Antioxidation method of low-sulfur semi-sweet wine

Abstract

The invention relates to the technical field of food processing, and discloses a low-sulfur semi-sweet wine anti-oxidation method which comprises the following steps: S1, selecting wine grapes, removing stems, crushing and squeezing to obtain grape juice; s2, performing alcoholic fermentation on the grape juice, and stopping fermentation when the residual sugar content is 12-45g / L to obtain base wine; s3, an antioxidant combination is added into the base liquor, the antioxidant combination comprises 5-10 mg / L of glutathione, 5-10 mg / L of mannan and 15-20 mg / L of sulfite, and the materials are mixed to be uniform; and S4, filtering the base wine added with the antioxidant, bottling, and storing to obtain the low-sulfur semi-sweet wine. Through the synergistic effect of glutathione, mannan and sulfite, the antioxidant insufficiency under the low SO2 concentration is made up, and the dual effects of low vulcanization and stable quality are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, in particular to an antioxidant method for low-sulfur semi-sweet wine. Background Art

[0002] In the brewing and storage process of semi-sweet wine, preventing oxidation is a key technical requirement to ensure stable quality. Existing technologies usually use sulfite (SO2) as the main antioxidant, and its addition amount is generally 30-50 mg / L, which delays the oxidation reaction by scavenging free radicals and inhibiting the activity of polyphenol oxidase (PPO) and peroxidase (POD). The use of SO2 has been used in the wine industry for a long time, which can effectively control the growth of microorganisms and reduce the formation of quinone compounds in the wine. In addition, some processes are combined with physical methods, such as introducing inert gas (nitrogen or argon) during the pressing or fermentation stage to reduce oxygen contact, but anti-oxidation mainly relies on the chemical action of SO2. During storage, wine is usually placed in an environment of 10-15°C to further slow down the oxidation process.

[0003] However, in traditional processes, the amount of SO2 added usually reaches 50 mg / L to ensure the antioxidant effect, but this increases health risks. For example, it may increase the metabolic burden on the liver or cause allergic reactions. The World Health Organization (WHO) and the International Organization of Vine and Wine (OIV) have established strict limit standards for this. At the same time, the antioxidant capacity of high-concentration SO2 is limited, and the DPPH free radical scavenging rate is only about 50%, which makes it difficult to fully inhibit the oxidation reaction during storage, resulting in a decrease in wine quality. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a low-sulfur semi-sweet wine antioxidant method to solve the problem that the antioxidant capacity of high-concentration SO2 is limited and the DPPH free radical scavenging rate is only about 50%, making it difficult to fully inhibit the oxidation reaction during storage.

[0005] To achieve the above objectives, the present invention is implemented by the following technical scheme: a low-sulfur semi-sweet wine antioxidant method, comprising the following steps:

[0006] S1. Select wine grapes, remove stems, crush and squeeze to obtain grape juice;

[0007] S2, subjecting the grape juice to alcohol fermentation, and terminating the fermentation when the residual sugar content is 12-45 g / L to obtain base wine;

[0008] S3, adding an antioxidant combination to the base wine, wherein the antioxidant combination includes 5-10 mg / L glutathione, 5-10 mg / L mannan and 15-20 mg / L sulfite, and mixing them evenly;

[0009] S4. Filter the base wine added with antioxidants, bottle it and store it to obtain a low-sulfur semi-sweet wine.

[0010] Preferably, the sugar content of the wine grapes described in step S1 is ≥25%.

[0011] Preferably, the wine grapes described in step S1 are of the 'Petit Manseng' variety.

[0012] Preferably, an inert gas is introduced during the pressing process in step S1, and the inert gas is selected from nitrogen or argon to reduce the contact between grape juice and oxygen.

[0013] Preferably, the temperature of the alcoholic fermentation in step S2 is 15-18°C, and Saccharomyces cerevisiae is used for fermentation.

[0014] Preferably, the temperature of the alcoholic fermentation in step S2 is 15-18°C, and the fermentation is terminated when the residual sugar content reaches 25-35 g / L.

[0015] Preferably, the specific addition amounts of the antioxidant combination in step S3 are: glutathione 8-10 mg / L, mannan 8-10 mg / L, and sulfite 18-20 mg / L.

[0016] Preferably, the antioxidant combination in step S3 is added to the base wine in the form of a solution and mixed evenly by stirring.

[0017] Preferably, the storage conditions in step S4 are storage at 10-15°C for 6-12 months, and direct sunlight should be avoided during storage.

[0018] Preferably, the storage conditions in step S4 are storage at 10-15°C for 5-7 months, and the DPPH free radical scavenging rate of the obtained low-sulfur semi-sweet wine is ≥60%, and the OD420 value is ≤0.2.

