Micro-oxygenated fermented wine and method for its preparation

Abstract

The present application belongs to the technical field of wine brewing, and particularly relates to a micro-oxygen fermentation wine and a preparation method thereof. After alcohol fermentation and aging, a micro-oxygen fermentation wine is obtained from pressed juice, wherein the pressed juice includes any one of free run juice, moderately pressed juice and heavily pressed juice. The free run juice is aged in a glass container, the moderately pressed juice is aged in a glass container or a pottery jar, and the heavily pressed juice is aged in any one of a glass container, a pottery jar and an oak barrel. The prepared micro-oxygen fermentation wine has high quality, high total aroma, low degradation of total phenol, total anthocyanin and tannin, and moderate oxidation promotes anthocyanin polymerization. The wine body is red and stable, the fruit aroma is rich, the balance of acidity, sweetness and tannin is good, the aftertaste is long, and the green oxidation odor is less.

Description

Technical Field

[0001] This invention belongs to the field of winemaking technology, specifically relating to a micro-oxygen fermented wine and its preparation method. Background Technology

[0002] Currently, in the winemaking process of Marselan dry red wine, although the pressing stage before fermentation has achieved the separation of skins and juice and the fermentation of clear juice, there are still significant technical blind spots in subsequent processing.

[0003] Current processes employ a "one-size-fits-all" approach to fermentation management for all stages of juice production (free-run juice, medium-pressed juice, and heavy-pressed juice). This involves uniformly implementing a strategy of continuous aeration for over 60 minutes daily or complete anaerobic (no aeration) fermentation. The uncontrollable micro-oxygen permeability easily leads to excessive degradation of anthocyanins in heavy-pressed juice, causing a rapid decline in the wine's red hue during aging. This ignores the significant differences in the composition of phenols, anthocyanins, and aroma precursors within the juice under different pressing pressures. This homogenized oxygen supply mode results in accelerated oxidative browning in free-run juice due to insufficient tannin protection, while heavy-pressed juice suffers from increased astringency due to excessive tannin polymerization, ultimately leading to a poor balance between astringency and aroma in the final product.

[0004] In summary, the wine produced by existing fermentation processes is of low quality. Summary of the Invention

[0005] To address the shortcomings of the existing technology, this invention provides a micro-oxygen fermented wine and its preparation method, which can solve the technical problem of low wine quality obtained by existing wine preparation methods.

[0006] This invention is achieved by adopting the following technical solution: A method for preparing microaerobic fermented wine includes the following steps: After pressing, the juice undergoes alcoholic fermentation and aging to obtain micro-aerobic fermented wine. The pressed juice includes any one of free-flowing juice, medium-pressed juice, and heavy-pressed juice. The alcoholic fermentation is carried out by aerating the juice for 20 to 30 minutes per day for every 10 to 20 L of pressed juice, with an aeration rate of 35 to 37 mL / min, until the residual sugar is less than or equal to 4 g / L. The free-flowing juice is prepared from grapes pressed under pressure of 0~0.15 bar, the medium-pressed juice is prepared from grapes pressed under pressure of greater than 0.15 bar and less than or equal to 0.80 bar, and the heavy-pressed juice is prepared from grapes pressed under pressure of greater than 0.80 bar and less than or equal to 1.00 bar. Free-run juice is aged in glass containers, medium-pressed juice in glass containers or earthenware jars, and heavy-pressed juice in any of the following: glass containers, earthenware jars, and oak barrels. The term "free-flowing juice" refers to grape juice obtained by naturally flowing out of the grape pomace without applying mechanical pressure or relying solely on the gravity of the grape pulp after the grapes have been destemmed and crushed. "Medium-pressed juice" refers to grape juice obtained by pressing the grape pomace with low to medium pressing pressure after the free-flowing juice collection is completed.

[0007] Preferably, the pressing pressure is controlled at 0.15 bar < P ≤ 0.80 bar. Heavy-pressed juice refers to grape juice obtained by further pressing the grape pomace after medium pressing, with the pressing pressure increased. Preferably, the pressing pressure is 0.80 bar < P ≤ 1.00 bar.

[0008] Furthermore, the alcoholic fermentation process involves aeration for 25 minutes per day for every 15L of pressed juice, with an air flow rate of 36mL / min.

[0009] Furthermore, the alcoholic fermentation is carried out by aerating the fruit juice for 20 minutes per day for every 10L of pressed juice, with an aeration rate of 35mL / min.

[0010] Furthermore, the alcoholic fermentation process involves aeration for 30 minutes per day for every 20L of pressed juice, with an air flow rate of 37mL / min.

[0011] Furthermore, the aging process is carried out at a constant temperature and away from light, with the temperature ranging from 14°C to 17°C.

[0012] Furthermore, the aging process is carried out at a constant temperature and away from light, with the temperature being 14°C.

[0013] Furthermore, the aging process is carried out at a constant temperature and away from light, with the temperature being 17°C.

[0014] Furthermore, the aging time is greater than or equal to 90 days.

[0015] Furthermore, it also includes adding potassium metabisulfite to the pressed juice, followed by alcoholic fermentation.

[0016] Furthermore, 35mg~45mg of potassium metabisulfite is added to each liter of pressed juice.

[0017] Furthermore, 35 mg of potassium metabisulfite is added to each liter of pressed juice.

[0018] Furthermore, 45 mg of potassium metabisulfite is added to each liter of pressed juice.

[0019] Furthermore, 40 mg of potassium metabisulfite is added to each liter of pressed juice.

[0020] The micro-aerobic fermented wine prepared by the above method.

