A double color double flavor yogurt and a preparation method thereof

Abstract

The application discloses a double-color double-flavor yogurt and a preparation method thereof, and relates to the technical field of yogurt. The double-color double-flavor yogurt is formed by co-fermentation of upper milk gruel and lower milk gruel in a packaging container. The upper milk gruel comprises: light cream, coconut oil, sodium caseinate, white granulated sugar, concentrated whey protein, Tween-60, a first emulsion stabilizer, hydroxypropyl distarch phosphate, raw cow milk, yogurt fermentation bacteria, a first plant-derived flavoring coloring material, and the balance of water. The lower milk gruel comprises: raw cow milk, white granulated sugar, sodium caseinate, skimmed milk powder, a second emulsion stabilizer, yogurt fermentation bacteria, a second plant-derived flavoring coloring material, and the balance of water. The double-color double-flavor yogurt can be prepared by co-fermentation of the upper milk gruel and the lower milk gruel in the packaging container according to the specific formula, and can bring double wonderful experiences of vision and taste to consumers, and effectively meet the needs of consumers.

Description

Technical Field

[0001] This invention relates to the field of yogurt technology, specifically to a two-color, two-flavor yogurt and its preparation method. Background Technology

[0002] Yogurt is a fermented dairy product that is popular due to its digestive benefits, ease of absorption, ability to regulate gut microbiota, and ability to boost immunity. Furthermore, as demand for yogurt continues to grow in the consumer market, yogurt products have become increasingly diverse, including set yogurt, stirred yogurt, drinkable yogurt, and Greek yogurt, offering consumers more choices.

[0003] Among them, the fermentation process of set-type yogurt is carried out in the packaging container, so that the finished product retains the curd state due to fermentation, has a rich natural fermented aroma, is delicate and smooth, has a thick texture, a suitable balance of sweet and sour, and a lingering aftertaste, giving it a strong competitive advantage in the consumer market.

[0004] However, existing set-type yogurts are usually produced using a single fermentation process, resulting in a highly uniform flavor and color. Each cup of set-type yogurt can only provide a single flavor and color experience, which is difficult to satisfy consumers' dual pursuit of visual appeal and flavor diversity. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides a two-color, two-flavor yogurt and its preparation method. By fermenting the upper and lower milk slurries together in a packaging container using a specific formula, a two-color, two-flavor yogurt can be produced, which can bring consumers a wonderful visual and taste experience and effectively meet consumer needs.

[0006] This invention provides a two-color, two-flavor yogurt, which is made by fermenting an upper layer of milk and a lower layer of milk together in a packaging container; The upper layer of milk, by mass fraction, comprises: 8-10.2% light cream, 10-14% coconut oil, 0.8-2% sodium caseinate, 5-10% white sugar, 1.5-7% concentrated whey protein, 0.1-0.2% Tween-60, 0.19-0.24% first emulsifying stabilizer, 0.3-0.5% hydroxypropyl distarch phosphate, 40-50% raw milk, 0.001-0.005% yogurt fermentation bacteria, 0-0.4% first plant-derived flavor coloring substance, and the balance being water; The lower layer of milk slurry comprises, by mass fraction: 70-71% raw milk, 3-7% white sugar, 0-0.3% sodium caseinate, 3-6% skim milk powder, 0.4-0.45% second emulsifying stabilizer, 0.001-0.005% yogurt fermentation bacteria, 0-0.4% second plant-derived flavor coloring substance, and the remainder being water; At least one of the first plant-derived flavor coloring substance and the second plant-derived flavor coloring substance is present, and the flavor and color of the first plant-derived flavor coloring substance and the second plant-derived flavor coloring substance are different.

[0007] Specifically, the upper layer of milk comprises, 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 emulsifying stabilizer, 0.3% hydroxypropyl distarch phosphate, 50% raw milk, 0.005% yogurt fermentation bacteria, 0% first plant-derived flavor coloring substance, and the remainder being water; The lower layer of milk slurry comprises, by mass fraction: 70% raw milk, 6% white sugar, 0.3% sodium caseinate, 5% skim milk powder, 0.4% second emulsifying stabilizer, 0.005% yogurt fermentation bacteria, 0.4% second plant-derived flavor coloring substance, and the remainder is water.

[0008] Specifically, the first emulsifying stabilizer, by mass fraction relative to the total mass of the upper layer of milk, comprises: 0.08% sodium citrate, 0.03% carrageenan, 0.02% agar, 0.01% locust bean gum, and 0.05% mono- and diglyceride fatty acid esters; The second emulsifying stabilizer comprises, by mass fraction relative to the total mass of the lower layer of milk, 0.05% pectin, 0.15% dipotassium hydrogen phosphate, and 0.2% sodium citrate.

[0009] Specifically, the yogurt fermentation bacteria include *Lactobacillus delbrueckii* subsp. *bulgaricus* and *Streptococcus salivarius* subsp. *thermophilus*. The first plant-derived flavor coloring substance includes one of the following: 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-derived flavor coloring substance includes one of the following: 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.

[0010] Specifically, the volume ratio of the upper milk layer to the lower milk layer is in the range of 1:3 to 3:1.