[0019] The present invention provides an antioxidant method for low-sulfur semi-sweet wine. It has the following beneficial effects:

[0020] 1. Through the synergistic effect of glutathione (GSH) 5-10 mg / L, mannan (Man) 5-10 mg / L and sulfite (SO2) 15-20 mg / L, the present invention reduces the SO2 dosage from 50 mg / L in the traditional process to 15-20 mg / L, a reduction of about 60-70%. At the same time, the DPPH free radical scavenging rate is maintained between 60-70%, which is higher than about 50% of the traditional SO2 treatment. This antioxidant combination utilizes the free radical scavenging ability of GSH and the phenolic protection effect of Man to make up for the antioxidant deficiency at low SO2 concentrations, achieving the dual effects of low sulfurization and stable quality.

[0021] 2. By adding mannan (Man), the content of ester aroma substances (such as isoamyl acetate and ethyl octanoate) in semi-sweet wine is increased by 50 - 80% compared with traditional SO2 treatment, and the formation of complex fruit and flower aromas is promoted. Experiments show that Man promotes the formation of esters by binding with phenolic substances, while GSH protects terpene compounds from oxidation, compensating for the inhibitory effect of high-dose SO2 on aroma substances. After storage for 6 - 12 months, the aroma characteristics of the wine sample change from the caramel aroma of traditional treatment to fresh fruit aroma or complex flower aroma, significantly improving the sensory properties of semi-sweet wine.

[0022] 3. By utilizing the antioxidant effects of GSH and Man, the OD420 value is controlled within 0.14 - 0.18, which is about 40 - 50% lower than the 0.25 - 0.30 of traditional SO2 treatment, effectively delaying the formation of quinones and brown polymers generated by polyphenol oxidation. GSH reacts with oxygen preferentially, and Man stabilizes phenolic substances through hydrogen bonds. The two work together to reduce non-enzymatic browning, enabling the wine body to remain light golden yellow after storage for 6 - 12 months, instead of the amber color of traditional treatment. This effect improves the visual quality and stability of the wine.

[0023] 4. Through the application of the antioxidant combination, the sensory score of the wine sample is increased from 80 - 82 points of traditional SO2 treatment to 85 - 90 points, and the balance between acidity and sweetness is improved. In the traditional process, acid substances (such as octanoic acid) accumulate due to oxidation, resulting in a sour and unbalanced taste. However, this method controls the oxidation process, reduces the content of acid substances by about 30 - 40%, and retains the sweetness characteristic of 25 - 35 g / L of residual sugar, making the wine body present a fresh, full and long-lasting aftertaste, improving the overall drinking quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a diagram showing the antioxidant property differences of white wine under different concentrations of antioxidants of the present invention;

[0025] Figure 2 It is a diagram showing the main components of monomeric phenols and aroma substances in semi-sweet wine under different antioxidants of the present invention;

[0026] Figure 3 It is a schematic diagram of sensory description scores of the present invention;

[0027] Figure 4 It is a heat map showing the differences in polyphenol and amino acid substances in semi-sweet wine under the interaction of different antioxidants of the present invention;

[0028] Figure 5 It is a schematic diagram of the sensory evaluation of the wine of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0030] Please refer to the attached Figure 1 - attached Figure 5 , an antioxidant method for low-sulfur semi-sweet wine provided by an embodiment of the present invention includes the following steps:

[0031] S1. Select wine grapes, remove the stems, crush and press to obtain grape juice;

[0032] S2. Ferment the grape juice alcoholically, and terminate the fermentation when the residual sugar content reaches 12 - 45 g / L to obtain base wine;

[0033] S3. Add an antioxidant combination to the base wine. The antioxidant combination includes glutathione 5 - 10 mg / L, mannan 5 - 10 mg / L, and sulfite 15 - 20 mg / L, and mix evenly;

[0034] S4. Filter the base wine added with antioxidants, bottle and store it to obtain low-sulfur semi-sweet wine.

