Preparation method of naturally air-dried grape wine

Abstract

The invention discloses a preparation method of naturally air-dried grape wine. The preparation method comprises the steps of grape screening, natural air drying, fermentation regulation, aging and the like. The fruit clusters are hung on the branches for natural air drying, the stability of the grape quality in the air drying process is remarkably improved, nutrients are continuously provided through the tree body, accumulation of flavor substances is promoted, and the complexity and uniqueness of the grape wine are improved. According to the method, the air drying time can be effectively shortened, resource consumption and environmental pollution are reduced, and meanwhile, the obtained wine has the characteristics of dark purplish red, rich and elegant fragrance and mellow and full wine body, is suitable for long-term aging and has excellent sensory characteristics and physical and chemical indexes.

Description

Technical Field

[0001] The present invention relates to the technical field of wine brewing, and in particular to a method for preparing naturally air-dried wine. Background Art

[0002] As a beverage with a long history and widespread popularity, winemaking techniques are constantly evolving. Traditional winemaking primarily involves basic steps such as harvesting, crushing, and fermentation. However, for high-quality wines, particularly sweet wines or those with unique flavors, specialized techniques are often required to enhance quality and flavor. Air-drying grapes to make wine is an ancient and unique winemaking method. Traditionally, this method involves laying bunches of grapes flat on specially constructed wooden racks, stacked one on top of the other, in a ventilated, but light-proof room to naturally air-dry for 90 to 120 days. However, this traditional drying method is demanding in terms of environmental conditions, requiring strict control of temperature, humidity, and ventilation. Failure to do so can easily lead to problems such as mold and rot, while increasing labor costs and resource consumption. Furthermore, traditional drying methods overlook the role that the grape tree may play in the drying process, failing to fully utilize the exchange and interaction between the tree and the bunch to enhance the complexity and uniqueness of the grape's flavor.

[0003] With the development of the modern wine industry, consumers' requirements for wine quality and flavor diversity are constantly increasing. How to optimize the air-drying process and fully tap the flavor potential of grapes while ensuring the quality of wine has become an urgent problem to be solved. At the same time, from the perspective of sustainable development, reducing resource consumption and environmental pollution during the air-drying process is also one of the challenges facing the wine brewing industry. Therefore, it is of great practical significance and application value to develop a new air-drying process that can improve the quality stability of grapes during the air-drying process and give full play to the positive influence of the tree on the flavor of grapes. The present invention aims to improve air circulation conditions and reduce the risk of mildew and rot by hanging the fruit clusters on branches for natural air-drying, while utilizing the tree to provide nutrients and protection for the fruit clusters, thereby maximizing the flavor complexity and uniqueness of the wine, thereby solving the problems existing in the prior art. Summary of the Invention

[0004] The purpose of the invention is to provide a method for preparing naturally air-dried wine, which solves the problems mentioned in the background technology.

[0005] The present invention is achieved by providing a method for preparing naturally air-dried wine, comprising the following steps:

[0006] S1: After veraison, the grapes are manually screened to remove diseased, rotten, and under-roasted grapes. After screening, watering is discontinued, and the grapes are allowed to air-dry and concentrate naturally on the branches. The grapes are wine grape varieties with moderately thick skins and strong disease resistance, preferably Cabernet Sauvignon or Marselan. The grapes are grown in semi-arid regions with annual rainfall below 400 mm, specifically Ningxia, Tibet, and Xinjiang. Furthermore, S2: The raw grapes are randomly inspected and tested. When the sugar content reaches 26-28° Brix, they are manually harvested. The harvested grapes are manually sorted again to remove moldy and rotten grapes. Specifically, S3: The selected grapes are 100% destemmed and crushed before being canned. Potassium metabisulfite and pectinase are added during canning. The potassium metabisulfite is added at a rate of 40 mg / L, calculated as sulfur dioxide, and the pectinase is added at a rate of 30 mg / L. After loading, a homogenization cycle is performed, and physical and chemical parameters are tested.