[0011] This invention also provides a method for preparing two-color, two-flavor yogurt, comprising the following steps: S1. Mix the following ingredients in the specified amounts: light cream, coconut oil, sodium caseinate, white sugar, concentrated whey protein, Tween-60, first emulsifying stabilizer, hydroxypropyl distarch phosphate, raw milk, and first plant-derived flavor coloring substance. Add water to the target total mass and then perform high-shear emulsification and homogenization treatment sequentially at 60-70°C. After cooling, the first upper layer of milk is obtained. S2. Mix the raw milk, white sugar, sodium caseinate, skim milk powder, second emulsifier, and second plant-derived flavor coloring agent according to the formula, add water to the target total mass, and perform high-shear emulsification and homogenization treatment in sequence at 60-70℃. After cooling, the first lower layer of milk slurry is obtained. S3. Add the formula amount of yogurt fermentation bacteria to the first upper layer of milk slurry and stir evenly to obtain the second upper layer of milk slurry. S4. Add the formula amount of yogurt fermentation bacteria to the first lower layer of milk slurry and stir evenly to obtain the second lower layer of milk slurry. S5. First, fill the second lower layer milk slurry into the packaging container, and then fill the packaging container with the second upper layer milk slurry to obtain a two-color, two-layer milk slurry to be fermented. S6. Place the two-color, two-layer milk slurry to be fermented at 40-45℃ for anaerobic fermentation for 340-380 minutes, cool to terminate fermentation, and obtain two-color, two-flavor yogurt.

[0012] Specifically, in steps S1 and S2, the duration of the high-shear emulsification treatment is 5 to 10 minutes, and the rotation speed of the high-shear emulsification treatment is 5800 to 6200 rpm. In steps S1 and S2, the primary homogenization pressure range of the homogenization process is 10–15 MPa, and the secondary homogenization pressure range of the homogenization process is 1–5 MPa.

[0013] Specifically, in steps S1 and 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.

[0014] Specifically, in step S6, the cooling to terminate fermentation includes: Lower the temperature to 3–5°C and maintain it for at least 300 minutes.

[0015] Specifically, the pH range of the two-color, two-flavor yogurt is 4.5 to 4.7.

[0016] Compared with the prior art, the beneficial effects of the present invention are: In the two-color, two-flavor yogurt of the present invention, the upper and lower milk slurries have different special formula designs, which enable the upper and lower milk slurries to be stably separated, thereby allowing the upper and lower milk slurries to ferment together in the same packaging container while maintaining separation, laying a solid foundation for the formation of two-color, two-flavor yogurt. Moreover, by controlling the content and types of the first and second plant-derived flavor coloring substances, different colors and flavor combinations can be formed between the upper and lower layers of milk, 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). This two-tone, two-flavor yogurt has a delicate and smooth texture in both the top and bottom layers, a rich and harmonious flavor, good color layering stability, and no whey separation, providing consumers with a wonderful dual experience for both their eyes and taste buds, effectively meeting their needs. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart of the preparation method of two-color, two-flavor yogurt in an embodiment of the present invention; Figure 2 This is a schematic diagram of the finished product state of the two-color, two-flavor yogurt in Example 1; Figure 3 This is a schematic diagram of the finished product state of the two-color, two-flavor yogurt in Example 2; Figure 4 This is a schematic diagram of the finished product state of the two-color, two-flavor yogurt in Example 3; Figure 5 This is a schematic diagram of the finished product state of the two-color, two-flavor yogurt in Comparative Example 1; Figure 6 This is a schematic diagram of the finished product state of the two-color, two-flavor yogurt in Comparative Example 2; Figure 7 This is a schematic diagram of the finished product state of the two-color, two-flavor yogurt in Comparative Example 3; Figure 8 This is a schematic diagram of the finished product state of the two-color, two-flavor yogurt in Comparative Example 4. Figure 9 This is a schematic diagram of the finished product state of the two-color, two-flavor yogurt in proportion 5. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention provides a two-color, two-flavor yogurt, which is made by fermenting the upper and lower layers of milk together in a packaging container. This breaks the traditional single-fermentation process for producing set-type yogurt, and allows for the simultaneous fermentation of two flavors of milk in the same packaging container. This produces a two-color, two-flavor yogurt that provides consumers with a wonderful visual and gustatory experience, effectively meeting their needs.

[0021] Specifically, the upper layer of milk, by mass fraction, includes: 8-10.2% light cream, 10-14% coconut oil, 0.8-2% sodium caseinate, 5-10% white sugar, 1.5-7% concentrated whey protein, 0.1-0.2% Tween-60, 0.19-0.24% primary emulsifying stabilizer, 0.3-0.5% hydroxypropyl distarch phosphate, 40-50% raw milk, 0.001-0.005% yogurt fermentation bacteria, 0-0.4% primary plant-derived flavor coloring substance, and the balance being water.

[0022] In the upper layer of milk: Whipping cream (8-10.2%) provides a high fat content, giving the top layer of milk an extremely rich, smooth, mousse-like texture and a rich milky flavor; the high fat content makes the top layer of milk lighter and fluffier than the bottom layer of milk.

[0023] Coconut oil (10-14%) and heavy cream together serve as the main fat sources, significantly increasing the fat content of the top layer of milk and enhancing its rich milky aroma and texture.

[0024] Sodium caseinate (0.8-2%) mainly acts as an emulsifier and stabilizer, which can encapsulate fat globules (cream, coconut oil) to prevent fat from floating or agglomerating, forming a stable emulsion and ensuring a uniform and delicate texture. At the same time, as a thickener, it can increase the viscosity and water-holding capacity of the upper milk layer, which helps to stabilize the gel structure during fermentation.

