A method of improving the quality of red wine

Abstract

The application provides a method for improving the quality of red wine, and relates to the technical field of food. The method comprises the following steps: crushing grapes after removing stems and performing pulsed electric field treatment to obtain a treated product; performing carbon dioxide impregnation on the treated product to obtain an impregnated product; removing grape residues in the impregnated product, mixing the impregnated product with Saccharomyces cerevisiae, and performing alcohol fermentation to obtain a clear wine liquid; mixing the clear wine liquid with Oenococcus and performing malolactic fermentation to obtain a fermented product; and performing intermittent pulsed electric field treatment on the fermented product. The application can efficiently extract polyphenols and aroma components in raw materials, reduce acidity, improve the quality of red wine, and greatly shorten the impregnation time of red wine. The red wine treated by the method has higher microbial stability and antioxidant property, and the obtained red wine has stable color, rich fruit aroma and mellow taste. The application shortens the brewing time of red wine, improves the production efficiency of red wine, and the obtained red wine has better quality.

Description

Technical Field

[0001] This invention relates to the field of food technology, and in particular to a method for improving the quality of red wine. Background Technology

[0002] Wine is an alcoholic beverage with complex flavors, made from fresh grapes or grape juice through the combined action of yeast and bacteria. It is characterized by its rich aroma, complex taste, and health benefits. Winemaking is a complex and time-consuming process, and its quality is influenced by a variety of factors, including the geographical environment in which the grapes are grown, the winemaking techniques, the choice of fermenting agents, aging processes, and microbial spoilage.

[0003] In winemaking, the maceration process significantly impacts the sensory quality of the wine. Compared to white wine, red wine requires a longer maceration period before fermentation. Traditional carbonic maceration involves placing whole grapes in a sealed container filled with CO2, causing anaerobic metabolism within the grape cells before alcoholic fermentation and subsequent processing. Because the fruit undergoes intracellular metabolism and maceration under anaerobic conditions, a series of complex chemical changes occur within the berry cells during maceration, including the conversion of small amounts of sugar into alcohol, the degradation of malic acid, partial dissolution of pectin, protein hydrolysis, and the extraction and formation of secondary metabolites such as phenols and volatile compounds. Compared to traditional maceration, this process can maximize the preservation of nutrients and the formation of unique flavor compounds in the wine. However, traditional carbonic maceration requires ensuring the integrity of the grapes, which increases the difficulty of harvesting and transportation. Furthermore, grapes are easily damaged during destemming and loading into fermentation tanks. Damaged grapes can undergo alcoholic fermentation under the action of natural yeasts present on the grape skin, thus affecting the effectiveness of carbonic maceration. Furthermore, carbonic maceration typically requires 5–7 days, which can lead to excessively long maceration times. This allows undesirable tannins to leach into the extract, negatively impacting the wine's quality. Therefore, improving the extraction efficiency of polyphenols and aroma components during the winemaking process, thereby enhancing wine quality, remains a challenge for the wine industry.

[0004] Newly made wines typically have a sour and astringent taste, are cloudy, have a dull color, and poor stability. They require long aging processes, during which oxidation-reduction, esterification, condensation, and polymerization occur in the wine to improve its quality. Aging is crucial for quality improvement in wine production. Traditional aging involves storing newly made wine in oak barrels in cellars for several months to several years to produce the final product. While natural aging can improve quality, it is time-consuming, costly, and susceptible to microbial contamination, thus impacting a company's production capacity and economic benefits. Therefore, accelerating wine aging, shortening the aging period, and reducing production costs are of great importance to wine production.

