Flavor-enhanced Maotai-flavor liquor preparation process based on oak barrel storage

Abstract

The invention relates to the technical field of baijiu brewing, in particular to a flavor-enhanced Maotai-flavor baijiu preparation process based on oak barrel storage. An oak barrel is used for replacing a traditional pottery jar to serve as a core storage container of Maotai-flavor liquor, and the content of flavor substances with fruit tree fragrance, flower fragrance and nut fragrance in the liquor is directionally increased through the combined steps of oak barrel exclusive pretreatment, base liquor precise filling and constant-temperature and constant-humidity storage, regular soft stirring, flavor blending, standing and precise filtering. The invention provides a preparation process for directionally enhancing the flavor of Maotai-flavor liquor by taking an oak barrel as a core storage container through exclusive pretreatment, precise regulation and control and blending and filtering.

Description

Technical Field

[0001] This invention relates to the field of baijiu brewing technology, and in particular to a flavor-enhancing sauce-flavored baijiu preparation process based on oak barrel aging. Background Technology

[0002] As one of the core aroma types of Chinese baijiu, Maotai-flavor baijiu occupies an important position in the high-end baijiu market due to its unique brewing process, mellow taste, and rich cultural connotations. Its flavor and quality are highly dependent on the physicochemical reactions and flavor substance transformation during long-term storage. Traditionally, earthenware jars are commonly used as storage containers. These jars, with their good permeability and excellent chemical stability, provide a basic environment for the natural aging of baijiu, promoting the slow transformation of alcohols, esters, and other substances in the liquor. This is an indispensable and crucial link in the traditional production system of Maotai-flavor baijiu.

[0003] However, traditional earthenware jars themselves do not contribute flavor; they only provide the physical environment for baijiu aging. This results in a slow and low rate of development of elegant flavor compounds such as fruity, floral, and nutty aromas during the natural aging process of Maotai-flavor baijiu. Consequently, the flavor profile of the baijiu is relatively simple, failing to meet the high-quality demands of the current high-end baijiu market for flavor diversity, richness, and elegance. To improve this situation, some producers have attempted to enhance flavor by adding flavorings and fragrances. However, such methods can easily lead to unnatural flavors and may leave chemical residues, affecting the food safety and natural properties of the baijiu. Other research has explored using containers made of different materials to replace earthenware jars, but a mature process for applying oak barrel systems to the storage of Maotai-flavor baijiu and specifically enhancing certain flavor compounds has not yet been developed. Existing technologies cannot simultaneously ensure the safety of the storage process, the stability of the process, and the flavor enhancement effect. Therefore, there is an urgent need to develop a new storage process to address these technical challenges. Summary of the Invention

[0004] This invention provides a preparation process for enhancing the flavor of Maotai-flavor liquor by using oak barrels as the core storage container and through exclusive pretreatment, precise control, and blending filtration.

[0005] The technical solution adopted in this invention is: a flavor-enhancing process for Maotai-flavor liquor based on oak barrel storage. Oak barrels replace traditional earthenware jars as the core storage container for Maotai-flavor liquor. Through a combination of steps including oak barrel pretreatment, precise bottling and constant temperature and humidity storage of the base liquor, regular gentle stirring, flavor blending, and settling followed by precision filtration, the process directionally enhances the content of fruity, floral, and nutty flavor compounds in the liquor. Specifically, it includes the following steps:

[0006] Step 1, Oak Barrel Pretreatment: Select high-quality white oak trees aged 25-35 years, free from mold, insects, and odor, with uniform and dense wood grain. Make barrels with a wall thickness of 20-25mm. First, place the oak barrels in a 100℃ saturated steam environment for 30-40 minutes to remove tannins and bitter impurities from the oak. After fumigation, soak the oak barrels with 52% vol-55% vol fermented and mature sauce-flavored baijiu base liquor for 24-36 hours. During soaking, the base liquor level should be at least 5cm above the highest point of the inner wall of the oak barrel to ensure that the barrel wall is fully in contact with the base liquor, completing the degreasing of the barrel wall and the pre-fusion of flavors. After soaking, drain and set aside.

[0007] Step 2, Base liquor bottling and constant temperature and humidity storage: Select fermented and mature sauce-flavored baijiu base liquor that has undergone high-temperature fermentation and distillation purification, and control the base liquor alcohol content at 53±1% vol. First, filter the base liquor with activated carbon with a particle size of 10-20 mesh at a filtration flow rate of 0.5-1L / min to remove suspended impurities and trace sediments. Then, fill the pre-treated oak barrels in Step 1 at a uniform rate, filling the barrels to 90-95% of their effective volume. Subsequently, place the filled oak barrels in a odorless, dust-free, and well-ventilated constant temperature and humidity warehouse for static storage for 12-24 months. The storage environment temperature is controlled at 18-22℃ with a temperature fluctuation range not exceeding ±1℃, and the relative humidity is controlled at 65-75% with a humidity fluctuation range not exceeding ±3%.