[0025] White sugar (5-10%) is mainly used as a sweetener to balance the sourness produced by the fermentation of the upper layer of milk and provide a pleasant sweetness.

[0026] Concentrated whey protein (1.5-7%) mainly serves as a protein fortifier, thickener, and water-holding agent. It can significantly increase the protein content of the upper layer of milk and improve its nutritional value. During heating and acidification, whey protein can form a gel network, which enhances the strength, consistency, and stability of the gel during fermentation of the upper layer of milk. It has good water-holding capacity, making its texture more solid and full, supporting the structure with high fat content. Moreover, it has good solubility and is less likely to cause a powdery texture.

[0027] Tween-60 (0.1-0.2%) mainly acts as an emulsifier, working synergistically with sodium caseinate to assist in emulsifying high-fat content (especially coconut oil), ensuring that the fat phase is evenly dispersed in the aqueous phase, preventing oil-water separation, and improving the system stability of the upper milk slurry.

[0028] The first emulsifying stabilizer (0.19–0.24%) is used to stabilize the emulsification system of the upper milk slurry and the gel structure during fermentation of the upper milk slurry. It also thickens, prevents water separation, and improves the taste.

[0029] Hydroxypropyl distarch phosphate (0.3-0.5%) is mainly used as a thickener, stabilizer and gelling agent. It can significantly increase the viscosity and consistency of the upper milk slurry, provide a full texture and good adhesion to the wall. It can maintain its thickening effect under acidic and heat treatment conditions, which helps to stabilize the gel structure of the upper milk slurry during fermentation, prevent water separation, and give the product a thicker, pudding-like or custard-like texture.

[0030] Raw milk (40-50%) is the basic raw material for the upper layer of milk, providing the basic flavor and nutrition of yogurt; lactose in raw milk is the main substrate for lactic acid bacteria fermentation, and casein in raw milk forms the main gel network structure during acidification.

[0031] Yogurt starter cultures (0.001–0.005%) are the starter cultures. During the fermentation of the upper layer of milk, lactose in the upper layer of milk is used to produce acid (lactic acid), which causes casein micelles to aggregate and form a gel structure, giving the upper layer of yogurt its characteristic sour taste and texture.

[0032] The first plant-derived flavor coloring substance (0-0.4%) uses edible roots, stems, leaves, flowers or fruits of plants as raw materials, mainly as flavoring agents and natural pigments, to provide the upper layer of milk with specific plant-derived flavor and corresponding color; 0% indicates that the layer can be plain.

[0033] Water is mainly used as a diluent to adjust the concentration and viscosity of the upper layer of milk.

[0034] Preferably, the upper layer of milk comprises, 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 emulsifying stabilizer, 0.3% hydroxypropyl distarch phosphate, 50% raw milk, 0.005% yogurt fermentation bacteria, 0% first plant-derived flavor coloring substance, and the balance being water.

[0035] The top layer of milk in this optimized formula is designed with "original milk mousse" as its core experience. It is made by combining specific mass fractions of light cream, coconut oil, sodium caseinate, white sugar, whey protein concentrate, Tween-60, primary emulsifier, hydroxypropyl distarch phosphate, and raw milk, with the remainder being water. This creates a stable, high-fat, low-protein emulsion system that is light, smooth, and floats steadily on top of the bottom layer of milk, with a clear and natural boundary.

[0036] Specifically, the lower layer of milk, by mass fraction, includes: 70-71% raw milk, 3-7% white sugar, 0-0.3% sodium caseinate, 3-6% skim milk powder, 0.4-0.45% secondary emulsifying stabilizer, 0.001-0.005% yogurt fermentation bacteria, 0-0.4% secondary plant-derived flavor coloring substance, and the balance being water.

[0037] In the lower layer of milk: Raw milk (70-71%) is the main ingredient in the lower layer of milk, providing 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 milk makes the lower layer of milk closer to the base of traditional yogurt, with a more "pure" flavor.

[0038] 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.

[0039] Sodium caseinate (0-0.3%) is mainly used as a thickener to slightly improve the texture and smoothness of the lower layer of milk, increase stability and water retention, and prevent slight whey separation. Its dosage in the lower layer of milk is very low, and its effect is not as critical as in the upper layer of milk. 0% means that sodium caseinate can be completely omitted and relies on other ingredients for stability.

[0040] Skim milk powder (3-6%) is mainly used as a protein fortifier. It can increase the total protein in the lower layer of milk, improve the gel strength during fermentation, increase viscosity, improve texture (making it more solid), and reduce water separation. In addition, skim milk powder can provide an extra milky flavor.

[0041] The second emulsifying stabilizer (0.4-0.45%) 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 texture.

[0042] Yogurt starter cultures (0.001–0.005%) are the starter cultures. During the fermentation of the lower layer of milk, lactose in the lower layer of milk is used to produce acid (lactic acid), which causes casein micelles to aggregate and form a gel structure, giving the lower layer of yogurt its characteristic sour taste and texture.

[0043] The second plant-derived flavor coloring substance (0-0.4%) uses edible roots, stems, leaves, flowers or fruits of plants as raw materials, mainly as flavoring agents and natural pigments, to provide specific plant-derived flavors and corresponding colors to the lower layer of milk; 0% indicates that this layer can be plain.

[0044] Water is mainly used as a diluent to adjust the concentration and viscosity of the lower layer of milk.