[0021] The integrated production process of graded pressing raw materials with unified micro-oxygen fermentation and differentiated micro-oxygen aging containers is designed for three types of grape raw materials with different polyphenol gradients: free-flowing juice, medium-pressed juice, and heavy-pressed juice. It is equipped with a dedicated micro-oxygen control production mode to achieve long-term stability of color, phenols, aroma, and antioxidant capacity of wines made from different raw materials. It is suitable for wineries to produce Marselan dry red wine on a large scale and in a stable manner.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention provides a method for preparing micro-aerobic fermented wine, comprising the following steps: pressing juice is subjected to alcoholic fermentation and aging to obtain micro-aerobic fermented wine, wherein the pressing juice includes any one of free-flowing juice, medium-pressed juice, and heavy-pressed juice; the alcoholic fermentation is carried out by aerating for 20-30 minutes per day for every 10-20L of pressing juice, with an aeration flow rate of 35-37mL / min, until the residual sugar is less than or equal to 4g / L; the free-flowing juice refers to grape juice obtained by naturally flowing out of the grape pomace without applying mechanical pressure or relying solely on the gravity of the grape pulp after destemming and crushing; the medium-pressed juice refers to grape juice obtained by pressing the grape pomace with low to medium pressing pressure after the collection of free-flowing juice. Preferably, the pressing pressure is controlled at 0.15 bar < P ≤ 0.80 bar. Heavy-pressed juice refers to grape juice obtained by further pressing the grape pomace after medium pressing, with the pressing pressure increased. The preferred pressing pressure is 0.80 bar < P ≤ 1.00 bar. Free-run juice is aged in glass containers, medium-pressed juice in glass containers or earthenware jars, and heavy-pressed juice in glass containers, any one of glass containers, earthenware jars, and oak barrels. The resulting micro-aerobic fermented wine is of high quality, with high total aroma, low degradation of total phenols, total anthocyanins, and tannins. Moderate oxidation promotes anthocyanin polymerization, resulting in a stable red color, rich fruit aroma, balanced sweet and sour tannins, a long finish, and few astringent or oxidative off-flavors.

[0023] 2. The preparation method provided by this invention is a universal fermentation process that reduces the difficulty of production control. Grape juices of three types with huge differences in polyphenols (free flow, medium, and heavy flow) can all use the 25min / d micro-aerobic fermentation process without the need for separate fermentation control procedures. This simplifies equipment operation and reduces process switching costs in factories. Compared with no oxygen or long-term oxygenation, all raw materials can improve the total aroma and reduce polyphenol oxidation loss, thus uniformly solving the problems of thin aroma and unstable color during the fermentation stage.

[0024] 3. The preparation method provided by this invention uses differentiated micro-oxygen containers to precisely match raw materials and optimize quality in a targeted manner; ① Low-polyphenol self-flowing juice paired with low-oxygen glass bottles inhibits oxidative browning from the source, preserves fresh floral and fruity aromas for a long time, and avoids the rapid damage to the color of the wine caused by high oxygen in oak barrels; ② Medium pressing is divided into two routes: glass bottles are suitable for short-term distribution products in supermarkets, while earthenware jars create mellow mineral mid-range wines, catering to different market demands; ③ Heavy pressing of high-polyphenol raw materials has high oxidation tolerance, and all three types of containers can produce differentiated products: glass bottles lock in the color of fresh fruit, earthenware jars have high antioxidant properties suitable for long-term wine storage, and oak barrels enrich polyphenols to form a mellow and aging style, realizing the development of multiple product lines from one raw material.

[0025] 4. The preparation method provided by this invention can significantly improve the long-term storage stability of wine, extend the shelf life, and pre-complete the primary polymerization of anthocyanins during fermentation with moderate micro-oxygenation, thereby reducing the risk of oxidation during subsequent aging. The aging containers are matched with oxygen permeation rates based on the oxygen tolerance of the raw materials: glass bottles retain anthocyanins to the maximum extent, ceramic jars minimize the loss of antioxidants, and oak relies on high polyphenol reserves to offset oxygen damage. The deterioration problems such as fading, aroma decay, and increased astringency in the three types of finished products during shelf life are significantly alleviated, and the consistency of quality between batches is greatly improved. Attached Figure Description

[0026] Figure 1 The effect of different oxygenation times on wine; where A represents total phenol content; B represents total flavonoid content; C represents total anthocyanin content; and D represents total tannin content.

[0027] Figure 2 In the diagram, A represents the content of various aroma components after fermentation; B represents the cumulative aroma components of different treatments.

[0028] Figure 3 A heatmap showing the clustering of aroma components at the end of fermentation.

[0029] Figure 4 In the chart, A represents the total phenol content of the three types of raw materials after aging in different containers; B represents the total flavonoid content; C represents the total anthocyanin content (bar chart); and D represents the total tannin content.

[0030] Figure 5 In the diagram, A represents the content of various aroma components after aging; B represents the cumulative aroma components after different treatments; F represents free-run juice; MP represents medium-pressed juice; and HP represents heavy-pressed juice.

[0031] Figure 6 This is a cluster analysis diagram of aroma components after aging.

[0032] Figure 7Comparison of CIELAB color parameters (L, a, b) after aging in different micro-oxygen containers; where A is the L* lightness (brightness) of each treatment after aging; B is the a* chromaticity parameter (red-green axis chromaticity) of each treatment after aging; C is the b* chromaticity parameter (yellow-blue axis chromaticity) of each treatment after aging; D is the C*ab chromaticity of each treatment after aging; and E is the h*ab of each treatment after aging.

[0033] Figure 8 Comparison of the decline in DPPH antioxidant capacity under different treatments. Detailed Implementation

[0034] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods. Specific explanations are needed as follows:

[0035] The oak planks used for French oak barrels are imported from the Limousin forest region of France, naturally air-dried for 24 months, and then processed and moderately baked by Hantongjiang Oak Products (Yantai) Co., Ltd.

[0036] Example 1: A method for preparing microaerobic fermented wine, the specific steps of which are as follows: S1 is grape juice obtained by destemming and crushing Marselan grapes and allowing it to flow naturally without applying mechanical pressure, relying solely on the gravity of the grape pulp. This is abbreviated as F. For every liter of F, add 40 mg of potassium metabisulfite and 200 mg of yeast (16 x 16).

