Method for preparing blueberry fruit wine by low-temperature fermentation

Abstract

The application discloses a method for preparing blueberry fruit wine through low-temperature fermentation and blueberry fruit wine prepared by the method. The method comprises the following steps: crushing blueberries to prepare pulp, adding partial heavy potassium sulfite, pectinase and beta-glucosidase, performing vacuum pulse treatment and squeezing to obtain blueberry juice; adjusting the soluble solid content of the blueberry juice, performing micro-nano bubble hydration treatment, adding a compound fermentation inoculum and mannoprotein to perform alcohol fermentation, performing pressure filtration to obtain blueberry fermentation liquor; adding polyethylene glycol modified EPS to the fermentation liquor, standing and clarifying, supplementing partial heavy potassium sulfite after filtration, performing pulse electric field aging, performing microporous membrane filtration and filling to obtain finished products. Through the synergistic optimization of enzymolysis, fermentation and aging technology, the problems of low low-temperature fermentation efficiency and insufficient release of flavor substances are effectively solved, the finished fruit wine is clear and bright, the color is stable, the functional ingredients are fully retained, the flavor is rich and harmonious, the production cycle is short, and the scientific and feasible innovative path is provided for the industrialized production of blueberry fruit wine.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, specifically relating to a method for preparing blueberry wine through low-temperature fermentation. Background Technology

[0002] Blueberries are rich in dietary bioactive compounds, such as vitamin C, folic acid, flavonoids, and phenolic substances, which have functions such as protecting eyesight, softening blood vessels, and enhancing human immunity. Pink Blue Blueberries are one of the late-ripening varieties of rabbiteye blueberries, known for their firm, crisp fruit, high balance of sweet and sour flavors, and unique lemon aroma. They also boast high yields and good storage and transportation properties. Their fruit has a moderate sugar-acid ratio and a high anthocyanin content, which contributes excellent flavor and color to wines.

[0003] Existing low-temperature fermentation methods for blueberry wine suffer from problems such as long fermentation cycles, a thin body, and a bland taste. Micro-nano bubble technology, as a novel assisted fermentation technique, generates micro-nano bubbles with a higher specific surface area, which is beneficial for improving the mass transfer efficiency of the blueberry fermentation system and increasing the utilization efficiency of nutrients in the fermentation substrate by fermenting microorganisms, thus accelerating the fermentation process. However, the hydroxyl radicals generated when micro-nano bubbles break under external influences can adversely affect anthocyanins in the blueberry fermentation system, thereby impacting the quality and nutritional value of the blueberry wine. Therefore, it is urgent to explore relevant methods to improve the long low-temperature fermentation cycle of blueberry wine while ensuring the retention of nutrients and maintaining good stability of the wine. Summary of the Invention

[0004] Technical Problem to be Solved: To address the aforementioned technical problems, the present invention discloses a method for preparing blueberry wine through low-temperature fermentation, and the blueberry wine prepared by this method. The method involves first crushing and pulping blueberries, then adding potassium metabisulfite, pectinase, and β-glucosidase, followed by vacuum pulse treatment and pressing to obtain blueberry juice. After adjusting the soluble solids content of the blueberry juice, it undergoes micro-nano bubble hydration treatment, followed by the addition of a compound fermentation agent and mannoprotein for alcoholic fermentation. The mixture is then filtered to obtain the blueberry fermentation broth. Polyethylene glycol-modified EPS is added to the fermentation broth, and the mixture is allowed to stand for clarification. After filtration, potassium metabisulfite is added again, and the mixture is then aged under a pulsed electric field, filtered through a microporous membrane, and bottled to obtain the finished product. This invention effectively solves the problems of low efficiency and insufficient release of flavor substances in low-temperature fermentation through the synergistic optimization of enzymatic hydrolysis, fermentation, and aging technologies. The finished wine is clear and bright, with stable color, sufficient retention of functional components, and a rich and harmonious flavor. Furthermore, the production cycle is short, providing a scientifically feasible and innovative path for the industrial production of blueberry wine.

[0005] Technical solution: A method for preparing blueberry wine through low-temperature fermentation, comprising the following steps: S1. Select ripe pink and blue blueberries, crush them and pulp them to obtain blueberry pulp; S2. Add 30-80 mg / L potassium metabisulfite, pectinase and β-glucosidase to blueberry pulp, then perform vacuum pulse treatment, and press to obtain blueberry juice; S3. After adjusting the soluble fixed content of blueberry juice to 20-22°Brix, perform micro-nano bubble hydration treatment, then add 0.1-0.35% fermentation agent and 2-5g / L mannoprotein for alcoholic fermentation, and filter to remove the precipitate to obtain blueberry fermentation liquid; S4. Add polyethylene glycol-modified EPS to blueberry fermentation broth and let stand for 6-12 hours. After filtration, add 30-80 mg / L potassium metabisulfite for pulsed electric field aging treatment, and then ultrafilter and bottle to obtain blueberry wine.

[0006] Preferably, the amount of pectinase added in S2 is 0.1-0.3%, and the amount of β-glucosidase added is 0.15-0.25%, based on the volume of blueberry pulp.

[0007] Preferably, the conditions for vacuum pulse processing in S2 are: temperature 40-50℃, vacuum pressure 10-30kPa, pulse ratio (1.5-3):1, and processing times 4-7 times.