[0005] Furthermore, the winemaking process is susceptible to the influence of spoilage microorganisms, leading to an increase in the content of volatile acids (D-lactic acid and acetic acid) in the wine. This results in a pungent acetic acid, nutty, or rotten apple aroma, altering the wine's sensory characteristics and reducing its commercial value. Common spoilage microorganisms in wine are primarily yeasts, lactic acid bacteria, and acetic acid bacteria. These microorganisms are part of the natural microbial community of grape skins. Because the raw materials are not washed and sterilized during winemaking, these microorganisms enter the alcoholic fermentation environment when the grapes are crushed. The growth of these natural microbial communities limits the development of fermentation agents added to the wine, leading to changes in the final wine's quality. SO2 is currently the most commonly used additive for controlling spoilage microorganisms in wine. As an antimicrobial agent, SO2 can inhibit the growth of harmful yeasts and bacteria during fermentation, preventing microbial spoilage during production and storage. However, different microbial strains have significant differences in their sensitivity to SO2, and a certain concentration of free SO2 is required for it to have an inhibitory effect. SO2 is often used at different stages of the winemaking process (after raw material crushing, before fermentation, before maturation, and before bottling), which can lead to excessive addition of SO2. This can cause unpleasant flavors in the wine and even negatively impact consumer health, including allergic reactions, headaches, asthma, and abdominal pain. Therefore, wines made more naturally, without added chemicals, and with truly healthy ingredients better meet the needs of wine consumers.

[0006] In recent years, researchers have employed various physical and chemical methods to optimize winemaking processes in order to obtain wines of better quality. Chinese patent (CN201710542769.X) discloses a method for winemaking using carbon dioxide low-temperature maceration. The drawbacks of this method are that the maceration time requires 5-7 days, which is long and may cause undesirable tannins to enter the wine, affecting its flavor. Furthermore, the process requires maintaining a temperature of 3-10℃, which is demanding and difficult to control. Chinese patent (CN111925880A) discloses a method for making sulfur-free red wine. This method involves freezing the grape berries before using high-density carbon dioxide for sterilization and maceration. Therefore, this method is complex and requires a specialized reactor for high-density carbon dioxide treatment. Chinese patent (CN116144437A) discloses an aging method to enhance the complexity of wine. The drawbacks of this method are that the process requires alcoholic fermentation, secondary fermentation, malolactic fermentation, clarification, and then aging, taking approximately 15 months and resulting in low production efficiency. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a method for improving the quality of red wine. This invention utilizes a pulsed electric field in conjunction with high-voltage carbon dioxide maceration in the winemaking process, which solves the problem of grape skin breakage affecting carbon dioxide maceration during winemaking, shortens the maceration and aging time of the wine, and improves the production efficiency of the wine.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] This invention provides a method for improving the quality of red wine, comprising the following steps:

[0010] 1) After destemming and crushing the grapes, they are subjected to pulsed electric field treatment to obtain the treated material;

[0011] 2) Impregnate the treated material obtained in step 1) with carbon dioxide to obtain an impregnated material;

[0012] 3) After removing the grape pomace from the maceration obtained in step 2), mix it with wine yeast and ferment it with alcohol to obtain a clear wine.

[0013] 4) The clarified wine obtained in step 3) is mixed with alcoholic bacteria and then subjected to malolactic fermentation to obtain the fermented product;

[0014] 5) The fermentation product obtained in step 4) is subjected to intermittent pulsed electric field treatment to obtain intermittently treated product;

[0015] 6) Filter the intermittent material obtained in step 5) to obtain red wine as the filtrate.

[0016] Preferably, the conditions for the pulse electric field treatment in step 1) include: pulse intensity of 15-25 kV / cm, pulse frequency of 600-1000 Hz, pulse width of 40-60 μs, and pulse time of 6.0 ms.

[0017] Preferably, the conditions for carbon dioxide impregnation in step 2) include: a temperature of 8–18°C, a time of 18–48 h, and a pressure of 20–45 MPa.

[0018] Preferably, the amount of brewing yeast added in step 3) is 0.5 g / L.

[0019] Preferably, the conditions for alcoholic fermentation in step 3) include: a temperature of 20-28°C, a time of 8 days, and stirring once a day.

[0020] Preferably, the amount of *Bacillus oryzae* added in step 4) is 0.01 g / L.

[0021] Preferably, the conditions for step 4) malic-lactic acid fermentation include: a temperature of 20-25°C and a time of 12-18 days.

[0022] Preferably, the conditions for the intermittent pulsed electric field treatment in step 5) include: pulse intensity of 20-25 kV / cm, pulse frequency of 500-800 Hz, number of treatments of 60-100 times, and interval of 30-60 seconds between each treatment.

