Preparation process of lonicera japonica leaf wine yogurt containing selenium-rich kong corn

Abstract

The application discloses a preparation process of a morinda leaf wine yogurt containing selenium-rich black millet, and comprises the following operation steps: low-temperature pretreatment of the selenium-rich black millet, dealcoholization treatment of the black millet wine, preparation of a yogurt base, low-temperature compounding and post-maturation after filling. The application realizes the triple-nutritional synergy of morinda leaf anthocyanins, selenium-rich black millet fungal selenium polysaccharides and black millet wine fermentation amino acids, solves the system stability of the wine and the yogurt, the thermal degradation of anthocyanins and the irritability of the wine, and has the advantages of antioxidation, selenium supplementation and intestinal regulation, stable color, smooth taste, light wine fragrance and the suitability for adult health-care consumer groups.

Description

Technical Field

[0001] This invention relates to the field of fermented dairy product processing technology, and in particular to a preparation process of a fermented yogurt made from selenium-enriched sorghum rice and glutinous rice leaves. Background Technology

[0002] Yogurt, as a traditional fermented dairy product, is rich in protein, calcium, and probiotics, and is widely loved by consumers. However, the nutritional composition of regular yogurt is relatively simple, mainly consisting of milk protein and lactic acid bacteria, lacking plant-derived antioxidants and trace elements, making it difficult to meet the growing demand of modern consumers for functional and differentiated dairy products.

[0003] In recent years, functional yogurt has become a hot research topic in the dairy industry.

[0004] In the prior art, patent publication number "CN116172066A" discloses a yogurt containing vitamin C and anthocyanins and its preparation method. The method involves mixing first raw milk, vitamin C, anthocyanins, and rennet, stirring to obtain a first mixture; adding calcium salt and vegetable oil to the first mixture to form a water-in-oil emulsion, then adding acid, centrifuging, and washing to obtain microencapsulated particles of vitamin C and anthocyanins; adding the microencapsulated particles to second raw milk, stirring to obtain a second mixture; and adding white sugar and a starter culture to the second mixture to prepare yogurt. This method, which prepares anthocyanins into microencapsulated particles before adding them to the emulsion for fermentation, involves a complex process and introduces non-yogurt-specific components such as vegetable oil.

[0005] Patent CN122030465A discloses a method for preparing stable anthocyanin yogurt, comprising the following steps: preparing anthocyanin extract; mixing and stirring the anthocyanin extract with sodium caseinate, and drying to obtain a sodium caseinate-anthocyanin complex; adding the sodium caseinate-anthocyanin complex to a milk base, stirring until completely dissolved, inoculating the mixture with yogurt fermentation bacteria, and fermenting to obtain stable anthocyanin yogurt. Premixing and drying anthocyanins with sodium caseinate before fermentation constitutes a solid-phase composite process.

[0006] Patent CN116439283A discloses a method for preparing a highly stable mulberry anthocyanin complex and its application in yogurt products. The preparation method includes the following steps: extracting dried mulberries to obtain mulberry extract; mixing the mulberry extract with reconstituted milk by shearing, then allowing it to stand and hydrate to obtain a hydrate; homogenizing the hydrate, sterilizing it, and then inoculating it with a fermenting agent, wherein the fermenting agent is food-grade lactic acid bacteria, to obtain the mulberry anthocyanin complex; mixing the mulberry extract with reconstituted milk and then inoculating it with lactic acid bacteria for co-fermentation, wherein the anthocyanins need to withstand the degradation effect of β-glucosidase during the fermentation process.

[0007] None of the above schemes involve the introduction of fermented rice components, nor do they contain selenium polysaccharides of fungal origin.

