Double-color double-flavor yoghurt and preparation method thereof

Abstract

The invention discloses double-color double-flavor yoghurt and a preparation method thereof, and relates to the technical field of yoghurt, the double-color double-flavor yoghurt is prepared by co-fermenting upper-layer milk slurry and lower-layer milk slurry in a packaging container; the upper-layer milk pulp is prepared from single cream, coconut oil, sodium caseinate, white granulated sugar, whey protein concentrate, tween-60, a first emulsion stabilizer, hydroxy propyl distarch phosphate, raw milk, yoghourt zymophyte, a first plant source flavor coloring substance and the balance of water; the lower-layer milk slurry comprises raw milk, white granulated sugar, sodium caseinate, skim milk powder, a second emulsion stabilizer, yoghourt zymophyte, a second plant-source flavor coloring substance and the balance of water. The double-color double-flavor yoghourt can be prepared by co-fermenting the upper-layer milk pulp and the lower-layer milk pulp according to a specific formula in the packaging container, so that double wonderful experience can be brought to the visual sense and the taste sense of consumers, and the requirements of the consumers are effectively met.

Description

Technical Field

[0001] The invention relates to the technical field of yogurt, and in particular to a double-color and double-flavor yogurt and a preparation method thereof. Background Art

[0002] Yogurt, a fermented dairy product, is highly popular among consumers for its digestive benefits, ease of absorption, ability to regulate intestinal flora, and immune-boosting properties. Furthermore, as demand for yogurt continues to grow in the consumer market, yogurt product formats are becoming increasingly diverse, with the emergence of set yogurt, stirred yogurt, drinkable yogurt, Greek yogurt, and other yogurt products, providing consumers with a wider range of choices.

[0003] Among them, the fermentation process of coagulated yogurt is carried out in the packaging container, so that the finished product retains the curd state due to fermentation. It has a strong natural fermentation aroma, delicate and smooth, thick texture, appropriate sweet and sour taste, and endless aftertaste, and has a strong competitive advantage in the consumer market.

[0004] However, existing set yogurt is usually produced by a single fermentation process, and its flavor and color are naturally highly uniform. Each cup of set yogurt can only provide a single flavor and single color experience, which makes it difficult to meet consumers' dual pursuit of product visual appeal and taste diversity. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology. The present invention provides a two-color and two-flavor yogurt and a preparation method thereof. By fermenting the upper layer of milk slurry and the lower layer of milk slurry designed with a specific formula together in a packaging container, a two-color and two-flavor yogurt can be produced, which can bring a double wonderful experience to consumers' vision and taste, and effectively meet the needs of consumers.

[0006] The present invention provides a double-color and double-flavor yogurt, which is prepared by fermenting an upper layer of milk pulp and a lower layer of milk pulp together in a packaging container;

[0007] The upper layer of milk slurry comprises, by mass fraction, 8-10.2% of cream, 10-14% of coconut oil, 0.8-2% of sodium caseinate, 5-10% of white sugar, 1.5-7% of concentrated whey protein, 0.1-0.2% of Tween-60, 0.15-0.24% of a first emulsion stabilizer, 0.3-0.5% of hydroxypropyl distarch phosphate, 40-50% of raw milk, 0.001-0.005% of yogurt fermentation bacteria, 0-0.4% of a first plant-derived flavor coloring matter, and the balance being water;

[0008] The lower layer of milk slurry comprises, by mass fraction, 70-71% raw cow's milk, 3-7% white sugar, 0-0.3% sodium caseinate, 3-6% skimmed milk powder, 0.25-0.45% second emulsion stabilizer, 0.001-0.005% yogurt fermentation bacteria, 0-0.4% second plant-derived flavor coloring matter, and the balance being water;

[0009] There is at least one of the first plant-derived flavor and coloring substance and the second plant-derived flavor and coloring substance, and the first plant-derived flavor and coloring substance and the second plant-derived flavor and coloring substance are different in flavor and color.

[0010] Specifically, the upper layer of milk slurry comprises, by mass fraction, 8% of light cream, 10% of coconut oil, 2% of sodium caseinate, 10% of white sugar, 3.5% of concentrated whey protein, 0.1% of Tween-60, 0.19% of a first emulsion stabilizer, 0.3% of hydroxypropyl distarch phosphate, 50% of raw milk, 0.005% of yogurt fermentation bacteria, 0% of a first plant-derived flavor coloring matter, and the balance being water;

[0011] The lower layer of milk slurry comprises, by mass fraction, 70% raw cow's milk, 6% white sugar, 0.3% sodium caseinate, 5% skimmed milk powder, 0.4% second emulsification stabilizer, 0.005% yogurt fermentation bacteria, 0.4% second plant-derived flavor coloring matter, and the balance being water.

[0012] Specifically, the first emulsion stabilizer comprises, in terms of mass fraction relative to the total mass of the upper milk slurry, 0.08% sodium citrate, 0.03% carrageenan, 0.02% agar, 0.01% locust bean gum, and 0.05% mono- and diglycerol fatty acid esters;

[0013] Calculated by mass fraction relative to the total mass of the lower layer milk slurry, the second emulsion stabilizer includes: 0.05% pectin, 0.15% dipotassium hydrogen phosphate and 0.2% sodium citrate.

[0014] Specifically, the yogurt fermentation bacteria include Lactobacillus delbrueckii subspecies bulgaricus and Streptococcus salivarius subspecies thermophilic;

[0015] The first plant-derived flavor coloring substance comprises one of concentrated strawberry juice, concentrated mango juice, concentrated pineapple juice, concentrated passion fruit juice, concentrated watermelon juice, concentrated cantaloupe juice, concentrated orange juice, concentrated tangerine juice, concentrated blueberry juice, concentrated sea buckthorn juice, concentrated coconut juice, concentrated kale juice, cocoa powder, and matcha powder;

[0016] The second plant-based flavor coloring substance includes one of concentrated strawberry juice, concentrated mango juice, concentrated pineapple juice, concentrated passion fruit juice, concentrated watermelon juice, concentrated cantaloupe juice, concentrated orange juice, concentrated tangerine juice, concentrated blueberry juice, concentrated sea buckthorn juice, concentrated coconut juice, concentrated kale juice, cocoa powder, and matcha powder.

[0017] Specifically, the volume ratio of the upper layer of milk slurry to the lower layer of milk slurry is in the range of 1:3 to 3:1.