[0037] S2. Then, alcoholic fermentation is carried out under the following conditions: constant temperature of 19℃, aeration for 25 minutes daily, peristaltic pump at 36 mL / min, and fermentation is completed when the residual sugar reaches 3.2 g / L, yielding microaerobic fermented wine F2.

[0038] S3. After alcoholic fermentation, the wine is poured into a glass bottle with a screw cap and aged at 15°C in the dark for 90 days to obtain micro-oxygen fermented glass bottle aged wine BF, abbreviated as BF.

[0039] The micro-oxygen fermentation glass bottle aged wine of Example 1 has a relatively high L*, a clear body, a stable red color, a prominent fruit aroma, a 38.5% reduction in antioxidant capacity, no oxidative off-odors, and is suitable for short-term circulation of 1-2 years.

[0040] Example 2: A method for preparing microaerobic fermented wine, the specific steps of which are as follows: Based on Example 1, after collecting the free-flowing juice, the grape pomace is pressed under medium pressure to obtain grape juice. Preferably, the pressing pressure is controlled at 0.5 bar to obtain medium-pressed juice, abbreviated as MP. After the alcoholic fermentation of the medium-pressed juice is completed, microaerophilic fermented wine MP2, abbreviated as MP2, is obtained, which is bottled and aged at 15°C in the dark for 90 days to obtain microaerophilic fermented glass bottle aged wine BM, abbreviated as BM.

[0041] BM received the highest overall sensory rating, with a balanced sweet and sour taste and pure fruity aroma, making it suitable for affordable dry red wines in supermarkets.

[0042] Example 3: A method for preparing microaerobic fermented wine, the specific steps of which are as follows: Based on Example 2, "filling into a glass bottle" was changed to "filling into an unglazed ceramic jar"; micro-oxygen fermented wine, abbreviated as TM, was obtained.

[0043] TM has a DPPH reduction of 35.9%, softened tannins, and a slight mineral flavor, making it suitable for mid-range estate wines aged 2-3 years.

[0044] Example 4: A method for preparing microaerobic fermented wine, the specific steps of which are as follows: Based on Example 2, after medium pressing, the pressing pressure is further increased to further press the grape pomace to obtain grape juice. A preferred pressing pressure is 1.00 bar, yielding heavily pressed juice, abbreviated as HP. After alcoholic fermentation, the juice is bottled and aged at 15°C in the dark for 90 days to obtain microaerophilic fermented wine HP2, abbreviated as BH.

[0045] BH has an a* of 10.74 and a total anthocyanin of 9.19 mg / L, with the best color and a rich tropical and stone fruit aroma, emphasizing a young and fresh fruit style.

[0046] Example 5: A method for preparing microaerobic fermented wine, the specific steps of which are as follows: Based on Example 4, "filling into a glass bottle" was changed to "filling into an unglazed ceramic jar"; micro-oxygen fermented wine was obtained, abbreviated as TH.

[0047] TH's DPPH decreased by only 27.7%, and it had the best antioxidant retention among the three types of containers. It has a mild taste, a distinct mineral flavor, and is suitable for medium to long-term storage.

[0048] Example 6: A method for preparing microaerobic fermented wine, the specific steps of which are as follows: Based on Example 4, "filling into glass bottles" was changed to "French oak barrels"; micro-aerobic fermented wine was obtained, abbreviated as XH.

[0049] XH has a 27.2% increase in total phenols, the highest content of anthocyanins and derivatives, a rich body with aromas of caramel, clove oak, and firm tannins, making it suitable for high-end aged wines.

[0050] Comparative Example 1: A method for preparing wine, the specific steps of which are as follows: S1. Add 40mg of potassium metabisulfite and 200mg of yeast to the free-flowing juice, medium-pressed juice and heavy-pressed juice respectively.

[0051] S2. Then, alcoholic fermentation is carried out under the following conditions: constant temperature of 19℃, fermentation until the residual sugar is less than 4g / L; wine 1, wine 2 and wine 3 are obtained respectively.

[0052] In Comparative Example 1, the three types of wines produced by non-aerobic fermentation showed severe oxidation and yellowing of the free-flowing juice, with almost no loss of fruit aroma.

[0053] Comparative Example 2: A method for preparing wine, the specific steps of which are as follows: S1. Add 40mg of potassium metabisulfite and 200mg of yeast to the free-flowing juice, medium-pressed juice and heavy-pressed juice respectively.

[0054] S2. Then, alcoholic fermentation is carried out under the following conditions: constant temperature of 19℃, aeration for 75 minutes per day, peristaltic pump at 36 mL / min, until the residual sugar is less than 4 g / L; wines 4, 5 and 6 are obtained.

[0055] Compared with the three wines in Comparative Example 2, all raw materials underwent long-term oxygen fermentation for 75 minutes per day. As a result, the polyphenols in the three types of wine were significantly degraded, resulting in a weak aroma and a prominent astringency.

[0056] Comparative Example 3: A method for preparing wine, the specific steps of which are as follows: S1. Add 40mg potassium metabisulfite and 200mg x16 yeast to the free-flowing juice.

[0057] S2. Then, alcoholic fermentation is carried out under the following conditions: constant temperature of 19℃, aeration for 150 minutes per day, peristaltic pump at 36 mL / min, until the residual sugar is less than 4 g / L; wine is obtained.

[0058] The red color of wine #7 has noticeably faded, and the flavors are unbalanced.

[0059] Compared with the three control groups, all embodiments of the present invention show significant improvements in color, phenols, aroma, and sensory stability, and different raw materials can achieve the optimal quality of their respective styles.

