Brewing method for producing black rice wine by anthocyanin extraction and reduction process

Abstract

The invention relates to the technical field of wine brewing, in particular to a brewing method for producing black rice wine by an anthocyanin extraction and reduction process, which comprises the following steps of: adding edible grade sulfurous acid or potassium metabisulfite and condensed tannin into raw black rice wine which meets specific quality indexes and is used as a solvent to prepare an extraction solvent; the method comprises the following steps: carrying out negative pressure extraction on black rice under specific conditions, freezing to remove fat, and carrying out multi-stage filtration to obtain a high-cleanliness anthocyanin extracting solution; the black rice subjected to anthocyanin extraction is subjected to wall breaking and crushing, liquid cooking and gelatinization, liquefaction, saccharification, pure fermentation, squeezing, wine decoction and other procedures to prepare raw wine, and finally an anthocyanin extracting solution is added in proportion in the wine storage link to complete reduction. The problems of high loss rate of anthocyanin in the black rice, difficulty in cooking and gelatinization, low wine yield and the like in the traditional process are solved, the utilization rate of the anthocyanin reaches 85% or above, the wine yield is increased by 3%-5%, energy and water resources are saved, sewage discharge is reduced, the color, the nutrition and the taste of the black rice wine are improved, and automatic development of the industry is promoted.

Description

Technical Field

[0001] This invention relates to the field of brewing technology, specifically a brewing method for producing black rice wine using an anthocyanin extraction and reduction process. Background Technology

[0002] Black rice, also known as black millet, is a grain crop with both nutritional value and health benefits. It is widely used in food processing, especially in the brewing industry. Black rice wine, made from black rice, is highly favored by consumers due to its rich nutritional content. Black rice contains abundant anthocyanins, protein, fat, fiber, and minerals such as potassium, magnesium, zinc, selenium, and manganese. Anthocyanins, as a natural pigment, not only give black rice wine its unique purplish-red color but also possess strong antioxidant and free radical scavenging activities, which are beneficial to human health. Therefore, black rice is also known as the "King of Grains."

[0003] In the traditional production process of black glutinous rice wine, black glutinous rice is typically used as the raw material, and the wine is brewed through a series of processes including soaking, steaming and gelatinizing, liquefaction, saccharification, fermentation, pressing, storage, filtration, and bottling. However, this traditional process has many technical challenges that seriously affect the quality and production efficiency of black glutinous rice wine. First, the loss of anthocyanins is extremely prominent. Anthocyanins in black glutinous rice are easily soluble in water. During the soaking process, a large amount of anthocyanins dissolves into the soaking water and is lost with the discharge of the soaking water. In the subsequent steaming and cooking process, the high temperature environment causes the anthocyanins to degrade rapidly, destroying their structure and causing them to lose their original color and activity. In addition, during the fermentation process, the growth and reproduction of microorganisms will engulf and metabolize the anthocyanins, further aggravating the loss of anthocyanins. Statistics show that the loss of anthocyanins in black rice during traditional processing is as high as 80%. This not only significantly reduces the sensory color of black rice wine, causing it to lose its unique purplish-red hue, but also leads to a sharp reduction in the content of nutrients such as anthocyanins, flavonoids, and polyphenols in the wine, greatly diminishing its functionality and making it difficult to meet consumers' demand for healthy beverages.

[0004] Secondly, black rice is difficult to gelatinize during cooking. The seed coat of black rice has a hard, dense fibrous layer that tightly wraps around the internal endosperm (starch layer). During the steaming process, steam struggles to penetrate the hard seed coat fiber layer to reach the endosperm, resulting in insufficient gelatinization of the endosperm and leading to a series of problems: First, the rate of undercooked rice is high, with some black rice failing to gelatinize completely, resulting in undercooked rice. Second, the steaming time is long; to maximize endosperm gelatinization, the steaming time must be extended, reducing production efficiency. Third, the cooked rice is prone to re-gelatinization; even if it temporarily gelatinizes after steaming, it easily hardens again during cooling, affecting subsequent liquefaction and saccharification processes. Fourth, acid production is likely during fermentation; insufficiently gelatinized starch is difficult for microorganisms to decompose and utilize, instead providing conditions for the growth and reproduction of miscellaneous bacteria, leading to increased acidity in the mash and decreased quality of the liquor. Fifth, the alcohol yield is low; insufficient starch gelatinization prevents it from being fully converted into fermentable sugars, thus affecting alcohol production and reducing the alcohol yield. Sixth, energy consumption increases; the long steaming process requires a large amount of energy, increasing production costs.

[0005] In addition, traditional processes also suffer from problems such as water waste, large wastewater discharge, and long production cycles. During the soaking stage, black rice typically needs to be soaked for over 48 hours to ensure full water absorption, consuming a large amount of water and generating substantial amounts of soaking wastewater. This wastewater contains many nutrients, and direct discharge not only pollutes the environment but also wastes resources. During fermentation, because the starch in black rice is encased in the seed coat, enzymes cannot fully function, resulting in low saccharification and fermentation conversion rates, insufficient subsequent sugar supply to yeast, slow yeast proliferation, shortened yeast mortality period, and increased mortality. This easily leads to fermentation stagnation and rancidity of the fermented mash, prolonging the fermentation cycle and increasing production risks. Furthermore, undigested starch and other substances can clog pipes during mash transportation, hindering smooth production.

[0006] In summary, traditional black glutinous rice wine production processes suffer from numerous problems, including high anthocyanin loss, difficulty in gelatinization during cooking, low alcohol yield, high energy consumption, severe water waste, and long production cycles. These issues seriously hinder the development of the black glutinous rice wine industry. Therefore, there is an urgent need for a new black glutinous rice wine brewing method that can solve these problems, thereby improving the quality and production efficiency of black glutinous rice wine and promoting the sustainable development of the black glutinous rice wine industry. Summary of the Invention

[0007] This invention aims to solve the technical problems existing in the traditional black glutinous rice wine brewing process, such as high anthocyanin loss rate, difficulty in gelatinizing black glutinous rice during cooking, low alcohol yield, high energy consumption, serious water waste, and long production cycle. It provides a brewing method for producing black glutinous rice wine using an anthocyanin extraction and reduction process, so as to improve the utilization rate of anthocyanins in black glutinous rice, improve the color and nutritional quality of black glutinous rice wine, increase the alcohol yield, shorten the production cycle, reduce energy and water consumption, and reduce wastewater discharge.

