Staged Chinese prickly ash rice vinegar preparation method and staged Chinese prickly ash rice vinegar preparation device

Abstract

The invention provides a staged Chinese prickly ash rice vinegar preparation method. The method comprises the following steps: (1) pretreatment of Chinese prickly ash; (2) performing staged treatment on the Chinese prickly ash; (3) compound fermentation of a rice vinegar matrix; (4) after-ripening stabilizing treatment.Aiming at the defects in the prior art, efficient retention and flavor integration of volatile and non-volatile components of the Chinese prickly ash are achieved through a staged directional extraction and fermentation coordinated regulation technology, a first extract is added for the first time in the alcoholic fermentation period, and terpene is converted into an ester flavor precursor through yeast metabolism; in the acetic acid fermentation period, adding the second extract in three times in a gradient manner to realize gradual combination of amide substances and acetic acid molecules; the first extract is added for the second time in the after-ripening stage to restore fragrance through hydrogen bond recombination. The process solves the problems of serious loss of effective components and unbalanced flavor in the traditional technology, and the obtained Chinese prickly ash rice vinegar is strong in spicy flavor, soft in sourness and rich in functional components.

Description

Technical Field

[0001] This invention relates to the field of brewing technology in food processing, and in particular to a staged method and apparatus for preparing Sichuan pepper rice vinegar. Background Technology

[0002] Rice vinegar is an acidic condiment made primarily from starchy substances through a triple process of saccharification, alcoholic fermentation, and acetic acid fermentation. It is rich in organic acids, amino acids, and trace elements, possessing both a mellow taste and a unique sour aroma. Driven by market demand, vinegar is evolving from a basic condiment to a more functional and personalized product. For example, Sichuan pepper, a spice originating from the pre-Qin period and considered both food and medicine, shows unique development potential. The volatile oils, alkaloids, and unsaturated fatty amides in Sichuan pepper, when combined with vinegar, can produce the following effects: a rich and layered taste experience through the synergistic effect of numbing and aromatic flavor compounds and acetic acid molecules; and the traditional health benefits of warming the middle jiao (spleen and stomach), dispelling cold, removing dampness, and relieving pain. Existing technology CN112725137A discloses a Sichuan pepper rice vinegar and its preparation method, but it only involves pulverizing the pepper, adding water, and then boiling to obtain an extract, which is then added to vinegar. While this quickly imparts a numbing sensation to the vinegar, it still has the following problems: 1. Incomplete extraction of effective components: The extraction rate of effective components (such as volatile oil and unsaturated fatty acid amide) in Sichuan pepper is low. Traditional processes cannot distinguish between volatile and non-volatile components in Sichuan pepper, resulting in a high loss rate of heat-sensitive volatile oils such as limonene and linalool during high-temperature treatment, and a low extraction rate of non-volatile numbing substances such as Sichuan pepper amide. 2. Poor flavor harmony: The synergistic fermentation effect of rice vinegar and Sichuan peppercorns has not been fully developed. The addition of a single extract leads to insufficient combination of numbing substances with the acetic acid system, resulting in a problem of abrupt numbing sensation and unbalanced sour and fragrant flavor in the finished product. 3. Loss of functional activity: The traditional boiling method destroys functional substances such as ferulic acid (an antioxidant active ingredient) in Sichuan pepper, reducing its antioxidant capacity by about 28% compared to fresh Sichuan pepper. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a staged method for preparing Sichuan pepper rice vinegar, which enables more effective extraction and retention of active ingredients, resulting in Sichuan pepper rice vinegar with superior quality and flavor.

[0004] To achieve the above objectives, the present invention provides a staged method for preparing Sichuan pepper rice vinegar, comprising the following steps: (1) Pretreatment of Sichuan pepper: Spread the Sichuan pepper evenly on a baking tray and bake in a hot air circulating oven at 40~50℃ for 5~8 minutes until the moisture content is ≤8%, then grind it to 40~60 mesh.