[0008] Preferably, the conditions for the micro-nano bubble hydration treatment in S3 are an ultrasonic frequency of 35-50 kPa, an ultrasonic power of 250-500 W, and a treatment time of 1-5 min.

[0009] Preferably, the ratio of *Saccharomyces cerevisiae* and *Lactobacillus rhamnosus* in the fermentation agent in S3 is (1-4):(0.5-1.5), and the concentration of the fermentation agent is (4-8)×10⁻⁶. 7 CFU / mL.

[0010] Preferably, the fermentation conditions for alcoholic fermentation in S3 are a fermentation temperature of 15-18℃ and a fermentation time of 7-10 days.

[0011] Preferably, the preparation method of polyethylene glycol modified EPS in S4 is to mix polyethylene glycol and EPS in a mass ratio of 1:(0.5-2) and dissolve them in water, and treat them at 30-50℃ and 300-600 rpm for 1-2.5h, and then dry them to obtain polyethylene glycol modified EPS.

[0012] Preferably, the amount of polyethylene glycol-modified EPS added in S4 is 0.5-1wt%; the conditions for pulsed electric field catalytic aging treatment are: electric field strength 20-40kV / cm, pulse frequency 400-600Hz, treatment temperature 20-35℃, pulse width 5-15μs, and treatment time 1-2h.

[0013] Blueberry wine prepared by any of the methods described above. Beneficial effects

[0014] 1. This invention employs vacuum pulse treatment and enzymatic pretreatment of blueberries to lay the foundation for low-temperature fermentation of blueberry wine. The vacuum environment causes gas expansion within the blueberry cells, creating a pressure difference. The pulse process generates a physical impact similar to cavitation, causing microcracks in the cell walls and membranes, increasing cell permeability, disrupting the binding of nutrients and pectin, facilitating the action of pectinase and β-glucosidase, and opening pathways for subsequent reactions and nutrient release, thus benefiting the microorganisms' nutrient acquisition during fermentation. Pectinase breaks down the glycosidic bonds of pectin in the cell wall into oligosaccharides, releasing bound nutrients; β-glucosidase breaks down oligosaccharides into glucose, increasing the fermentable sugar content, ensuring thorough fermentation, and also releasing free flavor compounds, enhancing the flavor of the wine. The combined enzymatic hydrolysis of these two enzymes reduces the viscosity of the fermentation substrate, improves mass transfer resistance, optimizes fluidity, promotes contact between the microorganisms and nutrients, and improves the efficiency and uniformity of low-temperature fermentation.

[0015] 2. This invention employs micro-nano bubble technology to create a compound microbial strain (Saccharomyces cerevisiae and Lactobacillus rhamnosus), supplemented with mannoprotein for the low-temperature alcoholic fermentation stage of blueberries, thereby improving fermentation capacity and rate. Micro-nano bubbles efficiently dissolve oxygen, meeting the aerobic metabolism requirements of Saccharomyces cerevisiae and solving the problem of slow microbial proliferation due to insufficient dissolved oxygen at low temperatures. Their micro-stirring and micro-turbulence effects enhance the contact between nutrients and microbial cells, solving the problem of slow nutrient supply due to slow diffusion of substances at low temperatures, laying the physical foundation for efficient fermentation. Lactobacillus rhamnosus metabolizes blueberry organic acids into mild products, reducing acid strength and avoiding toxic inhibition of Saccharomyces cerevisiae; the substances it produces activate Saccharomyces cerevisiae pathways, improving energy metabolism efficiency, enhancing fermentation activity, and solving the problem of slow fermentation speed. Mannoprotein forms a complex system with anthocyanins, improving its stability; it forms a protective membrane on the Saccharomyces cerevisiae cell membrane, maintaining intracellular homeostasis; its polysaccharide structure promotes the synthesis of stress-resistant proteins by yeast, enhancing low-temperature survival and metabolic activity, ensuring efficient low-temperature fermentation of blueberries.

[0016] 3. This invention utilizes polyethylene glycol-modified EPS clarification and pulsed electric field technology to accelerate the aging of blueberry wine, resulting in a clear, bright, full-bodied, and flavorful product, while simultaneously improving aging efficiency and shortening aging time. Polyethylene glycol-modified EPS combines with hydrophobic impurities in blueberry wine to form flocs, which settle under gravity and are removed by simple filtration. Its steric hindrance effect prevents EPS molecules from agglomerating, increases the contact area with impurities to enhance adsorption, and the polysaccharide skeleton encapsulates suspended particles to prevent dispersion, thoroughly removing turbid components. Furthermore, the modified EPS preferentially adsorbs turbid impurities, with extremely low adsorption of core components such as anthocyanins, maximizing the preservation of the wine's nutrition and flavor, and providing a pure matrix for accelerated aging. The high-intensity electric field energy of the pulsed electric field breaks intermolecular forces, accelerates esterification reactions, generates mild aroma components, promotes a balance between tannin polymerization and depolymerization, reduces bitterness, and results in a mellow and harmonious taste, breaking through the limitations of traditional aging methods. The electric field can also stabilize the structure of pigment molecules, inhibit oxidative degradation, maintain uniform and lasting color, accelerate the diffusion of flavor substances, promote the integration of fruit aroma and wine aroma, enhance the flavor intensity and layering, and enable fruit wine to reach the maturity of traditional aging in a short time.