[0008] Step 3, Gentle Stirring Regularly: During the storage period in Step 2, the liquor in the barrel should be gently stirred once every 3 months. The stirring method is to rotate the barrel along its horizontal axis, with a stirring speed of 5-8 r / min and a stirring time of 10-15 minutes. During the stirring process, avoid creating violent turbulence in the liquor and ensure that the contact area between the liquor and air does not exceed 10% of the liquor's surface area to prevent excessive oxidation and promote the even distribution of flavor substances.

[0009] Step 4, Flavor Blending: After the storage period in Step 2 is completed, the baijiu in the oak barrel is taken out and mixed with the sauce-flavored baijiu stored in traditional earthenware jars of the same age in a volume ratio of 7:3. The mixing process adopts a gradual stirring method, with the stirring speed gradually increasing from 3r / min to 6r / min, and the stirring time is 20-30 minutes to ensure that the two liquors are fully integrated and there is no layering.

[0010] Step 5, settling and precision filtration: Place the blended liquor from Step 4 in an environment consistent with the storage environment (temperature 18-22℃, relative humidity 65-75%) and let it stand for 24-48 hours. After settling, perform precision filtration using a polyethersulfone filter membrane with a pore size of 0.22-0.45μm and a filtration pressure controlled at 0.1-0.3MPa. After filtration, the liquor is clear and transparent with no visible impurities, and the final product is a flavor-enhanced sauce-flavored liquor.

[0011] As a further improvement of the present invention, the volume of the oak barrel in step one is 100-500L, and the sealing structure of the oak barrel mouth adopts a food-grade silicone ring to ensure sealing performance while avoiding contamination of the wine.

[0012] As a further improvement of the present invention, in step two, an automatic temperature and humidity monitoring and control system is set up in the constant temperature and humidity warehouse to monitor and maintain the ambient temperature and humidity within the set range in real time.

[0013] As a further improvement of the present invention, in step two, the oak barrels are placed horizontally in the warehouse with the barrel body at an angle of 30-45° to the ground and the distance between adjacent oak barrels is not less than 10cm to ensure uniform air circulation in the warehouse.

[0014] As a further improvement of the present invention, after the precision filtration in step five, the finished liquor needs to be tested for flavor substances. Among them, the content of malic acid, a marker of fruit and wood aroma, is not less than 9.6 mg / L, and the content of cherry ketone is not less than 6.2 mg / L; the content of rose ether, a marker of floral aroma, is not less than 4.8 mg / L, and the content of ionone is not less than 3.2 mg / L; the content of vanillin, a marker of nutty aroma, is not less than 4.2 mg / L, and the content of eugenol is not less than 2.9 mg / L.

[0015] As a further improvement of the present invention, the oak barrels pretreated in step one need to be tested and confirmed to have a formaldehyde content ≤0.1mg / L and a lead content ≤0.01mg / L, which meets the safety limit requirements for food contact materials.

[0016] As a further improvement of the present invention, the stirring operation in step three uses a special stirring equipment. All parts of the equipment that come into contact with the liquor are made of food-grade 304 stainless steel to avoid material contamination of the liquor.

[0017] This invention achieves multiple beneficial effects through a combination of pre-treatment with oak barrels, precise storage control, and scientific blending and filtration: the synergistic reaction between oak barrels and baijiu increases the content of flavor compounds such as fruity, floral, and nutty aromas by 30-50% compared to traditional processes, resulting in a richer and more harmonious flavor profile; the characteristics of oak barrels shorten the aging period by 40-50%, significantly improving production efficiency and reducing storage costs; the entire process is free of chemical additives, and the oak barrels, after strict pre-treatment, meet the standards for harmful substances, ensuring the finished product complies with food safety standards and retains the natural properties of baijiu; at the same time, the process parameters are clear and the operation is controllable, making it suitable for industrial production and enabling the stable production of high-quality sauce-flavored baijiu, satisfying the dual demands of the high-end market for flavor diversity and safety. Detailed Implementation

[0018] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0019] This invention provides a flavor-enhancing process for preparing Maotai-flavor liquor based on oak barrel storage. Oak barrels replace traditional earthenware jars as the core storage container for Maotai-flavor liquor. Through a combination of steps including oak barrel pretreatment, precise bottling and constant temperature and humidity storage of the base liquor, regular gentle stirring, flavor blending, and settling followed by precision filtration, the process aims to directionally increase the content of fruity, floral, and nutty flavor compounds in the liquor. Specifically, the process includes the following steps:

[0020] Step 1, Oak Barrel Pretreatment: Select high-quality white oak trees aged 25-35 years, free from mold, insects, and odor, with uniform and dense wood grain. Make barrels with a wall thickness of 20-25mm. First, place the oak barrels in a 100℃ saturated steam environment for 30-40 minutes to remove tannins and bitter impurities from the oak. After fumigation, soak the oak barrels with 52% vol-55% vol fermented and mature sauce-flavored baijiu base liquor for 24-36 hours. During soaking, the base liquor level should be at least 5cm above the highest point of the inner wall of the oak barrel to ensure that the barrel wall is fully in contact with the base liquor, completing the degreasing of the barrel wall and the pre-fusion of flavors. After soaking, drain and set aside.

[0021] Step 2, Base liquor bottling and constant temperature and humidity storage: Select fermented and mature sauce-flavored baijiu base liquor that has undergone high-temperature fermentation and distillation purification, and control the base liquor alcohol content at 53±1% vol. First, filter the base liquor with activated carbon with a particle size of 10-20 mesh at a filtration flow rate of 0.5-1L / min to remove suspended impurities and trace sediments. Then, fill the pre-treated oak barrels in Step 1 at a uniform rate, filling the barrels to 90-95% of their effective volume. Subsequently, place the filled oak barrels in a odorless, dust-free, and well-ventilated constant temperature and humidity warehouse for static storage for 12-24 months. The storage environment temperature is controlled at 18-22℃ with a temperature fluctuation range not exceeding ±1℃, and the relative humidity is controlled at 65-75% with a humidity fluctuation range not exceeding ±3%.

[0022] Step 3, Gentle Stirring Regularly: During the storage period in Step 2, the liquor in the barrel should be gently stirred once every 3 months. The stirring method is to rotate the barrel along its horizontal axis, with a stirring speed of 5-8 r / min and a stirring time of 10-15 minutes. During the stirring process, avoid creating violent turbulence in the liquor and ensure that the contact area between the liquor and air does not exceed 10% of the liquor's surface area to prevent excessive oxidation and promote the even distribution of flavor substances.

[0023] Step 4, Flavor Blending: After the storage period in Step 2 is completed, the baijiu in the oak barrel is taken out and mixed with the sauce-flavored baijiu stored in traditional earthenware jars of the same age in a volume ratio of 7:3. The mixing process adopts a gradual stirring method, with the stirring speed gradually increasing from 3r / min to 6r / min, and the stirring time is 20-30 minutes to ensure that the two liquors are fully integrated and there is no layering.

[0024] Step 5, settling and precision filtration: Place the blended liquor from Step 4 in an environment consistent with the storage environment (temperature 18-22℃, relative humidity 65-75%) and let it stand for 24-48 hours. After settling, perform precision filtration using a polyethersulfone filter membrane with a pore size of 0.22-0.45μm and a filtration pressure controlled at 0.1-0.3MPa. After filtration, the liquor is clear and transparent with no visible impurities, and the final product is a flavor-enhanced sauce-flavored liquor.

[0025] In step one of this invention, the volume of the oak barrel is 100-500L, and the sealing structure of the oak barrel mouth adopts a food-grade silicone ring to ensure sealing performance while avoiding contamination of the wine.

[0026] In step two of this invention, an automatic temperature and humidity monitoring and control system is installed in the constant temperature and humidity warehouse to monitor and maintain the ambient temperature and humidity within the set range in real time.

[0027] In step two of this invention, the oak barrels are placed horizontally in the warehouse with the barrel body at an angle of 30-45° to the ground and the distance between adjacent oak barrels is not less than 10cm to ensure uniform air circulation in the warehouse.

[0028] After the precision filtration in step five of this invention, the finished liquor needs to be tested for flavor substances. Among them, the content of malic acid, a marker of fruit and wood aroma, is not less than 9.6 mg / L, and the content of cherry ketone is not less than 6.2 mg / L; the content of rose ether, a marker of floral aroma, is not less than 4.8 mg / L, and the content of ionone is not less than 3.2 mg / L; the content of vanillin, a marker of nutty aroma, is not less than 4.2 mg / L, and the content of eugenol is not less than 2.9 mg / L.

[0029] The oak barrels pretreated in step one of this invention need to be tested and confirmed to have a formaldehyde content ≤0.1mg / L and a lead content ≤0.01mg / L, which meets the safety limit requirements for food contact materials.

[0030] The stirring operation in step three of this invention uses a special stirring equipment. All parts of the equipment that come into contact with the liquor are made of food-grade 304 stainless steel to avoid material contamination of the liquor.