[0005] (2) Staged extraction of Sichuan pepper: The process is carried out in stages. The pretreated peppercorns are processed in the first stage to extract the volatile oils and obtain the first extract. The tailings are then processed in the second stage to extract the non-volatile oils and obtain the second extract. (3) Compound fermentation of rice vinegar substrate A1, Alcoholic fermentation: After steaming rice to a gelatinization degree of ≥85%, cool it to 32℃, inoculate it with red yeast rice at a mass ratio of 15% and saccharify it for 24 hours. After saccharification is completed, add the first extract obtained in step A1 and ferment it for 4 to 5 days under temperature control at 28~32℃. When the alcohol content reaches 11%~12%vol, stop the fermentation. A2, Acetic acid fermentation: After the alcoholic fermentation is completed, water is added to adjust the alcohol content to 6.5~7.0%vol, and then acetic acid bacteria are inoculated to carry out acetic acid fermentation. During the acetic acid fermentation, the pepper soaking solution obtained by high temperature ultrasonic extraction in step A2 is added. The fermentation is completed when the alcohol content of the vinegar mash is <1%vol and the acidity is ≥5.0g / 100mL (calculated as acetic acid).

[0006] (4) Post-fermentation stabilization treatment: The fermented pepper rice vinegar is pasteurized and aged at low temperature of 10-15℃ for 10-15 days.

[0007] The advantages of the above technical solution are: This application extracts the first and second extracts in stages, allowing for targeted extraction based on the material characteristics. First, the volatile oily substances in Sichuan pepper are extracted. Specifically, the main components are limonene (accounting for 25%~35% of the total volatile oil), linalool (15%~20%), linalyl acetate (8%~12%), and other volatile oils, as well as a small amount of water-soluble small-molecule aldehydes and ketones aroma precursors. These oily substances are extracted to form the first extract. Subsequently, the remaining non-volatile components are extracted in the second stage. The extract (Sichuan pepper amide) mainly consists of amides and alkaloids such as hydroxy-α-sanshool and Sichuan pepper alkaloids, as well as phenolic antioxidants such as ferulic acid and quercetin, forming a second extract. These extracts are then added at different stages in subsequent processing to efficiently extract and retain the volatile oils and Sichuan pepper amides in Sichuan pepper. This process preserves the effective components and heat-sensitive aroma components of Sichuan pepper while harmonizing the flavor characteristics of Sichuan pepper rice vinegar. Ultimately, it achieves a three-dimensional synergistic optimization of flavor quality, functional characteristics, and processing technology, effectively solving the core problems of severe loss of effective components and flavor imbalance.

[0008] Further features of the present invention: In step (2), the first stage adopts low-temperature cold extraction, in which pretreated pepper and water are mixed at a ratio of 1:5 (g / mL) and left to stand at 4~8℃ for 36~48h to extract volatile components, and the first extract is obtained by filtration. The second stage adopts high-temperature ultrasonic extraction: the tailings after cold extraction are reconstituted with 50℃ pure water at a ratio of 1:10 (g / mL), and then ultrasonically treated to assist in the extraction of non-volatile components, and the second extract is obtained by filtration.

[0009] Through further design, in the first stage, low-temperature cold extraction (4~8℃) is used to inhibit the volatilization of volatile oils by heat. At the same time, long-term standing (36~48h) allows these oily components to fully dissolve. For non-volatile oils, high temperature is used to destroy the cell wall structure of Sichuan pepper, combined with high-frequency ultrasonic vibration, to accelerate the dissolution of these water-soluble or alcohol-soluble components, improve the extraction efficiency, and eliminate the need for additional chemical solvents. The overall extraction threshold is low. Furthermore, the combination of cold extraction followed by high-temperature ultrasonic extraction can extract as many effective components as possible from the same raw material, reduce the amount of effective components remaining, and indirectly reduce production costs.

[0010] Further configuration of the present invention: In step (2), the first stage adopts low-pressure extraction, the pretreated peppers are loaded into the extraction vessel, and supercritical carbon dioxide with a pressure of 10~15Mbar and a temperature of 35~45℃ is introduced for extraction for 1~2h. The first extract is collected in the separation vessel. The second stage adopts high-pressure extraction: the pressure of the tail material after the first stage treatment in the extraction vessel is increased to 25~35Mbar and the temperature is 50~60℃ for extraction to continue for 1.5~2.5h. The second extract is collected in the separation vessel.