[0017] 4. This invention achieves efficient brewing and quality improvement of blueberry wine under low-temperature conditions through the synergistic optimization of enzymatic hydrolysis, fermentation and aging technologies. It not only shortens the production cycle, but also breaks through the bottlenecks of traditional processes in terms of color stability, flavor complexity and taste balance, providing an innovative path for the industrial production of fruit wine that is both scientific and feasible. Attached Figure Description

[0018] Figure 1 The graphs show the changes in soluble solids content over fermentation time for Examples 1-6. Figure 2 The graphs show the changes in soluble solids content over fermentation time for Examples 7-12. Figure 3 The graphs show the changes in soluble solids content over fermentation time for Comparative Examples 1-6. Detailed Implementation

[0019] The present invention will be further described below with reference to embodiments. These embodiments are illustrative of the present invention, but the present invention is not limited to these embodiments: Example 1

[0020] A method for preparing blueberry wine through low-temperature fermentation includes the following steps: S1. Select 500g of ripe pink blueberries and use a pulper to crush and pulp them to obtain blueberry pulp; S2. Add 300mg potassium metabisulfite, 6g pectinase and 9g β-glucosidase to 6L of blueberry pulp, and perform vacuum pulse treatment at 45℃, 20kPa and pulse ratio of 1.5:1 (i.e., vacuum time 30min, normal pressure time 20min), for a total of 5 cycles, with an interval of 15min between each cycle, and obtain blueberry juice after pressing. S3. Mix 2.5g of brewer's yeast and 2.5g of Lactobacillus rhamnosus, then add to 50mL of 5% (w / w) white sugar solution and activate at 37℃ for 30min. Adjust the inoculum concentration to 6.5×10⁻⁶. 7 CFU / mL was used to obtain a well-activated fermentation agent; S4. Add white sugar to 5L of blueberry juice to adjust the soluble solids content to 22°Brix. Then, treat with micro-nano bubble hydration at 25℃, 40kPa, and 300W for 2 minutes. Add the fermentation agent prepared in S3 and 10g of mannose protein. Ferment at 18℃ until the soluble solids value stops decreasing for 3 consecutive days (which is the endpoint of alcoholic fermentation). Filter to remove the precipitate and obtain the blueberry fermentation liquid. S5. Mix 10g polyethylene glycol and 10g lactic acid bacteria extracellular polysaccharide (EPS) in water, treat at 40℃ and 400 rpm for 2h, and dry to obtain polyethylene glycol modified EPS; S6. Add 2g of polyethylene glycol modified EPS to 4L of blueberry fermentation liquid and let stand for 6h. After filtration, add 200mg of potassium metabisulfite and accelerate aging at 25℃, electric field strength 20kV / cm, frequency 400Hz, and pulse width 10μs for 1h. Quickly cool down to 2℃ and maintain for 24h. Filter using a microporous membrane and then return to room temperature for bottling to obtain blueberry wine. Example 2

[0021] A method for preparing blueberry wine through low-temperature fermentation includes the following steps: S1. Select 500g of ripe pink blueberries and use a pulper to crush and pulp them to obtain blueberry pulp; S2. Add 300mg potassium metabisulfite, 12g pectinase and 15g β-glucosidase to 6L of blueberry pulp, and perform vacuum pulse treatment at 45℃, 20kPa and pulse ratio of 1.5:1 (i.e., vacuum time 30min, normal pressure time 20min), for a total of 5 cycles, with an interval of 15min between each cycle. After pressing, obtain blueberry juice. S3. Mix 2.5g of brewer's yeast and 2.5g of Lactobacillus rhamnosus, then add to 50mL of 5% (w / w) white sugar solution and activate at 37℃ for 30min. Adjust the inoculum concentration to 6.5×10⁻⁶. 7 CFU / mL was used to obtain a well-activated fermentation agent; S4. Add white sugar to 5L of blueberry juice to adjust the soluble solids content to 22°Brix. Then, treat with micro-nano bubble hydration at 25℃, 40kPa, and 300W for 2 minutes. Add the fermentation agent prepared in S3 and 10g of mannose protein. Ferment at 18℃ until the soluble solids value stops decreasing for 3 consecutive days (which is the endpoint of alcoholic fermentation). Filter to remove the precipitate and obtain the blueberry fermentation liquid. S5. Mix 10g polyethylene glycol and 10g lactic acid bacteria extracellular polysaccharide (EPS) in water, treat at 40℃ and 400 rpm for 2h, and dry to obtain polyethylene glycol modified EPS; S6. Add 2g of polyethylene glycol modified EPS to 4L of blueberry fermentation liquid and let stand for 6h. After filtration, add 200mg of potassium metabisulfite and accelerate aging at 25℃, electric field strength 20kV / cm, frequency 400Hz, and pulse width 10μs for 1h. Quickly cool down to 2℃ and maintain for 24h. Filter using a microporous membrane and then return to room temperature for bottling to obtain blueberry wine. Example 3