[0008] The technical solution adopted by this invention to solve its technical problem is: a brewing method for producing black rice wine using anthocyanin extraction and reduction process, comprising the following steps: (1) Preparation of black rice anthocyanin extract: ① The black rice wine with an alcohol content of 15% vol-16% vol, total acid (calculated as lactic acid) of 4.5 g / L-6.5 g / L, total sugar (calculated as glucose) ≤15.0 g / L, pH 3.2-4.6, non-sugar solids ≥7.0 g / L, amino acid nitrogen ≥0.1 g / L, calcium oxide ≤0.5 g / L, lead (calculated as Pb) ≤0.15 mg / kg, benzoic acid ≤0.05 g / kg, and no detectable Salmonella and Staphylococcus aureus was selected as the extraction solvent; ② Add food-grade sulfurous acid or potassium metabisulfite to the original wine, stir, and control the total SO2 content to 150mg-180mg / L and the free SO2 content to 40mg / L-100mg / L. Then add 150mg / L-200mg / L of food-grade condensed tannins and dissolve them. ③ After washing and draining the black rice, put it into the extraction tank, add the prepared extraction solvent at a ratio of 1:2-1:2.5 (m:v), seal the tank, and replace the air with 99.9% food-grade nitrogen at a pressure of 0.01-0.02 MPa for 5-10 minutes. ④ Turn on the negative pressure pump to bring the pressure inside the tank to -0.05 to -0.08 MPa, heat to 45℃-55℃, and extract under constant temperature and negative pressure for 1-1.5 hours; ⑤ The extract is transferred to a cooling tank and cooled to below 30°C with 4-10°C chilled water. The coarse filtrate is obtained by filtering through 5-10μm paperboard. ⑥ The coarse filtrate is cooled to -3℃ to -5℃ in three stages, frozen and kept warm for 6-7 days, the oil layer is removed, and then filtered through 0.8-1.0μm paperboard to obtain anthocyanin extract; (2) Fermentation of black rice wine: ① After extracting anthocyanins, black rice is ground with water to a fineness of 1-2 mm using a cell wall breaking mill. It is then added to a saccharification tank at a material-to-water ratio of 1:2.0-1:2.5 (m:v), α-amylase is added, and the mixture is heated to above 95℃ and kept warm for 30 minutes. The temperature is then lowered to 58℃-62℃, saccharifying enzyme is added, and the mixture is kept warm for 30 minutes. Finally, the temperature is lowered to below 30℃. ②Pour the saccharified liquid into the fermentation tank, add slurry water, black rice-domesticated yeast and pure yeast, ferment at 25℃-28℃, start stirring after 8-12 hours, then stir every 3-4 hours, control the temperature ≤30℃, stir in the morning and evening after 72 hours until the mash is clear; (3) Anthocyanin reduction: After fermentation, the wine is pressed, heated and stored. Anthocyanin extract is added in proportion during storage.

[0009] Specifically, in step (1) ③, the black rice is rinsed with running water until the rinsing water is clear and free of impurities.

[0010] Specifically, in step (1) ④, the heating is carried out by steam heating in the jacket of the extraction tank, and the extraction circulation pump is turned on during the heating process to make the extract flow in circulation.

[0011] Specifically, in step (2) ①, the amount of α-amylase added is 0.1%-0.3% of the mass of black rice, and the amount of saccharifying enzyme added is 0.2%-0.4% of the mass of black rice.

[0012] Specifically, in step (2) ②, the amount of black rice domestication yeast added is 0.5%-1.0% of the saccharification liquid volume, and the amount of pure yeast added is 0.3%-0.6% of the black rice mass.

[0013] Specifically, in step (3), the proportion of anthocyanin extract added is 5%-10% of the volume of the original wine.

[0014] Specifically, in step (1) ⑥, the freezing and heat preservation process uses a constant temperature freezing tank with a temperature fluctuation range of ±0.5℃.

[0015] Specifically, in step (2) ②, the fermentation tank is made of stainless steel, and the fermentation tank is sterilized at high temperature before fermentation, with a sterilization temperature of 121℃ and a time of 30 minutes.

[0016] Specifically, in step (3), the temperature of the wine is controlled at 85℃-90℃ for 20-30 minutes, the temperature of the wine is controlled at 15℃-20℃, and the storage time is 3-6 months.

[0017] Specifically, in step (1)①, the black rice wine is made from black rice that has been traditionally fermented, pressed, filtered, and aged for more than 3 months.

[0018] The beneficial effects of this invention are: (1) Significantly improve the utilization rate of anthocyanins: This invention effectively solves the problem of anthocyanin loss during soaking, cooking and fermentation in traditional processes by first extracting anthocyanins from black rice and then adding the anthocyanin extract back to the original wine during the wine storage process. This makes the utilization rate of anthocyanins from black rice reach more than 85%, significantly improving the color and nutritional quality of black rice wine, maintaining its beautiful purplish-red hue, and being rich in nutrients such as anthocyanins, flavonoids and polyphenols.

[0019] (2) Solving the problem of gelatinization during cooking: The black rice after anthocyanin extraction is ground using a cell wall breaking grinding equipment, which breaks down the hard seed coat fiber layer and releases the endosperm. Combined with the liquid cooking gelatinization process, the black rice starch can be fully gelatinized, effectively reducing the raw rice rate and shortening the cooking gelatinization time. Compared with the traditional process, the cooking gelatinization time is shortened by 10-15 minutes, while saving energy. According to statistics, 0.1-0.2 tons of coal can be saved per ton of wine.

[0020] (3) Improve alcohol yield and production efficiency: The combination of cell wall breaking grinding and liquid gelatinization process enables starch to be fully decomposed and utilized by enzyme preparations, which improves the saccharification and fermentation conversion rate. In addition, the use of black rice domesticated yeast and pure yeast provides sufficient nutrition for yeast growth and reproduction, promotes yeast proliferation, prolongs yeast life, and thus improves alcohol yield. The alcohol yield is 3%-5% higher than that of traditional process. At the same time, the fermentation cycle is also greatly shortened, 20-24 hours shorter than that of traditional process, which improves production efficiency and reduces production risk.