[0011] By further designing the process, the first stage employs supercritical carbon dioxide low-pressure extraction. Utilizing the gas-like diffusion and liquid-like solubility of supercritical carbon dioxide, volatile oily substances are extracted at a relatively low temperature, resulting in high extraction efficiency. During the process, the oxidation and decomposition of volatile oils are reduced. In the second stage, the remaining material from the first stage, along with the supercritical carbon dioxide, is heated and pressurized to enter the second stage of processing. This results in higher overall efficiency, no solvent residue after extraction, and thorough separation.

[0012] Further features of the present invention: In step (3), the pepper soaking liquid obtained by high temperature ultrasonic extraction in step A2 is added three times. The first addition is made at the initial stage of fermentation when the alcohol content is 6.5~7.0%vol; the second addition is made at the middle stage of fermentation when the acidity is 3~4g / 100mL; and the third addition is made at the later stage of fermentation when the acidity is ≥4.5g / 100mL and the alcohol content is ≤2.0%vol.

[0013] By further configuring the process, the first addition (at the initial stage of fermentation, with an alcohol content of 6.5~7.0% vol) utilizes the high-alcohol environment to promote the dissolution of amides; the second addition (at the mid-stage of fermentation, with an acidity of 3~4 g / 100 mL) enables the molecular binding of amides and acetic acid through the metabolic activity of acetic acid bacteria; and the third addition (at the late stage of fermentation, with an acidity ≥4.5 g / 100 mL and an alcohol content ≤2.0% vol) completes flavor shaping and the retention of functional components. This phased addition of the ultrasonic extract utilizes the acetic acid metabolized by acetic acid bacteria to bind with the amides in Sichuan pepper, allowing the numbing sensation to be gently integrated into the acetic acid system, constructing a three-dimensional flavor network of "numbing-sour-fragrant" and improving the flavor harmony of the finished product. In addition, phenolic substances (such as ferulic acid and quercetin) in the high-temperature ultrasonic extract remain stable in the organic acid environment metabolized by acetic acid bacteria, and their antioxidant activity forms a synergistic antioxidant system with the organic acids in the vinegar, enhancing the functional characteristics of the product.

[0014] A further provision of the present invention: In step (4), the first extract from step A1 is added again, and during low-temperature aging, it is stirred once every 48 hours to promote flavor fusion and allow impurities to settle naturally.

[0015] Further features of the present invention: In step (4), the pasteurization temperature is 65°C and the sterilization time is 30 min; the added first extract needs to be sterilized by a 0.22 μm microporous membrane, and the dissolved oxygen is controlled to be ≤0.5 mg / L during aging.

[0016] A further feature of the present invention is that in step (4), the amount of the first extract added is 3% to 5% of the volume of the sterilized vinegar solution.

[0017] By further adjusting the process, the first extract was added at the beginning of alcoholic fermentation to promote the metabolism of yeast to produce esters such as linalyl acetate. The added low-temperature cold extract directly replenishes the heat-sensitive aroma components. The free limonene in the cold extract undergoes transesterification with the esters in the vinegar (ethyl acetate) (such as generating linalyl acetate), and the flavor network is reconstructed through hydrogen bonding to achieve a three-dimensional enhancement of the numbing and aromatic flavor and a softening of the acidity.

[0018] The present invention also provides a device for preparing Sichuan pepper rice vinegar, including a carbon dioxide storage tank. The carbon dioxide storage tank includes an outlet pipe and an inlet pipe that are respectively connected to an extraction vessel and a separation vessel. A delivery pump and a first heater are provided on the outlet pipe. A connecting pipe is provided between the extraction vessel and the separation vessel. A first pressure regulating valve is provided on the connecting pipe. A second pressure regulating valve is provided on the inlet pipe.

[0019] With further configuration, the extraction vessel and separation vessel are connected respectively through the gas outlet and gas inlet pipes of the carbon dioxide storage tank. With the help of a delivery pump, a first heater, and two sets of pressure regulating valves, the delivery pump ensures the delivery of carbon dioxide and can regulate the pressure of carbon dioxide in the extraction vessel in conjunction with the first pressure regulating valve. The first heater can heat the delivered carbon dioxide to the target extraction temperature, and the subsequent second pressure regulating valve can control the pressure of carbon dioxide after entering the separation vessel. After the extract is sent into the separation vessel, the carbon dioxide is de-supercritical, and the carbon dioxide and extract are separated and returned to the carbon dioxide storage tank, so that the carbon dioxide is circulated, while the extract remains in the separation vessel. The overall efficiency is high and the stability is strong.