[0045] Preferably, the lower layer of milk slurry comprises, by mass fraction: 70% raw milk, 6% white sugar, 0.3% sodium caseinate, 5% skim milk powder, 0.4% second emulsifying stabilizer, 0.005% yogurt fermentation bacteria, 0.4% second plant-derived flavor coloring substance, and the remainder being water.

[0046] The lower layer of this preferred formula, made with specific mass fractions of raw milk, white sugar, sodium caseinate, skim milk powder, a second emulsifying stabilizer, a second plant-derived flavor coloring substance, and the remainder water, creates a "carrying base" with plant-derived flavor and color. During fermentation, it forms a stable gel structure with good strength, effectively supporting the weight of the upper layer and preventing it from collapsing and mixing.

[0047] It should be noted that at least one of the first plant-based flavor coloring substance and the second plant-based flavor coloring substance is present in the upper and lower layers of milk. The flavors and colors of the first and second plant-based flavor coloring substances are different, so as to form a two-color, two-flavor yogurt.

[0048] In the two-color, two-flavor yogurt of the present invention, the upper and lower milk slurries have different special formula designs, which enable the upper and lower milk slurries to be stably separated, thereby allowing the upper and lower milk slurries to ferment together in the same packaging container while maintaining separation, laying a solid foundation for the formation of two-color, two-flavor yogurt. Moreover, by controlling the content and types of the first and second plant-derived flavor coloring substances, different colors and flavor combinations can be formed between the upper and lower layers of milk, 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). This two-tone, two-flavor yogurt has a delicate and smooth texture in both the top and bottom layers, a rich and harmonious flavor, good color layering stability, and no whey separation, providing consumers with a wonderful dual experience for both their eyes and taste buds, effectively meeting their needs.

[0049] In some specific embodiments, the first emulsifying stabilizer comprises, by mass fraction relative to the total mass of the upper milk layer, 0.08% sodium citrate, 0.03% carrageenan, 0.02% agar, 0.01% locust bean gum, and 0.05% mono- and diglyceride fatty acid esters.

[0050] Before the fermentation of the upper milk slurry, sodium citrate can stabilize the emulsion by reducing the surface tension at the oil-water interface; carrageenan, agar, and locust bean gum can be adsorbed on the particle surface to form a protective layer, preventing particle aggregation and effectively improving emulsion stability; mono- and diglyceride fatty acid esters can co-adsorb with sodium caseinate at the fat globule interface, effectively improving emulsion stability.

[0051] During the fermentation of the top layer of milk, sodium citrate maintains a pH greater than 4.0, preventing excessive gel shrinkage and water separation. Carrageenan synergistically forms an elastic framework with casein, improving the stability of the gel structure. Agar compensates for the brittleness of carrageenan, preventing the two-tone, two-flavor yogurt from softening during transportation. Locust bean gum, when combined with carrageenan, significantly enhances the strength of the gel. During the fermentation of the top layer of milk, carrageenan, agar, locust bean gum, and casein work synergistically to form a gel network, while fat is embedded in the gel network in a spherical shape, preventing the formation of a fat separation layer and reducing the greasy taste.

[0052] In some specific embodiments, the second emulsifying stabilizer comprises, by mass fraction relative to the total mass of the lower layer of milk, 0.05% pectin, 0.15% dipotassium hydrogen phosphate, and 0.2% sodium citrate.

[0053] Before the lower layer of milk ferments, pectin can adsorb onto the surface of the particles to form a protective layer, preventing particle aggregation and effectively improving emulsion stability; dipotassium hydrogen phosphate and sodium citrate can stabilize the emulsion by reducing the surface tension at the oil-water interface.

[0054] During the fermentation of the lower layer of milk, pectin can form a gel network in an acidic environment, which helps to increase 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 the fermentation of the lower layer of milk, and also acts as a calcium ion shield to prevent pectin from coagulating prematurely. Sodium citrate works synergistically with dipotassium hydrogen phosphate for buffering, and can also improve the gel strength of pectin.

[0055] In some specific embodiments, the yogurt fermentation bacteria include Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus.

[0056] Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus can synergistically promote milk fermentation. During fermentation, Lactobacillus delbrueckii subsp. bulgaricus can produce not only lactic acid but also protein-degrading enzymes. Under the action of these enzymes, a large number of amino acids are released from casein, which can promote the development of Streptococcus salivarius subsp. thermophilus. Meanwhile, the formate and carbon dioxide produced by Streptococcus salivarius subsp. thermophilus can promote acid production by Lactobacillus delbrueckii subsp. bulgaricus.

[0057] In some specific embodiments, the first plant-derived flavor coloring substance may 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-derived substances with other flavors and colors; the second plant-derived flavor coloring substance may 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-derived substances with other flavors and colors.

[0058] These plant-derived flavor colorings all have excellent flavor and striking color, making them superior flavoring agents and natural pigments.

[0059] In some specific embodiments, the volume ratio of the upper milk layer to the lower milk layer ranges from 1:3 to 3:1, and the corresponding volume ratio can be selected according to the feedback from the consumer market. Optionally, the volume ratio of the upper milk layer to the lower milk layer can be 1:3, 1:2, 1:1, 2:1, or 3:1.