[0008] Regarding fermented rice yogurt, patent CN111149863A discloses a fermented rice yogurt and its preparation method. The method includes the following steps: a four-step fermentation process for making thick yogurt: milk is sterilized, then inoculated with starter cultures and fermented to obtain a fermented liquid; the fermented liquid is first filtered to remove whey, then homogenized, and then left at a low temperature to mature, resulting in yogurt; the fermented rice is filtered, heated, and cooked to obtain pre-treated fermented rice; the yogurt and pre-treated fermented rice are mixed evenly, and then subjected to a second low-temperature fermentation to obtain the fermented rice yogurt. However, this method has the following shortcomings: the fermented rice is ordinary glutinous rice wine, which does not contain anthocyanins and selenium polysaccharide functional components; high-temperature cooking at 80-90℃ will destroy the heat-sensitive active nutritional components in the fermented rice; alcohol content control is not involved, and the finished product may have an overly strong and pungent taste; the stability of the system after mixing fermented rice and yogurt is not resolved.

[0009] In the realm of cereal yogurt, current technologies primarily utilize conventional grains such as black rice and oats, adding them after puffing or enzymatic hydrolysis. However, selenium-enriched sorghum black rice, a unique grain ingredient possessing high dietary fiber, fungal selenium polysaccharides, and anthocyanin adsorption capacity, has not yet been applied in the dairy industry. Sorghum black rice boasts a selenium content as high as 87 μg / 100g and contains fungal polysaccharides with a purity of up to 73.66%, but its heat sensitivity means that conventional high-temperature processing methods can lead to significant degradation of its active components.

[0010] Nanzhu leaves are rich in anthocyanins and polyphenols, and traditionally they are mainly used for coloring black glutinous rice. In the yogurt industry, patent CN104026232A discloses a method for making fermented yogurt, which involves simmering chrysanthemum, *Smilax glabra*, rose, *Ligusticum chuanxiong*, loquat flower, Nanzhu leaves, and *Codonopsis pilosula* leaves in 5-6 times the amount of water over low heat for 40-50 minutes, filtering to remove residue, and obtaining a medicinal liquid. Nanzhu leaves appear only as a trace amount of herbal ingredient, not as a core functional component, and the traditional low-heat extraction method results in significant loss of active ingredients.

[0011] Based on the shortcomings of existing technologies, the main problems are as follows: (1) Ordinary yogurt is only fermented with cow's milk and lacks the synergistic combination of three nutrients: anthocyanins from the leaves of the southern candle, selenium-enriched sorghum black rice fungus selenium polysaccharide and amino acids from fermented rice wine, resulting in a single nutritional profile. (2) There is a lack of a two-way critical low-temperature pretreatment method for selenium-enriched grains, which cannot take into account both starch gelatinization modification and the retention of selenium active components. (3) Existing fermented rice yogurt does not involve de-alcoholization process, and the alcohol taste is too strong and irritating, resulting in poor palatability; (4) There is a lack of methods to deal with the poor stability of anthocyanins, the easy separation and fading of products, and the short shelf life. Summary of the Invention

[0012] The purpose of this invention is to provide a preparation process for Nanzhuye fermented yogurt containing selenium-enriched sorghum black rice, which has the advantages of achieving triple nutritional synergy of Nanzhuye anthocyanins, selenium-enriched sorghum black rice fungal selenium polysaccharides and fermented amino acids of black rice, and solving the problems of system stability, anthocyanin thermal degradation and alcoholic irritation of fermented rice and yogurt.

[0013] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A preparation process for a yogurt made with selenium-enriched sorghum black rice and *Vigna oleifera* leaves includes the following steps: S1. Low-temperature pretreatment of selenium-enriched sorghum black rice; Soak the selenium-rich sorghum black rice pieces in water, then steam them at a low temperature of 60-65℃ for 10-20 minutes to pregelatinize and soften the starch on the surface of the black rice. Let it cool before use; S2, De-alcoholization treatment of black rice wine; Place the fermented rice wine in an open container and stir at low speed for 8-15 minutes under a temperature of 35-42℃ and negative pressure ventilation. Through the selective volatilization of low-boiling-point ethanol, the alcohol content is reduced from 1.0-1.5% vol to 0.3-0.6% vol, removing the pungent ethanol odor while retaining the fermentation aroma substances. Filtering removes coarse rice residue; S3. Preparation of yogurt base; After homogenizing the raw milk, pasteurize it, cool it to 40-44℃, inoculate it with a compound fermentation strain, and ferment it at a constant temperature for 5-7 hours until the pH reaches 4.2-4.6, then coagulate it into plain yogurt. Cool the original flavor yogurt to 35°C; S4, low-temperature compounding; Add the selenium-enriched sorghum glutinous rice pretreated in step S1, the glutinous rice wine after de-alcoholization in step S2, the concentrated juice of cold-pressed southern candelilla leaves, trehalose and stabilizer to the original flavor yogurt in step S3 in sequence, and stir at low speed for 6 to 10 minutes at 35 to 38°C, with the temperature not exceeding 38°C throughout the process. S5. Post-filling curing; The material mixed evenly in step S4 is aseptically packaged and then refrigerated at 0-4℃ for 10-14 hours to obtain the finished product.