[0020] A further feature of the present invention is that a second heater is also provided on the connecting pipe.

[0021] By further configuring the system, a second heater is added to the connecting pipe, which can further regulate the temperature of carbon dioxide entering the separation vessel. When supercritical carbon dioxide carries the extract from the extraction vessel into the separation vessel through the connecting pipe, the second heater can work with the second regulating valve to adjust the medium temperature in real time according to the process requirements of separation, ensuring efficiency and stability.

[0022] A further feature of the present invention is that a first one-way valve, a second one-way valve, and a third one-way valve are respectively provided on the outlet pipe, the connecting pipe, and the inlet pipe. The first one-way valve is located between the carbon dioxide storage tank and the delivery pump, the second one-way valve is located between the extraction vessel and the first pressure regulating valve, and the third one-way valve is located at the rear end of the second pressure regulating valve.

[0023] By further configuring the outlet pipe, connecting pipe, and inlet pipe, a first one-way valve, a second one-way valve, and a third one-way valve are respectively installed. The first one-way valve, located between the carbon dioxide storage tank and the delivery pump, effectively prevents carbon dioxide backflow, ensures stable operation of the delivery pump, and maintains the normal carbon dioxide delivery process. The second one-way valve, located between the extraction vessel and the first pressure regulating valve, prevents the reverse flow of substances in the extraction vessel, ensuring the effectiveness of pressure regulation and preventing impurities from flowing back and affecting the extraction effect. The third one-way valve, located downstream of the second pressure regulating valve, prevents abnormal backflow of substances in the pipeline, maintains a stable state after pressure regulation, and thus improves the safety, stability, and working efficiency of the entire system. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating Embodiment 1 of the present invention; Figure 2 This is a flowchart illustrating Embodiment 2 of the present invention; Figure 3 This is a schematic diagram of the device structure in Embodiment 2 of the present invention; The system includes: a carbon dioxide storage tank 1; an outlet pipe 11; a first check valve 111; an inlet pipe 12; a third check valve 121; an extraction vessel 2; a connecting pipe 21; a second check valve 211; a separation vessel 3; a transfer pump 4; a first heater 5; a first pressure regulating valve 6; a second pressure regulating valve 7; and a second heater 8. Detailed Implementation

[0025] Example 1 of the phased method for preparing Sichuan pepper rice vinegar of the present invention is as follows: Figure 1-3 As shown, it includes the following steps: Step 1: Take 150g of Hanyuan Dahongpao red peppercorns and 150g of Jiangjin green peppercorns, bake them in a 45℃ hot air circulating oven for 7 minutes until the moisture content is 7.8%, and then grind them to 50 mesh. Step 2, low-temperature cold extraction: Mix 300g of Sichuan pepper powder with 1500mL of 5℃ pure water, let stand at 6℃ for 40h, and filter to obtain 1280mL of the first extract; Step 3, high-temperature ultrasound: Add the cold extraction residue to 3000mL of 50℃ water and sonicate at a frequency of 40kHz and a power of 300W for 30min to assist in the extraction of non-volatile components. Filter to obtain 2850mL of the second extract. Step four, alcoholic fermentation: 10 kg of japonica rice was steamed, cooled to 32°C, inoculated with 1.5 kg of red yeast rice, saccharified for 24 hours, and then mixed with the first extract. Fermentation was carried out at 30°C for 5 days until the alcohol content reached 11.8% vol. After the alcoholic fermentation was completed, gas chromatography analysis showed that the limonene retention rate in the first extract was 89.6%.