[0060] This invention also provides a method for preparing two-color, dual-flavor yogurt. Figure 1 A schematic flowchart of a method for preparing two-color, two-flavor yogurt according to an embodiment of the present invention is shown, including the following steps: S1. Mix the following ingredients in the specified amounts: light cream, coconut oil, sodium caseinate, white sugar, concentrated whey protein, Tween-60, first emulsifying stabilizer, hydroxypropyl distarch phosphate, raw milk, and first plant-derived flavor coloring substance. Add water to the target total mass and then perform high-shear emulsification and homogenization treatment sequentially at 60-70°C. After cooling, the first upper layer of milk is obtained. First, all components except the yogurt fermentation bacteria are mixed together, and then subjected to high-shear emulsification and homogenization treatments sequentially within a specific temperature window (60-70℃). This process utilizes the combined action of sodium caseinate, Tween-60, the first emulsifying stabilizer, and hydroxypropyl distarch phosphate to transform the complex mixture containing oils (animal + plant), proteins, sugars, and other components into a highly stable, uniform, and delicate oil-in-water emulsion. After cooling, the oil-in-water emulsion system becomes even more stable.

[0061] Specifically, the high-shear emulsification treatment time ranges from 5 to 10 minutes, and the high-shear emulsification rotation speed ranges from 5800 to 6200 rpm, which can refine fat particles to the submicron level, preparing them for subsequent homogenization; preferably, the high-shear emulsification treatment time is 5 minutes, and the high-shear emulsification rotation speed is 6000 rpm.

[0062] Specifically, the primary homogenization pressure range for homogenization is 10–15 MPa, and the secondary homogenization pressure range is 1–5 MPa, which can further refine and disperse fat particles; preferably, the primary homogenization pressure for homogenization is 12 MPa, and the secondary homogenization pressure for homogenization is 2 MPa.

[0063] Furthermore, the temperature range of the first upper layer of milk is 20-30°C. Within this temperature window, the first upper layer of milk exhibits excellent stability and facilitates the subsequent addition of yogurt fermentation bacteria. Preferably, the temperature of the first upper layer of milk is 25°C.

[0064] S2. Mix the raw milk, white sugar, sodium caseinate, skim milk powder, second emulsifier, and second plant-derived flavor coloring agent according to the formula, add water to the target total mass, and perform high-shear emulsification and homogenization treatment in sequence at 60-70℃. After cooling, the first lower layer of milk slurry is obtained. First, mix all components except the yogurt fermentation bacteria together, and then perform high-shear emulsification and homogenization treatments sequentially within a specific temperature window (60-70℃) to fully disperse the proteins and form a stable proteosol system; after cooling, the proteosol system will be more stable.

[0065] Specifically, the high-shear emulsification treatment duration is 5–10 min, and the high-shear emulsification rotation speed is 5800–6200 rpm, which can effectively break down protein aggregates; preferably, the high-shear emulsification treatment duration is 5 min, and the high-shear emulsification rotation speed is 6000 rpm.

[0066] Specifically, the primary homogenization pressure range for homogenization is 10–15 MPa, and the secondary homogenization pressure range is 1–5 MPa, so that the protein is fully dispersed; preferably, the primary homogenization pressure is 12 MPa, and the secondary homogenization pressure is 2 MPa.

[0067] Furthermore, the temperature range of the first lower layer of milk slurry is 20-30°C. Within this temperature window, the first lower layer of milk slurry exhibits excellent stability and facilitates the subsequent addition of yogurt fermentation bacteria. Preferably, the temperature of the first lower layer of milk slurry is 25°C.

[0068] S3. Add the formula amount of yogurt starter to the first upper layer of milk and stir well to obtain the second upper layer of milk. The stirring process needs to be gentle to avoid deactivating the yogurt fermentation bacteria.

[0069] S4. Add the formula amount of yogurt starter to the first lower layer of milk mixture and stir well to obtain the second lower layer of milk mixture. The stirring process needs to be gentle to avoid deactivating the yogurt fermentation bacteria.

[0070] S5. First, fill the second lower layer of milk into the packaging container, and then fill the packaging container with the second upper layer of milk to obtain the fermented two-color double-layer milk. When filling the second upper layer of milk, it is necessary to pour it slowly to avoid impacting the second lower layer of milk, which would blur the boundary between the second upper layer and the second lower layer of milk.

[0071] S6. Place the two-color, two-layer milk mixture to be fermented at 40-45℃ for anaerobic fermentation for 340-380 minutes, then cool to stop fermentation and obtain two-color, two-flavor yogurt.

[0072] By precisely controlling temperature, time, and anaerobic processes, the differentiated coagulation behavior of the upper and lower layers of milk slurry is coordinated, enabling co-fermentation and ensuring dual-color separation and dual flavor.

[0073] To achieve anaerobic fermentation, the packaging container can be covered with a lid or sealed with plastic wrap.

[0074] Preferably, the two-color, two-layer milk slurry to be fermented is placed at 43°C for anaerobic fermentation for 360 minutes.

[0075] Specifically, cooling to terminate fermentation includes: Lowering the temperature to 3–5°C and maintaining this temperature for at least 300 minutes not only induces dormancy in the yogurt fermentation bacteria but also allows the gel structure to age completely, preventing dehydration and shrinkage. Preferably, the temperature is lowered to 4°C.

[0076] Specifically, the pH range of two-tone, two-flavor yogurt is 4.5 to 4.7, with moderate acidity and good flavor.