[0018] The present invention also provides a method for preparing double-color and double-flavor yogurt, comprising the following steps:

[0019] S1. Mixing the formulated amounts of cream, coconut oil, sodium caseinate, white sugar, whey protein concentrate, Tween-60, a first emulsification stabilizer, hydroxypropyl distarch phosphate, raw cow's milk, and a first plant-based flavor coloring substance, adding water to a target total mass, and sequentially performing a high shear emulsification treatment and a homogenization treatment at 60-70° C., and cooling to obtain a first upper layer of milk slurry;

[0020] S2, mixing the formulated amounts of raw milk, white sugar, sodium caseinate, skimmed milk powder, a second emulsion stabilizer, and a second plant-derived flavor coloring substance, adding water to a target total mass, and sequentially performing a high shear emulsification treatment and a homogenization treatment at 60-70° C., and cooling to obtain a first lower layer of milk slurry;

[0021] S3, adding a formulated amount of yogurt fermentation bacteria to the first upper layer of milk slurry, and stirring evenly to obtain a second upper layer of milk slurry;

[0022] S4, adding a formula amount of yogurt fermentation bacteria to the first lower layer of milk slurry, and stirring evenly to obtain a second lower layer of milk slurry;

[0023] S5. First, fill the second lower layer of milk slurry into a packaging container, and then fill the second upper layer of milk slurry into the packaging container to obtain a double-color double-layer milk slurry to be fermented;

[0024] S6. Place the double-color double-layer milk slurry to be fermented at 40-45° C. for 340-380 min, cool it to terminate the fermentation, and obtain double-color double-flavor yogurt.

[0025] Specifically, in step S1 and step S2, the duration of the high shear emulsification treatment is in the range of 5 to 10 minutes, and the speed of the high shear emulsification treatment is in the range of 5800 to 6200 rpm / min;

[0026] In step S1 and step S2, the first-level homogenization pressure of the homogenization and slurry treatment is in the range of 10 to 15 MPa, and the second-level homogenization pressure of the homogenization and slurry treatment is in the range of 1 to 5 MPa.

[0027] Specifically, in step S1 and step S2, the temperature range of the first upper layer of milk slurry is 20-30°C, and the temperature range of the first lower layer of milk slurry is 20-30°C.

[0028] Specifically, in step S6, the cooling and terminating fermentation includes:

[0029] Lower the temperature to 3-5°C and maintain it for at least 300 minutes.

[0030] Specifically, the pH range of the double-color and double-flavor yogurt is 4.5 to 4.7.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] In the dual-color dual-flavor yogurt of the present invention, the upper layer of milk pulp and the lower layer of milk pulp have different special formula designs, so that the upper layer of milk pulp and the lower layer of milk pulp can be stably separated, so that the upper layer of milk pulp and the lower layer of milk pulp can be fermented together in the same packaging container while maintaining the separation state, laying a solid foundation for the formation of dual-color dual-flavor yogurt;

[0033] Moreover, by controlling the content and type of the first plant-derived flavor coloring substance and the second plant-derived flavor coloring substance, the upper layer of milk slurry and the lower layer of milk slurry can form different colors and flavor combinations, such as upper layer original flavor (original color) - lower layer plant-derived flavor (plant-derived color), upper layer plant-derived flavor (plant-derived color) - lower layer original flavor (original color), upper layer first plant-derived flavor (first plant-derived color) - lower layer second plant-derived flavor (second plant-derived color);

[0034] The upper and lower layers of this double-color, double-flavored yogurt have a delicate and smooth taste, rich and harmonious flavor, good color stratification stability, and no whey precipitation. It can bring a double wonderful experience to consumers' vision and taste, effectively meeting consumers' needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 1 is a schematic flow chart of a method for preparing a dual-color, dual-flavor yogurt according to an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the finished product of the double-color and double-flavor yogurt of Example 1;

[0038] Figure 3 This is a schematic diagram of the finished product of the double-color and double-flavor yogurt of Example 2;

[0039] Figure 4 This is a schematic diagram of the finished product of the double-color and double-flavor yogurt of Example 3;

[0040] Figure 5 This is a schematic diagram of the finished product of the double-color and double-flavor yogurt of Comparative Example 1;

[0041] Figure 6 This is a schematic diagram of the finished product of the double-color and double-flavor yogurt of Comparative Example 2;

[0042] Figure 7 This is a schematic diagram of the finished product of the double-color and double-flavor yogurt of Comparative Example 3;

[0043] Figure 8 This is a schematic diagram of the finished product of the double-color and double-flavor yogurt of Comparative Example 4;

[0044] Figure 9 Schematic diagram of the finished product state of the double-color and double-flavor yogurt of Comparative Example 5. DETAILED DESCRIPTION

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 making any creative efforts shall fall within the scope of protection of the present invention.

[0046] The present invention provides a double-color double-flavor yogurt, which is made by fermenting an upper layer of milk pulp and a lower layer of milk pulp together in a packaging container, breaking the traditional mode of producing solidified yogurt by a single fermentation process. The double-color double-flavor yogurt can be fermented in the same packaging container at the same time, and can produce a double-color double-flavor yogurt, which can bring a double wonderful experience of vision and taste to consumers and effectively meet the needs of consumers.

[0047] Specifically, the upper layer of milk slurry includes, by mass fraction: 8-10.2% of light cream, 10-14% of coconut oil, 0.8-2% of sodium caseinate, 5-10% of white sugar, 1.5-7% of concentrated whey protein, 0.1-0.2% of Tween-60, 0.15-0.24% of the first emulsion stabilizer, 0.3-0.5% of hydroxypropyl distarch phosphate, 40-50% of raw milk, 0.001-0.005% of yogurt fermentation bacteria, 0-0.4% of the first plant-based flavor coloring matter, and the balance is water.

[0048] In the upper layer of milk:

[0049] Light cream (8-10.2%) can provide a high fat content, giving the upper layer of milk an extremely rich, mellow, smooth mousse-like taste and rich milk flavor; the high fat content makes the upper layer of milk lighter and fluffier than the lower layer of milk.

[0050] Coconut oil (10-14%) and cream together serve as the main fat source, significantly increasing the fat content of the upper layer of milk and enhancing the rich milky aroma and taste of the upper layer of milk.