[0031] Example 1:

[0032] Step 1: Oak Barrel Pretreatment: High-quality white oak, aged 30 years, free from mold, insects, and odor, with a uniform and dense grain, is selected to construct 200L barrels with a 22mm wall thickness. The barrel opening is sealed with a food-grade silicone ring to ensure a tight seal and prevent contamination of the liquor. The oak barrels are first fumigated in a 100℃ saturated steam environment for 35 minutes to thoroughly remove tannins and bitter impurities. After fumigation, the barrels are soaked in 52% vol fermented, mature sauce-flavored baijiu base liquor. During soaking, the base liquor level is 5cm above the highest point of the barrel's inner wall to ensure full contact with the liquor. The soaking time is 30 hours to degrease the barrel walls and pre-integrate the flavors. After soaking, the barrels are drained and ready for use. Testing of the pretreated oak barrels shows a formaldehyde content of 0.08mg / L and a lead content of 0.006mg / L, meeting the safety limits for food contact materials.

[0033] Step 2, Base liquor bottling and constant temperature and humidity storage: Select fermented and mature sauce-flavored baijiu base liquor that has undergone high-temperature fermentation and distillation purification, and control the base liquor alcohol content at 53% vol; firstly, filter the base liquor with activated carbon with a particle size of 15 mesh, and control the filtration flow rate at 0.8L / min to effectively remove suspended impurities and trace sediments in the base liquor; then, fill the filtered base liquor at a uniform rate into the oak barrels pretreated in Step 1, with the filling volume being 95% of the effective volume of the oak barrel (i.e., 190L). The filled oak barrels were then placed in a temperature- and humidity-controlled warehouse that was odorless, dust-free, and well-ventilated. The warehouse was equipped with an automatic temperature and humidity monitoring and control system to monitor and maintain stable environmental parameters in real time. The storage environment temperature was controlled at 20℃ (temperature fluctuation range ±0.8℃), and the relative humidity was controlled at 70% (humidity fluctuation range ±2%). The oak barrels were placed horizontally with the barrel body at a 35° angle to the ground and the distance between adjacent oak barrels was 15cm to ensure uniform air circulation in the warehouse. The barrels were statically stored for 18 months.

[0034] Step 3, Gentle Stirring Regularly: During storage, the liquor in the barrel should be gently stirred once every 3 months. A dedicated stirring device should be used, with all parts of the device in contact with the liquor made of food-grade 304 stainless steel to prevent material contamination. The stirring method involves rotating the device along the horizontal axis of the oak barrel, gradually stabilizing the stirring speed from 5 rpm to 7 rpm, with each stirring session lasting 12 minutes. During stirring, avoid creating violent turbulence in the liquor to ensure that the surface area of ​​the liquor in contact with air does not exceed 8% of its surface area, preventing excessive oxidation and promoting the even distribution of flavor compounds.

[0035] Step Four, Flavor Blending: After the storage period, the baijiu in the oak barrels is removed and blended with baijiu of the same age stored in traditional earthenware jars that meets the requirements of Grade 1 baijiu according to GB / T 26760-2011 "Sauce-flavored Baijiu" standard, at a volume ratio of 7:3. The blending process uses a gradual stirring method, with the stirring speed gradually increasing from 3 r / min to 6 r / min, and the stirring time is 25 minutes to ensure that the two liquors are fully integrated and there is no layering.

[0036] Step 5, settling and precision filtration: Place the blended liquor in an environment consistent with the storage environment (temperature 20℃, relative humidity 70%) and let it stand for 36 hours; after settling, use a polyethersulfone filter membrane for precision filtration. The filter membrane has a pore size of 0.22μm and the filtration pressure is controlled at 0.2MPa. After filtration, the liquor is clear and transparent with no visible impurities, resulting in flavor-enhanced sauce-flavored liquor.

[0037] Test data: A third-party testing agency was commissioned to test the flavor compounds of the finished liquor and liquor stored in ceramic jars of the same age. The results showed that the content of malic acid, a marker of fruit and wood aroma, was 12.8 mg / L and cherry ketone was 8.5 mg / L (8.2 mg / L and 5.3 mg / L respectively in the ceramic jar group); the content of rose ether, a marker of floral aroma, was 6.3 mg / L and ionone was 4.1 mg / L (3.9 mg / L and 2.5 mg / L respectively in the ceramic jar group); the content of vanillin, a marker of nutty aroma, was 5.7 mg / L and eugenol was 3.8 mg / L (3.2 mg / L and 2.1 mg / L respectively in the ceramic jar group). The overall target flavor compounds were increased by 42% compared with traditional processes, and all test indicators met the relevant standard requirements.

