-120 parts light cream, 50-55 parts sweetened condensed milk, 3-5 parts whey protein powder, 3-5 parts cheese powder, and 4-6 parts gelatin; the inoculation amount of lactic acid bacteria is 0.01-0.015 UC / kg of raw materials.

2. The milk skin flavored yogurt according to claim 1, characterized in that, It also includes 0.03-0.05 parts of beta-carotene.

3. The milk skin flavored yogurt according to claim 1, characterized in that, The lactic acid bacteria include *Streptococcus salivarius* subsp. *thermophilus*, *Lactobacillus delbrueckii* subsp. *bulgaricus*, *Lactococcus lactis* subsp. *lactophoresis*, and *Lactococcus fatense*; and / or, the ratio of the amounts of *Streptococcus salivarius* subsp. *thermophilus*, *Lactobacillus delbrueckii* subsp. *bulgaricus*, *Lactococcus lactis* subsp. *lactophoresis*, and *Lactococcus fatense* is 1:(0.5-0.6):(0.5-0.6):(0.5-0.6).

4. The milk skin flavored yogurt according to claim 1, characterized in that, The thickness of the milk skin layer is 1-2mm.

5. A method for preparing milk skin-flavored yogurt according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Heat the raw milk to 50-60℃, then add white sugar, whey protein powder, cheese powder and gelatin and stir. Then add light cream and sweetened condensed milk and mix to obtain the fermentation base. S2. Homogenize 45%-55% of the fermentation substrate, and do not homogenize the remaining fermentation substrate. Mix the homogenized and non-homogenized fermentation substrates together. S3. Sterilize the mixed fermentation base material and cool it down to 1-6℃. Activate the lactic acid bacteria strains and inoculate the activated lactic acid bacteria into the cooled fermentation base material and stir. Heat the inoculated material to 40-45℃ and fill it after heating. Maintain the filling temperature at 39-42℃. Ferment the filled base material at 41-45℃ to obtain milk skin flavored yogurt.

6. The method for preparing milk skin flavored yogurt according to claim 1, characterized in that, In step S1, β-carotene is added before stirring.

7. The method for preparing milk skin-flavored yogurt according to claim 1, characterized in that, In step S2, 50% of the fermentation substrate is homogenized.

8. The method for preparing milk skin flavored yogurt according to claim 1, characterized in that, In step S2, the pressure of the homogenization process is 18-20 MPa, and the temperature of the homogenization process is 50-65°C.

9. The method for preparing milk skin-flavored yogurt according to claim 1, characterized in that, In step S3, stir for 3-5 minutes every hour during the heating process to prevent the fat from floating to the surface.

10. The method for preparing milk skin-flavored yogurt according to claim 1, characterized in that, In step S3, the fermentation time is 5-7 hours; fermentation is complete when the acidity of the milk skin flavored yogurt reaches 70-80°T; and / or, in step S3, after fermentation, the milk skin flavored yogurt is further subjected to low-temperature post-ripening at 1-6°C for 12-24 hours.

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