[0022] A method for preparing blueberry wine by low-temperature fermentation includes the following steps: S1. Select 500g of ripe pink blueberries and use a pulper to crush and pulp them to obtain blueberry pulp; S2. Add 300mg potassium metabisulfite, 18g pectinase and 12g β-glucosidase to 6L of blueberry pulp, and perform vacuum pulse treatment at 45℃, 20kPa and pulse ratio of 1.5:1 (i.e., vacuum time for 30min and normal pressure time for 20min), for a total of 5 cycles, with an interval of 15min between each cycle, and obtain blueberry juice after pressing; S3. Mix 4g of brewer's yeast and 1g of Lactobacillus rhamnosus, then add to 50mL of 5% (w / w) white sugar solution and activate at 37℃ for 30min. Adjust the bacterial concentration to 6.5×10⁻⁶. 7 CFU / mL was used to obtain a well-activated fermentation agent; S4. Add white sugar to 5L of blueberry juice to adjust the soluble solids content to 22°Brix. Then, treat with micro-nano bubble hydration at 25℃, 40kPa, and 300W for 2 minutes. Add the fermentation agent prepared in S3 and 10g of mannose protein. Ferment at 18℃ until the soluble solids value stops decreasing for 3 consecutive days (which is the endpoint of alcoholic fermentation). Filter to remove the precipitate and obtain the blueberry fermentation liquid. S5. Mix 10g polyethylene glycol and 10g lactic acid bacteria extracellular polysaccharide (EPS) in water, treat at 40℃ and 400 rpm for 2h, and dry to obtain polyethylene glycol modified EPS; S6. Add 2g of polyethylene glycol modified EPS to 4L of blueberry fermentation liquid and let stand for 6h. After filtration, add 200mg of potassium metabisulfite and accelerate aging at 25℃, electric field strength 20kV / cm, frequency 400Hz, and pulse width 10μs for 1h. Quickly cool down to 2℃ and maintain for 24h. Filter using a microporous membrane and then return to room temperature for bottling to obtain blueberry wine. Example 4

[0023] A method for preparing blueberry wine by low-temperature fermentation includes the following steps: S1. Select 500g of ripe pink blueberries and use a pulper to crush and pulp them to obtain blueberry pulp; S2. Add 300mg potassium metabisulfite, 18g pectinase and 12g β-glucosidase to 6L of blueberry pulp, and perform vacuum pulse treatment at 40℃, 15kPa and pulse ratio of 2:1 (i.e., vacuum time 40min, normal pressure time 20min), for a total of 4 cycles, with an interval of 15min between each cycle, and obtain blueberry juice after pressing. S3. Mix 4g of brewer's yeast and 1g of Lactobacillus rhamnosus, then add to 50mL of 5% (w / w) white sugar solution and activate at 37℃ for 30min. Adjust the bacterial concentration to 6.5×10⁻⁶. 7 CFU / mL was used to obtain a well-activated fermentation agent; S4. Add white sugar to 5L of blueberry juice to adjust the soluble solids content to 22°Brix. Then, treat with micro-nano bubble hydration at 25℃, 40kPa, and 300W for 2 minutes. Add the fermentation agent prepared in S3 and 10g of mannose protein. Ferment at 18℃ until the soluble solids value stops decreasing for 3 consecutive days (which is the endpoint of alcoholic fermentation). Filter to remove the precipitate and obtain the blueberry fermentation liquid. S5. Mix 10g polyethylene glycol and 10g lactic acid bacteria extracellular polysaccharide (EPS) in water, treat at 40℃ and 400 rpm for 2h, and dry to obtain polyethylene glycol modified EPS; S6. Add 2g of polyethylene glycol modified EPS to 4L of blueberry fermentation liquid and let stand for 6h. After filtration, add 200mg of potassium metabisulfite and accelerate aging at 25℃, electric field strength 20kV / cm, frequency 400Hz, and pulse width 10μs for 1h. Quickly cool down to 2℃ and maintain for 24h. Filter using a microporous membrane and then return to room temperature for bottling to obtain blueberry wine. Example 5

[0024] A method for preparing blueberry wine by low-temperature fermentation includes the following steps: S1. Select 500g of ripe pink blueberries and use a pulper to crush and pulp them to obtain blueberry pulp; S2. Add 300mg potassium metabisulfite, 18g pectinase and 12g β-glucosidase to 6L of blueberry pulp, and perform vacuum pulse treatment at 45℃, 30kPa and pulse ratio of 3:1 (i.e., vacuum time 30min, normal pressure time 10min), for a total of 6 cycles, with an interval of 15min between each cycle, and obtain blueberry juice after pressing. S3. Mix 4g of brewer's yeast and 1g of Lactobacillus rhamnosus, then add to 50mL of 5% (w / w) white sugar solution and activate at 37℃ for 30min. Adjust the bacterial concentration to 6.5×10⁻⁶. 7 CFU / mL was used to obtain a well-activated fermentation agent; S4. Add white sugar to 5L of blueberry juice to adjust the soluble solids content to 22°Brix. Then, treat with micro-nano bubble hydration at 25℃, 40kPa, and 300W for 2 minutes. Add the fermentation agent prepared in S3 and 10g of mannose protein. Ferment at 18℃ until the soluble solids value stops decreasing for 3 consecutive days (which is the endpoint of alcoholic fermentation). Filter to remove the precipitate and obtain the blueberry fermentation liquid. S5. Mix 10g polyethylene glycol and 10g lactic acid bacteria extracellular polysaccharide (EPS) in water, treat at 40℃ and 400 rpm for 2h, and dry to obtain polyethylene glycol modified EPS; S6. Add 2g of polyethylene glycol modified EPS to 4L of blueberry fermentation liquid and let stand for 6h. After filtration, add 200mg of potassium metabisulfite and accelerate aging at 25℃, electric field strength 20kV / cm, frequency 400Hz, and pulse width 10μs for 1h. Quickly cool down to 2℃ and maintain for 24h. Filter using a microporous membrane and then return to room temperature for bottling to obtain blueberry wine. Example 6