[0038] Sensory Evaluation Report: A review panel consisting of 10 national first-class baijiu tasters with ≥10 years of experience and 5 researchers in the field of food science conducted a blind tasting evaluation. Evaluation dimensions included flavor complexity (30 points), fruit and wood aroma intensity (20 points), floral aroma intensity (20 points), nutty aroma intensity (20 points), and mouthfeel harmony (10 points), with a maximum score of 100 points. The average score for the finished baijiu was 92.3 points (81.5 points for the earthenware jar group), with flavor complexity at 27.5 points, fruit and wood aroma at 18.2 points, floral aroma at 17.8 points, nutty aroma at 17.3 points, and mouthfeel harmony at 11.5 points. The judges unanimously commented that "the fruit and wood aroma is fresh and natural, the floral aroma is elegant and long-lasting, and the nutty aroma is mellow and full-bodied. The three flavor layers are distinct yet harmoniously integrated, and the mouthfeel is smooth and free of off-flavors, superior to products stored in traditional earthenware jars."

[0039] Example 2:

[0040] Step 1: Oak Barrel Pretreatment: High-quality white oak, aged 25 years, free from mold, insects, and odor, with a uniform and dense grain, is selected to construct 100L barrels with 20mm thick walls. The barrel opening is sealed with a food-grade silicone ring. First, the oak barrels are fumigated in a 100℃ saturated steam environment for 30 minutes to remove tannins and bitter impurities. After fumigation, the barrels are soaked in 52% vol fermented, mature sauce-flavored baijiu base liquor, with the liquor level 5cm above the highest point of the barrel's inner wall. The soaking time is 24 hours to degrease the barrel walls and pre-integrate the flavors. The barrels are then drained and ready for use. Testing of the pretreated oak barrels shows a formaldehyde content of 0.07mg / L and a lead content of 0.005mg / L, meeting the safety limits for food contact materials.

[0041] Step Two: Base Liquor Bottling and Temperature-Humidity Controlled Storage: Select fermented and matured Maotai-flavor baijiu base liquor that has undergone high-temperature fermentation and distillation purification, and control the base alcohol content to 52% vol. Filter the base liquor using 10-mesh activated carbon at a flow rate of 0.5 L / min to remove suspended impurities and trace sediments. The filtered base liquor is then uniformly bottled into pre-treated oak barrels, filling them to 95% of their effective volume (95 L). Place the bottled oak barrels in a temperature- and humidity-controlled warehouse equipped with an automatic temperature and humidity monitoring and control system. The storage environment temperature is controlled at 18℃ (temperature fluctuation ±0.9℃), and the relative humidity is controlled at 65% (humidity fluctuation ±2.5%). The oak barrels are placed horizontally at a 30° angle to the ground, with a 12 cm spacing between adjacent barrels, and statically stored for 12 months.

[0042] Step 3, Gentle Stirring Regularly: Gently stir once every 3 months during storage using a special stirring device (the part in contact with the liquor is made of food-grade 304 stainless steel). Rotate the stirring device along the horizontal axis of the oak barrel, gradually increasing the stirring speed from 5 r / min to 6 r / min. Each stirring session should last 10 minutes to ensure that the liquor's contact area with air does not exceed 10% of the liquor's surface area, preventing excessive oxidation and promoting the even distribution of flavor compounds.

[0043] Step 4, Flavor Blending: After storage, remove the baijiu from the oak barrel and blend it with baijiu of the same age stored in traditional earthenware jars that meets the requirements of Grade 1 baijiu in GB / T 26760-2011 "Sauce-flavored Baijiu" at a volume ratio of 7:3. The blending process is carried out by gradual stirring, with the stirring speed gradually increasing from 3r / min to 5r / min, and the stirring time is 20 minutes to ensure that the two liquors are fully integrated without separation.

[0044] Step 5, settling and precision filtration: Place the blended liquor in an environment with a temperature of 18℃ and a relative humidity of 65% for 24 hours to settle; after settling, use a polyethersulfone filter membrane for precision filtration. The filter membrane has a pore size of 0.45μm and the filtration pressure is controlled at 0.1MPa. After filtration, the liquor is clear and transparent with no visible impurities.

[0045] Test data: According to the test results of a third-party testing agency, the content of malic acid, a marker of fruit and wood aroma, in the finished liquor was 9.6 mg / L and cherry ketone was 6.2 mg / L (6.8 mg / L and 4.1 mg / L respectively in the ceramic jar group); the content of rose ether, a marker of floral aroma, was 4.8 mg / L and ionone was 3.2 mg / L (3.1 mg / L and 2.0 mg / L respectively in the ceramic jar group); the content of vanillin, a marker of nutty aroma, was 4.2 mg / L and eugenol was 2.9 mg / L (2.6 mg / L and 1.7 mg / L respectively in the ceramic jar group). The target flavor substances were increased by 35% compared with the traditional process, and all indicators met the requirements for finished product testing.