[0035] Specifically, the selection of wine grapes in step S1 needs to ensure that their fruit maturity is appropriate to guarantee the balance of sugar conversion into alcohol during the subsequent fermentation process, while retaining sufficient residual sugar to meet the taste requirements of semi-sweet wines. Stemming and crushing are completed by mechanical equipment. A stainless-steel stemming and crushing machine can be selected to ensure complete separation of the stems from the berries, avoiding excessive infiltration of tannin substances in the stems into the grape juice and affecting the softness of the wine body. The pressing process can use a bladder press, with the pressure controlled between 0.5 - 1.5 bar to gently extract the grape juice and avoid excessive release of bitter substances in the peel. The alcoholic fermentation in step S2 needs to be carried out in a sealed fermentation tank. It is recommended to use a stainless-steel fermentation tank equipped with a temperature control system to maintain the stability of the fermentation temperature. During the fermentation process, the residual sugar content can be periodically detected, and high-performance liquid chromatography (HPLC) or a refractometer can be used for determination to ensure that the residual sugar content is precisely controlled within the range of 12 - 45 g / L at the end of fermentation. The selection of antioxidants in step S3 is based on their synergistic effects in semi-sweet wines. Glutathione (GSH), as a tripeptide compound, can react with oxygen through its sulfhydryl group to preferentially protect phenolic substances from oxidation; Mannan (Man), derived from the yeast cell wall, has the ability to form hydrogen bonds with phenolic substances, which can effectively delay color oxidation and promote the generation of ester aromas; Sulfite (SO2) is added in the form of sodium bisulfite or potassium metabisulfite. Its low-dose use aims to balance microbial inhibition and health safety. When adding, it can be first dissolved in a small amount of distilled water to make a solution and then slowly added to the base wine to avoid too high a local concentration. The filtration in step S4 can be carried out using a 0.45 μm microporous filter membrane to remove suspended particles and microorganisms and ensure the clarity of the wine body. After bottling, it is sealed with a glass bottle. The bottle mouth can use a cork or a screw cap. The storage environment needs to maintain a relative humidity of 60 - 80% to prevent the cork from drying or the wine liquid from volatilizing.

[0036] The sugar content of the wine grapes in step S1 is ≥ 25%.

[0037] Specifically, the selection of wine grapes with a sugar content ≥ 25% is a key technical requirement of this method. This sugar level is usually determined by the soluble solid content (SSC), and a handheld refractometer is used to conduct field tests on grape fruits before harvest to ensure that the fruits reach the optimal maturity. The high sugar content not only provides sufficient substrate for fermentation but also ensures the sweetness characteristics of semi-sweet wines, which is suitable for producing wine styles with rich fruit aromas and a soft taste. The recommended harvest time is when the grape fruits have completely changed color and the peel is slightly soft. At this time, the sugar accumulation in the grapes reaches its peak, and the acidity is moderate (the total acid content is generally 5-8 g / L, calculated as tartaric acid). If the sugar content is insufficient, it can be adjusted by adding food-grade glucose or concentrated grape juice before fermentation, but it must comply with national food safety standards. In addition, the selection of high-sugar grapes is also related to the antioxidant effect because sugar may accelerate browning through the Maillard reaction during storage, while the antioxidant combination of this method can effectively inhibit this process and maintain the light golden color of the wine body.

[0038] In step S1, the wine grapes are of the 'Petit Manseng' variety.

[0039] Specifically, due to its thick skin, loose fruit clusters, and late maturity, the 'Petit Manseng' variety has become the preferred grape variety recommended by this method. This variety is native to France and is widely planted in Shanxi, China. Its fruits have a high sugar content (up to 25-28%) and moderate acidity (5-7 g / L), and emit typical aromas of peaches, honey, and cinnamon when ripe, making it very suitable for brewing high-quality semi-sweet wines. It is recommended to pick by hand during harvest to reduce fruit damage. After harvest, crushing and pressing should be completed within 24 hours to avoid fruit oxidation or microbial contamination. The high sugar content of 'Petit Manseng' makes it easy to retain residual sugar during fermentation, and its natural aroma components (such as terpene compounds) synergistically interact with the antioxidant combination of this method, significantly enhancing the floral and fruit aroma characteristics of the wine body. Experiments have shown that after adding antioxidants, the content of ester aroma substances (such as isoamyl acetate and ethyl octanoate) in semi-sweet wines brewed with 'Petit Manseng' is increased by about 20-30% compared with other varieties, and the sensory score is also higher, showing a good match between the variety and the method.

[0040] In step S1, an inert gas is introduced during the pressing process. The inert gas is selected from nitrogen or argon to reduce the contact between the grape juice and oxygen.

[0041] Specifically, introducing inert gas during the pressing process is an optional optimization step of this method, aiming to reduce the exposure time of grape juice to oxygen, thereby reducing the oxidation reactions catalyzed by polyphenol oxidase (PPO) and peroxidase (POD). Nitrogen is preferentially recommended due to its low cost and wide availability. It can be introduced into the pressing equipment through gas cylinders at a flow rate of 0.2 - 0.5 L / min to ensure that the grape juice is in a low-oxygen environment during pressing. Argon, as an alternative option, can more effectively settle on the surface of grape juice due to its higher density, providing better protection, but it is more costly and is suitable for the production of high-end wine styles. The use of inert gas can reduce the dissolved oxygen content in grape juice to below 2 mg / L, significantly reducing the generation of quinone compounds and maintaining the light color tone of the wine body. Experimental data shows that for grape juice protected by nitrogen, the OD420 value (a chromaticity index) during subsequent fermentation and storage is reduced by approximately 15 - 20% compared to the unprotected group, demonstrating its auxiliary role in antioxidant protection. During operation, attention should be paid to the purity of the gas (≥99.9%) to avoid introducing impurities that may affect the wine quality.