[0007] Further, S4: after the raw materials are put into the tank, the temperature is returned to 16°C, and high-alcohol-resistant yeast is inoculated to start fermentation; the fermentation temperature is controlled at 24-26°C; during the fermentation period, two cycles of immersion are carried out every day, and the volume of each immersion is one-third of the volume of the fermentation liquid; fermentation aids are added as needed according to the nitrogen content that can be absorbed by the yeast in the fermentation liquid, and the amount of fermentation aids added is 300g per ton of fermentation liquid; when the sugar content of the fermentation liquid is less than 5g / L, the temperature is raised to 28-30°C for post-immersion treatment, and the post-immersion time is 3-5 days; during the post-immersion period, the cap is rinsed for 10 minutes every day, and tasting is used to confirm whether the tannin taste meets the expectations.

[0008] Among them, S5: after the post-maceration is completed, the wine is separated, and lactic acid bacteria are added to the separated wine to carry out malo-lactic fermentation; the temperature is maintained at 21°C during the malo-lactic fermentation; when the detection confirms that the malo-lactic fermentation is completed, potassium metabisulfite is added to terminate the fermentation, and the potassium metabisulfite is added in an amount of 40 mg / L calculated as sulfur dioxide.

[0009] Further, S6: the wine after the malolactic fermentation is transferred to a 300L oak barrel for aging; the oak barrel is a French oak barrel or an American oak barrel, and the ratio can be adjusted according to demand, for example, the ratio of French oak barrels to American oak barrels is 4:1; the aging temperature is 15-18°C, and the aging time is 18-24 months; during the aging period, the barrel is added every 1.5-2 months to ensure that the original wine is in a full barrel state.

[0010] In particular, the method of the present invention significantly improves the quality stability of grapes during the air-drying process by hanging the grape clusters on branches for natural air-drying. Compared with the traditional flat-laying drying method, this air-drying method has the following innovations:

[0011] First, air circulation is improved, reducing the risk of grape mold and rot. Because the grape clusters hang from the branches, air can reach their surfaces from multiple directions, reducing the potential for moisture accumulation. Furthermore, the tree provides physical support for the clusters, preventing damage from accumulation. Second, air-drying time is shortened; this air-drying time is only 15-20 days later than normal harvesting, compared to the 90-120 days required by traditional air-drying methods, significantly reducing resource consumption and environmental pollution.

[0012] Third, it enhances the complexity of flavor; by continuously providing nutrients to the grape clusters through the tree, it promotes the accumulation of grape flavor substances, which greatly enhances the complexity and uniqueness of the flavor of the wine produced while retaining the typicality of the variety.

[0013] Furthermore, the wine produced by the present invention exhibits excellent sensory properties and physicochemical indicators. The wine is deep purple-red in color and has a rich, elegant, and long-lasting aroma, including black fruits, violets, dried roses, coffee, and caramel. It is round and full-bodied, with a strong structure and a harmonious balance, making it suitable for producing high-quality, long-term aging wines. The wine has an alcohol content of 16.1%-16.8% vol, a residual sugar content of 3.5-4.2 g / L, a total acid content of 6.8-7.5 g / L, a volatile acid content of 0.72-0.81 g / L, and a dry extract content of 36-38 g / L.

[0014] The beneficial effects of the present invention are achieved through the following technical features: first, by hanging the grape bunches on branches for natural air-drying, the stability of the grape quality during the air-drying process is ensured; second, the tree body is used to continuously provide nutrients to the grape bunches, which promotes the accumulation of grape flavor substances; finally, by optimizing the brewing process, the resulting wine has a high alcohol content, a low residual sugar content, an appropriate amount of total acid and volatile acid, and rich dry extract, ensuring the high quality and long-term aging potential of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a sensory evaluation result table of a naturally air-dried wine of the present invention;

[0016] Figure 2 This is a table showing the physical and chemical test results of a naturally air-dried wine of the present invention;

[0017] Figure 3 The present invention is a flow chart of a method for preparing naturally air-dried wine. DETAILED DESCRIPTION

[0018] The specific embodiments of the present invention are described in conjunction with the accompanying drawings. Figure 1 and Figure 2 Provide a detailed description. Figure 1The sensory evaluation results of the naturally air-dried wines prepared in Example 1 and Example 2 are shown. Figure 2 The corresponding physical and chemical test results are listed. The following is a detailed description of the technical solution of the present invention from the aspects of grape screening and air drying, fermentation process optimization, and aging process control.