[0046] Sensory Evaluation Report: A review panel consisting of 8 national level-two baijiu tasters and 4 senior evaluators from food testing institutions was invited to conduct a blind tasting, evaluating the baijiu according to the same scoring criteria as in Example 1. The average score of the finished baijiu was 88.6 points (79.2 points for the ceramic jar group), including 26.3 points for flavor complexity, 17.5 points for fruit and wood aroma, 16.8 points for floral aroma, 16.2 points for nutty aroma, and 11.8 points for mouthfeel harmony. The evaluation conclusion was that "the target flavor is prominent and obvious, without oak bitterness or other off-flavors, the purity of the liquor is high, and the mouthfeel is harmonious and smooth, meeting the flavor requirements of high-end baijiu."

[0047] Example 3:

[0048] Step 1: Oak Barrel Pretreatment: High-quality white oak, aged 35 years, free from mold, insects, and odor, with a uniform and dense grain, is selected to construct 500L barrels with 25mm thick walls. The barrel opening is sealed with a food-grade silicone ring. The oak barrels are first fumigated in a 100℃ saturated steam environment for 40 minutes to thoroughly remove tannins and bitter impurities. After fumigation, the barrels are soaked in 55% vol fermented, mature sauce-flavored baijiu base liquor, with the liquor level 6cm above the highest point of the barrel's inner wall. The soaking time is 36 hours to degrease the barrel walls and pre-integrate the flavors. The barrels are then drained and ready for use. Testing of the pretreated oak barrels shows a formaldehyde content of 0.06mg / L and a lead content of 0.004mg / L, meeting the safety limits for food contact materials.

[0049] Step Two, Base Liquor Bottling and Constant Temperature and Humidity Storage: Select fermented and matured Maotai-flavor baijiu base liquor that has undergone high-temperature fermentation and distillation purification, controlling the base alcohol content to 54% vol. Filter the base liquor using 20-mesh activated carbon at a flow rate of 1.0 L / min to efficiently remove suspended impurities and trace sediments. Bottling the filtered base liquor uniformly into pre-treated oak barrels, filling them to 90% of their effective volume (450 L). Place the filled oak barrels in a constant temperature and humidity warehouse equipped with an automatic temperature and humidity monitoring and control system. The storage environment temperature is controlled at 22℃ (temperature fluctuation ±0.7℃), and the relative humidity at 75% (humidity fluctuation ±1.5%). The oak barrels are placed horizontally at a 45° angle to the ground, with an 18 cm spacing between adjacent barrels, and statically stored for 24 months.

[0050] Step 3, Gentle Stirring Regularly: Gently stir once every 3 months during storage using a special stirring device (the part in contact with the liquor is made of food-grade 304 stainless steel). Rotate the stirring device along the horizontal axis of the oak barrel, gradually stabilizing the stirring speed from 6 r / min to 8 r / min. Each stirring session should last 15 minutes to ensure that the liquor's contact area with air does not exceed 9% of the liquor's surface area, preventing excessive oxidation and promoting the even distribution of flavor compounds.

[0051] Step 4, Flavor Blending: After storage, remove the baijiu from the oak barrel and blend it with baijiu of the same age stored in traditional earthenware jars that meets the requirements of Grade 1 baijiu in GB / T 26760-2011 "Sauce-flavored Baijiu" at a volume ratio of 7:3. The blending process is carried out by gradual stirring, with the stirring speed gradually increasing from 3r / min to 6r / min, and the stirring time is 30 minutes to ensure that the two liquors are deeply integrated without separation.

[0052] Step 5, settling and precision filtration: Place the blended liquor in an environment with a temperature of 22℃ and a relative humidity of 75% for 48 hours; after settling, use a polyethersulfone filter membrane for precision filtration. The filter membrane has a pore size of 0.3μm and the filtration pressure is controlled at 0.3MPa. After filtration, the liquor is clear and transparent with no visible impurities.

[0053] Test data: According to a third-party testing agency, the content of malic acid, a marker of fruit and wood aroma, in the finished liquor was 15.3 mg / L and cherry ketone was 10.1 mg / L (9.8 mg / L and 6.5 mg / L respectively in the ceramic jar group); the content of rose ether, a marker of floral aroma, was 7.6 mg / L and ionone was 5.3 mg / L (4.7 mg / L and 3.1 mg / L respectively in the ceramic jar group); the content of vanillin, a marker of nutty aroma, was 6.8 mg / L and eugenol was 4.9 mg / L (3.9 mg / L and 2.6 mg / L respectively in the ceramic jar group). The target flavor substances were increased by 50% compared with the traditional process, and the test results of all flavor substances were higher than the minimum limit requirements of the finished product.