[0026] Step 5, Acetic Acid Fermentation: After alcoholic fermentation, water is added to adjust the alcohol content to 7.0% vol, and acetic acid bacteria are inoculated to start acetic acid fermentation. During the deep liquid fermentation at 32℃, the second extract is added in three gradients (950 mL each time). The specific dynamic effects are as follows: First addition (day 3, alcohol content 6.8% vol): The high alcohol environment activates the acetic acid bacteria acyltransferase, promoting the dissolution of hydrophobic zanthamide (dissolution rate 88.7%); Second addition (day 6, acidity 3.8 g / 100 mL): Acetic acid bacteria enter the logarithmic growth phase, and the acetic acid produced by metabolism forms a complex with the amide through hydrophobic binding, reducing the sour taste stimulation index to 4.3; Third addition (day 9, acidity 5.0 g / 100 mL): Under low alcohol conditions (≤2.0% vol), the amide and organic acid self-assemble into nanomicelles (dynamic light scattering detection particle size 165 nm, PDI=0.21), achieving a sustained release of numbing sensation, which lasts for 35 seconds. Fermentation was terminated when the total acid content reached 5.3 g / 100 mL (calculated as acetic acid).

[0027] Step Six: After pasteurizing the vinegar at 65℃ for 30 minutes, add the first extract (4% of the sterilized vinegar volume) filtered through a 0.22μm microporous membrane, and place in a 12℃ constant temperature tank. Aging is carried out for 13 days using intermittent magnetic stirring (200 rpm, 5 minutes / 48 hours), with dissolved oxygen controlled below 0.3 mg / L. The final product has a volatile oil content of 0.9 mg / mL, a DPPH free radical scavenging rate of 62%, and a turbidity of 4.8 NTU. Sensory evaluation shows a rich numbing aroma, a mellow acidity (acidity 5.3 g / 100 mL), and a flavor harmony score of 9.2 out of 10.

[0028] The Sichuan peppercorn rice vinegar of this application is characterized by its rich numbing aroma and mellow acidity. By blending red and green Sichuan peppercorns in a 1:1 ratio and employing a phased addition strategy, the finished product combines the intense numbing aroma of red Sichuan peppercorns with the refreshing fruity aroma of green Sichuan peppercorns. Furthermore, through low-temperature aging, the organic acid-amide complexation process ensures that the total acidity of the finished product is ≥5.0g / 100mL, while achieving a mellow acidity score of 9 / 10 (compared to ≤6.2 for traditional processes).

[0029] An embodiment 2 of the present invention, a staged method for preparing Sichuan pepper rice vinegar and its preparation apparatus, is described below. It includes a carbon dioxide storage tank 1, which has an outlet pipe 11 and an inlet pipe 12 respectively connecting an extraction vessel 2 and a separation vessel 3. The outlet pipe 11 is equipped with a delivery pump 4 and a first heater 5. A connecting pipe 21 is provided between the extraction vessel 2 and the separation vessel 3. A first pressure regulating valve 6 is provided on the connecting pipe 21, a second pressure regulating valve 7 is provided on the inlet pipe 12, and a second heater 8 is also provided on the connecting pipe 21.

[0030] The outlet pipe 11, the connecting pipe 21, and the inlet pipe 12 are respectively equipped with a first one-way valve 111, a second one-way valve 211, and a third one-way valve 121. The first one-way valve 111 is located between the carbon dioxide storage tank 1 and the transfer pump 4. The second one-way valve 211 is located between the extraction vessel 2 and the first pressure regulating valve 6. The third one-way valve 211 is located at the rear end of the second pressure regulating valve 7.