[0021] (4) Saving resources and reducing pollution: This invention eliminates the 48-hour soaking process in the traditional process, saving 3-6 tons of water per ton of wine and reducing sewage discharge by 2-5 tons. It not only saves water resources but also reduces sewage treatment costs and reduces environmental pollution.

[0022] (5) Improve the quality of wine and promote the development of the industry: The process of this invention has the least impact on the aroma, taste and stability of black rice wine, and can preserve the fresh original flavor and natural substances of the product to the greatest extent, so that black rice wine forms the product characteristics of "fresh, refreshing, clean and elegant", thus improving the quality of wine. In addition, the process is easy to realize mechanized and automated operation, improves the level of mechanization and automation in the industry, and promotes the technological upgrading and sustainable development of the black rice wine industry. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] Figure 1 The flowchart provided by this invention describes a brewing method for producing black rice wine using an anthocyanin extraction and reduction process. Detailed Implementation

[0025] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0026] like Figure 1 As shown, the brewing method for producing black rice wine using an anthocyanin extraction and reduction process according to the present invention includes three steps: preparation of black rice anthocyanin extract, fermentation of black rice wine, and anthocyanin reduction, as detailed below: (1) Preparation of anthocyanin extract from black rice ① Extraction Solvent Selection: Black rice wine meeting specific quality indicators was selected as the extraction solvent. The alcohol content of this wine was 15% vol-16% vol, total acid (calculated as lactic acid) was 4.5 g / L-6.5 g / L, total sugar (calculated as glucose) ≤15.0 g / L, pH value was 3.2-4.6, non-sugar solids ≥7.0 g / L, amino acid nitrogen ≥0.1 g / L, calcium oxide ≤0.5 g / L, lead (calculated as Pb) ≤0.15 mg / kg, benzoic acid ≤0.05 g / kg, and Salmonella and Staphylococcus aureus were not detectable. Using black rice wine as the extraction solvent, the alcohol content increased the extraction rate of anthocyanins, and the acidity of the wine helped adjust the pH value, resulting in a beautiful purplish-red hue for the anthocyanins.

[0027] ② Preparation of extraction solvent: First, add food-grade sulfurous acid or potassium metabisulfite to the above-mentioned black rice wine, stir thoroughly and then test to ensure that the total SO2 content in the wine is controlled between 150mg-180mg / L and the free SO2 content is controlled between 40mg / L-100mg / L. The addition of sulfurous acid or potassium metabisulfite can effectively prevent anthocyanins from being oxidized during the extraction process. Next, add food-grade condensed tannin to the wine, with the dosage controlled between 150mg / L-200mg / L, and stir until the condensed tannin is fully dissolved in the wine. The condensed tannin can form a non-covalent complex with anthocyanins through intermolecular interactions. Under acidic conditions, the positively charged anthocyanins and the negatively charged regions of the tannins are electrostatically attracted, thereby stabilizing the anthocyanin chromophore, delaying the degradation of anthocyanins and enhancing the color of the black rice wine.

[0028] ③ Extraction Operation: First, place the black rice into the extraction tank and wash it with running water until the water is clear and free of impurities to remove ash and impurities. After washing, drain the surface water of the black rice and close the bottom valve of the extraction tank. Second, add the prepared fermented wine to the extraction tank according to a black rice to extraction solvent ratio of 1:2-1:2.5 (m:v), ensuring the black rice is completely soaked in the extraction solvent. Simultaneously, monitor the pH value of the extraction system and control it between 3.8 and 4.8. Third, tighten the extraction tank lid valve to ensure the extraction tank is sealed. Open the nitrogen-oxygen replacement valve and introduce 99.9% food-grade nitrogen into the extraction tank to displace the air in the headspace above the extraction tank. To prevent anthocyanins from being oxidized during extraction, the pressure inside the extraction tank is controlled at 0.01-0.02 MPa during nitrogen purging, and the purging time is 5-10 minutes. After purging, the nitrogen-oxygen purging valve is closed. The fourth step involves turning on the extraction circulation pump to circulate the raw liquor within the extraction tank. Simultaneously, the raw liquor is evenly sprayed onto the surface of the black rice through a rotating nozzle at the top of the tank. This continuous circulation of the extract increases the contact area between the extract and the black rice material, thereby improving the anthocyanin extraction efficiency. The fifth step involves turning on the negative pressure pump to create a negative pressure environment inside the extraction tank. When the pressure inside the tank reaches -0.05 MPa to -0.08 MPa, the jacketed steam in the extraction tank is activated to heat the material inside. Step 6: Control the heating temperature of the material in the tank between 45℃ and 55℃, and perform constant temperature negative pressure extraction at this temperature for 1-1.5 hours. After extraction, turn off the steam valve, negative pressure pump, and circulation pump in sequence. Step 7: After the pressure in the extraction tank drops to atmospheric pressure, open the extract collection valve at the bottom of the extraction tank to transfer the black rice anthocyanin extract into the cooling tank. Quickly turn on the stirring device in the cooling tank and introduce 4-10℃ chilled water into the jacket of the cooling tank. Use the Miller plate in the jacket of the tank for cooling. When the temperature of the extract drops below 30℃, turn off the stirring device and the cooling chilled water. Step 8: Connect the cooled extract to the filter through a pipeline and use a 5-10μm paperboard filter to filter the extract. The liquid is filtered to remove some impurities, yielding a coarse filtrate of black rice anthocyanin extract. In the ninth step, the coarse filtrate is sent to a freezer for three-stage cooling, lowering the temperature to -3℃ to -5℃. The cooled coarse filtrate is then transferred to an insulated tank and kept frozen for 6-7 days. During this freezing process, the temperature fluctuation range of the insulated tank is controlled within ±0.5℃. During this process, a solidified oil layer (mainly composed of germ oil) forms on the surface of the extract. This oil layer is removed using a filter screen, achieving degreasing. In the tenth step, the low-temperature insulation process also promotes the aggregation and sedimentation of large molecules in the extract, forming an aggregate layer. The side valve at the bottom of the insulated tank is opened, and the extract is passed through a 0.8-1...The extract is then filtered again using a 0μm paperboard filter to further remove impurities. The filtered filtrate is then bottled for later use. In the eleventh step, sensory and color value tests are performed on the filtered extract. Sensoryly, the extract is a purplish-red liquid, and the color value test result must be ≥15 (E1%1cm535nm). This completes the preparation of the black rice anthocyanin extract.