[0042] In step S2, the temperature of alcoholic fermentation is 15 - 18 °C, and Saccharomyces cerevisiae is used for fermentation.

[0043] Specifically, controlling the alcoholic fermentation temperature at 15 - 18 °C is based on best practices for white wine production. This temperature range can not only ensure the activity of Saccharomyces cerevisiae (such as Saccharomyces cerevisiae) but also slow down the loss of volatile aroma substances. The fermentation tank can be equipped with a cold water circulation system to adjust the temperature through an external jacket or an internal cooling pipe. The temperature fluctuation should be controlled within ±0.5 °C to ensure a stable fermentation process. The choice of Saccharomyces cerevisiae can be adjusted according to the wine style. Commercial dry yeast (such as Lalvin D47 or EC-1118) is recommended, which has excellent low-temperature tolerance and can promote the formation of ester and alcohol aroma substances. During fermentation, it is necessary to stir regularly (1 - 2 times a day) to avoid yeast sedimentation and uneven fermentation. The fermentation time is generally 10 - 20 days, depending on the initial sugar content and the target residual sugar content. Experimental verification shows that in the base wine fermented at 15 - 18 °C, the retention rate of terpene compounds (such as geraniol) is increased by approximately 10 - 15%, laying a foundation for the subsequent antioxidant to play its role.

[0044] In step S2, the temperature of alcoholic fermentation is 15 - 18 °C, and the fermentation is terminated when the residual sugar content reaches 25 - 35 g / L.

[0045] Specifically, the fermentation temperature is further limited to the range of 15-18°C. Combining with the optimization goal of residual sugar content of 25-35 g / L, it aims to produce wine with a typical semi-sweet style. This residual sugar range is achieved by prematurely terminating fermentation. The cryogenic method (lowering the temperature of the fermentation tank to 0-2°C) or the alcohol addition method (adding food-grade alcohol to reach an alcohol content of 14-15%) can be used to inhibit yeast activity. The specific method is selected according to the production scale. The residual sugar content of 25-35 g / L not only meets the international semi-sweet wine standard (defined by OIV), but also matches the high-sugar characteristics of the 'Petit Manseng' variety, can highlight its peach and honey aromas, and at the same time avoid the greasy taste caused by excessive sweetness. During the fermentation process, the high-performance liquid chromatography method can be used to monitor the ratio of glucose and fructose to ensure a balanced residual sugar composition (glucose: fructose is about 1:1). The experimental results show that after subsequent antioxidant treatment of the base wine with a residual sugar of 25-35 g / L, the content of acid substances (such as octanoic acid) decreases by about 30-40%, and the balance of the wine body is better.

[0046] In step S3, the specific addition amounts of the antioxidant combination are: glutathione 8-10 mg / L, mannan 8-10 mg / L, and sulfite 18-20 mg / L.

[0047] Specifically, the specific addition amounts of the antioxidant combination are optimized to glutathione 8-10 mg / L, mannan 8-10 mg / L, and sulfite 18-20 mg / L. This range is screened based on experimental data to achieve the best antioxidant effect and flavor improvement under the premise of low sulfur. Glutathione (GSH) is recommended to use food-grade powder or solution (purity ≥ 98%). Its addition amount of 8-10 mg / L can significantly increase the DPPH free radical scavenging rate to more than 60%, while protecting phenolic substances such as epicatechin and catechin and delaying their oxidative degradation. Mannan (Man) can be extracted from yeast derivatives, and the purity needs to be ≥ 90%. Its addition amount of 8-10 mg / L reduces color oxidation (the OD420 value decreases by about 10-15%) by binding to phenolic substances and promotes the increase of the content of ester aromas (such as hexyl acetate) by about 20-25%. Sulfite (SO2) is added at a low dose of 18-20 mg / L, which can not only inhibit the growth of spoilage microorganisms (such as lactic acid bacteria), but also avoid the loss of aroma caused by binding to terpene aromas, meeting the market demand for low-sulfur wines. When adding, the three antioxidants can be premixed in distilled water with a volume of 5-10 times according to the ratio and slowly added to the base wine to avoid precipitation or abnormal odor caused by local overdose.

[0048] In step S3, the antioxidant combination is added to the base wine in the form of a solution and mixed evenly by stirring.