[0051] Sodium caseinate (0.8-2%) is mainly used as an emulsifier and stabilizer. It can wrap fat globules (cream, coconut oil), prevent fat from floating up or agglomerating, form a stable emulsion, and ensure a uniform and delicate texture. At the same time, as a thickener, it can increase the viscosity and water retention of the upper layer of milk, which helps to stabilize the gel structure during fermentation.

[0052] White sugar (5-10%) is mainly used as a sweetener to balance the sour taste produced by the fermentation of the upper milk and provide a pleasant sweet feeling.

[0053] Whey protein concentrate (1.5-7%) is mainly used as a protein fortifier, thickener and water-binding agent, which can significantly increase the protein content of the upper layer of milk and improve its nutritional value. Whey protein can form a gel network during heating and acidification, enhancing the strength, consistency and stability of the gel during fermentation of the upper layer of milk. It has good water-holding capacity, making the texture more solid and full, supporting the high-fat content structure. In addition, it has good solubility and is not easy to cause a powdery feeling.

[0054] Tween-60 (0.1-0.2%) is mainly used as an emulsifier, synergistically working with sodium caseinate to assist in emulsifying high-content fat (especially coconut oil), ensuring that the fat phase is evenly dispersed in the water phase, preventing oil-water separation, and improving the system stability of the upper milk slurry.

[0055] The first emulsion stabilizer (0.15-0.24%) is used to stabilize the emulsification system of the upper milk slurry and the gel structure of the upper milk slurry during fermentation. It can also thicken the milk, prevent water separation and improve the taste.

[0056] Hydroxypropyl distarch phosphate (0.3-0.5%) is mainly used as a thickener, stabilizer and gelling agent. It can significantly increase the viscosity of the upper layer of milk slurry, improve the consistency of the upper layer of milk slurry, provide a full texture and good wall adhesion; it can still maintain the thickening effect under acidic and heat treatment conditions, help stabilize the gel structure of the upper layer of milk slurry during fermentation, prevent water precipitation, and give the product a thicker, pudding or custard-like taste.

[0057] Raw milk (40-50%) is the basic raw material of the upper milk layer, which can provide the basic flavor and nutrition of yogurt; the lactose in raw milk is the main substrate for lactic acid bacteria fermentation, and the casein in raw milk forms the main gel network structure when acidified.

[0058] Yogurt fermentation bacteria (0.001-0.005%) are fermentation agents. During the fermentation process of the upper layer of milk, they use the lactose in the upper layer of milk to produce acid (lactic acid), causing the casein micelles to aggregate to form a gel structure, giving the upper layer of yogurt its characteristic sour taste and texture.

[0059] The first plant-derived flavor coloring substance (0-0.4%) is made from edible roots, stems, leaves, flowers or fruits of plants, and is mainly used as a flavoring agent and natural pigment to provide the upper layer of milk with a specific plant-derived flavor and corresponding color; 0% means that this layer can be original.

[0060] Water is mainly used as a diluent to adjust the concentration and viscosity of the upper milk slurry.

[0061] Preferably, the upper layer of milk slurry includes, by mass fraction, 8% light cream, 10% coconut oil, 2% sodium caseinate, 10% white sugar, 3.5% concentrated whey protein, 0.1% Tween-60, 0.19% first emulsification stabilizer, 0.3% hydroxypropyl distarch phosphate, 50% raw milk, 0.005% yogurt fermentation bacteria, 0% first plant-based flavor coloring matter, and the balance is water.

[0062] The upper layer of milk slurry of this preferred formula takes "original milk mousse" as the core experience. It is formed by combining specific mass fractions of light cream, coconut oil, sodium caseinate, white sugar, concentrated whey protein, Tween-60, the first emulsifier stabilizer, hydroxypropyl distarch phosphate and raw milk, as well as the remaining amount of water. It can form a stable high-fat, low-protein emulsion system that is light and smooth, and can stably float above the lower layer of milk slurry with a natural and clear boundary.

[0063] Specifically, the lower layer of milk slurry includes, by mass fraction: 70-71% raw cow's milk, 3-7% white sugar, 0-0.3% sodium caseinate, 3-6% skimmed milk powder, 0.25-0.45% second emulsification stabilizer, 0.001-0.005% yogurt fermentation bacteria, 0-0.4% second plant-based flavor coloring matter, and the balance is water.

[0064] In the lower layer of milk:

[0065] Raw cow's milk (70-71%) is the main raw material of the lower layer of milk, which can provide the main milk proteins (especially casein, which is the core of the yogurt gel network), lactose (fermentation substrate), milk fat (low content), minerals and flavor; the high proportion of raw cow's milk makes the lower layer of milk closer to the base of traditional yogurt and the flavor is more "pure".

[0066] White sugar (3-7%) is mainly used as a sweetener, which can provide sweetness to balance the fermentation acidity of the lower layer of milk.

[0067] Sodium caseinate (0-0.3%) is mainly used as a thickener to slightly improve the smoothness of the texture of the lower layer of milk, increase stability and water retention, and prevent slight whey precipitation; its usage in the lower layer of milk is very low and its role is not as critical as in the upper layer of milk; 0% means that sodium caseinate can be completely omitted and stability depends on other ingredients.

[0068] Skimmed milk powder (3-6%) is mainly used as a protein fortifier, which can increase the total protein of the lower layer of milk, improve the gel strength of the lower layer of milk during fermentation, increase the viscosity, improve the texture (making it more solid), and reduce water extraction; in addition, skimmed milk powder can provide additional frankincense flavor.

[0069] The second emulsifier stabilizer (0.25-0.45%) has the core function of thickening and stabilizing the gel structure of the lower layer of milk during fermentation, preventing water separation (water retention), and improving the smooth taste.

[0070] Yogurt fermentation bacteria (0.001-0.005%) are fermentation agents. During the fermentation process of the lower layer of milk slurry, they use the lactose in the lower layer of milk slurry to produce acid (lactic acid), causing the casein micelles to aggregate to form a gel structure, giving the lower layer of yogurt its characteristic sour taste and texture.

[0071] The second plant-derived flavor coloring substance (0-0.4%) is made from edible roots, stems, leaves, flowers or fruits of plants, and is mainly used as a flavoring agent and natural pigment to provide a specific plant-derived flavor and corresponding color to the lower layer of milk; 0% means that this layer can be original.

[0072] Water is mainly used as a diluent to adjust the concentration and viscosity of the lower layer of milk.