[0023] Preferably, the pore size of the filter membrane used in step 6) is 0.25 to 0.45 μm.

[0024] Preferably, the grape variety in step 1) includes Muscat grape.

[0025] Beneficial effects:

[0026] 1. In the raw material pretreatment stage, a pulsed electric field combined with high-pressure carbon dioxide maceration is used to treat grape raw materials to obtain the extract. Traditional carbon dioxide maceration requires ensuring the integrity of the grape raw materials, which increases the difficulty of grape harvesting and transportation. Furthermore, grapes are easily damaged during destemming and loading into fermentation tanks. Damaged grapes will undergo alcoholic fermentation under the action of natural yeasts present on the grape skin surface, thus affecting the maceration effect. In addition, carbon dioxide maceration winemaking generally requires 5-7 days, which results in excessively long maceration time, allowing some undesirable tannins to enter the extract and affect the quality of the wine. Pulsed electric field pretreatment of grape raw materials induces electroporation of plant cells, increasing the permeability of cell membranes to ions and macromolecules. This promotes the transfer of intracellular substances such as polyphenols (phenolic acids, flavanols, flavonols, anthocyanins, stilbene, tannins) and esters (isoamyl acetate, hexyl acetate, ethyl laurate) from the grape skins and seeds into the grape extract during the carbon dioxide maceration process. Compared to traditional maceration processes, this invention can significantly shorten grape maceration time, improve maceration efficiency, and yield higher levels of polyphenols and aroma components. Furthermore, under the influence of a pulsed electric field, a potential difference is created on the microbial cell membrane, increasing cell membrane permeability or causing electroporation, leading to intracellular fluid loss. This inactivates the natural microorganisms present on the grape skin, preventing contamination and alcoholic fermentation of the wine during the maceration process.

[0027] 2. Before aging, the wine is treated with an intermittent pulsed electric field to accelerate the effective collision of molecules in the wine, increase the rate of chemical reactions such as oxidation-reduction, esterification, condensation, and polymerization, and inactivate various microorganisms in the wine to terminate fermentation. Compared with traditional aging processes, the aging time is shortened, and the microbial stability of the wine is enhanced during the aging process.

[0028] This invention, applied to red wine production, efficiently extracts polyphenols and aroma components from raw materials, reduces acidity, improves wine quality, and significantly shortens maceration time. Wine treated with this method exhibits higher microbial stability and antioxidant properties, resulting in wines with stable color, rich fruit aromas, and a full-bodied taste. This invention shortens winemaking time, increases production efficiency, and yields higher-quality wines. Furthermore, this invention eliminates the need for adding exogenous substances that increase the risk of chemical contamination in the wine, has low equipment investment costs, is simple to operate, easy to control, and boasts advantages such as low energy consumption and high efficiency, enabling large-scale industrial production. Detailed Implementation

[0029] This invention provides a method for improving the quality of red wine, comprising the following steps:

[0030] 1) After destemming and crushing the grapes, they are subjected to pulsed electric field treatment to obtain the treated material;

[0031] 2) Impregnate the treated material obtained in step 1) with carbon dioxide to obtain an impregnated material;

[0032] 3) After removing the grape pomace from the maceration obtained in step 2), mix it with wine yeast and ferment it with alcohol to obtain a clear wine.

[0033] 4) The clarified wine obtained in step 3) is mixed with alcoholic bacteria and then subjected to malolactic fermentation to obtain the fermented product;

[0034] 5) The fermentation product obtained in step 4) is subjected to intermittent pulsed electric field treatment to obtain intermittently treated product;

[0035] 6) Filter the intermittent material obtained in step 5) to obtain red wine as the filtrate.

[0036] This invention involves destemming and crushing grapes, then subjecting them to pulsed electric field treatment to obtain the treated product.

[0037] In this invention, the grape variety preferably includes Muscat grape. In this invention, the conditions for the pulsed electric field treatment preferably include: pulse intensity of 15–25 kV / cm, pulse frequency of 600–1000 Hz, pulse width of 40–60 μs, and pulse duration of 6.0 ms.