[0029] (2) Fermentation of black rice wine ① Pretreatment and Saccharification: First, after anthocyanin extraction, remove the black rice from the extraction tank, add an appropriate amount of water, and then put it into a cell-wall breaking and grinding device for grinding. During grinding, control the fineness of the material to 1-2mm. Cell-wall breaking grinding can break down the hard seed coat fiber layer of the black rice, releasing the internal endosperm (starch layer), which facilitates subsequent gelatinization and saccharification. Second, add the ground black rice material with an appropriate amount of slurry to the saccharification tank, controlling the material-to-water ratio between 1:2.0 and 1:2.5 (m:v). Third, add α-amylase to the saccharification tank at a rate of 0.1%-0.3% of the black rice mass, turn on the stirring device in the saccharification tank, and open... The steam valve of the heating coil heats the material until the temperature reaches above 95℃. This temperature is maintained for 30 minutes to allow the starch in the black rice to fully gelatinize and undergo initial liquefaction. Next, the steam valve is closed, and the cooling water in the jacket of the saccharification tank is turned on to rapidly lower the material temperature to 58℃-62℃. Saccharifying enzyme is added to the saccharification tank at a rate of 0.2%-0.4% of the black rice's mass. This temperature is maintained for 30 minutes to further saccharify the liquefied starch into fermentable sugars. Finally, after saccharification, the material temperature is rapidly lowered to below 30℃ using the jacketed cooling water to complete the gelatinization, liquefaction, and saccharification process of the black rice, yielding a black rice saccharification liquid.

[0030] ② Fermentation process: First, the black rice saccharification liquid, cooled to below 30℃ in the insulated container, is piped to the fermentation tank, and an appropriate amount of slurry water is added according to the fermentation requirements. Second, black rice-based yeast and pure yeast starter are added to the fermentation tank, with the amount of black rice-based yeast added being 0.5%-1.0% of the volume of the saccharification liquid, and the amount of pure yeast starter added being 0.3%-0.6% of the mass of the black rice. Third, the temperature in the fermentation tank is controlled at 25℃-28℃ for fermentation. The first stirring is performed 8-12 hours after the start of fermentation, and then stirring is performed every 3-4 hours. During stirring, the temperature of the mash is closely monitored to ensure that the temperature is controlled below 30℃ to prevent the yeast from becoming inactive due to excessive temperature. Fourth, after 72 hours of fermentation, the stirring frequency is adjusted to once in the morning and once in the evening, and stirring is continued until the mash becomes clear, at which point fermentation is complete. It should be noted that the fermentation tank is made of stainless steel and must be sterilized at high temperature before fermentation. The sterilization temperature is 121℃ and the sterilization time is 30 minutes to prevent contamination by other microorganisms and ensure the smooth progress of fermentation.

[0031] (3) Anthocyanin reduction After fermentation, the fermented mash is pressed to separate the wine from the lees. The pressed wine is then heated at 85℃-90℃ for 20-30 minutes to kill microorganisms, prevent spoilage, and promote clarification. After heating, the wine is transferred to storage tanks at 15℃-20℃ for 3-6 months to further age and mature. During storage, 5%-10% of the original wine volume is added to the prepared black rice anthocyanin extract and stirred thoroughly to restore the anthocyanins to the black rice wine, maximizing the retention of anthocyanins in the black rice wine.

[0032] Example 1

[0033] This embodiment provides a brewing method for producing black rice wine using anthocyanin extraction and reduction technology. The specific steps are as follows: (1) Preparation of anthocyanin extract from black rice ① Selection of extraction solvent: The raw wine of black rice that has been traditionally fermented, pressed, filtered and aged for more than 3 months was selected as the extraction solvent. The quality of the raw wine was tested and the results are as follows: alcohol content 15% vol, total acid (calculated as lactic acid) 4.5 g / L, total sugar (calculated as glucose) 12.0 g / L, pH value 3.2, non-sugar solids 7.0 g / L, amino acid nitrogen 0.1 g / L, calcium oxide 0.3 g / L, lead (calculated as Pb) 0.1 mg / kg, benzoic acid 0.03 g / L, and Salmonella and Staphylococcus aureus were not detected, which meets the quality requirements of the extraction solvent.

[0034] ② Preparation of extraction solvent: Take 1000L of the black rice wine that meets the requirements, add food-grade potassium metabisulfite while stirring at 100r / min for 30 minutes. After stirring, use a sulfur dioxide detector to detect the total SO2 and free SO2 content in the wine. The results show that the total SO2 content is 150mg / L and the free SO2 content is 40mg / L, which meets the requirements. Then add 150g of food-grade condensed tannin to the wine and continue stirring at 100r / min for 20 minutes until the condensed tannin is completely dissolved to obtain the extraction solvent.