[0073] Preferably, the lower layer of milk slurry includes, by mass fraction, 70% raw cow's milk, 6% white sugar, 0.3% sodium caseinate, 5% skimmed milk powder, 0.4% second emulsification stabilizer, 0.005% yogurt fermentation bacteria, 0.4% second plant-based flavor coloring matter, and the balance is water.

[0074] The lower layer of milk slurry in this preferred formula is made by combining specific mass fractions of raw milk, white sugar, sodium caseinate, skimmed milk powder, a second emulsifier stabilizer and a second plant-derived flavor coloring substance, as well as the remaining amount of water, to create a "load-bearing base" with plant-derived flavor and color. During fermentation, it can form a stable gel structure with good strength, which can effectively support the weight of the upper layer and avoid collapse and mixing.

[0075] It should be noted that in the upper layer of milk slurry and the lower layer of milk slurry, there is at least one of the first plant-based flavor coloring substance and the second plant-based flavor coloring substance, and the first plant-based flavor coloring substance and the second plant-based flavor coloring substance have different flavors and colors to form a two-color double-flavor yogurt.

[0076] In the dual-color dual-flavor yogurt of the present invention, the upper layer of milk pulp and the lower layer of milk pulp have different special formula designs, so that the upper layer of milk pulp and the lower layer of milk pulp can be stably separated, so that the upper layer of milk pulp and the lower layer of milk pulp can be fermented together in the same packaging container while maintaining the separation state, laying a solid foundation for the formation of dual-color dual-flavor yogurt;

[0077] Moreover, by controlling the content and type of the first plant-derived flavor coloring substance and the second plant-derived flavor coloring substance, the upper layer of milk slurry and the lower layer of milk slurry can form different colors and flavor combinations, such as upper layer original flavor (original color) - lower layer plant-derived flavor (plant-derived color), upper layer plant-derived flavor (plant-derived color) - lower layer original flavor (original color), upper layer first plant-derived flavor (first plant-derived color) - lower layer second plant-derived flavor (second plant-derived color);

[0078] The upper and lower layers of this double-color, double-flavored yogurt have a delicate and smooth taste, rich and harmonious flavor, good color stratification stability, and no whey precipitation. It can bring a double wonderful experience to consumers' vision and taste, effectively meeting consumers' needs.

[0079] In some specific embodiments, the first emulsion stabilizer includes, based on the mass fraction relative to the total mass of the upper milk slurry, 0.08% sodium citrate, 0.03% carrageenan, 0.02% agar, 0.01% locust bean gum and 0.05% mono- and diglycerides of fatty acids.

[0080] Before the upper layer of milk ferments, sodium citrate can stabilize the emulsion by reducing the surface tension of the oil-water interface; carrageenan, agar and locust bean gum can be adsorbed on the surface of the particles to form a protective layer, preventing aggregation between particles and effectively improving the emulsion stability; mono- and diglycerol fatty acid esters can be co-adsorbed with sodium caseinate at the fat globule interface, effectively improving the emulsion stability.

[0081] During the fermentation of the upper milk layer, sodium citrate maintains a pH above 4.0, preventing the gel from shrinking too quickly and causing water precipitation. Carrageenan synergizes with casein to build an elastic skeleton, enhancing the stability of the gel structure. Agar compensates for the carrageenan's brittleness, preventing softening during transportation of the dual-color, dual-flavor yogurt. Locust bean gum, when combined with carrageenan, significantly enhances the gel's strength. During the fermentation of the upper milk layer, carrageenan, agar, locust bean gum, and casein work synergistically to form a gel network, while fat is embedded in this network in the form of globules, preventing the formation of a fat precipitation layer and reducing the greasy taste.

[0082] In some specific embodiments, the second emulsion stabilizer includes, by mass fraction relative to the total mass of the lower layer milk slurry, 0.05% pectin, 0.15% dipotassium hydrogen phosphate, and 0.2% sodium citrate.

[0083] Before the lower layer of milk ferments, pectin can be adsorbed on the surface of the particles to form a protective layer, preventing aggregation between particles and effectively improving the emulsion stability; dipotassium hydrogen phosphate and sodium citrate can stabilize the emulsion by reducing the surface tension of the oil-water interface.

[0084] When the lower layer of milk is fermenting, pectin can form a gel network in an acidic environment, which is beneficial to increase the viscosity and consistency, and can improve the stability of the lower layer of milk after fermentation; dipotassium hydrogen phosphate acts as a buffer to prevent excessive acidification during fermentation of the lower layer of milk, and on the other hand, it acts as a calcium ion shielding agent to prevent pectin from premature coagulation; sodium citrate synergistically buffers with dipotassium hydrogen phosphate on the one hand, and on the other hand can enhance the strength of pectin gel.

[0085] In some specific embodiments, the yogurt fermentation bacteria include Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus.

[0086] Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius thermophilus subsp. can synergistically promote milk fermentation; among them, Lactobacillus delbrueckii subsp. bulgaricus can not only produce acid (lactic acid) during the fermentation process, but also produce proteolytic enzymes. Under the action of this enzyme, a large number of amino acids are released from casein, which can promote the development of Streptococcus salivarius thermophilus subsp.; and the formate and carbon dioxide produced by Streptococcus salivarius thermophilus subsp. can promote the acid production of Lactobacillus delbrueckii subsp. bulgaricus.

[0087] In some specific embodiments, the first plant-based flavor coloring substance can be concentrated strawberry juice, or concentrated mango juice, or concentrated pineapple juice, or concentrated passion fruit juice, or concentrated watermelon juice, or concentrated cantaloupe juice, or concentrated orange juice, or concentrated tangerine juice, or concentrated blueberry juice, or concentrated sea buckthorn juice, or concentrated coconut juice, or concentrated kale juice, or cocoa powder, or matcha powder, or other edible plant-based substances with other flavors and colors; the second plant-based flavor coloring substance can be concentrated strawberry juice, or concentrated mango juice, or concentrated pineapple juice, or concentrated passion fruit juice, or concentrated watermelon juice, or concentrated cantaloupe juice, or concentrated orange juice, or concentrated tangerine juice, or concentrated blueberry juice, or concentrated sea buckthorn juice, or concentrated coconut juice, or concentrated kale juice, or cocoa powder, or matcha powder, or other edible plant-based substances with other flavors and colors.

[0088] These plant-derived flavor and coloring substances all have good flavor and eye-catching color, and are excellent flavoring agents and natural pigments.