[0049] Specifically, adding the antioxidant combination to the base liquor in the form of a solution is a key process requirement to ensure uniformity and stability. When preparing the solution, it is recommended to use deionized water or distilled water, with the water temperature controlled at 20-25°C to avoid destroying the activity of GSH at high temperatures. The concentration of the premixed solution can be adjusted according to the volume of the base liquor. For example, 1-2 L of the antioxidant solution is prepared for every 100 L of the base liquor. When adding, a peristaltic pump or manual slow pouring is used, and the speed is controlled at 50-100 mL / min to ensure that the antioxidants are fully dispersed in the liquor. During the stirring process, a mechanical stirrer can be used, with a rotation speed of 100-200 rpm and a stirring time of 5-10 minutes until there is no obvious stratification or precipitation in the liquor. Experiments show that adding in the form of a solution can increase the solubility of the antioxidant by about 15-20% compared with directly adding the dry powder, reducing the risk of turbidity in the liquor body caused by local concentration differences. In addition, after stirring evenly, it can be left to stand for 1-2 hours to observe the clarity of the liquor. If there is a small amount of precipitation, it can be removed by subsequent filtration to ensure the stability of the liquor quality.

[0050] The storage condition in step S4 is to store at 10-15°C for 6-12 months, and avoid direct sunlight during storage.

[0051] Specifically, the storage conditions of 10-15°C for 6-12 months are an optimized choice based on the oxidation process and flavor maturation of semi-sweet wine. This temperature range can effectively slow down the non-enzymatic browning reaction and the volatilization of aroma substances, while maintaining the microbial stability of the liquor body. It is recommended to use a constant-temperature wine cellar or cold storage for the storage environment, equipped with a temperature and humidity control system, with the temperature fluctuation controlled within ±1°C and the relative humidity maintained at 60-80% to prevent oxygen infiltration caused by dry corks. The storage time of 6-12 months allows the antioxidants to fully play their role. Experimental data shows that when stored for 6 months, the concentration of ester aroma substances (such as ethyl octanoate) reaches the peak, and the liquor body presents complex fruity and floral aromas; after extending to 12 months, the balance of the liquor body is further improved, but some volatile compounds may decrease slightly. Avoiding direct sunlight is a key requirement. Dark glass bottles (such as green or brown) can be used for packaging, with an ultraviolet light blocking rate ≥90% to reduce free radical reactions caused by light and ensure the long-term stability of color and aroma.

[0052] The storage condition in step S4 is to store at 10-15°C for 5-7 months, and the DPPH free radical scavenging rate of the prepared low-sulfur semi-sweet wine is ≥60%, and the OD420 value is ≤0.2.

[0053] Specifically, the storage conditions are further optimized to 10 - 15°C for 5 - 7 months, aiming to balance quality improvement and production efficiency while clarifying the technical effect indicators. The storage time of 5 - 7 months is applicable to small and medium - scale production, enabling the synergistic effect of antioxidants to be achieved within a relatively short cycle and reducing inventory costs. Experimental verification shows that when stored for 5 months, the DPPH free - radical scavenging rate can reach 60 - 65%, indicating a significant enhancement in the antioxidant capacity of the wine body; after 7 months of storage, this index can be stabilized above 65%, showing a continuous antioxidant effect. The OD420 value ≤ 0.2 is an important quantitative standard for the light color of white wine. Through the protective effects of GSH and Man, this method enables the wine body to maintain a light golden yellow color, avoiding changes to amber or brownish - red, and the chromaticity stability is improved by approximately 20% compared to traditional SO2 treatment. In addition, volatile compounds can be sampled regularly during storage and analyzed for the content of esters and alcohols using headspace solid - phase microextraction - gas chromatography - mass spectrometry (HS - SPME - GC / MS) to ensure that the aroma complexity of the wine body meets the expectations.

[0054] The following is an introduction in combination with specific embodiments:

[0055] Example 1: Minimum data scheme

[0056] Process steps:

[0057] S1. Raw material selection and pre - treatment

[0058] Select 'Petit Manseng' wine - making grapes with a sugar content of 25%. After manual picking, use a stainless - steel destemmer - crusher for destemming and crushing. Then use a bladder press to press at a pressure of 0.5 bar to obtain grape juice without introducing inert gas.

[0059] S2. Fermentation and preliminary brewing

[0060] Place the grape juice in a stainless - steel fermentation tank, add Lalvin D47 wine - making yeast, control the fermentation temperature at 15°C, and ferment for 10 days until the residual sugar content reaches 12 g / L. Then terminate the fermentation by the freezing method (cooling to 0°C) to obtain the base wine.

[0061] S3. Antioxidant addition

[0062] Add an antioxidant combination to the base wine: glutathione (GSH) 5 mg / L, mannan (Man) 5 mg / L, and sulfite (SO2) 15 mg / L. Dissolve the three antioxidants in 5 - fold volume of distilled water at 20°C to make a solution, and use a peristaltic pump to add it to the base wine at a speed of 50 mL / min, and stir for 5 minutes (rotation speed 100 rpm) until homogeneous.

[0063] S4. Bottling and storage

[0064] Filter the base wine with a 0.45μm microporous membrane, fill it into green glass bottles and seal with corks. Store it in a wine cellar at a constant temperature of 10°C for 6 months, keep the humidity at 60%, and avoid direct sunlight.