[0025] A method for preparing blueberry wine by low-temperature fermentation includes the following steps: S1. Select 500g of ripe pink blueberries and use a pulper to crush and pulp them to obtain blueberry pulp; S2. Add 300mg potassium metabisulfite, 18g pectinase and 12g β-glucosidase to 6L of blueberry pulp, and perform vacuum pulse treatment at 45℃, 20kPa and pulse ratio of 1.5:1 (i.e., vacuum time for 30min and normal pressure time for 20min), for a total of 5 cycles, with an interval of 15min between each cycle, and obtain blueberry juice after pressing; S3. Mix 2.5g of brewer's yeast and 2.5g of Lactobacillus rhamnosus, then add to 50mL of 5% (w / w) white sugar solution and activate at 37℃ for 30min. Adjust the inoculum concentration to 6.5×10⁻⁶. 7 CFU / mL was used to obtain a well-activated fermentation agent; S4. Add white sugar to 5L of blueberry juice to adjust the soluble solids content to 22°Brix. Then, perform micro-nano bubble hydration treatment at 25℃, 45kPa, and 400W for 1 minute. Add the fermentation agent prepared in S3 and 10g of mannose protein. Ferment at 18℃ until the soluble solids value stops decreasing for 3 consecutive days (which is the endpoint of alcoholic fermentation). Filter to remove the precipitate and obtain the blueberry fermentation liquid. S5. Mix 10g polyethylene glycol and 10g lactic acid bacteria extracellular polysaccharide (EPS) in water, treat at 40℃ and 400 rpm for 2h, and dry to obtain polyethylene glycol modified EPS; S6. Add 2g of polyethylene glycol modified EPS to 4L of blueberry fermentation liquid and let stand for 6h. After filtration, add 200mg of potassium metabisulfite and accelerate aging at 25℃, electric field strength 20kV / cm, frequency 400Hz, and pulse width 10μs for 1h. Quickly cool down to 2℃ and maintain for 24h. Filter using a microporous membrane and then return to room temperature for bottling to obtain blueberry wine. Example 7

[0026] A method for preparing blueberry wine by low-temperature fermentation includes the following steps: S1. Select 500g of ripe pink blueberries and use a pulper to crush and pulp them to obtain blueberry pulp; S2. Add 300mg potassium metabisulfite, 18g pectinase and 12g β-glucosidase to 6L of blueberry pulp, and perform vacuum pulse treatment at 45℃, 20kPa and pulse ratio of 1.5:1 (i.e., vacuum time for 30min and normal pressure time for 20min), for a total of 5 cycles, with an interval of 15min between each cycle, and obtain blueberry juice after pressing; S3. Mix 2.5g of brewer's yeast and 2.5g of Lactobacillus rhamnosus, then add to 50mL of 5% (w / w) white sugar solution and activate at 37℃ for 30min. Adjust the inoculum concentration to 6.5×10⁻⁶. 7 CFU / mL was used to obtain a well-activated fermentation agent; S4. Add white sugar to 5L of blueberry juice to adjust the soluble solids content to 22°Brix. Then, perform micro-nano bubble hydration treatment at 25℃, 45kPa, and 500W for 2 minutes. Add the fermentation agent prepared in S3 and 10g of mannose protein. Ferment at 18℃ until the soluble solids value stops decreasing for 3 consecutive days (which is the endpoint of alcoholic fermentation). Filter to remove the precipitate and obtain the blueberry fermentation liquid. S5. Mix 10g polyethylene glycol and 10g lactic acid bacteria extracellular polysaccharide (EPS) in water, treat at 40℃ and 400 rpm for 2h, and dry to obtain polyethylene glycol modified EPS; S6. Add 2g of polyethylene glycol modified EPS to 4L of blueberry fermentation liquid and let stand for 6h. After filtration, add 200mg of potassium metabisulfite and accelerate aging at 25℃, electric field strength 20kV / cm, frequency 400Hz, and pulse width 10μs for 1h. Quickly cool down to 2℃ and maintain for 24h. Filter using a microporous membrane and then return to room temperature for bottling to obtain blueberry wine. Example 8

[0027] A method for preparing blueberry wine by low-temperature fermentation includes the following steps: S1. Select 500g of ripe pink blueberries and use a pulper to crush and pulp them to obtain blueberry pulp; S2. Add 300mg potassium metabisulfite, 18g pectinase and 12g β-glucosidase to 6L of blueberry pulp, and perform vacuum pulse treatment at 45℃, 20kPa and pulse ratio of 1.5:1 (i.e., vacuum time for 30min and normal pressure time for 20min), for a total of 5 cycles, with an interval of 15min between each cycle, and obtain blueberry juice after pressing; S3. Mix 6g of brewer's yeast and 3g of Lactobacillus rhamnosus, then add to 90mL of 5% (w / w) white sugar solution and activate at 37℃ for 30min. Adjust the bacterial concentration to 6.5×10⁻⁶. 7 CFU / mL was used to obtain a well-activated fermentation agent; S4. Add white sugar to 5L of blueberry juice to adjust the soluble solids content to 22°Brix. Then, perform micro-nano bubble hydration treatment at 25℃, 45kPa, and 400W for 1 minute. Add the fermentation agent prepared in S3 and 20g of mannose protein. Ferment at 18℃ until the soluble solids value stops decreasing for 3 consecutive days (which is the endpoint of alcoholic fermentation). Filter to remove the precipitate and obtain the blueberry fermentation liquid. S5. Mix 10g polyethylene glycol and 10g lactic acid bacteria extracellular polysaccharide (EPS) in water, treat at 40℃ and 400 rpm for 2h, and dry to obtain polyethylene glycol modified EPS; S6. Add 2g of polyethylene glycol modified EPS to 4L of blueberry fermentation liquid and let stand for 6h. After filtration, add 200mg of potassium metabisulfite and accelerate aging at 25℃, electric field strength 20kV / cm, frequency 400Hz, and pulse width 10μs for 1h. Quickly cool down to 2℃ and maintain for 24h. Filter using a microporous membrane and then return to room temperature for bottling to obtain blueberry wine. Example 9