[0089] In some specific embodiments, the volume ratio of the upper layer of milk slurry to the lower layer of milk slurry ranges from 1:3 to 3:1, and the corresponding volume ratio can be selected based on the response of the consumer market. Optionally, the volume ratio of the upper layer of milk slurry to the lower layer of milk slurry can be 1:3, 1:2, 1:1, 2:1, or 3:1.

[0090] The present invention also provides a method for preparing double-color and double-flavor yogurt. Figure 1 The flowchart of the method for preparing the dual-color and dual-flavor yogurt according to the embodiment of the present invention is shown, which includes the following steps:

[0091] S1. Mixing the formulated amounts of cream, coconut oil, sodium caseinate, white sugar, whey protein concentrate, Tween-60, a first emulsification stabilizer, hydroxypropyl distarch phosphate, raw cow's milk, and a first plant-based flavor coloring substance, adding water to a target total mass, and sequentially performing a high shear emulsification treatment and a homogenization treatment at 60-70° C., and cooling to obtain a first upper layer of milk slurry;

[0092] First, all components except yogurt fermentation bacteria are mixed together, and then high-shear emulsification and homogenization treatments are carried out in sequence within a specific temperature window (60-70°C). This process utilizes the combined effects of sodium caseinate, Tween-60, a first emulsion stabilizer and hydroxypropyl distarch phosphate to transform a complex mixture containing oils (animal + plant), proteins, sugars and other ingredients into a highly stable, uniform and fine oil-in-water emulsion; after cooling, the oil-in-water emulsion system will become more stable.

[0093] Specifically, the duration of the high shear emulsification treatment is in the range of 5 to 10 minutes, and the speed of the high shear emulsification treatment is in the range of 5800 to 6200 rpm / min, which can refine the fat particles to the submicron level and prepare for subsequent homogenization; preferably, the duration of the high shear emulsification treatment is 5 minutes, and the speed of the high shear emulsification treatment is 6000 rpm / min.

[0094] Specifically, the first-level homogenization pressure range of the homogenization treatment is 10-15MPa, and the second-level homogenization pressure range of the homogenization treatment is 1-5MPa, which can further refine and disperse the fat particles; preferably, the first-level homogenization pressure of the homogenization treatment is 12MPa, and the second-level homogenization pressure of the homogenization treatment is 2MPa.

[0095] Furthermore, the temperature range of the first upper layer of milk slurry is 20-30°C. Within this temperature window, the stability of the first upper layer of milk slurry is excellent and it is convenient to add yogurt fermentation bacteria later; preferably, the temperature of the first upper layer of milk slurry is 25°C.

[0096] S2, mixing the formulated amounts of raw milk, white sugar, sodium caseinate, skimmed milk powder, a second emulsion stabilizer, and a second plant-derived flavor coloring substance, adding water to a target total mass, and sequentially performing a high shear emulsification treatment and a homogenization treatment at 60-70° C., and cooling to obtain a first lower layer of milk slurry;

[0097] First, mix the other components except yogurt fermentation bacteria together, and perform high-shear emulsification treatment and homogenization treatment in a specific temperature window (60-70°C) in sequence to fully disperse the protein and form a stable protein sol system; after cooling, the protein sol system will be more stable.

[0098] Specifically, the duration of the high shear emulsification treatment is in the range of 5 to 10 minutes, and the speed of the high shear emulsification treatment is in the range of 5800 to 6200 rpm / min, which can effectively break up protein aggregates; preferably, the duration of the high shear emulsification treatment is 5 minutes, and the speed of the high shear emulsification treatment is 6000 rpm / min.

[0099] Specifically, the primary homogenization pressure range of the homogenization treatment is 10-15 MPa, and the secondary homogenization pressure range of the homogenization treatment is 1-5 MPa, so that the protein is fully dispersed; preferably, the primary homogenization pressure of the homogenization treatment is 12 MPa, and the secondary homogenization pressure of the homogenization treatment is 2 MPa.

[0100] Furthermore, the temperature range of the first lower layer of milk slurry is 20-30°C. Within this temperature window, the stability of the first lower layer of milk slurry is excellent and it is convenient to add yogurt fermentation bacteria later. Preferably, the temperature of the first lower layer of milk slurry is 25°C.

[0101] S3, adding a formula amount of yogurt fermentation bacteria to the first upper layer of milk slurry, stirring evenly to obtain a second upper layer of milk slurry;

[0102] The stirring process needs to be gentle to avoid inactivating the yogurt fermentation bacteria.

[0103] S4, adding a formula amount of yogurt fermentation bacteria to the first lower layer of milk slurry, stirring evenly to obtain a second lower layer of milk slurry;

[0104] The stirring process needs to be gentle to avoid inactivating the yogurt fermentation bacteria.

[0105] S5, first filling the second lower layer of milk slurry into the packaging container, and then filling the second upper layer of milk slurry into the packaging container to obtain the double-color double-layer milk slurry to be fermented;

[0106] When filling the second upper layer of milk slurry, it is necessary to pour slowly to avoid impacting the second lower layer of milk slurry, which will cause the boundary between the second upper layer of milk slurry and the second lower layer of milk slurry to be blurred.

[0107] S6. Place the double-color double-layer milk slurry to be fermented at 40-45° C. for 340-380 min, cool it to terminate the fermentation, and obtain a double-color double-flavor yogurt.

[0108] Through the precise triple control of temperature, time and anaerobic conditions, the differentiated coagulation behaviors of the upper and lower layers of milk are coordinated, joint fermentation is achieved, and dual color separation and dual flavors are guaranteed.

[0109] In order to achieve anaerobic fermentation, the packaging container can be covered with a lid or sealed with plastic wrap.

[0110] Preferably, the double-color double-layer milk slurry to be fermented is placed under conditions of 43° C. for 360 minutes for anaerobically fermentation.

[0111] Specifically, cooling and terminating fermentation includes:

[0112] The temperature is lowered to 3-5°C and maintained for at least 300 minutes, which not only allows the yogurt fermentation bacteria to enter dormancy, but also allows the gel structure to complete aging and prevent dehydration shrinkage. Preferably, the temperature is lowered to 4°C.

[0113] Specifically, the pH range of the double-color and double-flavor yogurt is 4.5 to 4.7, with moderate acidity and good flavor.