[0038] The present invention involves impregnating the obtained processed material with carbon dioxide to obtain an impregnated product. In the present invention, the preferred conditions for carbon dioxide impregnation include: a temperature of 8–18°C, a time of 18–48 h, and a pressure of 20–45 MPa.

[0039] This invention removes grape pomace from the obtained maceration mixture, mixes it with brewer's yeast, and ferments it alcoholically to obtain a clarified wine. This invention does not have a specific limitation on the source of the brewer's yeast; conventional strains are acceptable. In this invention, the preferred amount of brewer's yeast added is 0.5 g / L. In this invention, the preferred conditions for alcoholic fermentation include: a temperature of 20–28°C, a time of 8 days, and stirring once daily.

[0040] This invention involves mixing the clarified wine with *Saccharomyces cerevisiae* and then subjecting it to malolactic fermentation to obtain a fermented product. The source of the *Saccharomyces cerevisiae* is not specifically limited; conventional strains are acceptable. Preferably, the amount of *Saccharomyces cerevisiae* added is 0.01 g / L. The preferred conditions for malolactic fermentation include a temperature of 20–25°C and a time of 12–18 days.

[0041] This invention involves subjecting the obtained fermentation product to intermittent pulsed electric field treatment to obtain an intermittently treated product. In this invention, the preferred conditions for the intermittent pulsed electric field treatment include: a pulse intensity of 20–25 kV / cm, a pulse frequency of 500–800 Hz, a treatment frequency of 60–100 times, and an interval of 30–60 seconds between treatments.

[0042] The present invention filters the obtained intermittently processed material, and the resulting filtrate is red wine. In the present invention, the pore size of the filter membrane used for filtration is preferably 0.25 to 0.45 μm.

[0043] To further illustrate the present invention, the following detailed description is provided in conjunction with embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0044] Example 1

[0045] A method to improve the quality of red wine, comprising the following steps:

[0046] 1) Select Muscat grapes as raw materials, strictly screen the raw materials, select grapes with high ripeness and good color, and remove bad fruits;

[0047] 2) After the grapes are destemmed and crushed, the raw materials are treated with a pulsed electric field, with the temperature controlled at 6℃. The pulsed electric field treatment parameters are: pulse intensity 25kV / cm; pulse frequency 1000Hz; pulse width 60μs; pulse time 6.0ms.

[0048] 3) Fill the fermentation tank with carbon dioxide gas to completely remove the air inside the tank, send the treated grape raw material into the fermentation tank, maintain the anaerobic environment in the fermentation tank, the pressure in the fermentation tank is 35MPa, the temperature is controlled at 8℃, and the maceration time is 36h.

[0049] 4) After filtering the obtained grape extract to remove the grape pomace, add wine yeast at a concentration of 0.5 g / L for alcoholic fermentation. Ferment at 25°C for 8 days to obtain the wine.

[0050] 5) After the obtained wine is clarified and poured back into the container, add 0.01 g / L of *Bacillus oryzae* to carry out malolactic fermentation and ferment at 25°C for 12 days.

[0051] 6) After the malolactic fermentation of the wine is completed, the wine is treated with an intermittent pulsed electric field. The parameters of the pulsed electric field treatment are: pulse intensity 20kV / cm; pulse frequency 600Hz; number of treatments 60 times; interval time 30s; the wine after malolactic fermentation is filtered with a 0.45μm membrane and aged at 12℃ for 1 month to obtain aged wine.

[0052] Example 2

[0053] A method to improve the quality of red wine, comprising the following steps:

[0054] 1) Select Muscat grapes as raw materials, strictly screen the raw materials, select grapes with high ripeness and good color, and remove bad fruits;

[0055] 2) After the grapes are destemmed and crushed, they are treated with a pulsed electric field while the temperature is controlled at 12℃. The pulsed electric field treatment parameters are: pulse intensity 20kV / cm; pulse frequency 800Hz; pulse width 50μs; pulse time 6.0ms.