[0035] ③ Extraction Operation: First, select 500 kg of high-quality black rice and put it into the extraction tank. Open the water inlet valve at the top of the extraction tank and wash the black rice with running water. Observe the clarity of the rinsing water during the washing process. When the rinsing water becomes clear and free of impurities, close the water inlet valve and open the drain valve at the bottom of the extraction tank to drain the water from the surface of the black rice. Then close the drain valve. Second, add 1000 L of the prepared extraction solvent to the extraction tank according to the black rice to extraction solvent ratio of 1:2 (m:v), ensuring that the black rice is completely immersed in the extraction solvent. Use a pH meter to test the pH value of the extraction system. The test result is 3.8, which meets the requirements. Third, tighten the valve of the extraction tank lid and close the... Close all valves connecting to the outside environment, open the nitrogen-oxygen replacement valve, and introduce 99.9% food-grade nitrogen into the extraction tank at a rate of 50 L / min. Simultaneously monitor the pressure inside the extraction tank. When the pressure reaches 0.01 MPa, maintain this pressure and continue introducing nitrogen for 5 minutes to fully displace the air above the extraction tank. After replacement, close the nitrogen-oxygen replacement valve. Fourth, turn on the extraction circulation pump to circulate the extract within the extraction tank at a flow rate of 200 L / h. Simultaneously, activate the rotating nozzle at the top of the tank to evenly spray the extract onto the surface of the black rice. Fifth, turn on the negative pressure pump to slowly reduce the pressure inside the extraction tank. When the pressure reaches -0.05 MPa, maintain the negative pressure state. Open the steam valve in the extraction tank jacket, maintaining the steam pressure at 0.2 MPa to heat the material inside. Closely monitor the material temperature during heating. When the temperature reaches 45℃, adjust the steam valve to maintain the material temperature at 45℃ for constant temperature negative pressure extraction for 1.5 hours. Sixth, after extraction, first close the steam valve, then turn off the negative pressure pump after 5 minutes. Once the pressure inside the extraction tank returns to normal, turn off the circulation pump and open the extract collection valve at the bottom of the extraction tank to transfer the black rice anthocyanin extract into the cooling tank. Quickly turn on the stirring device in the cooling tank at a stirring speed of 80 r / min. Introduce 4℃ chilled water into the cooling tank jacket at a flow rate of 150 L / h. The extract was cooled using a Miller plate sandwiched between tank layers. The temperature of the extract was checked every 10 minutes. When the temperature dropped below 30°C, the stirring device and cooling water were turned off. In the seventh step, the cooled extract was connected to a 5μm paperboard filter through a pipe. The filtration pressure was controlled at 0.1 MPa, and the filtration rate was 100 L / h. The extract was filtered to obtain a coarse filtrate of black rice anthocyanins. In the eighth step, the coarse anthocyanin filtrate was sent to a refrigeration unit for three-stage cooling: the first stage to 10°C, the second stage to 0°C, and the third stage to -3°C. The cooled coarse filtrate was then pumped into an insulated tank, which was placed in a constant-temperature freezer. The temperature of the freezer was controlled at -3°C, with a temperature fluctuation range of ±0°C.The extract was frozen at 5℃ for 6 days. During this period, the liquid level was observed daily. Once a solidified oil layer formed, it was removed using a 100-mesh filter. In the ninth step, after the freezing period, the side valve at the bottom of the insulated tank was opened, and the extract was filtered through a 0.8μm cardboard filter at a pressure of 0.12 MPa and a filtration rate of 80 L / h. The filtered liquid was then transferred to a clean storage tank for later use. In the tenth step, sensory and color value tests were performed on the filtered extract. Sensory testing showed the extract to be a purplish-red liquid with no odor. Color value testing was conducted using a UV-Vis spectrophotometer at 535nm wavelength, with a 1cm cuvette and a 1% concentration of the extract. The result was 15 (E1%1cm535nm), meeting the requirements. The preparation of the black rice anthocyanin extract was thus completed.

[0036] (2) Fermentation of black rice wine ① Pretreatment and Saccharification: First, after anthocyanin extraction, 480 kg of black rice was removed from the extraction tank and weighed. 960 kg of water was added, and the mixture was then ground in a cell-wall breaking and grinding equipment at 3000 rpm for 30 minutes. After grinding, a laser particle size analyzer was used to check the fineness of the material, which was 2 mm, meeting the requirements. Second, the ground black rice and slurry were added to the saccharification tank. The total mass of the material was 1440 kg, including 480 kg of black rice and 960 kg of water, with a material-to-water ratio of 1:2.0 (m:v). Third, 0.48 kg of α-amylase (0.1% of the black rice mass) was added to the saccharification tank, and the stirring device inside the saccharification tank was turned on. At a speed of 120 r / min, open the steam valve of the heating coil, with a steam pressure of 0.3 MPa, to heat the material. Check the material temperature every 5 minutes. When the temperature rises to 95℃, adjust the steam valve to maintain the material temperature above 95℃ for 30 minutes. After the heat preservation is completed, close the steam valve and turn on the cooling water in the jacket of the saccharification tank. The cooling water temperature is 20℃ and the flow rate is 200 L / h to quickly lower the material temperature. When the temperature drops to 58℃, add 0.96 kg of saccharifying enzyme (0.2% of the mass of black rice) to the saccharification tank, maintain the stirring speed at 120 r / min, and keep it at 58℃ for 30 minutes. After the heat preservation is completed, continue to flow cooling water to quickly lower the material temperature to below 30℃, obtaining the black rice saccharification liquid.

[0037] ② Fermentation Process: First, the black rice saccharification liquid is piped to a sterilized stainless steel fermentation tank with a volume of 3000L. Before transport, the fermentation tank is sterilized at 121℃ for 30 minutes and cooled to below 30℃. 560L of slurry is added to the fermentation tank, bringing the total volume to 2000L. Second, 10L of black rice-based yeast (0.5% of the saccharification liquid volume) and 1.44kg of pure yeast starter (0.3% of the black rice mass) are added to the fermentation tank, and the fermentation tank inlet is closed. Third, the temperature control system of the fermentation tank is activated, and the fermentation process begins. The temperature inside the fermentation tank is controlled at 25℃ for fermentation. After 8 hours of fermentation, the stirring device of the fermentation tank is turned on for the first stirring, which lasts for 10 minutes at a speed of 50 r / min. After that, stirring is done once every 4 hours for 10 minutes each time. During the stirring process, a temperature sensor is used to monitor the temperature of the mash to ensure that the temperature of the mash does not exceed 30℃. In the fourth step, after 72 hours of fermentation, the stirring frequency is adjusted to once in the morning and once in the evening, and stirring is continued. The state of the mash is observed every day. When the mash becomes clear, the bubbles produced during fermentation are significantly reduced, the dregs sink, and the mash gradually becomes clear, the fermentation is considered complete.