[0028] A method for preparing blueberry wine by low-temperature fermentation includes the following steps: S1. Select 500g of ripe pink blueberries and use a pulper to crush and pulp them to obtain blueberry pulp; S2. Add 300mg potassium metabisulfite, 18g pectinase and 12g β-glucosidase to 6L of blueberry pulp, and perform vacuum pulse treatment at 45℃, 20kPa and pulse ratio of 1.5:1 (i.e., vacuum time for 30min and normal pressure time for 20min), for a total of 5 cycles, with an interval of 15min between each cycle, and obtain blueberry juice after pressing; S3. Mix 10g of brewer's yeast and 5g of Lactobacillus rhamnosus, then add to 150mL of 5% (w / w) white sugar solution and activate at 37℃ for 30min. Adjust the bacterial concentration to 6.5×10⁻⁶. 7 CFU / mL was used to obtain a well-activated fermentation agent; S4. Add white sugar to 5L of blueberry juice to adjust the soluble solids content to 22°Brix. Then, perform micro-nano bubble hydration treatment at 25℃, 45kPa, and 400W for 1 minute. Add the fermentation agent prepared in S3 and 20g of mannose protein. Ferment at 18℃ until the soluble solids value stops decreasing for 3 consecutive days (which is the endpoint of alcoholic fermentation). Filter to remove the precipitate and obtain the blueberry fermentation liquid. S5. Mix 10g polyethylene glycol and 10g lactic acid bacteria extracellular polysaccharide (EPS) in water, treat at 40℃ and 400 rpm for 2h, and dry to obtain polyethylene glycol modified EPS; S6. Add 2g of polyethylene glycol modified EPS to 4L of blueberry fermentation liquid and let stand for 6h. After filtration, add 200mg of potassium metabisulfite and accelerate aging at 25℃, electric field strength 20kV / cm, frequency 400Hz, and pulse width 10μs for 1h. Quickly cool down to 2℃ and maintain for 24h. Filter using a microporous membrane and then return to room temperature for bottling to obtain blueberry wine. Example 10

[0029] A method for preparing blueberry wine by low-temperature fermentation includes the following steps: S1. Select 500g of ripe pink blueberries and use a pulper to crush and pulp them to obtain blueberry pulp; S2. Add 300mg potassium metabisulfite, 18g pectinase and 12g β-glucosidase to 6L of blueberry pulp, and perform vacuum pulse treatment at 45℃, 20kPa and pulse ratio of 1.5:1 (i.e., vacuum time for 30min and normal pressure time for 20min), for a total of 5 cycles, with an interval of 15min between each cycle, and obtain blueberry juice after pressing; S3. Mix 6g of brewer's yeast and 3g of Lactobacillus rhamnosus, then add to 90mL of 5% (w / w) white sugar solution and activate at 37℃ for 30min. Adjust the bacterial concentration to 6.5×10⁻⁶. 7 CFU / mL was used to obtain a well-activated fermentation agent; S4. Add white sugar to 5L of blueberry juice to adjust the soluble solids content to 22°Brix. Then, perform micro-nano bubble hydration treatment at 25℃, 45kPa, and 400W for 1 minute. Add the fermentation agent prepared in S3 and 20g of mannose protein. Ferment at 18℃ until the soluble solids value stops decreasing for 3 consecutive days (which is the endpoint of alcoholic fermentation). Filter to remove the precipitate and obtain the blueberry fermentation liquid. S5. Mix 10g polyethylene glycol and 10g lactic acid bacteria extracellular polysaccharide (EPS) in water, treat at 40℃ and 400 rpm for 2h, and dry to obtain polyethylene glycol modified EPS; S6. Add 4g of polyethylene glycol modified EPS to 4L of blueberry fermentation liquid and let stand for 10h. After filtration, add 200mg of potassium metabisulfite and accelerate aging at 25℃, electric field strength 20kV / cm, frequency 400Hz, and pulse width 10μs for 1h. Quickly cool down to 2℃ and maintain for 24h. Filter using a microporous membrane and then return to room temperature for bottling to obtain blueberry wine. Example 11