[0060] This invention addresses the shortcomings of existing technologies in the production of grape juice from different pressing processes, including large fluctuations in quality, oxidative deterioration, and flavor imbalance. The core solution consists of two main processes: Phase 1: All three types of pressed Marselan juices are fermented with 25 min / d daily micro-aerobic fermentation. This oxygenation parameter is suitable for free-flowing, medium-pressed, and heavily pressed juices. Moderate oxygenation promotes yeast metabolism, enhances ester fruit aroma, and moderately polymerizes anthocyanins, while avoiding excessive oxidation and degradation of polyphenols. The second stage: After fermentation, based on the inherent differences in polyphenols, color, and aroma of the three types of fruit juices, micro-oxygen aging containers are matched differently. Relying on the different micro-oxygen environments of three types of containers—glass bottles (low OTR), earthenware jars (medium stable micro-oxygen), and oak barrels (high oxygen + oak polyphenol leaching)—the quality of the corresponding raw wine is stabilized or improved in a targeted manner, forming a standardized production model that integrates graded pressing, unified micro-oxygen fermentation, and graded aging.

[0061] The raw material preparation of this invention involves graded pressing, harvesting ripe Marselan grapes from the eastern foothills of the Helan Mountains, removing moldy and unripe grapes, destemming and crushing them, and pressing them in three stages: (1) Microaerobic fermented wine F2. F2: Grape juice obtained by destemming and crushing grapes and letting it flow out naturally without applying mechanical pressure or relying solely on the gravity of the grape juice itself. It has the lowest content of polyphenols and anthocyanins, a bright body, and a fresh fruit aroma;

[0062] (2) Microaerobic fermentation wine F2. MP2: Grape juice obtained by pressing the grape pomace under low to medium pressure after the completion of free-flow juice collection. Preferably, the pressing pressure is controlled at 0.15 bar < P ≤ 0.80 bar, and the polyphenol and aroma indicators are balanced;

[0063] (3) Microaerobic fermented wine F2. HP: Grape juice obtained by further pressing the grape pomace after medium pressing. The preferred pressing pressure is 0.80 bar < P ≤ 1.00 bar. The total phenols, monomeric phenols, anthocyanins, and antioxidants content are the highest in the group, and the tannins are heavy.

[0064] After pressing, 40 mg / L potassium metabisulfite was added to the juice, which was then packaged into 15L glass fermentation tanks and inoculated with 200 mg / L commercial yeast X16 to start alcoholic fermentation.

[0065] This invention employs a graded and unified micro-aerobic alcohol fermentation process, maintaining a constant fermentation temperature of 18-20℃ and a peristaltic pump aeration flow rate of 36 mL / min. Four groups of aeration gradient controls are set up: no aeration 0 min / d, 25 min / d, 75 min / d, and 150 min / d. Before fermentation, dry ice is used to replace the air at the top of the tank, and the entire process is sealed and aerated. Aeration is carried out daily until the residual sugar is ≤4 g / L, at which point fermentation is terminated. Comprehensive physicochemical, polyphenol, aroma, and sensory analysis revealed that 25 min / d is the optimal micro-oxygenation parameter for all three types of pressed juices: Aroma indicators: 1123.69 mg / L for micro-oxygenated fermented wine F2, 1256.49 mg / L for micro-oxygenated fermented wine MP2, and 1323.90 mg / L for micro-oxygenated fermented wine HP2, showing the highest total aroma content under the same raw materials; Polyphenols and color: Compared to long-term oxygenation of 75 min or 150 min, the degradation of total phenols, total anthocyanins, and tannins was the lowest, with moderate oxidation promoting anthocyanin polymerization and a stable red color in the wine; Sensory performance: Rich fruit aroma, balanced sweet and sour tannins, long finish, and minimal off-flavors from oxidative processes.

[0066] Alcohols were the most abundant among all substance categories, with the highest concentration found in the pre-aging medium-pressed juice group. Compared to pre-aging, alcohols remained dominant after aging. Furthermore, the total aroma content increased with aging, likely due to micro-oxygenation enhancing the overall aroma content of wine, while significantly impacting alcohols, acids, and esters. All abbreviations in the figures are explained in Tables 1 and 2.

[0067] Table 1 Figure 1 Explanation of abbreviations in Chinese Free-flowing juice TF BF XF Medium-pressed juice TM BM XM Heavy pressing juice TH BH XH Table 2 Figure 1 Explanation of abbreviations in Chinese (Part 2) Oxygen-free group (CK) F1 MP1 HP1 Oxygenation 25 min / d F2 MP2 HP2 Oxygenation 75 min / d F3 MP3 HP3 Oxygenation 150 min / d F4 MP4 HP4 Depend on Figure 1 As shown in Figure A, the total phenol content in all groups generally decreased with increasing oxygenation time. The HP group maintained the highest total phenol content under all treatment conditions, significantly higher than the MP and F groups, indicating that pressing resulted in a higher content of phenolic substances in the grape juice. Oxygenation for 25 min / d led to a significant decrease in total phenols, which may be related to oxygen promoting the oxidative polymerization of phenolic substances. However, with increasing oxygenation time, the total phenol content gradually recovered and tended to stabilize, suggesting that the oxidation process may have reached a dynamic equilibrium.

[0068] Depend on Figure 1As shown in Figure B, compared with the control (CK), at an oxygenation time of 25 min / d, the total flavonoid content in group F decreased significantly, down 31.2% from the CK level, while the contents in groups MP and HP increased significantly, by 12.1% and 20.3%, respectively. With an oxygenation time increasing to 75 min / d, the total flavonoid content in all three groups decreased. When the oxygenation time was 150 min / d, the contents in all groups rebounded. The contents in group F (180.10 mg / L), group MP (190.09 mg / L), and group HP (217.6 mg / L) were significantly higher than those in the 75 min / d treatment group, but still lower than the CK level. Overall, group HP maintained the highest total flavonoid content under all treatment conditions, while group F was more sensitive to oxygenation, exhibiting the largest fluctuation in content.