[0014] In summary, the present invention has the following beneficial effects: 1. From steaming and cooling, to de-alcoholization and compounding and cooling, the temperature is controlled throughout the process to avoid the degradation of selenium polysaccharides and the oxidation of anthocyanins, thus ensuring the retention of organic selenium, polysaccharides and anthocyanins; 2. Low-temperature negative pressure de-alcoholization reduces the alcohol content, removes the pungent alcohol taste, and retains the aroma of fermented rice wine; 3. The product is rich in anthocyanins, fungal polysaccharides and organic selenium, which have antioxidant and immune-regulating effects, and has a smooth taste and delicate flavor; 4. The proportions of each step are accurate, easy to operate, and easy to achieve stable industrial production. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to the embodiments. Example 1:

[0016] A type of yogurt made with Nanzhuye (a type of fermented rice wine) containing selenium-enriched sorghum black rice is rich in three functional components: anthocyanins from Nanzhuye leaves, selenium polysaccharides from fungi in selenium-enriched sorghum black rice, and fermented amino acids from black rice wine. Among them, the anthocyanin content is ≥120mg / 100g, the organic selenium content is ≥0.06mg / kg, and the fungal polysaccharide content is ≥100mg / 100g. Nanzhuye fermented rice yogurt is a uniform purplish-black color, with a delicate fermented rice aroma and a smooth texture; Nanzhuye fermented rice yogurt has a water content of ≤5% when stored at 0-4℃ for 28 days.

[0017] The alcohol content of Nanzhuye fermented rice yogurt is ≤0.5% vol. Example 2:

[0018] A preparation process for a yogurt made with selenium-enriched sorghum black rice and Candle Leaf Fermentation. Based on 1000 finished products, the raw material weight ratio is as follows: 700 parts base milk, 150-200 parts Nanzhu black rice wine, 50-80 parts selenium-enriched sorghum black rice fragments, 20-40 parts Nanzhu leaf concentrate, 0.5-1.0 parts compound fermentation strain, 20-35 parts trehalose, 0.8-1.5 parts stabilizer, and drinking water.

[0019] The preparation method of Nanzhu Wumi Rice Wine is as follows: After crushing dried Nanzhu leaves, soak them in water for 6 hours to obtain basic dyeing juice. Soak glutinous rice in the juice for 12 hours to absorb the color. Steam it for 30 minutes to gelatinize it. After removing it from the steamer and cooling it to 60-65℃, spray it with cold-pressed fresh Nanzhu leaf juice, stir and add anthocyanins. Spread it to cool to 28-32℃ and mix it with sweet wine yeast. Ferment it at a constant temperature of 24℃ in a sealed container for 48-72 hours.

[0020] The concentrated juice of the southern candelilla leaf is prepared by cold pressing, without heating throughout the process; The compound fermentation strain is a combination of Bifidobacterium and Streptococcus thermophilus; The stabilizer is a compound stabilizer of pectin and gelatin.