[0056] 3) Fill the fermentation tank with carbon dioxide gas to completely remove the air inside the tank, and send the treated grape raw material into the fermentation tank to maintain an anaerobic environment. The temperature of this process is controlled at 8℃, the maceration time is 48h, and the pressure in the fermentation tank is 30MPa.

[0057] 4) After filtering the obtained grape extract to remove the grape pomace, add wine yeast at a concentration of 0.5 g / L for alcoholic fermentation, and ferment at 25℃ for 8 days.

[0058] 5) The obtained wine was clarified and poured back into the container. Then, malolactic fermentation was carried out by adding 0.01 g / L of *Bacillus oryzae* at 23°C for 18 days.

[0059] 6) After the malolactic fermentation of the wine is completed, the wine is treated with an intermittent pulsed electric field. The parameters of the pulsed electric field treatment are: pulse intensity 25kV / cm; pulse frequency 800Hz; number of treatments 80 times; interval time 60s; the wine after malolactic fermentation is filtered with a 0.25μm membrane and aged at 15℃ for 1 month to obtain aged wine.

[0060] Example 3

[0061] A method to improve the quality of red wine, comprising the following steps:

[0062] 1) Select Muscat grapes as raw materials, strictly screen the raw materials, select grapes with high ripeness and good color, and remove bad fruits;

[0063] 2) After the grapes are destemmed and crushed, they are treated with a pulsed electric field while the temperature is controlled at 8℃. The pulsed electric field treatment parameters are: pulse intensity 15kV / cm; pulse frequency 600Hz; pulse width 40μs; pulse time 6.0ms.

[0064] 3) Fill the fermentation tank with carbon dioxide gas to completely remove the air inside the tank, and send the treated grape raw material into the fermentation tank to maintain an anaerobic environment. The temperature of this process is controlled at 12℃, the maceration time is 18h, and the pressure in the fermentation tank is 45MPa.

[0065] 4) After filtering the obtained grape extract to remove the grape pomace, add wine yeast at a concentration of 0.5 g / L for alcoholic fermentation, and ferment at 28℃ for 8 days.

[0066] 5) The obtained wine was clarified and poured back into the container. Then, malolactic fermentation was carried out by adding 0.01 g / L of *Bacillus oryzae* at 25°C for 14 days.

[0067] 6) After the malolactic fermentation of the wine is completed, the wine is treated with an intermittent pulsed electric field. The parameters of the pulsed electric field treatment are: pulse intensity 20kV / cm; pulse frequency 500Hz; number of treatments 100; interval time 60s; the filtered wine is aged at 12℃ for 45 days to obtain aged wine.

[0068] Comparative Example 1

[0069] The difference from Example 1 is that after the grapes were destemmed and crushed, they were not treated with a pulsed electric field, but were directly cold-macerated in a fermenter filled with carbon dioxide gas for 5 days, and then fermented. The rest of the process is the same as in Example 1.

[0070] Comparative Example 2

[0071] The difference from Example 2 is that the wine was not treated with an intermittent pulsed electric field. Instead, the wine obtained after malolactic fermentation was naturally aged at 12°C for 1 month, 6 months, and 1 year to obtain aged wines. The rest of the process is the same as in Example 2.

[0072] Comparative Example 3

[0073] The difference from Example 3 is that carbon dioxide is filled into the fermenter to purge the air, and the pressure in the fermenter is maintained at 20 MPa. Everything else is the same as in Example 3.

[0074] Table 1 shows the oenological parameters of the aged wine from Example 1.

[0075] Table 1. Oculological parameters of the aged wine in Example 1

[0076]

[0077]

[0078] As shown in Table 1, the wine treated with the present invention exhibits better color stability, a significant increase in phenolic and ester compounds, a decrease in volatile acids, fusel oils, biogenic amines and other irritating substances, and a significant reduction in harmful microorganisms commonly found in wine production, such as yeast, lactic acid bacteria, and acetic acid bacteria, resulting in wines of better quality.

[0079] The detection methods for each indicator are supplemented as follows:

[0080] pH: Measured with a pH meter

[0081] Color intensity and hue: The CIELab color space method is used to detect the color of red wine.