[0069] Depend on Figure 1 As shown in Figure C, under non-oxygenated conditions, the anthocyanin content in the HP group was significantly higher than that in the F and MP groups. This is because the cell walls of the pericarp are broken down and anthocyanin dissolution increases during pressing. Compared with the control (CK), the content in all groups increased significantly after 25 min / d of oxygenation. The HP group (13.13 mg / L) and the MP group (5.69 mg / L) reached their peak values, while the F group (3.06 mg / L) showed a slight decrease, indicating that short-term oxygenation may have promoted the oxidative polymerization of anthocyanins. With increasing oxygenation time, the total anthocyanin content in all groups showed a decreasing trend. At 75 min / d, the HP and MP groups were still significantly higher than the F group; at 150 min / d, although the contents of the HP and MP groups decreased, the HP group maintained the highest level. This indicates that long-term oxygenation accelerates the oxidative degradation of anthocyanins, while heavily pressed juice, due to its higher initial polyphenol and pigment content, is relatively more resistant to oxidation.

[0070] Depend on Figure 1 As shown in D, the total tannin content in the HP group was significantly higher than that in the F and MP groups after different oxygenation times, because more tannins were extracted from the peel during the pressing process. The tannin content in the F group was the lowest, indicating that it mainly came from the free juice of the grape berries and the degree of structural tissue damage was low

[115] . With the increase of oxygenation time, the total tannin content in all oxygenated groups decreased significantly compared with the CK group. The HP group had the largest decrease, which was 23.7%, 36.8% and 63.2% respectively, while the F group had a relatively smaller decrease, which was 18.2%, 36.4% and 54.5% respectively. This indicates that oxygenation can promote the oxidation, polymerization or precipitation of tannins and is more sensitive to the effect on tannins in heavily pressed juice.

[0071] like Figure 2As shown, alcohols constitute a significant portion of the aroma composition, contributing to the production of aromas such as rose and clove. With increasing oxygenation time, the aroma components generally show a decreasing trend, indicating the reduction effect of oxygenation on volatile substances. It also shows that heavy pressing leads to the loss of some aroma components. Therefore, moderate oxygenation helps to accumulate aroma.

[0072] like Figure 3 As shown, F1 and HP1, F2 and F3, MP1 and MP2, MP3 and MP4, and HP3 and HP4 clustered into one group, indicating that wine samples from adjacent oxygenation times under the same treatment exhibit similar aromas. Aroma compounds can be divided into three main categories. The first and second categories, including octanoic acid, acetic acid, methyl methanol acetate, diethyl succinate, 2-ethyl-1-hexanol, phenylethanol, and n-hexanol, were present in higher concentrations in wines from the MP and HP groups with longer oxygenation times. The remaining components were present in higher concentrations in wines without oxygenation and those with 25 min / d of oxygenation. This indicates that oxygenation significantly affects the content and distribution of volatile compounds such as esters, alcohols, and acids, thereby influencing the aroma characteristics of the wine. This suggests that moderate oxygenation contributes to the formation of aroma components.

[0073] Figure 4 As shown in Figure A, the total phenols in all samples from the ceramic jars continued to decrease, with TH showing the largest decrease at 44.46%, followed by TM at 24.7%, and TF showing the smallest decrease at 14.1%. In the glass bottles, the total phenols also showed a decreasing trend, but the decrease was smaller than in the ceramic jars. BF saw a slight increase in the first month before falling back, ultimately decreasing by 1.2% from the initial level; BM decreased by 13.9%; and BH decreased by 25.8%. Therefore, the total content showed a slow decreasing trend during aging. Notably, the total phenol content in the oak barrels increased significantly. XF initially increased and then decreased, but remained higher than after fermentation after three months. XM and XH increased sharply in the first month, then decreased somewhat, but were 24.1% and 27.3% higher than after fermentation after three months, respectively. This is because polyphenols in the oak barrels dissolved into the wine, increasing the total phenol content and reacting with other phenolic substances.

[0074] Figure 4 As shown in Figure B, the total flavonoid content in the oak barrel group was generally higher than that in the glass bottle and earthenware groups, and remained at a high level even in the later stages of aging, demonstrating good flavonoid retention. While BH and XH had the same initial values, BH showed a smaller decrease, remaining at 212.61 mg / L after 3 months, higher than XH's 210.11 mg / L. In contrast, the flavonoid content in medium-pressed juice and free-run juice was generally lower than that in heavy-pressed juice across all containers, especially in glass bottles and oak barrels where the decrease was more pronounced. Therefore, aging heavy-pressed juice in earthenware is most conducive to the retention of total flavonoids, while the performance of medium-pressed juice and free-run juice varied across different containers. Glass bottles also provided good protection for heavy-pressed juice, while oak barrels showed greater fluctuations.

[0075] Figure 4 As shown in Figure C, the total anthocyanin content of all samples decreased with increasing aging time, but the rate of decrease varied depending on the container type and sample composition. Heavy-pressed juice had the highest anthocyanin content among all containers, followed by medium-pressed juice, with free-run juice having the lowest, reflecting the significant impact of pressing method on anthocyanin content. From a container perspective, glass bottles showed the best anthocyanin retention, with BH maintaining 9.19 mg / L after three months, significantly higher than TH and XH. Oak barrels exhibited the most significant anthocyanin degradation, with XH showing a 69.2% decrease after three months, while XF and XM also dropped below 1.75, indicating that oak barrels may promote anthocyanin oxidation and polymerization or adsorption loss due to the microaerobic environment. The anthocyanin trend in earthenware jars fell between the two, with TF and TM decreasing to 1.32 mg / L and 0.88 mg / L respectively after three months, lower than glass bottles but better than oak barrels. Therefore, glass bottles are more conducive to anthocyanin retention, while oak barrels accelerate their degradation.