[0065] Expected effects:

[0066] The DPPH free radical scavenging rate is about 60%, the OD420 value is 0.18, and the wine body is light golden yellow.

[0067] The content of ester aroma substances (such as isoamyl acetate) is increased by about 50% compared with the control group, the sensory score is 85 points, the taste is fresh, the fruit aroma is slightly single but the balance is good.

[0068] Example 2: The highest data plan

[0069] Process steps:

[0070] S1. Raw material selection and preliminary treatment

[0071] Select 'Chardonnay' wine grapes with a sugar content of 28%, manually pick them and use a stainless steel destemmer-crusher for destemming and crushing. Press them with a bladder press at a pressure of 1.5 bar, and introduce argon gas (flow rate 0.5 L / min) during the pressing process to reduce oxygen contact to obtain grape juice.

[0072] S2. Fermentation and preliminary brewing

[0073] Place the grape juice in a stainless steel fermentation tank with a cold water jacket, add EC-1118 wine yeast, control the fermentation temperature at 18°C, ferment for 20 days until the residual sugar content is 45 g / L, and terminate the fermentation by adding food-grade alcohol (to an alcohol content of 15%) to obtain the base wine.

[0074] S3. Addition of antioxidants

[0075] Add an antioxidant combination to the base wine: glutathione (GSH) 10 mg / L, mannan (Man) 10 mg / L, sulfite (SO2) 20 mg / L. Dissolve the three antioxidants in 10 times the volume of distilled water at 25°C to make a solution, and add it to the base wine with a peristaltic pump at a speed of 100 mL / min, and stir for 10 minutes (rotation speed 200 rpm) until uniform.

[0076] S4. Bottling and storage

[0077] Filter the base wine with a 0.45μm microporous membrane, fill it into brown glass bottles and seal with screw caps. Store it in a constant temperature cold storage at 15°C for 12 months, keep the humidity at 80%, and avoid direct sunlight.

[0078] Expected effects:

[0079] The DPPH free radical scavenging rate is approximately 70%, the OD420 value is 0.15, and the wine body is light golden yellow and clear.

[0080] The content of ester aroma substances (such as ethyl octanoate) is increased by approximately 80% compared with the control group, the sensory score is 90 points, the wine body is full, the aroma is complex, with rich peach and floral scents, and the taste is soft and persistent.

[0081] Example 3: Intermediate data solution

[0082] Process steps:

[0083] S1. Raw material selection and pre-treatment

[0084] Select 'Petit Manseng' wine grapes with a sugar content of 26%. After manual picking, use a stainless steel destemmer-crusher for destemming and crushing. Press with a bladder press at a pressure of 1.0 bar, and introduce nitrogen (flow rate 0.3 L / min) during the pressing process to obtain grape juice.

[0085] S2. Fermentation and primary brewing

[0086] Place the grape juice in a stainless steel fermentation tank, add Lalvin D47 wine yeast, control the fermentation temperature at 16 °C, and ferment for 15 days until the residual sugar content reaches 30 g / L. Then terminate the fermentation by the freezing method (cooling to 2 °C) to obtain the base wine.

[0087] S3. Addition of antioxidants

[0088] Add an antioxidant combination to the base wine: glutathione (GSH) 8 mg / L, mannan (Man) 8 mg / L, and sulfite (SO2) 18 mg / L. Dissolve the three antioxidants in 8 times the volume of distilled water at 22 °C to make a solution, and add it to the base wine with a peristaltic pump at a speed of 75 mL / min, and stir for 8 minutes (rotation speed 150 rpm) until uniform.

[0089] S4. Bottling and storage

[0090] Filter the base wine with a 0.45 μm microporous filter membrane, fill it into a green glass bottle and seal it with a cork, and store it in a constant temperature wine cellar at 12 °C for 9 months, keeping the humidity at 70% and avoiding direct sunlight.

[0091] Expected effects:

[0092] The DPPH free radical scavenging rate is approximately 65%, the OD420 value is 0.16, and the wine body is light golden yellow and stable.

[0093] The content of ester aroma substances (such as hexyl acetate) is increased by approximately 70% compared with the control group, the sensory score is 88 points, the wine body is balanced, the aroma presents peach, honey and slight floral scents, and the taste is refreshing and has a moderate complexity.

[0094] Example 4: Optimal Parameter Combination Scheme

[0095] Process Steps:

[0096] S1. Raw Material Selection and Pretreatment

[0097] Select 'Petit Manseng' wine grapes with a sugar content of 27%, handpick them, and use a stainless - steel destemmer - crusher for destemming and crushing. Then use a bladder press to press at a pressure of 1.2 bar, and introduce nitrogen (flow rate 0.4 L / min) during the pressing process to obtain grape juice.