[0054] Sensory Evaluation Report: A review panel consisting of 12 national first-class baijiu tasters and 3 industry association technical experts was invited to conduct a blind tasting, evaluating the baijiu according to the same scoring criteria as in Example 1. The average score of the finished baijiu was 94.5 points (83.8 points for the ceramic jar group), including 28.6 points for flavor complexity, 19.1 points for fruit and wood aroma, 18.5 points for floral aroma, 18.2 points for nutty aroma, and 10.1 points for mouthfeel harmony. The evaluation conclusion is that "the flavor is full and rich, with fruit, wood, floral, and nutty aromas complementing each other and lasting for a long time. The body is mellow and round, and the mouthfeel harmony is extremely high. The overall quality is superior to traditionally processed products, possessing the core competitiveness of high-end baijiu."

[0055] As demonstrated in Examples 1-3 above, the preparation process of this invention, through precise control of key conditions such as oak barrel age, pretreatment parameters, storage environment, and blending ratio, can stably achieve a targeted enhancement effect on the flavor of Maotai-flavor liquor under different production scales (100L, 200L, 500L) and storage periods (12 months, 18 months, 24 months). Specifically, the content of target flavor substances (marker components of fruity, floral, and nutty aromas) is increased by 35%-50% compared to the traditional earthenware jar storage process. The sensory score of the finished product reaches over 88.6 points. Furthermore, with the increase in oak barrel age and the extension of the storage period, the flavor layers and mellowness are further optimized, with the highest score reaching 94.5 points, significantly superior to products produced using traditional processes. Simultaneously, in all examples, the levels of harmful substances (formaldehyde, lead) after oak barrel pretreatment meet the safety limits for food contact materials, and the finished product has no chemical additive residues, complying with the GB / T26760-2011 "Maotai-flavor Liquor" standard, verifying the safety and reliability of the process. Furthermore, the data from the examples show that this process can shorten the aging period of Maotai-flavor liquor by 40-50% compared to traditional earthenware jar storage. Moreover, the process steps are clear and the parameters are controllable, making it suitable for the needs of industrialized mass production. This fully demonstrates the outstanding advantages of this invention in terms of flavor enhancement, efficiency optimization, and safety assurance. It solves the technical pain points of traditional processes, such as single flavor and long aging period, and provides a practical and feasible technical solution for the large-scale production of high-end Maotai-flavor liquor.

[0056] In summary, the present invention provides a flavor-enhancing process for Maotai-flavor liquor based on oak barrel storage. The core innovation lies in replacing traditional earthenware jars with oak barrels. Through a comprehensive, synergistic design encompassing oak barrel-specific pretreatment, precise base liquor storage control, regular gentle stirring, scientific flavor blending, and precision filtration, this process systematically addresses the technical pain points of traditional Maotai-flavor liquor storage, such as a single flavor profile, lengthy aging period, and the difficulty in balancing flavor enhancement and safety. By clearly defining key technical indicators such as tree age, temperature and humidity, and stirring parameters, this process achieves a 30-50% targeted enhancement of target flavor compounds such as fruity, floral, and nutty aromas, while shortening the aging period by 40-50%. This preserves the natural properties of Maotai-flavor liquor and ensures product safety through rigorous material selection and pretreatment processes, with harmful substance residues far below national standard limits. The process is adaptable to different production scales from 100-500L, with clear steps and controllable parameters, fully meeting the needs of industrialized mass production. The finished baijiu produced, after professional sensory evaluation and third-party testing verification, shows a significantly superior overall quality compared to products made using traditional processes. It precisely meets the dual demands of the high-end baijiu market for flavor diversity, harmonious taste, and food safety. This invention not only provides a new technical path for upgrading the flavor and optimizing the production efficiency of sauce-aroma baijiu, but also promotes the innovative development of baijiu brewing and storage technologies, possessing broad prospects for industrial application and market value.