[0076] Figure 4 As shown in D, the tannin content of all samples showed a continuous decreasing trend. In the earthenware jars, TH showed the largest decrease in tannin content, indicating that the initial tannin content of heavily pressed juice was the highest, and the decrease was also more significant. In the glass bottles, BF showed the smallest decrease, with an overall gentler decreasing trend than the earthenware jars, indicating that the glass bottles retained tannins better than the earthenware jars. The decrease in tannin content in the oak barrels was between that of the earthenware jars and the glass bottles, possibly due to the leaching of ellagic tannins in the oak barrels. Heavily pressed juice had the highest initial tannin content in all containers, but the tannin degradation was most significant in the earthenware jars, the tannin retention was best in the glass bottles, and the oak barrels showed a moderate degradation rate.

[0077] like Figure 5 As shown, isobutyric acid, phenylethyl alcohol, n-hexanol, L-(+)2,3-butanediol, 2,3-butanediol, n-pentanol, and isobutanol were present in higher concentrations in group H. Among different treatments, TM and XM clustered together because the OTR of oak barrels and earthenware jars was higher than that of glass bottles, and their microaerobic environments had similar effects on wine aromas. BF and BM clustered together because glass bottles have lower OTRs, slower internal reactions, and similar pressing methods, thus clustering them together.

[0078] like Figure 6 As shown, isobutyric acid, phenylethyl alcohol, n-hexanol, L-(+)2,3-butanediol, 2,3-butanediol, n-pentanol, and isobutanol were present in higher concentrations in group H. Among different treatments, TM and XM clustered together because the OTR of oak barrels and earthenware jars was higher than that of glass bottles, and their microaerobic environments had similar effects on wine aromas. BF and BM clustered together because glass bottles have lower OTRs, slower internal reactions, and similar pressing methods, thus clustering them together.

[0079] Depend on Figure 7 As shown in Figure A, during the three-month aging process, the L* values ​​of all treatment groups showed a continuous upward trend, indicating that the wine color gradually became brighter, a trend consistent with Wang Yue's results. Among them, the L* values ​​of the earthenware and glass bottle treatment groups showed the most significant increase, especially for medium-pressed and heavy-pressed juices. In contrast, the L* values ​​of the oak barrel treatment group were significantly lower than those of the corresponding earthenware and glass bottle treatments. The results indicate that L* increases more slowly during aging in oak barrels, possibly related to the microaerobic environment and the leaching of phenolic substances; while earthenware and glass bottles are more conducive to maintaining or enhancing the brightness of the wine, especially for medium-pressed and heavy-pressed juices.

[0080] Depend on Figure 7 As shown in B, the a* value of all samples decreased during the three-month aging period, indicating a gradual weakening of the red color. The decrease was more pronounced in the terracotta and oak barrel aged samples, while the decrease was relatively gradual in the glass bottle samples. Heavy-pressed juice had the highest initial a* value among all containers, but its rate of decline was faster. Compared to medium-pressed juice, free-run juice showed a higher ability to retain red color across all containers. Overall, glass bottle aging is beneficial for maintaining red color intensity, while heavy-pressed juice, although initially darker in color, exhibits poorer stability. Glass bottles had the highest a* value, followed by terracotta bottles, and finally oak barrels.

[0081] Depend on Figure 7 As shown in Figure C, the b* values ​​of the earthenware jar aged samples generally increased with aging time, with TH showing the most significant increase; the b* values ​​of TF and TM stabilized at 10.6 and 17.7, respectively. In the glass bottle aged samples, the b* values ​​of BM and BH decreased after one month, but BH showed a larger increase after three months, maintaining a high level and demonstrating strong color stability. The oak barrel aged samples generally had higher b* values ​​initially, especially XH, which reached around 30.0 before barrel entry, but subsequently dropped significantly to 21.1, indicating significant oxidation or pigment adsorption. In summary, heavily pressed juice exhibited the highest b* values ​​across all containers, particularly glass bottles and earthenware jars, while oak barrel aging initially increased color intensity but decreased it later. Therefore, wines aged in glass bottles had the highest b* values, followed by earthenware jars, and lastly oak barrels.

[0082] Depend on Figure 7As shown in D, wines aged in earthenware jars had higher C*ab values ​​before bottling, which then decreased, reaching 10.7, 17.8, and 23.5 respectively after 3 months. In wines aged in glass bottles, the C*ab values ​​for BF and BM remained consistently low with gradual changes; BF slightly increased from 8.0 to 8.2, while BM decreased from 14.8 to 14.1. In wines aged in oak barrels, the C*ab values ​​for XF and XH continuously increased, with XF showing the most significant increase, rising from 6.5 to 10.8. Therefore, wines aged in glass bottles have the best color, followed by those aged in earthenware jars, and lastly those aged in oak barrels.

[0083] Depend on Figure 7 As shown in E, during aging, the h*ab values ​​of all samples showed a decreasing trend and gradually stabilized. After one month of aging, there were significant differences in hue values ​​among different treatments, ranging from 43.2 to 54.6, with TM and TF showing higher values ​​and BH and XH lower values. With increasing aging time, by three months, the hue values ​​of all treatments tended to converge, indicating that the aging process has a homogenizing effect on different container and juice combinations. Overall, after three months, the h*ab values ​​of wines aged in earthenware jars were slightly higher than those in glass bottles and oak barrels, while the h*ab values ​​of wines aged in oak barrels were relatively the lowest, suggesting that oak barrels may promote faster pigment evolution. In conclusion, the aging container has some influence on hue evolution, but with increasing time, the differences between treatments decrease, and the hues tend to be more uniform.