[0077] The method for preparing the two-color, two-flavor yogurt of the present invention can fully utilize the special formula design of the upper and lower milk layers, enabling the upper and lower milk layers to ferment together in the same packaging container while maintaining their separate layers. Moreover, the resulting two-color, two-flavor yogurt has distinct upper and lower layers with clear boundaries, a delicate and smooth texture, a rich and harmonious flavor, good color layering stability, and no whey separation, providing consumers with a double delightful experience in both sight and taste, effectively meeting consumer demand.

[0078] Example 1 A two-tone, two-flavor yogurt is made by fermenting an upper layer of milk and a lower layer of milk together in a packaging container. 1000g of the upper layer milk includes: 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 the first emulsifying stabilizer, 3g of hydroxypropyl distarch phosphate, 500g of raw milk, 0.05g of yogurt starter culture, and the remainder being water. 1000g of the lower layer milk includes: 700g of raw milk, 60g of white sugar, 3g of sodium caseinate, 50g of skim milk powder, 4g of the second emulsifying stabilizer, 0.05g of yogurt starter culture, 4g of concentrated strawberry juice, and the remainder being water. The first emulsifying stabilizer includes: sodium citrate 0.8g, carrageenan 0.3g, agar 0.2g, locust bean gum 0.1g and mono- and diglyceride fatty acid esters 0.5g; the second emulsifying stabilizer includes: pectin 0.5g, dipotassium hydrogen phosphate 1.5g and sodium citrate 2g.

[0079] The preparation method of this two-color, two-flavor yogurt includes the following steps: (1) Mix the following ingredients together: light cream, coconut oil, sodium caseinate, white sugar, concentrated whey protein, Tween-60, first emulsifying stabilizer, hydroxypropyl distarch phosphate and raw milk. Add water to the target total mass of 1000g (the mass of yogurt fermentation bacteria is too small to be counted in the target total mass). Then, perform high-shear emulsification and homogenization treatment at 65℃. After cooling to 25℃, the first upper layer of milk slurry is obtained. The high-shear emulsification treatment lasted for 5 minutes and the rotation speed was 6000 rpm. The primary homogenization pressure for the homogenization treatment was 12 MPa, and the secondary homogenization pressure for the homogenization treatment was 2 MPa.

[0080] (2) Mix the raw milk, white sugar, sodium caseinate, skim milk powder, second emulsifier and concentrated strawberry juice in the formula amount, and add water to the target total mass of 1000g (the mass of yogurt fermentation bacteria is too small and can be ignored, so it is not included in the target total mass). Then, perform high shear emulsification and homogenization treatment in sequence at 65℃, and cool to 25℃ to obtain the first lower layer of milk slurry. The high-shear emulsification treatment lasted for 5 minutes and the rotation speed was 6000 rpm. The primary homogenization pressure for the homogenization treatment was 12 MPa, and the secondary homogenization pressure for the homogenization treatment was 2 MPa.

[0081] (3) Add the formula amount of yogurt fermentation bacteria to the first upper layer of milk and gently stir to obtain the second upper layer of milk.

[0082] (4) Add the formula amount of yogurt fermentation bacteria to the first lower layer of milk and gently stir to obtain the second lower layer of milk.

[0083] (5) First, fill the second lower layer of milk into the packaging container, and then slowly fill the packaging container with the same volume of the second upper layer of milk to obtain the fermented two-color double-layer milk.

[0084] (6) Place the two-color, two-layer milk mixture to be fermented at 43°C for anaerobic fermentation for 360 min, then cool it to 4°C and maintain it for at least 300 min to terminate fermentation, to obtain two-color, two-flavor yogurt. Figure 2 A schematic diagram of the finished product state of the two-color, two-flavor yogurt of Example 1 is shown; at this time, the pH of the two-color, two-flavor yogurt is 4.6.

[0085] Example 2 A two-tone, two-flavor yogurt is made by fermenting an upper layer of milk and a lower layer of milk together in a packaging container. 1000g of the upper layer milk includes: 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 the first emulsifying stabilizer, 3g of hydroxypropyl distarch phosphate, 500g of raw milk, 0.05g of yogurt starter culture, and the remainder being water. 1000g of the lower layer milk includes: 700g of raw milk, 60g of white sugar, 0g of sodium caseinate, 60g of skim milk powder, 4.5g of the second emulsifying stabilizer, 0.05g of yogurt starter culture, 4g of concentrated strawberry juice, and the remainder being water. The first emulsifying stabilizer includes: 0.8g sodium citrate, 0.1g carrageenan, 0.2g agar, 0.3g locust bean gum, and 1g mono- and diglyceride fatty acid esters; the second emulsifying stabilizer includes: 2g pectin, 1g dipotassium hydrogen phosphate, and 1.5g sodium citrate.

[0086] The preparation method of this two-color, two-flavor yogurt is the same as in Example 1.

[0087] Figure 3 A schematic diagram of the finished product state of the two-color, two-flavor yogurt of Example 2 is shown.

[0088] Example 3 A two-tone, two-flavor yogurt is made by fermenting an upper layer of milk and a lower layer of milk together in a packaging container. 1000g of the upper layer milk 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 the first emulsifying stabilizer, 5g of hydroxypropyl distarch phosphate, 400g of raw milk, 0.05g of yogurt starter culture, and the remainder being water. 1000g of the lower layer milk comprises: 700g of raw milk, 60g of white sugar, 0g of sodium caseinate, 60g of skim milk powder, 2.5g of the second emulsifying stabilizer, 0.05g of yogurt starter culture, 2g of concentrated strawberry juice, and the remainder being water. The first emulsifying stabilizer includes: sodium citrate 0g, carrageenan 0.3g, agar 0.2g, locust bean gum 0.5g and mono- and diglyceride fatty acid esters 0.5g; the second emulsifying stabilizer includes: pectin 0g, dipotassium hydrogen phosphate 1g and sodium citrate 1.5g.