[0021] The following steps are included: S1. Low-temperature pretreatment of selenium-enriched sorghum black rice; After soaking the selenium-enriched sorghum black rice pieces in water, steam them at a low temperature of 60-65℃ for 10-20 minutes to pregelatinize and soften the starch on the surface of the black rice. At the same time, the temperature is controlled below the critical temperature for thermal decomposition of selenium polysaccharides to preserve the biological activity of fungal selenium polysaccharides and organic selenium. Let it cool before use; Among them, the low-temperature steaming temperature range of 60-65℃ is a two-way critical temperature window. The temperature is higher than the initial gelatinization temperature of sorghum starch by 60-63℃ to start the pregelatinization of the surface starch, so that the glutinous rice particles are softened and the pores are opened. At the same time, the temperature is strictly lower than the critical temperature of thermal decomposition of selenium polysaccharide of 70℃ to avoid the breakage of glycosidic bonds of fungal selenium polysaccharide and the dissociation of organic selenium bound structure. S2, De-alcoholization treatment of black rice wine; Place the fermented rice wine in an open container and stir at low speed for 8-15 minutes under a temperature of 35-42℃ and negative pressure ventilation. Through the selective volatilization of low-boiling-point ethanol, the alcohol content is reduced from 1.0-1.5% vol to 0.3-0.6% vol, removing the pungent ethanol odor while retaining the fermentation aroma substances. Filtering removes coarse rice residue; The process conditions for de-alcoholization are: temperature 40℃, open container, negative pressure ventilation, and low-speed stirring. These three factors work together to achieve selective de-alcoholization. The open design increases the gas-liquid contact area to promote ethanol volatilization, low-speed stirring reduces damage to the integrity of the wine grains, and negative pressure lowers the boiling point of ethanol to achieve low-temperature de-alcoholization. S3. Preparation of yogurt base; After homogenizing the raw milk, pasteurize it, cool it to 40-44℃, inoculate it with a compound fermentation strain, and ferment it at a constant temperature for 5-7 hours until the pH reaches 4.2-4.6, then coagulate it into plain yogurt. Cool the original flavor yogurt to 35°C; S4, low-temperature compounding; The selenium-enriched sorghum rice pretreated in step S1, the sorghum rice wine after de-alcoholization in step S2, the concentrated juice of cold-pressed southern sorghum leaves, trehalose, and stabilizer are sequentially added to the original flavor yogurt in step S3. The mixture is stirred at low speed for 6 to 10 minutes at 35 to 38°C, with the temperature not exceeding 38°C throughout the process. This allows the southern sorghum leaf anthocyanins, sorghum rice selenium polysaccharide, and yogurt casein to cross-link through non-covalent bonds, constructing a ternary non-covalent gel network structure and achieving a homogeneous and stable system. The low-temperature compounding process, which does not exceed 38℃ throughout, is because, under the steady-state acidity environment of yogurt at pH 4.2-4.6, the anthocyanin molecules of Candida albicans and the selenium polysaccharide molecules of Umi oolong tea are uniformly cross-linked with the hydrophilic groups on the surface of casein micelles through non-covalent bonds such as hydrogen bonds, hydrophobic interactions, and electrostatic adsorption. This spontaneously constructs a dense and uniform three-dimensional network gel structure, which encapsulates free whey, binds the flow of the aqueous phase, and fixes solid particles, thereby inhibiting whey precipitation, solid-liquid separation, and powder sedimentation from the microstructure perspective. When the compounding temperature exceeds 38℃, the intense thermal motion of casein micelles leads to the breakage of non-covalent cross-links, and the increased thermal activity of anthocyanins and polysaccharides prevents the formation of a regular composite network. As a result, the microstructure of the system is loose, and whey is rapidly precipitated. When the compounding temperature is ≤38℃, the molecular motion is mild, and the non-covalent bonds cross-link in an orderly manner to form a high-strength water-retaining gel network.

[0022] S5. Post-filling curing; The material mixed evenly in step S4 is aseptically packaged and then refrigerated at 0-4℃ for 10-14 hours to obtain the finished product. Example 3:

[0023] A preparation process for a yogurt made with selenium-enriched sorghum black rice and *Vigna oleifera* leaves includes the following steps: S1. Preparation of Nanzhu Wumi Wine; 750g of dried Cantharides leaves were crushed, soaked in 2500mL of water at room temperature for 6 hours, and filtered to obtain the basic dyeing juice; Soak 3000g of glutinous rice in the juice for 12 hours to allow it to fully absorb the color; Steam over water for 30 minutes until completely gelatinized; the temperature upon removal from the steamer should be approximately 92°C. Spread the rice out to cool to 62℃. Take 100g of fresh tender leaves of the Nandina domestica and add 500mL of room temperature purified water to cold-press the juice. Spray the juice onto the glutinous rice while stirring for 5 minutes. Continue to cool to 30℃, then evenly mix in 20g of sweet wine yeast; Seal in a ceramic jar and ferment at a constant temperature of 24℃ for 60 hours until a sweet wine is produced; Low-temperature pasteurization at 80℃ for 10 minutes yields Nanzhu Wumi wine for later use. S2, Low-temperature pretreatment of selenium-enriched sorghum black rice; Take 600g of selenium-enriched sorghum black rice fragments with a particle size of 2mm and soak them in water for 30 minutes; Steaming at 65℃ for 15 minutes in a water bath allows the starch on the surface of the black rice to be pregelatinized and the granules to soften, while retaining the activity of fungal selenium polysaccharides. Let it cool to room temperature before use; S3, De-alcoholization treatment of black rice wine; Take 1800g of the Nanzhu Wumi wine prepared in step S1, place it in an open container, and stir at low speed for 10min under 40℃ temperature and negative pressure ventilation conditions. The alcohol content was 1.12% vol before treatment and decreased to 0.43% vol after treatment. Filtering removes coarse rice residue; S4. Yogurt base preparation; 7000g of raw milk was homogenized, pasteurized at 85℃ for 10 minutes, cooled to 42℃, inoculated with 8g of a compound strain of Bifidobacterium and Streptococcus thermophilus, and fermented at a constant temperature for 6 hours until pH 4.4, and coagulated into plain yogurt. S5, low-temperature compounding; Cool the yogurt to 35°C, then add the selenium-enriched sorghum rice pretreated in step S2, the wine after de-alcoholization in step S3, 300g of cold-pressed Nanzhu leaf concentrate, 280g of trehalose, and 12g of pectin-gelatin compound stabilizer in sequence. Stir at low speed for 8 minutes, with the temperature not exceeding 38°C throughout the process. S6. After filling and ripening: After mixing evenly, aseptically package and refrigerate at 4℃ for 12 hours to obtain the finished product.

[0024] Finished product test data: anthocyanin content 152mg / 100g, organic selenium content 0.065mg / kg, fungal polysaccharide content 118mg / 100g, alcohol content 0.43%vol; The finished product is a uniform purplish-black color, the black rice is soft and glutinous without a hard core, the yogurt is smooth, and the fermented rice has a light and non-irritating aroma. Example 4:

[0025] A preparation process for a yogurt made with selenium-enriched sorghum black rice and *Vigna oleifera* leaves includes the following steps: S1. Preparation of Nanzhu Wumi Wine; 750g of dried Cantharides leaves were crushed, soaked in 2500mL of water at room temperature for 6 hours, and filtered to obtain the basic dyeing juice; Soak 3000g of glutinous rice in the juice for 12 hours to allow it to fully absorb the color; Steam over water for 30 minutes until completely gelatinized; the temperature upon removal from the steamer should be approximately 92°C. Spread the rice out to cool to 62℃. Take 100g of fresh tender leaves of the Nandina domestica and add 500mL of room temperature purified water to cold-press the juice. Spray the juice onto the glutinous rice while stirring for 5 minutes. Continue to cool to 30℃, then evenly mix in 20g of sweet wine yeast; Seal in a ceramic jar and ferment at a constant temperature of 24℃ for 60 hours until a sweet wine is produced; Low-temperature pasteurization at 80℃ for 10 minutes yields Nanzhu Wumi wine for later use. S2, Low-temperature pretreatment of selenium-enriched sorghum black rice; Take 500g of selenium-enriched sorghum black rice fragments with a particle size of 2mm and soak them in water for 30 minutes; Steaming at 62℃ for 20 minutes in a water bath allows the starch on the surface of the black glutinous rice to be pregelatinized and the granules to soften, while retaining the activity of fungal selenium polysaccharides. Let it cool to room temperature before use; S3, De-alcoholization treatment of black rice wine; Take 1500g of the Nanzhu Wumi wine prepared in step S1, place it in an open container, and stir at low speed for 12min under a temperature of 38℃ and negative pressure ventilation. The alcohol content was 1.15% vol before treatment and decreased to 0.38% vol after treatment. Filtering removes coarse rice residue; S4. Yogurt base preparation; 7000g of raw milk was homogenized, pasteurized at 85℃ for 10 minutes, cooled to 42℃, inoculated with 8g of a compound strain of Bifidobacterium and Streptococcus thermophilus, and fermented at a constant temperature for 6.5 hours until pH 4.3, and coagulated into plain yogurt. S5, low-temperature compounding; Cool the yogurt to 36°C, then add the selenium-enriched sorghum rice pretreated in step S2, the wine after de-alcoholization in step S3, 250g of cold-pressed Nanzhu leaf concentrate, 250g of trehalose, and 10g of pectin-gelatin compound stabilizer in sequence. Stir at low speed for 8 minutes, with the temperature not exceeding 37°C throughout the process. S6. After filling and ripening: After mixing evenly, aseptically package and refrigerate at 4℃ for 12 hours to obtain the finished product.