[0098] S2. Fermentation and Primary Brewing

[0099] Place the grape juice in a stainless - steel fermentation tank with a cold - water jacket, add EC - 1118 wine yeast, control the fermentation temperature at 17°C, ferment for 18 days until the residual sugar content reaches 35 g / L, and then terminate the fermentation by the freezing method (cooling to 1°C) to obtain the base wine.

[0100] S3. Addition of Antioxidants

[0101] Add an antioxidant combination to the base wine: glutathione (GSH) 10 mg / L, mannan (Man) 10 mg / L, and sulfite (SO2) 18 mg / L. Dissolve the three antioxidants in 10 - fold volume of distilled water at 25°C to make a solution, and use a peristaltic pump to add it to the base wine at a speed of 80 mL / min, and stir for 10 minutes (rotation speed 180 rpm) until it is uniform.

[0102] S4. Bottling and Storage

[0103] Filter the base wine using a 0.45 - μm microporous membrane, fill it into brown glass bottles and seal them with screw caps, and store them in a constant - temperature cold storage at 14°C for 7 months, with the humidity maintained at 75% and avoiding direct sunlight.

[0104] Expected Effects:

[0105] The DPPH free - radical scavenging rate is about 68%, the OD420 value is 0.14, the wine body is light golden - yellow and has high clarity.

[0106] The content of ester aroma substances (such as isoamyl acetate and ethyl laurate) is increased by about 75% compared with the control group, the sensory score is 89 points, the wine body is full, the aroma is complex, with obvious fruity, floral and slight cinnamon aromas, and the taste is fresh and has a long aftertaste.

[0107] Table 1: Comparison Table of Different Examples with the Existing Technology

[0108]

[0109] Explanation of Table Characters

[0110] 1. DPPH radical scavenging rate (%)

[0111] Definition: The DPPH (2,2-diphenyl-1-picrylhydrazyl radical) scavenging rate is an important indicator to measure the antioxidant capacity of wine, representing the percentage of the ability of antioxidant substances in the wine sample to scavenge free radicals.

[0112] Measurement method: The spectrophotometric method is used to measure the change in absorbance after the reaction of the DPPH solution with the wine sample at a wavelength of 517 nm, and the scavenging rate is calculated.

[0113] Existing technology (about 50%): Traditional SO2 treatment (50 mg / L) relies on the antioxidant effect of SO2, but due to the lack of synergy of natural antioxidants, the scavenging rate is relatively low, only about 50%, reflecting limited antioxidant capacity.

[0114] The present invention:

[0115] Example 1 (about 60%): The lowest concentration (GSH 5 mg / L, Man 5 mg / L, SO2 15 mg / L) has been increased to 60%, indicating that even at the lower limit parameters, the synergistic effect significantly enhances the antioxidant capacity.

[0116] Example 2 (about 70%): The highest concentration (GSH 10 mg / L, Man 10 mg / L, SO2 20 mg / L) reaches 70%. Due to the high antioxidant activity of GSH and the auxiliary effect of Man, the effect is optimal.

[0117] Example 4 (about 68%): The preferred parameters (GSH 10 mg / L, Man 10 mg / L, SO2 18 mg / L) are 68%, close to the upper limit, taking into account both the effect and the cost.

[0118] 2. OD420 value (chromaticity)

[0119] Definition: The OD420 value is the absorbance of white wine at a wavelength of 420 nm, reflecting the depth of the wine body color and the degree of oxidation. The higher the value, the more serious the browning.

[0120] Measurement method: Use a spectrophotometer to measure the filtered wine sample, and the value is usually between 0.1 - 0.5.

[0121] Existing technology (0.25 - 0.30): Due to insufficient protection in traditional SO2 treatment, polyphenols are oxidized to quinones and brown polymers after storage, and the OD420 value rises to 0.25 - 0.30, and the wine body shows an amber color.

[0122] The present invention:

[0123] Example 1 (0.18): Under the lowest parameters, the OD420 value is 0.18, and the color is light golden yellow, indicating that GSH and Man effectively delay oxidation.

[0124] Example 2 (0.15): Under the highest parameters, the value is 0.15, and the color is lighter. Due to the high concentration of antioxidants, the protective effect is enhanced.

[0125] Example 4 (0.14): Under the preferred parameters, the value is 0.14, close to the best color, showing the stability of the synergistic effect.

[0126] 3. Enhancement rate of ester aroma substances (%)

[0127] Definition: The enhancement rate of ester aroma substances (such as isoamyl acetate, ethyl octanoate) is based on the control group, and measures the percentage increase in the ester content in the wine sample of the present invention, reflecting the aroma complexity.

[0128] Measurement method: Headspace solid-phase microextraction-gas chromatography mass spectrometry (HS-SPME-GC / MS) is used, and 2-octanol is used as an internal standard for quantification.

[0129] Prior art (0%): Traditional SO2 treatment is used as a control benchmark. Since SO2 may combine with terpenes, the ester content does not increase significantly.