[0114] The preparation method of the double-color double-flavor yogurt of the present invention can give full play to the special formula design of the upper milk slurry and the lower milk slurry, so that the upper milk slurry and the lower milk slurry can be fermented together in the same packaging container while maintaining the layered state; moreover, the prepared double-color double-flavor yogurt has distinct colors and clear boundaries between the upper and lower layers, a delicate and smooth taste, a rich and coordinated flavor, good color layering stability, and no whey precipitation, which can bring a double wonderful experience to consumers' vision and taste, and effectively meet the needs of consumers.

[0115] Example 1

[0116] A double-color, double-flavored yogurt is prepared by fermenting an upper layer of milk slurry and a lower layer of milk slurry together in a packaging container. 1000g of the upper layer of milk slurry comprises: 80g of light cream, 100g of coconut oil, 20g of sodium caseinate, 100g of white sugar, 35g of concentrated whey protein, 1g of Tween-60, 1.9g of a first emulsifier, 3g of hydroxypropyl distarch phosphate, 500g of raw milk, 0.05g of yogurt fermentation bacteria, and the balance is water. 1000g of the lower layer of milk slurry comprises: 700g of raw milk, 60g of white sugar, 3g of sodium caseinate, 50g of skim milk powder, 4g of a second emulsifier, 0.05g of yogurt fermentation bacteria, 4g of concentrated strawberry juice, and the balance is water.

[0117] Among them, the first emulsion stabilizer includes: 0.8g sodium citrate, 0.3g carrageenan, 0.2g agar, 0.1g locust bean gum and 0.5g mono- and diglycerol fatty acid esters; the second emulsion stabilizer includes: 0.5g pectin, 1.5g dipotassium hydrogen phosphate and 2g sodium citrate.

[0118] The preparation method of the double-color and double-flavor yogurt comprises the following steps:

[0119] (1) The cream, coconut oil, sodium caseinate, white sugar, concentrated whey protein, Tween-60, the first emulsification stabilizer, hydroxypropyl distarch phosphate and raw milk in the formula amount are mixed together, and water is added to the target total mass of 1000 g (the mass of the yogurt fermentation bacteria is too small and can be basically ignored and not included in the target total mass), and high shear emulsification treatment and homogenization treatment are sequentially performed at 65° C., and the first upper milk slurry is obtained after cooling to 25° C.;

[0120] The duration of the high shear emulsification treatment is 5 minutes, and the rotation speed of the high shear emulsification treatment is 6000 rpm / min; the first-level homogenization pressure of the homogenization treatment is 12 MPa, and the second-level homogenization pressure of the homogenization treatment is 2 MPa.

[0121] (2) Mix the formulated amount of raw milk, white sugar, sodium caseinate, skimmed milk powder, a second emulsifier stabilizer, and concentrated strawberry juice, add water to a target total mass of 1000 g (the mass of yogurt fermentation bacteria is too small to be considered, and is not included in the target total mass), and perform high shear emulsification and homogenization treatments at 65° C. in sequence, and cool to 25° C. to obtain a first lower layer of milk slurry;

[0122] The duration of the high shear emulsification treatment is 5 minutes, and the rotation speed of the high shear emulsification treatment is 6000 rpm / min; the first-level homogenization pressure of the homogenization treatment is 12 MPa, and the second-level homogenization pressure of the homogenization treatment is 2 MPa.

[0123] (3) Add the formulated amount of yogurt fermentation bacteria to the first upper layer of milk slurry and gently stir to obtain the second upper layer of milk slurry.

[0124] (4) Add the formulated amount of yogurt fermentation bacteria to the first lower layer of milk slurry and gently stir to obtain the second lower layer of milk slurry.

[0125] (5) First, the second lower layer of milk slurry is filled into the packaging container, and then the second upper layer of milk slurry of the same volume is slowly filled into the packaging container to obtain the double-color double-layer milk slurry to be fermented.

[0126] (6) The double-color double-layer milk slurry to be fermented is placed under 43°C for anaerobic fermentation for 360 minutes, and then cooled to 4°C and kept for at least 300 minutes to terminate the fermentation, thereby obtaining a double-color double-flavor yogurt ( Figure 2 Schematic diagram showing the finished product state of the double-color and double-flavor yogurt of Example 1); at this time, the pH of the double-color and double-flavor yogurt is 4.6.

[0127] Example 2

[0128] A double-color, double-flavored yogurt is prepared by fermenting an upper layer of milk slurry and a lower layer of milk slurry together in a packaging container. 1000g of the upper layer of milk slurry comprises: 102g of light cream, 140g of coconut oil, 8g of sodium caseinate, 50g of white sugar, 15g of concentrated whey protein, 1g of Tween-60, 2.4g of a first emulsion stabilizer, 3g of hydroxypropyl distarch phosphate, 500g of raw milk, 0.05g of yogurt fermentation bacteria, and the balance is water. 1000g of the lower layer of milk slurry comprises: 700g of raw milk, 60g of white sugar, 0g of sodium caseinate, 60g of skim milk powder, 4.5g of a second emulsion stabilizer, 0.05g of yogurt fermentation bacteria, 4g of concentrated strawberry juice, and the balance is water.

[0129] Among them, the first emulsion stabilizer includes: 0.8g sodium citrate, 0.1g carrageenan, 0.2g agar, 0.3g locust bean gum and 1g mono- and diglycerol fatty acid esters; the second emulsion stabilizer includes: 2g pectin, 1g dipotassium hydrogen phosphate and 1.5g sodium citrate.

[0130] The preparation method of the double-color and double-flavor yogurt is the same as that of Example 1.

[0131] Figure 3 A schematic diagram showing the finished product state of the double-color and double-flavor yogurt of Example 2 is shown.

[0132] Example 3

[0133] A double-color, double-flavored yogurt is prepared by fermenting an upper layer of milk slurry and a lower layer of milk slurry together in a packaging container. 1000g of the upper layer of milk slurry comprises: 80g of light cream, 100g of coconut oil, 12g of sodium caseinate, 100g of white sugar, 70g of concentrated whey protein, 1g of Tween-60, 1.5g of a first emulsion stabilizer, 5g of hydroxypropyl distarch phosphate, 400g of raw milk, 0.05g of yogurt fermentation bacteria, and the balance is water. 1000g of the lower layer of milk slurry comprises: 700g of raw milk, 60g of white sugar, 0g of sodium caseinate, 60g of skim milk powder, 2.5g of a second emulsion stabilizer, 0.05g of yogurt fermentation bacteria, 2g of concentrated strawberry juice, and the balance is water.