[0038] (3) Anthocyanin reduction After fermentation, the fermented mash is pressed through a plate and frame filter press at a pressure of 0.2 MPa to separate the wine from the lees, yielding approximately 1800L of raw wine. The raw wine is then heated by pumping it into a heating apparatus at 85°C for 20 minutes, with continuous stirring (circulating stirring) to control the temperature and prevent overheating. After heating, the raw wine is cooled to below 20°C and transferred to a storage tank at 15°C for 3 months. In the first month of storage, 90L of prepared black rice anthocyanin extract is added to the 1800L of raw wine at a ratio of 5% of the raw wine volume. The stirring device in the storage tank is then turned on at 30 rpm for 30 minutes to ensure thorough mixing of the anthocyanin extract and the raw wine. Storage continues for another 3 months, completing the brewing of black rice wine.

[0039] The black rice wine brewed in this embodiment was subjected to quality testing, and the test results are as follows: alcohol content 14% vol, total acid (calculated as lactic acid) 5.0 g / L, total sugar (calculated as glucose) 8.0 g / L, pH value 3.5, anthocyanin content 250 mg / L, sensory color is purplish-red, clear and transparent, aroma is pure, taste is refreshing, which meets the high-quality standards of black rice wine.

[0040] Example 2

[0041] This embodiment provides a brewing method for producing black rice wine using anthocyanin extraction and reduction technology. The specific steps are as follows: (1) Preparation of anthocyanin extract from black rice ① Extraction solvent selection: The raw wine of black rice that has been traditionally fermented, pressed, filtered, and aged for more than 4 months was selected as the extraction solvent. The quality test results were as follows: alcohol content 15.5% vol, total acid (calculated as lactic acid) 5.0 g / L, total sugar (calculated as glucose) 10.0 g / L, pH value 3.8, non-sugar solids 7.5 g / L, amino acid nitrogen 0.12 g / L, calcium oxide 0.4 g / L, lead (calculated as Pb) 0.08 mg / kg, benzoic acid 0.02 g / L, Salmonella and Staphylococcus aureus were not detected, which met the requirements of the extraction solvent.

[0042] ② Preparation of extraction solvent: Take 1200L of the above raw wine, add food-grade sulfurous acid, stir at 110r / min for 25 minutes, and the total SO2 is 160mg / L and the free SO2 is 60mg / L; then add 180g of food-grade condensed tannin, stir for 18 minutes until dissolved, and the extraction solvent is obtained.

[0043] ③ Extraction Procedure: First, place 600 kg of black rice into the extraction tank, rinse with running water until the rinse water is clear, drain, and close the bottom valve. Second, add 1320 L of extraction solvent at a ratio of 1:2.2 (m:v), and check the pH to 4.2. Third, seal the extraction tank, purge with 99.9% nitrogen at a rate of 60 L / min and a pressure of 0.015 MPa for 8 minutes. Fourth, turn on the circulation pump (flow rate 220 L / h) and spray the black rice. Fifth, turn on the negative pressure pump to -0.06 MPa, purge with 0.22 MPa steam for heating, control the temperature at 50℃, and extract under constant temperature and negative pressure for 1.2 hours. Step 6: Stop the steam and negative pressure pump, transfer the extract to a cooling tank after atmospheric pressure, start stirring (90 r / min), and pass 6℃ chilled water (180 L / h) to cool to 28℃; Step 7: Filter through 5-10 μm paperboard (pressure 0.11 MPa, speed 110 L / h) to obtain coarse filtrate; Step 8: Cool to -4℃ in three stages, freeze and incubate for 6.5 days (storage temperature -4℃ ± 0.5℃), and remove the oil; Step 9: Filter through 0.9 μm paperboard (pressure 0.13 MPa, speed 85 L / h); Step 10: Detect the purple-red liquid, with a color value of 16 (E1% 1cm 535nm).

[0044] (2) Fermentation of black rice wine ① Pretreatment and saccharification: Step 1: 570 kg of extracted black rice was mixed with 1254 kg of water and ground using a cell wall breaking process (3200 r / min, 25 minutes) to a fineness of 1.8 mm. Step 2: The rice was placed in a saccharification tank with a material-to-water ratio of 1:2.2, and 1.14 kg (0.2%) of α-amylase was added. The mixture was kept at a temperature above 95°C for 30 minutes. Step 3: The temperature was lowered to 60°C, and 1.71 kg (0.3%) of saccharifying enzyme was added. The mixture was kept at this temperature for 30 minutes. ② Cool down to 28℃; Fermentation: First, put the saccharified liquid into a sterilized fermentation tank (121℃, 30 minutes), add 626L of slurry water, and the total volume is 2450L; Second, add 12.25L (0.6%) of domesticated yeast and 2.28kg (0.4%) of pure yeast; Third, control the temperature at 26℃, start stirring after 10 hours, stir every 3.5 hours, and control the temperature ≤30℃; Stir every morning and evening after 72 hours, and fermentation is complete when the mash is clear.

[0045] (3) Anthocyanin reduction: 2100L of raw wine was obtained by pressing, heated at 88℃ for 25 minutes, stored at 18℃ for 4 months, and 105L (5%) anthocyanin extract was added after 1.5 months of storage and stirred evenly.

[0046] Finished product test results: alcohol content 14.5% vol, total acid 5.2 g / L, anthocyanin content 265 mg / L, purplish-red color, refreshing taste.

[0047] Example 3

[0048] This embodiment provides a brewing method for producing black rice wine using anthocyanin extraction and reduction technology. The specific steps are as follows: (1) Preparation of anthocyanin extract from black rice ① Extraction solvent selection: Black rice wine aged for 5 months was selected. Test data: alcohol content 16% vol, total acid 5.5 g / L, total sugar 8.0 g / L, pH 4.0, non-sugar solids 8.0 g / L, amino acid nitrogen 0.15 g / L, calcium oxide 0.35 g / L, lead 0.05 mg / kg, benzoic acid 0.01 g / L, and the microbial test was qualified.

[0049] ②Preparation of extraction solvent: Take 1500L of raw wine, add potassium metabisulfite, stir at 120r / min for 30 minutes, and test the total SO2 at 170mg / L and free SO2 at 80mg / L; add 240g of condensed tannin and stir for 20 minutes to dissolve.