[0026] Finished product test data: anthocyanin content 138mg / 100g, organic selenium content 0.058mg / kg, fungal polysaccharide content 105mg / 100g, alcohol content 0.38%vol.

[0027] Comparative Example 1: A preparation process for a yogurt made with selenium-enriched sorghum black rice and *Vigna oleifera* leaves includes the following steps: S1. Preparation of Nanzhu Wumi Wine; 750g of dried Cantharides leaves were crushed, soaked in 2500mL of water at room temperature for 6 hours, and filtered to obtain the basic dyeing juice; Soak 3000g of glutinous rice in the juice for 12 hours to allow it to fully absorb the color; Steam over water for 30 minutes until completely gelatinized; the temperature upon removal from the steamer should be approximately 92°C. Spread the rice out to cool to 62℃. Take 100g of fresh tender leaves of the Nandina domestica and add 500mL of room temperature purified water to cold-press the juice. Spray the juice onto the glutinous rice while stirring for 5 minutes. Continue to cool to 30℃, then evenly mix in 20g of sweet wine yeast; Seal in a ceramic jar and ferment at a constant temperature of 24℃ for 60 hours until a sweet wine is produced; Low-temperature pasteurization at 80℃ for 10 minutes yields Nanzhu Wumi wine for later use. S2, Low-temperature pretreatment of selenium-enriched sorghum black rice; Take 600g of selenium-enriched sorghum black rice fragments with a particle size of 2mm and soak them in water for 30 minutes; Steaming at 65℃ for 15 minutes in a water bath allows the starch on the surface of the black rice to be pregelatinized and the granules to soften, while retaining the activity of fungal selenium polysaccharides. Let it cool to room temperature before use; S3, De-alcoholization treatment of black rice wine; Take 1800g of the Nanzhu Wumi wine prepared in step S1, place it in an open container, and stir at low speed for 10min under 40℃ temperature and negative pressure ventilation conditions. The alcohol content was 1.12% vol before treatment and decreased to 0.43% vol after treatment. Filtering removes coarse rice residue; S4. Yogurt base preparation; 7000g of raw milk was homogenized, pasteurized at 85℃ for 10 minutes, cooled to 42℃, inoculated with 8g of a compound strain of Bifidobacterium and Streptococcus thermophilus, and fermented at a constant temperature for 6 hours until pH 4.4, and coagulated into plain yogurt. S5, low-temperature compounding; Cool the yogurt to 55°C, then add the selenium-enriched sorghum rice pretreated in step S2, the wine after de-alcoholization in step S3, 300g of cold-pressed Nanzhu leaf concentrate, 280g of trehalose, and 12g of pectin-gelatin compound stabilizer in sequence, and stir at low speed for 8 minutes. S6. After filling and ripening: After mixing evenly, aseptically package and refrigerate at 4℃ for 12 hours to obtain the finished product.

[0028] Finished product test data: Anthocyanin content 84mg / 100g, a decrease of 44.7% compared to Example 3, anthocyanin retention rate 55.6%, slight whey separation in the product, slightly rough taste.