[0134] Among them, the first emulsion stabilizer includes: 0g sodium citrate, 0.3g carrageenan, 0.2g agar, 0.5g locust bean gum and 0.5g mono- and diglycerol fatty acid esters; the second emulsion stabilizer includes: 0g pectin, 1g dipotassium hydrogen phosphate and 1.5g sodium citrate.

[0135] The preparation method of the double-color and double-flavor yogurt is the same as that of Example 1.

[0136] Figure 4 A schematic diagram of the finished product state of the double-color and double-flavor yogurt of Example 3 is shown.

[0137] Comparative Example 1

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

[0139] The content of light cream in 1000g of upper milk is 0, and the content of coconut oil is 0. The difference is made up with water, and the rest remains unchanged.

[0140] Figure 5 A schematic diagram of the finished product state of the double-color and double-flavor yogurt of Comparative Example 1 is shown.

[0141] Comparative Example 2

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

[0143] The content of Tween-60 in 1000g of the upper milk slurry is 0g, and the difference is made up with water, while the others remain unchanged.

[0144] Figure 6 A schematic diagram of the finished product state of the double-color and double-flavor yogurt of Comparative Example 2 is shown.

[0145] Comparative Example 3

[0146] This comparative example is basically the same as Example 2, except that:

[0147] The content of sodium caseinate in 1000g of the upper milk slurry is 0g. The difference is made up with water, and the rest remains unchanged.

[0148] Figure 7 A schematic diagram of the finished product state of the double-color and double-flavor yogurt of Comparative Example 3 is shown.

[0149] Comparative Example 4

[0150] This comparative example is basically the same as Example 1, except that:

[0151] When preparing the first upper layer of milk slurry, high shear emulsification treatment was not performed at 65° C., and homogenization treatment was directly performed, while other conditions remained unchanged.

[0152] Figure 8 A schematic diagram of the finished product state of the double-color and double-flavor yogurt of Comparative Example 4 is shown.

[0153] Comparative Example 5

[0154] This comparative example is basically the same as Example 1, except that:

[0155] Anaerobic fermentation was carried out for 400 min, and other conditions remained unchanged.

[0156] Figure 9 A schematic diagram of the finished product state of the double-color and double-flavor yogurt of Comparative Example 5 is shown.

[0157] Sensory evaluation

[0158] Sensory evaluation was performed on the double-color and double-flavor yogurts of Examples 1 to 3 and Comparative Examples 1 to 5:

[0159] The sensory evaluation of the double-color and double-flavor yogurt was carried out according to the sensory evaluation standard table in Table 1. The main evaluation items included texture, color, flavor and taste. 50 professional sensory evaluators were selected to score the texture, color, flavor and taste of the double-color and double-flavor yogurt respectively. The average of each item was taken according to the score of the sensory evaluators, and the average score of the four items was summed as the sensory evaluation score of the double-color and double-flavor yogurt. The specific results are shown in Table 2.

[0160] Table 1 Sensory evaluation standards

[0161]

[0162]

[0163] Table 2 Sensory evaluation results

[0164]

[0165]

[0166]

[0167] The double-color and double-flavor yogurts of Examples 1 to 3 and Comparative Examples 1 to 5 are all yogurt products with an upper layer of milky original flavor (creamy yellow) and a lower layer of strawberry flavor (pink).

[0168] Among them, the total scores of the double-color and double-flavor yogurts of Examples 1 to 3 are all greater than 90, and they all have good texture, color, flavor and taste. They can present the visual impact of milk yellow and pink in the same packaging container, as well as two very different but mutually coordinated flavors of milk and strawberry. Moreover, the upper and lower layers of yogurt have a delicate and mellow taste, moderate sour and sweet, and a uniform taste.

[0169] By comparing Example 1 and Comparative Example 1, it can be seen that oil (cream and coconut oil) has a significant impact on the overall color, flavor and taste of yogurt. Lack of oil will cause the lower layer of milk slurry to easily diffuse deeply into the upper layer of milk slurry, and cannot be stably layered; lack of oil will also weaken the milk aroma of the upper layer of yogurt and cause the aroma of the upper and lower layers of yogurt to be unbalanced; lack of oil will also cause the overall yogurt to lose its mellow taste and make the overall sour taste of the yogurt too prominent.

[0170] Comparison of Example 1 and Comparative Example 2 shows that Tween-60 has a significant impact on the overall texture and color of yogurt. The lack of Tween-60 will cause the upper and lower layers of milk to deeply diffuse into each other and cannot be stably separated. Moreover, the lack of Tween-60 will also cause whey precipitation.

[0171] By comparing Example 1, Example 2 and Comparative Example 3, it can be seen that the lack of sodium caseinate in the lower layer of milk slurry does not affect the overall yogurt, but the lack of sodium caseinate in the upper layer of milk slurry will cause the overall color of the yogurt to deteriorate, and the upper layer of milk slurry will diffuse into the lower layer of milk slurry, and it cannot be stably layered.

[0172] By comparing Example 1 and Comparative Example 4, it can be seen that in the preparation process of the first upper layer of milk slurry, the high shear emulsification treatment has a significant impact on the taste of the upper layer of yogurt. The lack of high shear emulsification treatment will lead to uneven dispersion of oil, making the mouthfeel of the upper layer of yogurt greasy and slightly fatter.

[0173] Comparison of Example 1 and Comparative Example 5 shows that the fermentation time has a significant impact on the overall texture and taste of the yogurt. A too long fermentation time will result in more whey precipitation and make the yogurt more acidic.

[0174] In summary, the formula design and preparation method of the dual-color and dual-flavor yogurt of the present invention cooperate with each other within an appropriate range and work synergistically. The prepared dual-color and dual-flavor yogurt has a delicate, mellow and smooth taste, good color stratification stability, no whey precipitation, and the upper and lower yogurts have rich flavors and harmonious aromas. It can present the visual impact of two colors in the same packaging container, as well as two very different and mutually coordinated flavors, which provides new ideas for the development of subsequent yogurt products.