[0030] A method for preparing blueberry wine by low-temperature fermentation includes the following steps: S1. Select 500g of ripe pink blueberries and use a pulper to crush and pulp them to obtain blueberry pulp; S2. Add 300mg potassium metabisulfite, 18g pectinase and 12g β-glucosidase to 6L of blueberry pulp, and perform vacuum pulse treatment at 45℃, 20kPa and pulse ratio of 1.5:1 (i.e., vacuum time for 30min and normal pressure time for 20min), for a total of 5 cycles, with an interval of 15min between each cycle, and obtain blueberry juice after pressing; S3. Mix 6g of brewer's yeast and 3g of Lactobacillus rhamnosus, then add to 90mL of 5% (w / w) white sugar solution and activate at 37℃ for 30min. Adjust the bacterial concentration to 6.5×10⁻⁶. 7 CFU / mL was used to obtain a well-activated fermentation agent; S4. Add white sugar to 5L of blueberry juice to adjust the soluble solids content to 22°Brix. Then, perform micro-nano bubble hydration treatment at 25℃, 45kPa, and 400W for 1 minute. Add the fermentation agent prepared in S3 and 20g of mannose protein. Ferment at 18℃ until the soluble solids value stops decreasing for 3 consecutive days (which is the endpoint of alcoholic fermentation). Filter to remove the precipitate and obtain the blueberry fermentation liquid. S5. Mix 10g polyethylene glycol and 10g lactic acid bacteria extracellular polysaccharide (EPS) in water, treat at 40℃ and 400 rpm for 2h, and dry to obtain polyethylene glycol modified EPS; S6. Add 2g of polyethylene glycol modified EPS to 4L of blueberry fermentation liquid and let stand for 10h. After filtration, add 200mg of potassium metabisulfite and accelerate aging at 25℃, electric field strength 30kV / cm, frequency 500Hz, and pulse width 10μs for 2h. Quickly cool down to 2℃ and maintain for 24h. Filter using a microporous membrane and then return to room temperature for bottling to obtain blueberry wine. Example 12

[0031] A method for preparing blueberry wine by low-temperature fermentation includes the following steps: S1. Select 500g of ripe pink blueberries and use a pulper to crush and pulp them to obtain blueberry pulp; S2. Add 300mg potassium metabisulfite, 18g pectinase and 12g β-glucosidase to 6L of blueberry pulp, and perform vacuum pulse treatment at 45℃, 20kPa and pulse ratio of 1.5:1 (i.e., vacuum time for 30min and normal pressure time for 20min), for a total of 5 cycles, with an interval of 15min between each cycle, and obtain blueberry juice after pressing; S3. Mix 6g of brewer's yeast and 3g of Lactobacillus rhamnosus, then add to 90mL of 5% (w / w) white sugar solution and activate at 37℃ for 30min. Adjust the bacterial concentration to 6.5×10⁻⁶. 7 CFU / mL was used to obtain a well-activated fermentation agent; S4. Add white sugar to 5L of blueberry juice to adjust the soluble solids content to 22°Brix. Then, perform micro-nano bubble hydration treatment at 25℃, 45kPa, and 400W for 1 minute. Add the fermentation agent prepared in S3 and 20g of mannose protein. Ferment at 18℃ until the soluble solids value stops decreasing for 3 consecutive days (which is the endpoint of alcoholic fermentation). Filter to remove the precipitate and obtain the blueberry fermentation liquid. S5. Mix 10g polyethylene glycol and 10g lactic acid bacteria extracellular polysaccharide (EPS) in water, treat at 40℃ and 400 rpm for 2h, and dry to obtain polyethylene glycol modified EPS; S6. Add 2g of polyethylene glycol modified EPS to 4L of blueberry fermentation liquid and let stand for 6h. After filtration, add 200mg of potassium metabisulfite and accelerate aging at 25℃, electric field strength 40kV / cm, frequency 600Hz, and pulse width 10μs for 1.5h. Quickly cool down to 2℃ and maintain for 24h. Filter using a microporous membrane and then return to room temperature for bottling to obtain blueberry wine. Comparative Example 1

[0032] The difference between this comparative example and Example 11 is that vacuum pulse processing is not used; the remaining operations are the same as in Example 11. Comparative Example 2

[0033] The difference between this comparative example and Example 11 is that micro-nano bubble hydration treatment is not used; the remaining operations are the same as in Example 11. Comparative Example 3

[0034] The difference between this comparative example and Example 11 is that the polyethylene glycol modified EPS is replaced with diatomaceous earth, and the remaining operations are the same as in Example 11. Comparative Example 4

[0035] The difference between this comparative example and Example 11 is that the polyethylene glycol modified EPS is replaced with EPS, and the remaining operations are the same as in Example 11. Comparative Example 5

[0036] The difference between this comparative example and Example 11 is that only brewer's yeast is used for fermentation, while the remaining operations are the same as in Example 11. Comparative Example 6

[0037] The difference between this comparative example and Example 11 is that it does not use vacuum pulse treatment and micro-nano bubble hydration treatment, but only uses brewer's yeast fermentation. The remaining operations are the same as in Example 11.

[0038] Performance testing (1) Soluble solids content The soluble solids content was determined using a handheld saccharimeter.

[0039] The alcoholic fermentation endpoint for Examples 1-12 and Comparative Examples 1-6 was determined by the soluble solids content ceasing to decrease for three consecutive days. Figure 1 and Figure 2 It can be seen that the soluble solids content in Examples 1-12 tends to decrease with the extension of fermentation time, until the alcoholic fermentation stage is completed, with a fermentation cycle of 7-10 days; Figure 3 It can be seen that although the soluble solids in Comparative Examples 1-6 showed the same decreasing trend, the fermentation cycle was 12-15 days. The results indicate that vacuum pulse and micro / nano bubble hydration treatment can significantly improve the uniformity and abundance of the fermentation substrate, greatly enhance the metabolic utilization efficiency of the complex strains during fermentation, accelerate the sugar conversion rate, thereby significantly shortening the fermentation cycle and improving production efficiency.