[0031] It also includes the following steps: Step 1: Take 150g of Hanyuan Dahongpao red peppercorns and 150g of Jiangjin green peppercorns, bake them in a 45℃ hot air circulating oven for 7 minutes until the moisture content is 7.8%, and then grind them to 50 mesh. Step 2: The processed Hanyuan Dahongpao red peppercorns and Jiangjin green peppercorns are placed into the extraction vessel 2. Carbon dioxide from the carbon dioxide storage tank 1 is sent into the extraction vessel 2 through the delivery pump 4 and the gas outlet pipe 11. Then, through the first heater 5 and the first pressure regulating valve 6, the extraction vessel is brought to 10 Mbar and 40°C for 1.5 hours. Then, through the connecting pipe 21, the supercritical carbon dioxide and the extract therein are sent into the separation vessel 3. During the transportation process, the temperature is regulated by the second heater 8. After entering the separation vessel 3, the supercritical state of carbon dioxide is released by the second pressure regulating valve 7, so that the extract and carbon dioxide are separated, and 12.8g of the first extract is obtained and taken out. Step 3: Carbon dioxide storage tank 1 delivers carbon dioxide to extraction vessel 2 again via delivery pump 4. With the cooperation of first heater 5 and first pressure regulating valve 6, the extraction vessel reaches 30 Mbar and 55°C, and extraction lasts for 1.8 hours. Then, supercritical carbon dioxide and its extract are sent to separation vessel 3 through connecting pipe 21. During the delivery process, the temperature is regulated by second heater 8. After entering separation vessel 3, the supercritical state of carbon dioxide is released with the cooperation of second pressure regulating valve 7, so that the extract and carbon dioxide are separated, and 18.5g of second extract is obtained. Step 4, alcoholic fermentation: 10 kg of japonica rice was steamed, cooled to 32°C, and inoculated with 1.5 kg of red yeast rice for 24 hours. Then, the first extract (dissolved in 50 mL of ethanol) was added, and fermentation was carried out at 30°C for 5 days until the alcohol content reached 11.8% vol. After the alcoholic fermentation was completed, gas chromatography analysis showed that the limonene retention rate in the first extract was 89.6%.

[0032] Step 5, Acetic Acid Fermentation: After alcoholic fermentation, water is added to adjust the alcohol content to 7.0% vol, and acetic acid bacteria are inoculated to start acetic acid fermentation. During the deep liquid fermentation at 32℃, the second extract emulsion is added in three gradients (61.6g each time). The specific dynamic effects are as follows: First addition (day 3, alcohol content 6.8% vol): The high alcohol environment activates the acetic acid bacteria acyltransferase, promoting the dissolution of hydrophobic zanthamide (dissolution rate 88.7%); Second addition (day 6, acidity 3.8g / 100mL): Acetic acid bacteria enter the logarithmic growth phase, and the acetic acid produced by metabolism forms a complex with the amide through hydrophobic binding, reducing the sour taste stimulation index to 4.3; Third addition (day 9, acidity 5.0g / 100mL): Under low alcohol conditions (≤2.0% vol), the amide and organic acid self-assemble into nanomicelles (dynamic light scattering detection particle size 165nm, PDI=0.21), achieving a sustained release of numbing sensation, which lasts for 35 seconds. Fermentation was terminated when the total acid content reached 5.3 g / 100 mL (calculated as acetic acid).

[0033] Step Six: After pasteurizing the vinegar at 65℃ for 30 minutes, add the first extract (4% of the sterilized vinegar volume) filtered through a 0.22μm microporous membrane, and place in a 12℃ constant temperature tank. Aging is carried out for 13 days using intermittent magnetic stirring (200 rpm, 5 minutes / 48 hours), with dissolved oxygen controlled below 0.3 mg / L. The final product has a volatile oil content of 0.9 mg / mL, a DPPH free radical scavenging rate of 62%, and a turbidity of 4.8 NTU. Sensory evaluation shows a rich numbing aroma, a mellow acidity (acidity 5.3 g / 100 mL), and a flavor harmony score of 9 out of 10.

[0034] The Sichuan peppercorn rice vinegar of this application is characterized by its rich numbing aroma and mellow acidity. By blending red and green Sichuan peppercorns in a 1:1 ratio and employing a phased addition strategy, the finished product combines the intense numbing aroma of red Sichuan peppercorns with the refreshing fruity aroma of green Sichuan peppercorns. Furthermore, through low-temperature aging, the organic acid-amide complexation process ensures that the total acidity of the finished product is ≥5.0g / 100mL, while the acidity mellowness score reaches 8.7 / 10 (compared to ≤6.2 in traditional processes).

[0035] The above examples are merely one preferred embodiment of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solution of the present invention are all included within the protection scope of the present invention.