[0029] Comparative Example 2: A preparation process for a yogurt made with selenium-enriched sorghum black rice and *Vigna oleifera* leaves includes the following steps: S1. Preparation of Nanzhu Wumi Wine; 750g of dried Cantharides leaves were crushed, soaked in 2500mL of water at room temperature for 6 hours, and filtered to obtain the basic dyeing juice; Soak 3000g of glutinous rice in the juice for 12 hours to allow it to fully absorb the color; Steam over water for 30 minutes until completely gelatinized; the temperature upon removal from the steamer should be approximately 92°C. Spread the rice out to cool to 62℃. Take 100g of fresh tender leaves of the Nandina domestica and add 500mL of room temperature purified water to cold-press the juice. Spray the juice onto the glutinous rice while stirring for 5 minutes. Continue to cool to 30℃, then evenly mix in 20g of sweet wine yeast; Seal in a ceramic jar and ferment at a constant temperature of 24℃ for 60 hours until a sweet wine is produced; Low-temperature pasteurization at 80℃ for 10 minutes yields Nanzhu Wumi wine for later use. S2, Low-temperature pretreatment of selenium-enriched sorghum black rice; Take 600g of selenium-enriched sorghum black rice fragments with a particle size of 2mm and soak them in water for 30 minutes; Steaming at 65℃ for 15 minutes in a water bath allows the starch on the surface of the black rice to be pregelatinized and the granules to soften, while retaining the activity of fungal selenium polysaccharides. Let it cool to room temperature before use; S3. Preparation of yogurt base; 7000g of raw milk was homogenized, pasteurized at 85℃ for 10 minutes, cooled to 42℃, inoculated with 8g of a compound strain of Bifidobacterium and Streptococcus thermophilus, and fermented at a constant temperature for 6 hours until pH 4.4, and coagulated into plain yogurt. S4, low-temperature compounding; Cool the yogurt to 35°C, then add the selenium-enriched sorghum glutinous rice pretreated in step S2, the Nanzhu glutinous rice wine from step S1, 300g of cold-pressed Nanzhu leaf concentrate, 280g of trehalose, and 12g of pectin-gelatin compound stabilizer in sequence. Stir at low speed for 8 minutes, with the temperature not exceeding 38°C throughout the process. S6. After filling and ripening: After mixing evenly, aseptically package and refrigerate at 4℃ for 12 hours to obtain the finished product.

[0030] Finished product test data: alcohol content 1.08% vol, strong and pungent aroma, unpleasant taste, and palatability significantly worse than Example 3.

[0031] Comparative Example 3: A preparation process for a yogurt made with selenium-enriched sorghum black rice and *Vigna oleifera* leaves includes the following steps: S1. Preparation of Nanzhu Wumi Wine; 750g of dried Cantharides leaves were crushed, soaked in 2500mL of water at room temperature for 6 hours, and filtered to obtain the basic dyeing juice; Soak 3000g of glutinous rice in the juice for 12 hours to allow it to fully absorb the color; Steam over water for 30 minutes until completely gelatinized; the temperature upon removal from the steamer should be approximately 92°C. Spread the rice out to cool to 62℃. Take 100g of fresh tender leaves of the Nandina domestica and add 500mL of room temperature purified water to cold-press the juice. Spray the juice onto the glutinous rice while stirring for 5 minutes. Continue to cool to 30℃, then evenly mix in 20g of sweet wine yeast; Seal in a ceramic jar and ferment at a constant temperature of 24℃ for 60 hours until a sweet wine is produced; Low-temperature pasteurization at 80℃ for 10 minutes yields Nanzhu Wumi wine for later use. S2, Low-temperature pretreatment of selenium-enriched sorghum black rice; Take 600g of selenium-enriched sorghum black rice fragments with a particle size of 2mm and soak them in water for 30 minutes; Steaming at 85℃ for 15 minutes in a water bath allows the starch on the surface of the black glutinous rice to be pregelatinized and the granules to soften, while retaining the activity of fungal selenium polysaccharides. Let it cool to room temperature before use; S3, De-alcoholization treatment of black rice wine; Take 1800g of the Nanzhu Wumi wine prepared in step S1, place it in an open container, and stir at low speed for 10min under 40℃ temperature and negative pressure ventilation conditions. The alcohol content was 1.12% vol before treatment and decreased to 0.43% vol after treatment. Filtering removes coarse rice residue; S4. Yogurt base preparation; 7000g of raw milk was homogenized, pasteurized at 85℃ for 10 minutes, cooled to 42℃, inoculated with 8g of a compound strain of Bifidobacterium and Streptococcus thermophilus, and fermented at a constant temperature for 6 hours until pH 4.4, and coagulated into plain yogurt. S5, low-temperature compounding; Cool the yogurt to 35°C, then add the selenium-enriched sorghum rice pretreated in step S2, the wine after de-alcoholization in step S3, 300g of cold-pressed Nanzhu leaf concentrate, 280g of trehalose, and 12g of pectin-gelatin compound stabilizer in sequence. Stir at low speed for 8 minutes, with the temperature not exceeding 38°C throughout the process. S6. After filling and ripening: After mixing evenly, aseptically package and refrigerate at 4℃ for 12 hours to obtain the finished product.