[0040] (2) Light transmittance Take an appropriate amount of blueberry wine, using distilled water as a control, and measure the absorbance A at 660 nm. The transmittance is calculated using the formula T (%) = 10. -A .

[0041] (3) Sensory evaluation The sensory evaluation was conducted in accordance with the sensory evaluation method in GB / T 32783-2016 Blueberry Wine, and was carried out by 10 professional judges with reference to the sensory evaluation form (as shown in Table 1).

[0042] Table 2 Sensory Evaluation Criteria for Blueberry Wine

[0043] (4) Alcohol content The alcohol content of blueberry wine was determined with reference to GB 5009.225-2016, "National Food Safety Standard - Determination of Ethanol Concentration in Wine".

[0044] (5) Total sugar The total sugar content in blueberry wine was determined using the phenol-sulfuric acid method, with absorbance measured at a wavelength of 490 nm using glucose as a standard.

[0045] (6) Total acid The total acid content of blueberry wine was determined by acid-base titration.

[0046] (7) Total anthocyanins The total anthocyanin content of blueberry wine was determined by pH differential method.

[0047] (8) Total phenols The total phenol content of blueberry wine was determined using the Folin-Ciocalteu colorimetric method.

[0048] Table 2. Physicochemical properties of blueberry wine in Example 11 and Comparative Examples 1-6

[0049] As shown in Table 2, the blueberry wine prepared in Example 11 exhibits superior transmittance, sensory indicators, total anthocyanin content, and total phenolic content compared to Comparative Examples 1-6. This indicates that the preparation process of Example 11 has significant advantages in improving the quality of blueberry wine. Its optimized fermentation conditions and raw material ratio not only effectively preserve the active ingredients in blueberries but also enhance the clarity and sensory harmony of the wine. Furthermore, the alcohol content of Example 11 is significantly higher than that of Comparative Examples 1-6, indicating that the activity of the brewing yeast is better utilized during fermentation, resulting in higher sugar conversion efficiency. Combined with its moderate total sugar and total acid content, the wine exhibits a good balance of sweet and sour, with a more mellow and harmonious flavor, further verifying the crucial role of process optimization in improving the overall quality of blueberry wine.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the technical solutions of the present invention, shall still fall within the scope of protection of the present invention.

Claims

1. A method for preparing blueberry wine through low-temperature fermentation, characterized in that, Includes the following steps: S1. Select ripe pink and blue blueberries, crush them and pulp them to obtain blueberry pulp; S2. Add 30-80 mg / L potassium metabisulfite, pectinase and β-glucosidase to blueberry pulp and then perform vacuum pulse treatment, and press to obtain blueberry juice; the conditions for vacuum pulse treatment are temperature 40-50℃, vacuum pressure 10-30 kPa, pulse ratio (1.5-3):1, and treatment times 4-7 times; S3. After adjusting the soluble solids content of blueberry juice to 20-22°Brix, perform micro-nano bubble hydration treatment, then add 0.1-0.35% fermentation agent and 2-5g / L mannoprotein for alcoholic fermentation. Filter to remove precipitate to obtain blueberry fermentation liquid; the ratio of Saccharomyces cerevisiae and Lactobacillus rhamnosus in the fermentation agent is (1-4):(0.5-1.5); the fermentation conditions for alcoholic fermentation are a fermentation temperature of 15-18℃ and a fermentation time of 7-10 days. S4. Polyethylene glycol-modified lactic acid bacteria extracellular polysaccharide is added to blueberry fermentation broth and allowed to stand for 6-12 hours. After filtration, 30-80 mg / L potassium metabisulfite is added for pulsed electric field aging treatment. The blueberry wine is obtained by microporous membrane filtration and bottling. The preparation method of the polyethylene glycol-modified lactic acid bacteria extracellular polysaccharide is to mix polyethylene glycol and lactic acid bacteria extracellular polysaccharide at a mass ratio of 1:(0.5-2) and dissolve them in water, and treat them at 30-50℃ and 300-600 rpm for 1-2.5 hours. After drying, polyethylene glycol-modified lactic acid bacteria extracellular polysaccharide is obtained. The amount of polyethylene glycol-modified lactic acid bacteria extracellular polysaccharide added is 0.5-1 g / L of blueberry fermentation broth.

2. The method for preparing blueberry wine by low-temperature fermentation according to claim 1, characterized in that: The amount of pectinase added in S2 is 0.1-0.3%, and the amount of β-glucosidase added is 0.15-0.25%, based on the volume of blueberry pulp.

3. The method for preparing blueberry wine by low-temperature fermentation according to claim 1, characterized in that: The concentration of the activated fermentation agent is (4-8)×10⁻⁶. 7 CFU / mL.

4. The method for preparing blueberry wine by low-temperature fermentation according to claim 1, characterized in that: The conditions for pulsed electric field catalytic treatment are: electric field strength 20-40 kV / cm, pulse frequency 400-600 Hz, treatment temperature 20-35℃, pulse width 5-15 μs, and treatment time 1-2 h.

5. Blueberry wine prepared by the method according to any one of claims 1-4.

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