[0084] like Figure 8 As shown, after aging, the free radical scavenging rate of the free-run juice decreased in all containers, with TF showing the most significant decrease, dropping to 9.27% ​​after three months, while XF showed the smallest decrease. The scavenging rate of medium-pressed juice increased in the first month, then gradually decreased, with little difference between containers after three months. Among heavily pressed juices, BH maintained a high scavenging rate of 23.2% after three months, while TH decreased to 17.1%, with XH in the middle. In conclusion, heavily pressed juice still exhibits the highest ABTS free radical scavenging ability after three months of aging in glass bottles. The samples aged in earthenware jars showed the smallest decrease, with TF, TM, and TH dropping to 8.04%, 8.46%, and 10.49% respectively after three months, representing decreases of 25.7%, 35.9%, and 27.7% relative to their initial values. The samples aged in glass bottles experienced the most dramatic decrease, with BF, BM, and BH dropping to 6.65%, 7.17%, and 8.31% respectively, representing decreases of 38.5%, 45.7%, and 42.8%. The samples aged in oak barrels showed a moderate decrease, with XF, XM, and XH dropping to 7.48%, 8.08%, and 9.17%, representing decreases of 30.9%, 38.8%, and 36.8%. Within the same container, heavily pressed juice consistently maintained the highest clearance rate, indicating that it had the richest antioxidant base. In conclusion, aging in earthenware jars is more conducive to preserving the antioxidant activity of wine than glass bottles and oak barrels.

[0085] This invention relates to a graded and directional aging process after fermentation. F, MP, and HP are each matched with corresponding micro-oxygen containers, and the fermentation is carried out at a constant temperature of 14-17℃ in the dark for 90 days. The micro-oxygen characteristics of the three types of containers and their suitable raw materials are as follows: (1) Glass bottle (low oxygen permeable screw cap, OTR is the lowest), OTR stands for Oxygen Transmission Rate.

[0086] Micro-oxygen characteristics: minimal oxygen penetration, slow oxidation rate of polyphenols and pigments, maximizing the preservation of fresh fruit aroma and red hues; Suitable raw materials: ① The F2 is the only preferred container for self-flowing juice, solving the problem of low polyphenol content and easy oxidation and discoloration in self-flowing juice; ② The best choice for medium-pressed MP2 products with short-term circulation is the finished product with the highest overall sensory score; ③The heavily pressed HP2 fruit-flavored product has an a*=10.74 and a total anthocyanin content of 9.19mg / L, with the best color after full processing.

[0087] (2) Unglazed ceramic jar (moderately stable micro-oxygen permeation) Micro-oxygen characteristics: slow and trace oxygen supply through pores, minimal loss of antioxidants, slow softening of tannins, and imparting a slight mineral flavor; Suitable raw materials: ① The medium-pressed MP2 mid-range aged wine has an antioxidant reduction of only 35.9% and a lower bitterness; ②The heavily pressed HP2 high-antioxidant style wine has a DPPH free radical scavenging rate that decreases by only 27.7%, resulting in stronger long-term storage stability.

[0088] (3) Brand new French oak barrels (high oxygen exchange, oak polyphenols dissolution) Micro-oxygen features: The pores in the barrel wall continuously supply oxygen, while simultaneously dissolving oak tannins and woody aromas, promoting the formation of stable anthocyanin derivatives; Only suitable for heavy-pressed HP2: HP2's high polyphenol base can offset the pigment loss caused by oxygen. After aging, the total phenols increase by 27.2%, with 4481.86μg / L of anthocyanins and 2029.04μg / L of derivatives. The wine is full-bodied with oak and nutty aromas and is suitable for long-term aging.

[0089] Marselan grapes are destemmed and crushed, then pressed in three stages to produce free-run juice, medium-pressed juice, and heavy-pressed juice, all with the addition of potassium metabisulfite and active yeast. The three types of juice are fermented in separate tanks, undergoing a uniform 25-minute daily micro-aeration process at 18-20°C until residual sugar is ≤4g, yielding F2, MP2, and HP2 base wines. These base wines are then transferred to their respective aging containers and aged at 14-17°C in the dark for 90 days. F2: all glass bottles; MP2: short-term circulation glass bottles / 2-3 year aging earthenware jars (choose one); HP2: fresh fruit glass bottles / high-antioxidant earthenware jars / aged oak barrels (choose one as needed). After aging, the wines are filtered, stabilized, and aseptically bottled to produce finished wines in their respective styles.

[0090] This invention is the first to develop a universal micro-oxygen fermentation process for Marselan grape juice with three polyphenol gradients: free-flowing, medium, and heavy. It breaks through the limitations of previous methods that only optimized micro-oxygen for a single raw material, achieving a unified multi-gradient juice fermentation process and significantly simplifying the winery's production flow. It innovatively constructs an integrated coupling model of "unified micro-oxygen fermentation + differentiated micro-oxygen aging," matching different oxygen permeability containers based on the inherent phenolic reserves of the juice. It utilizes low / medium / high micro-oxygen environments to directionally regulate color, polyphenols, and aroma, solving the industry pain point of uneven quality during unified aging of different raw materials. The entire process is free of exogenous polysaccharides, tannins, and other additives, relying solely on precise oxygen control and container micro-oxygen environment regulation to achieve stable quality improvement in wine. This green winemaking process has low industrialization costs. One set of raw materials can generate multiple differentiated product production lines. The same batch of grapes can be pressed to produce crisp, commercially available, mid-range mineral, and high-end aged wines, enriching the product matrix, improving the comprehensive utilization rate of raw materials and the economic benefits of wineries, demonstrating significant substantive characteristics and remarkable industrial progress.