[0050] ③ Extraction procedure: Step 1: Wash and drain 750 kg of black rice, add 1875 L (1:2.5) of extraction solvent, pH 4.5; Step 2: Purge with nitrogen (70 L / min), pressure 0.02 MPa, for 10 minutes; Step 3: Spray with a circulating pump (250 L / h), negative pressure -0.07 MPa, 0.25 MPa steam, temperature controlled at 52℃, for 1.1 hours; Step 4: Transfer the extract to a cooling tank, stir at 100 rpm, purge with 8℃ chilled water (200 L / h), and cool to 25℃; Step 5: Filter through 8 μm paperboard (0.12 MPa, 120 L / h); Step 6: Cool to -4.5℃ in three stages, freeze for 7 days (storage temperature -4.5℃±0.5℃) to remove grease; Step 7: Filter through 0.95 μm filter; Step 8: Detect color value 17 (E1%1cm535nm), purple-red.

[0051] (2) Fermentation of black rice wine ① Pretreatment and saccharification: First step, 720kg of extracted black rice is mixed with 1800kg of water and ground (3500r / min, 20 minutes) to a fineness of 1.5mm; Second step, the material-to-water ratio in the saccharification tank is 1:2.5, 1.8kg (0.25%) of α-amylase is added, and the mixture is kept at 98℃ for 30 minutes; Third step, the temperature is lowered to 61℃, 2.16kg (0.3%) of saccharifying enzyme is added, the mixture is kept at 30 minutes, and then the temperature is lowered to 25℃; ② Fermentation: First step, the saccharified liquid is transferred to the fermentation tank, and 880L of slurry water is added, for a total volume of 3400L; Second step, 20.4L (0.8%) of domesticated yeast and 3.6kg (0.5%) of pure yeast starter are added; Third step, the temperature is controlled at 27℃, and the mixture is first raked after 11 hours, then raked every 3 hours, and after 72 hours, it is raked morning and evening.

[0052] (3) Anthocyanin reduction: 2900L of raw wine was obtained by pressing, heated at 89℃ for 28 minutes, stored at 19℃ for 5 months, and 203L (7%) of extract was added after 2 months of storage.

[0053] Finished product testing: alcohol content 15% vol, total acid 5.4 g / L, anthocyanins 280 mg / L, pure aroma, and stable color.

[0054] Example 4

[0055] This embodiment provides a brewing method for producing black rice wine using anthocyanin extraction and reduction technology. The specific steps are as follows: (1) Preparation of anthocyanin extract from black rice ① Extraction solvent selection: 3.5-month aged raw wine with an alcohol content of 15.2% vol, total acid 5.8 g / L, total sugar 11.0 g / L, pH 3.6, non-sugar solids 7.2 g / L, amino acid nitrogen 0.11 g / L, calcium oxide 0.45 g / L, lead 0.09 mg / kg, benzoic acid 0.04 g / L, and passed the microbial test.

[0056] ②Preparation of extraction solvent: Add sulfurous acid to 1100L of raw wine, stir at 105r / min for 28 minutes, total SO2 155mg / L, free SO2 50mg / L; add 165g of condensed tannin, stir for 15 minutes to dissolve.

[0057] ③ Extraction procedure: Step 1: Add 1100L (1:2.2) solvent to 500kg of black rice, pH 4.0; Step 2: Purge with nitrogen at 55L / min, pressure 0.012 MPa, for 6 minutes; Step 3: Circulate with pump at 210L / h, negative pressure -0.055 MPa, extract at 48℃ for 1.4 hours; Step 4: Cool to 27℃ and filter at 6μm; Step 5: Cool to -3.5℃ and freeze for 7 days to remove fat; Step 6: Filter at 0.85μm, color value 15.5.

[0058] (2) Fermentation of black rice wine ① Pretreatment and saccharification: 480 kg of extracted black rice was mixed with 1056 kg of water and ground (3100 r / min, 28 minutes) to a fineness of 1.9 mm. 0.96 kg (0.2%) of α-amylase was added to the saccharification tank and kept at 96℃ for 30 minutes. The temperature was then lowered to 59℃, and 1.44 kg (0.3%) of saccharifying enzyme was added. The temperature was kept at 30 minutes and then lowered to 27℃. ② Fermentation: The saccharified liquid was poured into the tank, and 564 L of slurry water was added, bringing the total volume to 2100 L. 10.5 L (0.5%) of yeast and 1.92 kg (0.4%) of yeast starter were added. The temperature was controlled at 25.5℃. The fermentation started after 9 hours, after 3.8 hours, and after 72 hours, the fermentation started in the morning and evening.

[0059] (3) Anthocyanin reduction: 1850L of raw wine was obtained by pressing, heated at 86℃ for 22 minutes, stored at 16℃ for 3.5 months, and 92.5L (5%) of extract was added.

[0060] Finished product: alcohol content 14.2% vol, total acid 5.1 g / L, anthocyanins 255 mg / L, refreshing taste.

[0061] Example 5

[0062] This embodiment provides a brewing method for producing black rice wine using anthocyanin extraction and reduction technology. The specific steps are as follows: (1) Preparation of anthocyanin extract from black rice ① Extraction solvent selection: 6-month aged raw wine with an alcohol content of 15.8% vol, total acid 6.5 g / L, total sugar 5.0 g / L, pH 4.6, non-sugar solids 9.0 g / L, amino acid nitrogen 0.18 g / L, calcium oxide 0.2 g / L, lead 0.03 mg / kg, benzoic acid 0.005 g / L, and passed the microbial test.

[0063] ②Preparation of extraction solvent: Add potassium metabisulfite to 2000L of raw wine, stir at 130r / min for 35 minutes, the total SO2 is 180mg / L and the free SO2 is 100mg / L; add 400g of condensed tannin, stir for 25 minutes to dissolve.

[0064] ③ Extraction procedure: Step 1: Add 2500L (1:2.5) solvent to 1000kg of black rice, pH 4.8; Step 2: Purge with nitrogen at 80L / min, pressure 0.02 MPa, for 10 minutes; Step 3: Circulate with pump at 300L / h, negative pressure -0.08 MPa, extract at 55℃ for 1 hour; Step 4: Cool to 22℃ and filter at 10μm; Step 5: Cool to -5℃ and freeze for 7 days to remove fat; Step 6: Filter at 1.0μm, color value 18.