[0175] The above is a detailed introduction to a double-color and double-flavor yogurt and a preparation method thereof provided by an embodiment of the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A double-color and double-flavor yogurt, characterized in that: The double-color and double-flavor yogurt is prepared by fermenting the upper layer of milk pulp and the lower layer of milk pulp together in a packaging container; The upper layer of milk slurry comprises, by mass fraction, 8-10.2% of cream, 10-14% of coconut oil, 0.8-2% of sodium caseinate, 5-10% of white sugar, 1.5-7% of concentrated whey protein, 0.1-0.2% of Tween-60, 0.15-0.24% of a first emulsion stabilizer, 0.3-0.5% of hydroxypropyl distarch phosphate, 40-50% of raw milk, 0.001-0.005% of yogurt fermentation bacteria, 0-0.4% of a first plant-derived flavor coloring matter, and the balance being water; The lower layer of milk slurry comprises, by mass fraction, 70-71% raw cow's milk, 3-7% white sugar, 0-0.3% sodium caseinate, 3-6% skimmed milk powder, 0.25-0.45% second emulsion stabilizer, 0.001-0.005% yogurt fermentation bacteria, 0-0.4% second plant-derived flavor coloring matter, and the balance being water; There is at least one of the first plant-derived flavor and coloring substance and the second plant-derived flavor and coloring substance, and the first plant-derived flavor and coloring substance and the second plant-derived flavor and coloring substance are different in flavor and color.

2. The double-color and double-flavor yogurt according to claim 1, characterized in that: The upper layer of milk slurry comprises, by mass fraction, 8% of light cream, 10% of coconut oil, 2% of sodium caseinate, 10% of white sugar, 3.5% of concentrated whey protein, 0.1% of Tween-60, 0.19% of a first emulsifier stabilizer, 0.3% of hydroxypropyl distarch phosphate, 50% of raw milk, 0.005% of yogurt fermentation bacteria, 0% of a first plant-derived flavor coloring matter, and the balance being water; The lower layer of milk slurry comprises, by mass fraction, 70% raw cow's milk, 6% white sugar, 0.3% sodium caseinate, 5% skimmed milk powder, 0.4% second emulsification stabilizer, 0.005% yogurt fermentation bacteria, 0.4% second plant-derived flavor coloring matter, and the balance being water.

3. The double-color and double-flavor yogurt according to claim 2, characterized in that: Calculated by mass fraction relative to the total mass of the upper milk slurry, the first emulsion stabilizer includes: 0.08% sodium citrate, 0.03% carrageenan, 0.02% agar, 0.01% locust bean gum, and 0.05% mono- and diglycerides of fatty acids; Calculated by mass fraction relative to the total mass of the lower layer milk slurry, the second emulsion stabilizer includes: 0.05% pectin, 0.15% dipotassium hydrogen phosphate and 0.2% sodium citrate.

4. The double-color and double-flavor yogurt according to claim 1, characterized in that: The yogurt fermentation bacteria include Lactobacillus delbrueckii subspecies bulgaricus and Streptococcus salivarius subspecies thermophilic; The first plant-derived flavor coloring substance comprises one of concentrated strawberry juice, concentrated mango juice, concentrated pineapple juice, concentrated passion fruit juice, concentrated watermelon juice, concentrated cantaloupe juice, concentrated orange juice, concentrated tangerine juice, concentrated blueberry juice, concentrated sea buckthorn juice, concentrated coconut juice, concentrated kale juice, cocoa powder, and matcha powder; The second plant-based flavor coloring substance includes one of concentrated strawberry juice, concentrated mango juice, concentrated pineapple juice, concentrated passion fruit juice, concentrated watermelon juice, concentrated cantaloupe juice, concentrated orange juice, concentrated tangerine juice, concentrated blueberry juice, concentrated sea buckthorn juice, concentrated coconut juice, concentrated kale juice, cocoa powder, and matcha powder.

5. The double-color and double-flavor yogurt according to claim 1, characterized in that: The volume ratio of the upper layer of milk slurry to the lower layer of milk slurry is in the range of 1:3 to 3:

1.

6. A method for preparing the double-color and double-flavor yogurt according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Mixing the formulated amounts of cream, coconut oil, sodium caseinate, white sugar, whey protein concentrate, Tween-60, a first emulsification stabilizer, hydroxypropyl distarch phosphate, raw cow's milk, and a first plant-based flavor coloring substance, adding water to a target total mass, and sequentially performing a high shear emulsification treatment and a homogenization treatment at 60-70° C., and cooling to obtain a first upper layer of milk slurry; S2, mixing the formulated amounts of raw milk, white sugar, sodium caseinate, skimmed milk powder, a second emulsion stabilizer, and a second plant-derived flavor coloring substance, adding water to a target total mass, and sequentially performing a high shear emulsification treatment and a homogenization treatment at 60-70° C., and cooling to obtain a first lower layer of milk slurry; S3, adding a formulated amount of yogurt fermentation bacteria to the first upper layer of milk slurry, and stirring evenly to obtain a second upper layer of milk slurry; S4, adding a formulated amount of yogurt fermentation bacteria to the first lower layer of milk slurry, and stirring evenly to obtain a second lower layer of milk slurry; S5. First, fill the second lower layer of milk slurry into a packaging container, and then fill the second upper layer of milk slurry into the packaging container to obtain a double-color double-layer milk slurry to be fermented; S6. Place the double-color double-layer milk slurry to be fermented at 40-45° C. for 340-380 min, cool it to terminate the fermentation, and obtain double-color double-flavor yogurt.

7. The method for preparing the double-color and double-flavor yogurt according to claim 6, wherein: In step S1 and step S2, the duration of the high shear emulsification treatment is in the range of 5 to 10 minutes, and the speed of the high shear emulsification treatment is in the range of 5800 to 6200 rpm / min; In step S1 and step S2, the first-level homogenization pressure of the homogenization and slurry treatment is in the range of 10 to 15 MPa, and the second-level homogenization pressure of the homogenization and slurry treatment is in the range of 1 to 5 MPa.

8. The method for preparing the double-color and double-flavor yogurt according to claim 6, wherein: In step S1 and step S2, the temperature range of the first upper layer of milk slurry is 20-30°C, and the temperature range of the first lower layer of milk slurry is 20-30°C.

9. The method for preparing the double-color and double-flavor yogurt according to claim 6, wherein: In step S6, the cooling and terminating fermentation comprises: Lower the temperature to 3-5°C and maintain it for at least 300 minutes.

10. The method for preparing the double-color and double-flavor yogurt according to claim 6, wherein: The pH range of the double-color and double-flavor yogurt is 4.5-4.7.

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