[0091] This invention discloses an integrated micro-aerobic fermentation and targeted aging method for stable production of Marselan grape juice, suitable for free-flowing juice, medium-pressed juice, and heavy-pressed juice, belonging to the field of winemaking technology. This invention obtains three types of polyphenol gradient juices through graded pressing of Marselan grapes, all of which undergo alcoholic fermentation using a uniform 25-minute daily micro-aerobic process. After fermentation, the juices are aged at constant temperature in three types of micro-aerobic containers—glass bottles, ceramic jars, and oak—based on their inherent color, polyphenol content, and antioxidant properties. The fermentation process of this invention is applicable to all three types of pressed raw materials, with moderate oxygenation enhancing aroma and stabilizing anthocyanins. Furthermore, the quality is optimized by utilizing different oxygen transfer rates in the containers: low-polyphenol free-flowing juice is processed in low-oxygen glass bottles to prevent oxidation and fading; medium-pressed juice is processed in glass bottles for short-term production and ceramic jars for medium- to long-term production; high-polyphenol heavy-pressed juice can produce three styles of wine as needed: fresh fruit, high-antioxidant, and aged wines. This invention solves the problems of quality fluctuations and shelf-life oxidation deterioration in different pressed juice batches, with standardized processes and universal equipment, suitable for the large-scale and stable production of Marselan dry red wine from the eastern foothills of the Helan Mountains.

[0092] The process of this invention is complete and highly adaptable to industrialization; the entire process of pressing, fermentation and aging has standardized and quantified parameters, requiring no complex additives, and relying solely on micro-oxygen regulation and container grading to achieve quality improvement. The equipment consists of winery-standard fermentation tanks, earthenware jars, oak barrels and glass bottles, without any special customized equipment. The oxygen supply can be increased proportionally according to the actual tank capacity used in production, and it can be used for large-scale continuous production of Marselan wines on the eastern foothills of Helan Mountain.

[0093] Furthermore, current technology relies on a single material for aging any juice: oak barrels or glass bottles. While traditional oak barrels can impart complex flavors such as smoke and vanilla, their uncontrollable micro-oxygen permeability can easily lead to excessive degradation of anthocyanins in heavily pressed juice, causing the red hue of the wine to fade rapidly during aging. On the other hand, glass bottles are completely sealed and cannot allow for necessary aerobic maturation, making it difficult to simultaneously enhance the aroma freshness and structure of free-flowing juice.

[0094] This invention features precise and quantitative micro-oxygen control, ensuring that the fruit aroma is not lost due to excessive oxidation of the free-run juice, and that the tannins are not astringent due to sufficient oxidation during heavy pressing. It is an adaptable fermentation process applicable to three types of pressed raw materials. After fermentation, this invention does not uniformly use oak barrels or glass bottles for aging, but can match the inherent polyphenol reserves of the raw materials. This prevents the red fruit aroma from being rapidly lost in the free-run juice with low polyphenols when it enters the oak barrel, and the heavy pressing with high polyphenols does not use only glass bottles, which can soften the tannins and enhance the complexity of aging.

[0095] This invention belongs to the field of Marselan winemaking technology on the eastern foothills of the Helan Mountains. It discloses an integrated method for stable wine production, adaptable to three types of grape juice: free-run, medium-pressed, and heavy-pressed juices, through a unified, optimal micro-aerobic fermentation coupled with differentiated aging containers. Using Marselan grapes as raw material, this invention conducts alcoholic fermentation separately for each of the three types of raw materials: free-run, medium-pressed, and heavy-pressed juices. The entire fermentation process employs a uniform 25 min / day micro-aerobic process. After fermentation, based on the inherent differences in phenolic compounds, aroma, and color among the three types of grape juice, earthenware jars, glass bottles, and oak barrels are used for targeted low-temperature aging, with standardized control of the micro-aerobic exchange rate throughout the process. This invention achieves targeted optimization of color, phenols, antioxidant capacity, and sensory flavor in wines made from different raw materials by uniformly and appropriately controlling micro-oxygen during the fermentation stage, thereby simultaneously increasing the total aroma content and stabilizing anthocyanins and polyphenols in three types of pressed wine samples. Furthermore, it matches corresponding oxygen-permeable aging containers according to the differences in polyphenol reserves in the raw materials, thus solving the problems of large quality fluctuations, shelf-life fading, aroma decay, and taste imbalance when brewing wines from different pressed grape juices in a unified manner. This provides a complete process solution for the standardized and stable mass production of Marselan wines from the region.

[0096] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing microaerobic fermented wine, characterized in that, Includes the following steps: After pressing, the juice undergoes alcoholic fermentation and aging to produce micro-aerobic fermented wine; The pressed juice includes any one of free-flowing juice, medium-pressed juice, and heavy-pressed juice; the free-flowing juice is grape juice obtained by flowing out naturally without applying mechanical pressure or by relying solely on the gravity of the grape pulp itself; the medium-pressed juice is prepared by pressing grapes under pressure greater than 0.15 bar and less than or equal to 0.80 bar; and the heavy-pressed juice is prepared by pressing grapes under pressure greater than 0.80 bar and less than or equal to 1.00 bar. The conditions for alcoholic fermentation are as follows: for every 10L to 20L of pressed juice, aeration is carried out for 20 to 30 minutes daily at a flow rate of 35 mL / min to 37 mL / min, until the residual sugar is less than or equal to 4 g / L. Free-run juice is aged in glass containers, medium-pressed juice in glass containers or earthenware jars, and heavy-pressed juice in any of the following: glass containers, earthenware jars, and oak barrels.

2. The preparation method according to claim 1, characterized in that, The alcoholic fermentation process involves aeration for 25 minutes per day for every 15L of pressed juice, with an air flow rate of 36mL / min.

3. The preparation method according to claim 1, characterized in that, The aging process involves constant temperature and protection from light, with a temperature range of 14℃ to 17℃.

4. The preparation method according to claim 1, characterized in that, The aging time is greater than or equal to 90 days.

5. The preparation method according to claim 1, characterized in that, It also includes adding potassium metabisulfite to the pressed juice, followed by alcoholic fermentation.

6. The preparation method according to claim 5, characterized in that, Add 35mg~45mg of potassium metabisulfite per liter of pressed juice.

7. The preparation method according to claim 4, characterized in that, Add 40mg of potassium metabisulfite per liter of pressed juice.

8. Microaerobic fermented wine prepared by the method according to any one of claims 1 to 7.

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