[0065] (2) Fermentation of black rice wine ① Pretreatment and saccharification: 960 kg of extracted black rice was mixed with 2400 kg of water and ground (3800 r / min, 18 minutes) to a fineness of 1.2 mm. 2.88 kg (0.3%) of α-amylase was added to the saccharification tank and kept at 100℃ for 30 minutes. The temperature was then lowered to 62℃, and 3.84 kg (0.4%) of saccharifying enzyme was added. The temperature was kept at 100℃ for 30 minutes and then lowered to 26℃. ② Fermentation: The saccharified liquid was poured into the tank, and 1240 L of slurry water was added, bringing the total volume to 4600 L. 36.8 L (1.0%) of yeast and 5.76 kg (0.6%) of yeast starter were added. The temperature was controlled at 28℃. The first stirring was done after 12 hours, the second stirring after 3 hours, and the third stirring after 72 hours, both morning and evening stirring.

[0066] (3) Anthocyanin reduction: 3800L of raw wine was obtained by pressing, heated at 90℃ for 30 minutes, stored at 20℃ for 6 months, and 380L (10%) of extract was added.

[0067] Finished product: alcohol content 15.2% vol, total acid 6.0 g / L, anthocyanins 320 mg / L, rich color, and mellow flavor.

[0068] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A brewing method for producing black rice wine using anthocyanin extraction and reduction technology, characterized in that, Includes the following steps: (1) Preparation of black rice anthocyanin extract: ① The black rice wine with an alcohol content of 15% vol-16% vol, total acid of 4.5 g / L-6.5 g / L, total sugar of ≤15.0 g / L, pH of 3.2-4.6, non-sugar solids of ≥7.0 g / L, amino acid nitrogen of ≥0.1 g / L, calcium oxide of ≤0.5 g / L, lead of ≤0.15 mg / kg, benzoic acid of ≤0.05 g / kg, and no detectable Salmonella or Staphylococcus aureus was selected as the extraction solvent; ② Add food-grade sulfurous acid or potassium metabisulfite to the original wine, stir, and control the total SO2 content to 150mg-180mg / L and the free SO2 content to 40mg / L-100mg / L. Then add 150mg / L-200mg / L of food-grade condensed tannins and dissolve them. ③ After washing and draining the black rice, put it into the extraction tank, add the prepared extraction solvent at a ratio of 1:2-1:2.5 (m:v), seal the tank, and replace the air with 99.9% food-grade nitrogen at a pressure of 0.01-0.02 MPa for 5-10 minutes. ④ Turn on the negative pressure pump to bring the pressure inside the tank to -0.05 to -0.08 MPa, heat to 45℃-55℃, and extract under constant temperature and negative pressure for 1-1.5 hours; ⑤ The extract is transferred to a cooling tank and cooled to below 30°C with 4-10°C chilled water. The coarse filtrate is obtained by filtering through 5-10μm paperboard. ⑥ The coarse filtrate is cooled to -3℃ to -5℃ in three stages, frozen and kept warm for 6-7 days, the oil layer is removed, and then filtered through 0.8-1.0μm paperboard to obtain anthocyanin extract; (2) Fermentation of black rice wine: ① After extracting anthocyanins, black rice is ground with water to a fineness of 1-2 mm using a cell wall breaking mill. It is then added to a saccharification tank at a material-to-water ratio of 1:2.0-1:2.5 (m:v), α-amylase is added, and the mixture is heated to above 95℃ and kept warm for 30 minutes. The temperature is then lowered to 58℃-62℃, saccharifying enzyme is added, and the mixture is kept warm for 30 minutes. Finally, the temperature is lowered to below 30℃. ②Pour the saccharified liquid into the fermentation tank, add slurry water, black rice-domesticated yeast and pure yeast, ferment at 25℃-28℃, start stirring after 8-12 hours, then stir every 3-4 hours, control the temperature ≤30℃, stir in the morning and evening after 72 hours until the mash is clear; (3) Anthocyanin reduction: After fermentation, the wine is pressed, heated and stored. Anthocyanin extract is added in proportion during storage.

2. The brewing method for producing black rice wine using an anthocyanin extraction and reduction process according to claim 1, characterized in that: In step (1) ③, the black rice is rinsed with running water until the rinsing water is clear and free of impurities.

3. The brewing method for producing black rice wine using an anthocyanin extraction and reduction process according to claim 1, characterized in that: In step (1) ④, the heating is carried out by steam heating in the jacket of the extraction tank, and the extraction circulation pump is turned on during the heating process to make the extract flow in circulation.

4. The brewing method for producing black rice wine using anthocyanin extraction and reduction process according to claim 1, characterized in that: In step (2)①, the amount of α-amylase added is 0.1%-0.3% of the mass of black rice, and the amount of saccharifying enzyme added is 0.2%-0.4% of the mass of black rice.

5. The brewing method for producing black rice wine using an anthocyanin extraction and reduction process according to claim 1, characterized in that: In step (2) ②, the amount of black rice domestication yeast added is 0.5%-1.0% of the saccharification liquid volume, and the amount of pure yeast added is 0.3%-0.6% of the black rice mass.

6. The brewing method for producing black rice wine using anthocyanin extraction and reduction process according to claim 1, characterized in that: In step (3), the proportion of anthocyanin extract added is 5%-10% of the volume of the original wine.

7. The brewing method for producing black rice wine using an anthocyanin extraction and reduction process according to claim 1, characterized in that: In step (1)⑥, the freezing and heat preservation process uses a constant temperature freezing tank with a temperature fluctuation range of ±0.5℃.

8. The brewing method for producing black rice wine using anthocyanin extraction and reduction process according to claim 1, characterized in that: In step (2) ②, the fermentation tank is made of stainless steel, and the fermentation tank is sterilized at high temperature before fermentation. The sterilization temperature is 121℃ and the time is 30 minutes.

9. The brewing method for producing black rice wine using an anthocyanin extraction and reduction process according to claim 1, characterized in that: In step (3), the temperature of the wine is controlled at 85℃-90℃ for 20-30 minutes, the temperature of the wine is controlled at 15℃-20℃, and the storage time is 3-6 months.

10. The brewing method for producing black rice wine using an anthocyanin extraction and reduction process according to claim 1, characterized in that: In step (1)①, the black rice wine is made from black rice that has been traditionally fermented, pressed, filtered, and aged for more than 3 months.

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