[0130] The present invention:

[0131] Example 1 (about 50%): It increases by 50% under the lowest parameters, and the initial effect of Man promoting ester formation is shown.

[0132] Example 2 (about 80%): It increases by 80% under the highest parameters, and the synergistic effect of Man and GSH maximizes the retention and formation of esters.

[0133] Example 4 (about 75%): It increases by 75% under the preferred parameters, close to the upper limit, with rich and balanced aroma.

[0134] 4. Sensory score (full score 100 points)

[0135] Definition: The sensory score is comprehensively evaluated by a professional tasting panel based on vision (20 points), smell (30 points) and taste (50 points), reflecting the overall quality of the wine.

[0136] Evaluation method: Refer to the national standard GB15038-2006, and a 10-person panel scores and takes the average value.

[0137] Prior art (80 - 82): Traditional SO2 treatment has a lower score of 80 - 82 due to oxidation resulting in caramel flavor and acidity imbalance.

[0138] The present invention:

[0139] Example 1 (85): It scores 85 points under the lowest parameters, with improved color and taste, and a slightly simple aroma.

[0140] Example 2 (90): It scores 90 points under the highest parameters, with a full-bodied wine, complex aroma, and the best quality.

[0141] Example 4 (89): It scores 89 points under the preferred parameters, is close to the best, and has outstanding balance.

[0142] 5. SO2 content (mg / L)

[0143] Definition: The SO2 content refers to the total amount of free and bound sulfites, measured in mg / L, and is a core indicator of low sulfuration.

[0144] Measurement method: Determined by iodometric titration or high performance liquid chromatography.

[0145] Prior art (50): The traditional process uses 50 mg / L SO2, exceeding the health and safety threshold (WHO recommends warning when < 10 mg / L).

[0146] The present invention:

[0147] Example 1 (15): The lowest is 15 mg / L, a reduction of 70%, with a significant low-sulfur effect.

[0148] Example 2 (20): The highest is 20 mg / L, still 60% lower than the traditional value.

[0149] Example 4 (18): The preferred is 18 mg / L, balancing low sulfur and stability.

[0150] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made therein without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An antioxidant method for low-sulfur semi-sweet wine, characterized in that, Including the following steps: S1. Select wine grapes, remove the stems, crush and press them to obtain grape juice; S2. Conduct alcoholic fermentation on the grape juice, and terminate the fermentation when the residual sugar content reaches 12 - 45 g / L to obtain base wine; S3. Add an antioxidant combination to the base wine, where the antioxidant combination includes glutathione 5 - 10 mg / L, mannan 5 - 10 mg / L, and sulfite 15 - 20 mg / L, and mix evenly; S4. Filter the base wine added with antioxidants, bottle it and store it to obtain low - sulfur semi - sweet wine.

2. The antioxidant method of the low-sulfur semi-sweet wine according to claim 1, wherein In step S1, the sugar content of the wine grapes is ≥25%; 3. The antioxidant method for low-sulfur semi-sweet wine according to claim 1, wherein In step S1, the wine grapes are of the 'Petit Manseng' variety; 4. The antioxidant method for low-sulfur semi-sweet wine according to claim 1, wherein In step S1, an inert gas is introduced during the pressing process, and the inert gas is selected from nitrogen or argon to reduce the contact between the grape juice and oxygen; 5. The antioxidant method for low-sulfur semi-sweet wine according to claim 1, wherein, In step S2, the temperature of the alcoholic fermentation is 15 - 18 °C, and Saccharomyces cerevisiae is used for fermentation; 6. The antioxidant method for low-sulfur semi-sweet wine according to claim 1, characterized in that, In step S2, the temperature of the alcoholic fermentation is 15 - 18 °C, and the fermentation is terminated when the residual sugar content reaches 25 - 35 g / L; 7. The antioxidant method for low-sulfur semi-sweet wine according to claim 1, wherein In step S3, the specific addition amounts of the antioxidant combination are: glutathione 8 - 10 mg / L, mannan 8 - 10 mg / L, and sulfite 18 - 20 mg / L; 8. The antioxidant method for low-sulfur semi-sweet wine according to claim 1, characterized in that, In step S3, the antioxidant combination is added to the base wine in the form of a solution and mixed evenly by stirring; 9. The antioxidant method for low-sulfur semi-sweet wine according to claim 1, characterized in that In step S4, the storage conditions are storing at 10 - 15 °C for 6 - 12 months, and avoiding direct sunlight during storage; 10. The antioxidant method for low-sulfur semi-sweet wine according to claim 1, characterized in that, In step S4, the storage conditions are storing at 10 - 15 °C for 5 - 7 months, and the DPPH free - radical scavenging rate of the obtained low - sulfur semi - sweet wine is ≥60%, and the OD420 value is ≤0.2.

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