[0089] The preparation method of this two-color, two-flavor yogurt is the same as in Example 1.

[0090] Figure 4 A schematic diagram of the finished product state of the two-color, two-flavor yogurt of Example 3 is shown.

[0091] Comparative Example 1 This comparative example is basically the same as Example 1, except that: The amount of light cream and coconut oil in 1000g of the top layer of milk is 0, and the difference is made up with water, while other contents remain unchanged.

[0092] Figure 5 A schematic diagram of the finished product state of the two-color, two-flavor yogurt of Comparative Example 1 is shown.

[0093] Comparative Example 2 This comparative example is basically the same as Example 1, except that: The content of Tween-60 in 1000g of upper layer milk is 0g, and the difference is made up with water, while other contents remain unchanged.

[0094] Figure 6 A schematic diagram of the finished product state of the two-color, two-flavor yogurt of Comparative Example 2 is shown.

[0095] Comparative Example 3 This comparative example is basically the same as Example 2, except that: The sodium caseinate content in 1000g of the upper layer of milk is 0g. The difference is made up with water, and everything else remains unchanged.

[0096] Figure 7 A schematic diagram of the finished product state of the two-color, two-flavor yogurt of Comparative Example 3 is shown.

[0097] Comparative Example 4 This comparative example is basically the same as Example 1, except that: When preparing the first upper layer of milk slurry, high-shear emulsification was not performed at 65°C; instead, homogenization was performed directly, while other processes remained unchanged.

[0098] Figure 8 A schematic diagram of the finished product state of the two-color, two-flavor yogurt in Comparative Example 4 is shown.

[0099] Comparative Example 5 This comparative example is basically the same as Example 1, except that: Anaerobic fermentation for 400 minutes, with other parameters remaining unchanged.

[0100] Figure 9 A schematic diagram of the finished product state of the two-color, two-flavor yogurt of Comparative Example 5 is shown.

[0101] Sensory evaluation Sensory evaluation was conducted on the two-color, two-flavor yogurts of Examples 1-3 and Comparative Examples 1-5: Sensory evaluation of the two-color, two-flavor yogurt was conducted according to the sensory evaluation criteria in Table 1. The main evaluation items included texture, color, flavor, and mouthfeel. Fifty professional sensory evaluators were selected to score the texture, color, flavor, and mouthfeel of the two-color, two-flavor yogurt. The average score of each item was taken as the average of the scores of the sensory evaluators, and the sum of the average scores of the four items was taken as the sensory evaluation score of the two-color, two-flavor yogurt. The specific results are shown in Table 2.

[0102] Table 1 Sensory Evaluation Criteria

[0103] Table 2 Sensory evaluation results

[0104] The two-color, two-flavor yogurts in Examples 1-3 and Comparative Examples 1-5 are all yogurt products with a creamy original flavor (milky yellow) on the top layer and a strawberry flavor (pink) on the bottom layer.

[0105] Among them, the total scores of the two-color, two-flavor yogurts in Examples 1 to 3 are all greater than 90. They all have good texture, color, flavor and mouthfeel. They can present a visual impact of milky yellow and pink in the same packaging container, and present two very different but harmonious flavors of milky aroma and strawberry flavor. Moreover, the two layers of yogurt have a delicate and mellow taste, moderate sweet and sour taste and uniform flavor.

[0106] Comparing Example 1 and Comparative Example 1, it can be seen that fats (whipping cream and coconut oil) have a significant impact on the overall color, flavor and texture of yogurt. A lack of fats will cause the lower layer of milk to diffuse more deeply into the upper layer, making it difficult to achieve stable separation. A lack of fats will also weaken the milky aroma of the upper layer of yogurt and cause an imbalance in the aroma between the upper and lower layers of yogurt. A lack of fats will also cause the yogurt to lose its rich texture and make the overall sourness of the yogurt too prominent.

[0107] Comparing Example 1 and Comparative Example 2, it can be seen 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 diffuse deeply into each other and cannot be stably separated; moreover, the lack of Tween-60 will also cause whey to separate.

[0108] 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 does not affect the overall yogurt, but the lack of sodium caseinate in the upper layer of milk will cause the overall color of the yogurt to deteriorate, and the upper layer of milk will diffuse to the lower layer of milk, making it unable to form stable layers.

[0109] Comparing Example 1 and Comparative Example 4, it can be seen that in the preparation of the first upper layer of milk, 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 result in uneven oil dispersion, making the upper layer of yogurt taste greasy and slightly fatty.

[0110] Comparing Example 1 and Comparative Example 5, it can be seen that fermentation time has a significant impact on the overall texture and taste of yogurt. Excessive fermentation time will result in more whey separation and make the yogurt more acidic overall.

[0111] In summary, the formulation design and preparation method of the two-color, two-flavor yogurt of the present invention work synergistically within a suitable range, resulting in a two-color, two-flavor yogurt with a delicate, rich, and smooth taste, good color layering stability, no whey separation, and rich and harmonious flavors in both the upper and lower yogurt layers. It can present a visually striking display of two colors in the same packaging container, as well as two very different yet harmonious flavors, providing new ideas for the development of subsequent yogurt products.