[0082] Total acidity, volatile acidity, phenolic acid, anthocyanins, flavonoids, esters, fusel oils, and biogenic amines: The content of various substances in the obtained aged wine was analyzed and detected by GC-MS.

[0083] Yeast, lactic acid bacteria, and acetic acid bacteria: Counting was performed using plate counting agar medium. Yeast culture medium was YGC solid medium; lactic acid bacteria culture medium was PDA solid medium; and acetic acid bacteria culture medium was MRS solid medium. Counting was performed after incubation under suitable conditions.

[0084] Table 2 shows the winemaking parameters of the aged wines from Example 2 and Comparative Example 2.

[0085]

[0086]

[0087] As shown in Table 2, the wine treated with the present invention has a more stable color, a significant increase in phenolic and ester compounds, and a decrease in irritating components such as acids, fusel oils, and biogenic amines. It possesses the unique aroma of naturally aged wine, has a smooth and delicate taste, and reaches the quality of wine aged for more than one year.

[0088] Table 3 shows the winemaking parameters of the aged wines from Example 3 and Comparative Example 3.

[0089]

[0090]

[0091] As shown in Table 3, the wine treated with this invention increases the pressure of carbon dioxide in the fermentation tank, which is more conducive to the extraction of phenolic and aromatic substances from the grapes, resulting in better color and improved wine quality.

[0092] Therefore, this invention, when used in red wine production, can efficiently extract polyphenols and aroma components from raw materials, reduce acidity, improve wine quality, and significantly shorten maceration time. Wine treated by this method exhibits higher microbial stability and antioxidant properties, resulting in wines with stable color, rich fruit aromas, and a full-bodied taste. This invention shortens winemaking time, improves production efficiency, and yields higher-quality wines. Furthermore, this invention eliminates the need for adding exogenous substances that increase the risk of chemical contamination in wine, has low equipment investment costs, is simple to operate, easy to control, and boasts advantages such as low energy consumption and high efficiency, enabling large-scale industrial production.

[0093] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for improving the quality of red wine, characterized in that, Includes the following steps: 1) After destemming and crushing the grapes, they are subjected to pulsed electric field treatment to obtain the treated material; The conditions for pulsed electric field processing include: pulse intensity of 15 kV / cm, pulse frequency of 600 Hz, pulse width of 40 μs, and pulse duration of 6.0 ms. 2) Impregnate the treated material obtained in step 1) with carbon dioxide to obtain an impregnated material; The conditions for carbon dioxide impregnation include: a temperature of 12°C, a time of 18 hours, and a pressure of 35 MPa, 30 MPa, or 45 MPa. 3) After removing the grape pomace from the maceration obtained in step 2), mix it with wine yeast for alcoholic fermentation to obtain a clear wine. 4) The clarified wine obtained in step 3) is mixed with alcoholic bacteria and then subjected to malolactic fermentation to obtain the fermented product; 5) The fermentation product obtained in step 4) is subjected to intermittent pulsed electric field treatment to obtain intermittently treated product; The conditions for the intermittent pulsed electric field treatment include: pulse intensity of 20 kV / cm, pulse frequency of 500 Hz, treatment number of 100 times, and interval of 60 seconds between each treatment. 6) Filter the intermittent material obtained in step 5) to obtain red wine as the filtrate.

2. The method according to claim 1, characterized in that, In step 3), the amount of brewing yeast added is 0.5 g / L.

3. The method according to claim 1, characterized in that, The conditions for alcoholic fermentation in step 3) include: a temperature of 20~28°C, a time of 8 days, and stirring once a day.

4. The method according to claim 1, characterized in that, In step 4), the amount of *Bacillus oryzae* added to the wine is 0.01 g / L.

5. The method according to claim 1, characterized in that, The conditions for step 4) malic-lactic acid fermentation include: a temperature of 20~25°C and a time of 12~18 days.

6. The method according to claim 1, characterized in that, The filter membrane used in step 6 has a pore size of 0.25~0.45μm.

7. The method according to claim 1, characterized in that, The grape varieties mentioned in step 1) include Muscat grapes.

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