[0019] In the grape screening and air-drying stage, wine grape varieties planted in semi-arid production areas, including Cabernet Sauvignon and Marselan, are first selected. These varieties have thicker skins and strong disease resistance, can adapt to low-humidity environments and reduce the risk of mildew. Taking Example 1 as an example, Cabernet Sauvignon grapes from the Xige Zhonglinka Winery planting base in Zuogong County, Tibet, are selected. The region has strong ultraviolet rays and strong winds, providing favorable conditions for the grapes to be naturally air-dried. After the grapes enter the color change period, they are manually screened to remove diseased, rotten, and poorly colored fruits to ensure the quality of the raw materials. After the screening is completed, watering is stopped and the grapes are allowed to naturally air-dry and concentrate on the branches. This stage utilizes the transpiration of the tree to promote water evaporation, and the fruit clusters are hung on the branches to achieve multi-directional air circulation, reducing humidity accumulation and thus reducing the occurrence of mildew and rot problems. The air-drying time is significantly shortened compared to traditional methods, and the sugar content of 26-28 ° Brix can be reached only 15-20 days later than normal harvesting. Example 2: Marselan grapes grown at the Xige Winery in Qingtongxia, Ningxia, are suitable for natural air drying due to their dry, rainless, and high evaporative climate. They were harvested manually on September 30 and October 20, respectively, after their glucose concentrations reached the standard. The grapes were then sorted again to remove unqualified grapes.

[0020] To optimize the fermentation process, harvested grapes were manually sorted and 100% destemmed and crushed before being pumped into the fermenter via a pulp pump. Potassium metabisulfite and pectinase were added upon entry, with the potassium metabisulfite added at 40 mg / L and the pectinase added at 30 mg / L, calculated as sulfur dioxide. After entry, a homogenization cycle was performed to ensure thorough mixing of the raw materials, and physical and chemical parameters were tested. For example, in Example 1, the test results showed a sugar content of 275 g / L, a total acid content of 14.3 g / L, and a pH of 3.1; in Example 2, the sugar content was 283 g / L, a total acid content of 15.3 g / L, and a pH of 3.2. After the raw materials were warmed to 16°C, high-alcohol-tolerant yeast was inoculated to initiate fermentation, with a yeast dosage of 250 g / t, and the temperature controlled between 24 and 26°C. During fermentation, two maceration cycles were performed daily, each maceration volume accounting for one-third of the fermentation broth volume. This procedure helps extract tannins and pigments from the grape skins, enhancing the wine's body and structure. When the specific gravity dropped to 0.994 or 0.995, the residual sugar content was measured. If it was below 5g / L, the temperature was raised to 28-30°C for post-maceration. The post-maceration period lasted for 3-5 days, with daily rinsing for 10 minutes and tasting to confirm that the tannins met the desired taste. In Examples 1 and 2, maceration was completed on the third day, and the alcohol content after separation was 16.1% and 16.8% vol, respectively, with residual sugar levels of 3.5g / L and 4.2g / L, respectively.

[0021] Malolactic fermentation is a key step in the present invention. After separation, the wine is added to the fermentation process with lactic acid bacteria, maintaining the fermentation temperature at approximately 21°C. In Examples 1 and 2, after 20 and 22 days of malolactic fermentation, the malic acid content was zero, and then 40 mg / L of sulfurous acid was added to terminate the fermentation. This step reduces the wine's acidity, enhances its taste, and imparts a creamy aroma.

[0022] The aging process further enhances the complexity and quality of the wine. After malolactic fermentation, the wine was transferred to 300L oak barrels for aging. Example 1 used French oak barrels, while Example 2 employed a mixture of French and American oak barrels in a 4:1 ratio. The aging temperature was controlled at 15-18°C for 18-24 months. During the aging period, barrels were added every 1.5-2 months to ensure that the base wine remained full to prevent oxidation. After long-term aging, the wine gradually developed a deep purple-red color and a rich, elegant aroma, including complex aromas such as black fruits, violets, dried roses, coffee, and caramel. According to the sensory evaluation results in Table 1, both Example 1 and Example 2 exhibited roundness, structure, and balance, retaining the typical varietal aromas of Cabernet Sauvignon and Marselan. The physical and chemical test results in Table 2 show that the alcohol content of the two wines is 16.1%vol and 16.8%vol, respectively, the residual sugar content is 3.5g / L and 4.2g / L, the total acid content is 7.5g / L and 6.8g / L, the volatile acid content is 0.81g / L and 0.72g / L, and the dry extract content is 36g / L and 38g / L. All indicators meet the standards of high-quality long-term aging wines.