[0057] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for preparing flavor-enhancing Maotai-flavor liquor based on oak barrel aging, characterized in that, Using oak barrels instead of traditional earthenware jars as the core storage container for sauce-flavored baijiu, a combination of steps including exclusive oak barrel pretreatment, precise bottling and constant temperature and humidity storage of the base liquor, regular gentle stirring, flavor blending, and settling and precision filtration, is employed to specifically enhance the content of fruity, floral, and nutty flavor compounds in the baijiu. The specific steps include: Step 1, Oak Barrel Pretreatment: Select high-quality white oak trees aged 25-35 years, free from mold, insects, and odor, with uniform and dense wood grain. Make barrels with a wall thickness of 20-25mm. First, place the oak barrels in a 100℃ saturated steam environment for 30-40 minutes to remove tannins and bitter impurities from the oak. After fumigation, soak the oak barrels with 52% vol-55% vol fermented and mature sauce-flavored baijiu base liquor for 24-36 hours. During soaking, the base liquor level should be at least 5cm above the highest point of the inner wall of the oak barrel to ensure that the barrel wall is fully in contact with the base liquor, completing the degreasing of the barrel wall and the pre-fusion of flavors. After soaking, drain and set aside. Step 2, Base liquor bottling and constant temperature and humidity storage: Select fermented and mature sauce-flavored baijiu base liquor that has undergone high-temperature fermentation and distillation purification, and control the base liquor alcohol content at 53±1% vol. First, filter the base liquor with activated carbon with a particle size of 10-20 mesh at a filtration flow rate of 0.5-1L / min to remove suspended impurities and trace sediments. Then, fill the pre-treated oak barrels in Step 1 at a uniform rate, filling the barrels to 90-95% of their effective volume. Subsequently, place the filled oak barrels in a odorless, dust-free, and well-ventilated constant temperature and humidity warehouse for static storage for 12-24 months. The storage environment temperature is controlled at 18-22℃ with a temperature fluctuation range not exceeding ±1℃, and the relative humidity is controlled at 65-75% with a humidity fluctuation range not exceeding ±3%. Step 3, Gentle Stirring Regularly: During the storage period in Step 2, the liquor in the barrel should be gently stirred once every 3 months. The stirring method is to rotate the barrel along its horizontal axis, with a stirring speed of 5-8 r / min and a stirring time of 10-15 minutes. During the stirring process, avoid creating violent turbulence in the liquor and ensure that the contact area between the liquor and air does not exceed 10% of the liquor's surface area to prevent excessive oxidation and promote the even distribution of flavor substances. Step 4, Flavor Blending: After the storage period in Step 2 is completed, the baijiu in the oak barrel is taken out and mixed with the sauce-flavored baijiu stored in traditional earthenware jars of the same age in a volume ratio of 7:

3. The mixing process adopts a gradual stirring method, with the stirring speed gradually increasing from 3r / min to 6r / min, and the stirring time is 20-30 minutes to ensure that the two liquors are fully integrated and there is no layering. Step 5, settling and precision filtration: Place the blended liquor from Step 4 in an environment consistent with the storage environment (temperature 18-22℃, relative humidity 65-75%) and let it stand for 24-48 hours. After settling, perform precision filtration using a polyethersulfone filter membrane with a pore size of 0.22-0.45μm and a filtration pressure controlled at 0.1-0.3MPa. After filtration, the liquor is clear and transparent with no visible impurities, and the final product is a flavor-enhanced sauce-flavored liquor.

2. The process for preparing flavor-enhanced Maotai-flavor liquor based on oak barrel aging according to claim 1, characterized in that, In step one, the volume of the oak barrel is 100-500L, and the barrel opening is sealed with a food-grade silicone ring to ensure sealing performance while avoiding contamination of the wine.

3. The process for preparing flavor-enhanced Maotai-flavor liquor based on oak barrel aging according to claim 1, characterized in that, In step two, an automatic temperature and humidity monitoring and control system is installed in the constant temperature and humidity warehouse to monitor and maintain the ambient temperature and humidity within the set range in real time.

4. The process for preparing flavor-enhanced Maotai-flavor liquor based on oak barrel aging according to claim 1, characterized in that, In step two, the oak barrels are placed horizontally in the warehouse with the barrel body at an angle of 30-45° to the ground and the distance between adjacent oak barrels is not less than 10cm to ensure uniform air circulation in the warehouse.

5. The process for preparing flavor-enhanced Maotai-flavor liquor based on oak barrel aging according to claim 1, characterized in that, After the precision filtration in step five, the finished liquor needs to be tested for flavor substances. Among them, the content of malic acid, a marker of fruit and wood aroma, is not less than 9.6 mg / L, and the content of cherry ketone is not less than 6.2 mg / L; the content of rose ether, a marker of floral aroma, is not less than 4.8 mg / L, and the content of ionone is not less than 3.2 mg / L; and the content of vanillin, a marker of nutty aroma, is not less than 4.2 mg / L, and the content of eugenol is not less than 2.9 mg / L.

6. The process for preparing flavor-enhanced Maotai-flavor liquor based on oak barrel aging according to claim 1, characterized in that, The oak barrels pretreated in step one must be tested to confirm that the formaldehyde content is ≤0.1mg / L and the lead content is ≤0.01mg / L, which meets the safety limit requirements for food contact materials.

7. The process for preparing flavor-enhanced Maotai-flavor liquor based on oak barrel aging according to claim 1, characterized in that, The stirring operation in step three uses a special stirring equipment. All parts of the equipment that come into contact with the liquor are made of food-grade 304 stainless steel to avoid material contamination of the liquor.