[0112] The foregoing has provided a detailed description of a two-color, two-flavor yogurt and its preparation method provided by the embodiments of the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A two-color, two-flavor yogurt, characterized in that, The two-color, two-flavor yogurt is made by fermenting the upper and lower layers of milk together in a packaging container; The upper layer of milk, by mass fraction, comprises: 8-10.2% light cream, 10-14% coconut oil, 0.8-2% sodium caseinate, 5-10% white sugar, 1.5-7% concentrated whey protein, 0.1-0.2% Tween-60, 0.19-0.24% first emulsifying stabilizer, 0.3-0.5% hydroxypropyl distarch phosphate, 40-50% raw milk, 0.001-0.005% yogurt fermentation bacteria, 0-0.4% first plant-derived flavor coloring substance, and the balance being water. The first emulsifying stabilizer, by mass fraction relative to the total mass of the upper layer of milk, comprises: 0.08% sodium citrate, 0.03% carrageenan, 0.02% agar, 0.01% locust bean gum, and 0.05% mono- and diglycerides of fatty acids. The lower layer of milk slurry comprises, by mass fraction: 70-71% raw milk, 3-7% white sugar, 0-0.3% sodium caseinate, 3-6% skim milk powder, 0.4-0.45% second emulsifying stabilizer, 0.001-0.005% yogurt fermentation bacteria, 0-0.4% second plant-derived flavor coloring substance, and the balance being water. The second emulsifying stabilizer, by mass fraction relative to the total mass of the lower layer of milk slurry, comprises: 0.05% pectin, 0.15% dipotassium hydrogen phosphate, and 0.2% sodium citrate. At least one of the first plant-derived flavor coloring substance and the second plant-derived flavor coloring substance is present, and the flavor and color of the first plant-derived flavor coloring substance and the second plant-derived flavor coloring substance are different; The volume ratio of the upper milk layer to the lower milk layer is in the range of 1:3 to 3:

1.

2. The two-color, two-flavor yogurt as described in claim 1, characterized in that, The upper layer of milk, by mass fraction, comprises: 8% light cream, 10% coconut oil, 2% sodium caseinate, 10% white sugar, 3.5% concentrated whey protein, 0.1% Tween-60, 0.19% first emulsifying stabilizer, 0.3% hydroxypropyl distarch phosphate, 50% raw milk, 0.005% yogurt fermentation bacteria, 0% first plant-derived flavor coloring substance, and the remainder being water; The lower layer of milk slurry comprises, by mass fraction: 70% raw milk, 6% white sugar, 0.3% sodium caseinate, 5% skim milk powder, 0.4% second emulsifying stabilizer, 0.005% yogurt fermentation bacteria, 0.4% second plant-derived flavor coloring substance, and the remainder is water.

3. The two-color, two-flavor yogurt as described in claim 1, characterized in that, The yogurt fermentation bacteria include Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus; The first plant-derived flavor coloring substance includes one of the following: 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-derived flavor coloring substance includes one of the following: 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.

4. A method for preparing a two-color, two-flavor yogurt as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Mix the following ingredients in the specified amounts: light cream, coconut oil, sodium caseinate, white sugar, concentrated whey protein, Tween-60, first emulsifying stabilizer, hydroxypropyl distarch phosphate, raw milk, and first plant-derived flavor coloring substance. Add water to the target total mass and then perform high-shear emulsification and homogenization treatment sequentially at 60-70°C. After cooling, the first upper layer of milk is obtained. S2. Mix the raw milk, white sugar, sodium caseinate, skim milk powder, second emulsifier, and second plant-derived flavor coloring agent according to the formula, add water to the target total mass, and perform high-shear emulsification and homogenization treatment in sequence at 60-70℃. After cooling, the first lower layer of milk slurry is obtained. S3. Add the formula amount of yogurt fermentation bacteria to the first upper layer of milk slurry and stir evenly to obtain the second upper layer of milk slurry. S4. Add the formula amount of yogurt fermentation bacteria to the first lower layer of milk slurry and stir evenly to obtain the second lower layer of milk slurry. S5. First, fill the second lower layer milk slurry into the packaging container, and then fill the packaging container with the second upper layer milk slurry to obtain a two-color, two-layer milk slurry to be fermented. S6. Place the two-color, two-layer milk slurry to be fermented at 40-45℃ for anaerobic fermentation for 340-380 minutes, cool to terminate fermentation, and obtain two-color, two-flavor yogurt.

5. The method for preparing two-color, two-flavor yogurt as described in claim 4, characterized in that, In steps S1 and S2, the duration of the high-shear emulsification treatment is 5 to 10 minutes, and the rotation speed of the high-shear emulsification treatment is 5800 to 6200 rpm. In steps S1 and S2, the primary homogenization pressure range of the homogenization process is 10–15 MPa, and the secondary homogenization pressure range of the homogenization process is 1–5 MPa.

6. The method for preparing two-color, dual-flavor yogurt as described in claim 4, characterized in that, In steps S1 and 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.

7. The method for preparing two-color, two-flavor yogurt as described in claim 4, characterized in that, In step S6, the cooling to terminate fermentation includes: Lower the temperature to 3-5°C and maintain it for at least 300 minutes.

8. The method for preparing two-color, two-flavor yogurt as described in claim 4, characterized in that, The pH range of the two-color, two-flavor yogurt is 4.5 to 4.7.

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