[0023] In the entire process, the innovative design of the air-drying method is the key. By hanging the fruit clusters on branches for natural air-drying, not only is smooth air circulation achieved, thereby significantly reducing the problem of mildew and rot, but the tree body is also fully utilized to continuously provide nutrients to the fruit clusters, promoting the accumulation of flavor substances. Compared with the traditional flat drying method that requires 90-120 days of air-drying time, the present invention only needs to extend the harvest period by 15-20 days to complete the air-drying, greatly shortening the production cycle and reducing resource consumption. In addition, the material exchange between the tree body and the fruit clusters makes the brewed wine have a higher complexity and uniqueness, greatly improving the added value of the product while retaining the typicality of the variety.

[0024] In summary, the present invention successfully addresses the issues of insufficient quality stability and flavor complexity associated with traditional air-drying methods by improving the grape drying process and optimizing the brewing process. In practical applications, this method is applicable to a variety of wine grape varieties grown in semi-arid regions, and is particularly well-suited for producing high-quality, long-aging wines. By strictly controlling the technical parameters of each step and incorporating scientific quality control measures, a product with a deep color, rich aroma, and a full, harmonious taste can be consistently produced, meeting market demand for high-end wines.

[0025] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing naturally air-dried wine, characterized in that: The following steps are involved: S1: After the grapes have completed veraison, they are manually screened to remove diseased, rotten, and poorly veraisoned grapes; after screening, watering is stopped and the grapes are allowed to naturally air-dry and concentrate on the branches; the grapes are wine grape varieties with moderately thick skins and strong disease resistance, grown in a semi-arid production area with an annual rainfall of less than 400 mm; S2: Grapes are randomly inspected and tested. When the sugar content of the grapes reaches 26-28°Brix, they are harvested manually. The harvested grapes are then manually sorted again to remove moldy and rotten grapes. S3: After 100% destemming and crushing of the selected grapes, they are placed in tanks. Potassium metabisulfite and pectinase are added during the addition of the grapes; the potassium metabisulfite is added in an amount of 40 mg / L calculated as sulfur dioxide, and the pectinase is added in an amount of 30 mg / L. After the addition of the grapes, a homogenization cycle is performed, and physical and chemical indicators are tested. S4: After the raw materials are put into the tank, the temperature is returned to 16°C, and high-alcohol-resistant yeast is inoculated to start fermentation; the fermentation temperature is controlled at 24-26°C; during the fermentation period, two cycles of immersion are performed every day, and the volume of each immersion is one-third of the volume of the fermentation liquid; fermentation aids are added as needed according to the nitrogen content that can be absorbed by the yeast in the fermentation liquid, and the amount of fermentation aids added is 300g per ton of fermentation liquid; when the sugar content of the fermentation liquid is less than 5g / L, the temperature is raised to 28-30°C for post-immersion treatment, and the post-immersion time is 3-5 days; during the post-immersion period, the cap is rinsed for 10 minutes every day; S5: After the post-maceration is completed, the wine is separated, and lactic acid bacteria are added to the separated wine to carry out malolactic fermentation; the temperature during the malolactic fermentation is maintained at 21° C.; when the malolactic fermentation is confirmed to be complete, potassium metabisulfite is added to terminate the fermentation, and the potassium metabisulfite is added in an amount of 40 mg / L calculated as sulfur dioxide; S6: After the malolactic fermentation, the wine is transferred to 300L oak barrels for aging; the oak barrels are French oak barrels or American oak barrels; the aging temperature is 15-18°C, and the aging time is 18-24 months; during the aging period, the wine is re-barreled every 1.5-2 months.

2. The method for preparing naturally air-dried wine according to claim 1, characterized in that: The grape variety is Cabernet Sauvignon or Marselan.

3. The method for preparing naturally air-dried wine according to claim 2, characterized in that: The grapes are grown in Ningxia, Tibet or Xinjiang.

4. The method for preparing naturally air-dried wine according to claim 1, wherein: The oak barrels are a mixture of French oak barrels and American oak barrels in a ratio of 4:

1.

5. The method for preparing naturally air-dried wine according to claim 1, characterized in that: The fermentation aid is a commercial yeast nutrient.

6. The method for preparing naturally air-dried wine according to claim 1, characterized in that: The barrel filling operation is completed manually or automatically to ensure that the original wine is in a full barrel state.

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