[0032] Finished product test data: Organic selenium content was 0.032 mg / kg, a decrease of 50.8% compared to Example 3; fungal polysaccharide content was 72 mg / 100g, a decrease of 39.0% compared to Example 3, indicating that high-temperature pretreatment led to a significant degradation of selenium polysaccharides and organic selenium.

[0033] Comparative Example 4: 28-day cold storage stability test The finished products of Example 3 and Comparative Example 1 were stored at 0–4°C for 28 days, with continuous monitoring throughout the process. Initial anthocyanin content 152 mg / 100 g 84 mg / 100 g 28-day anthocyanin content 125 mg / 100 g 58 mg / 100 g 28-day water retention 3.1% 18.7% Change in colour difference ΔE ≤2.5 ≥8.3 Sensory evaluation Uniform colour, no stratification Significant whey separation, stratification The experimental results show that the low-temperature compounding process at ≤38℃ of the present invention exhibits excellent system stability and anthocyanin retention capacity during 28 days of cold storage. The water separation rate is only 1 / 6 of that of the comparative example 1, the color difference change is much smaller than that of the comparative example, and the sensory quality is well maintained.

[0034] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A preparation process for a yogurt made with selenium-enriched sorghum black rice and *Vaccinium bracteatum* leaves, characterized in that, The following steps are included: S1. Low-temperature pretreatment of selenium-enriched sorghum black rice; Soak the selenium-rich sorghum black rice pieces in water, then steam them at a low temperature of 60-65℃ for 10-20 minutes to pregelatinize and soften the starch on the surface of the black rice. Let it cool before use; S2, De-alcoholization treatment of black rice wine; Place the fermented rice wine in an open container and stir at low speed for 8-15 minutes under a temperature of 35-42℃ and negative pressure ventilation. Through the selective volatilization of low-boiling-point ethanol, the alcohol content is reduced from 1.0-1.5% vol to 0.3-0.6% vol, removing the pungent ethanol odor while retaining the fermentation aroma substances. Filtering removes coarse rice residue; S3. Preparation of yogurt base; After homogenizing the raw milk, pasteurize it, cool it to 40-44℃, inoculate it with a compound fermentation strain, and ferment it at a constant temperature for 5-7 hours until the pH reaches 4.2-4.6, then coagulate it into plain yogurt. Cool the original flavor yogurt to 35°C; S4, low-temperature compounding; Add the selenium-enriched sorghum glutinous rice pretreated in step S1, the glutinous rice wine after de-alcoholization in step S2, the concentrated juice of cold-pressed southern candelilla leaves, trehalose and stabilizer to the original flavor yogurt in step S3 in sequence, and stir at low speed for 6 to 10 minutes at 35 to 38°C, with the temperature not exceeding 38°C throughout the process. S5. Post-filling curing; The material mixed evenly in step S4 is aseptically packaged and then refrigerated at 0-4℃ for 10-14 hours to obtain the finished product.