Claims

1. A staged method for preparing Sichuan peppercorn rice vinegar, characterized in that, The steps include the following: (1) Pretreatment of Sichuan pepper: Spread the Sichuan pepper evenly on a baking tray and bake in a hot air circulating oven at 40~50℃ for 5~8 minutes until the moisture content is ≤8%, then grind it to 40~60 mesh; (2) Sichuan peppercorns are processed in stages: The process is carried out in stages. The pretreated peppercorns are processed in the first stage to extract the volatile oils and obtain the first extract. The tailings are then processed in the second stage to extract the non-volatile oils and obtain the second extract. (3) Compound fermentation of rice vinegar substrate: A1, Alcoholic fermentation: After steaming rice to a gelatinization degree of ≥85%, cool it to 32℃, inoculate it with red yeast rice at a mass ratio of 15% and saccharify it for 24 hours. After saccharification is completed, add the first extract and ferment it for 4 to 5 days under temperature control at 28~32℃. When the alcohol content reaches 11%~12%vol, stop the fermentation. A2, Acetic acid fermentation: After the alcoholic fermentation is completed, water is added to adjust the alcohol content to 6.5~7.0% vol, and then acetic acid bacteria are inoculated to carry out acetic acid fermentation. During the acetic acid fermentation, the second extract is added. The alcohol content of the vinegar mash should be <1% vol, and the acidity should be ≥5.0g / 100mL (calculated as acetic acid). Fermentation is then completed. (4) Post-fermentation stabilization treatment: The fermented pepper rice vinegar is pasteurized and aged at low temperature of 10-15℃ for 10-15 days.

2. The staged method for preparing Sichuan pepper rice vinegar according to claim 1, characterized in that: In step (2), the first stage uses low-temperature cold extraction, where pretreated peppercorns are mixed with water at a ratio of 1:5 (g / mL) and left to stand at 4~8℃ for 36~48h to extract volatile components. The first extract is obtained by filtration. The second stage uses high-temperature ultrasonic extraction: the tailings after cold extraction are reconstituted with 50℃ pure water at a ratio of 1:10 (g / mL), followed by ultrasonic treatment to assist in the extraction of non-volatile components. The second extract is obtained by filtration.

3. The staged method for preparing Sichuan pepper rice vinegar according to claim 1, characterized in that: In step (2), the first stage uses low-pressure extraction. The pretreated peppercorns are loaded into the extraction vessel, and supercritical carbon dioxide at a pressure of 10~15Mbar and a temperature of 35~45℃ is introduced for extraction for 1~2 hours. The first extract is collected in the separation vessel. The second stage uses high-pressure extraction. The pressure of the tail material after the first stage treatment in the extraction vessel is increased to 25~35Mbar and the temperature is 50~60℃ for extraction for 1.5~2.5 hours. The second extract is collected in the separation vessel.

4. The staged method for preparing Sichuan pepper rice vinegar according to claim 1, 2, or 3, characterized in that: In step (3), the second extract is added in three portions, with the first addition occurring at the initial stage of fermentation when the alcohol content is 6.5-7.0% vol. The second addition should be made during the middle stage of fermentation, when the acidity is 3~4g / 100mL; The third addition is made in the later stage of fermentation when the acidity is ≥4.5g / 100mL and the alcohol content is ≤2.0%vol.

5. The staged method for preparing Sichuan pepper rice vinegar according to claim 1, 2, or 3, characterized in that: In step (4), after sterilization, the first extract is added again and stirred every 48 hours during low-temperature aging to promote flavor fusion and remove impurities by natural sedimentation.

6. The staged method for preparing Sichuan pepper rice vinegar according to claim 5, characterized in that: In step (4), the amount of the first extract added is 3% to 5% of the volume of the sterilized vinegar solution.

7. The staged method for preparing Sichuan pepper rice vinegar according to claim 5, characterized in that: In step (4), the pasteurization temperature is 65℃ and the sterilization time is 30min. The first extract added needs to be sterilized by a 0.22μm microporous membrane. During aging, the dissolved oxygen is controlled to be ≤0.5mg / L.

8. A Sichuan pepper rice vinegar preparation apparatus based on the staged method for preparing Sichuan pepper rice vinegar according to claim 3, characterized in that: It includes a carbon dioxide storage tank, which includes an outlet pipe and an inlet pipe that are respectively connected to an extraction vessel and a separation vessel. The outlet pipe is equipped with a delivery pump and a first heater. A connecting pipe is provided between the extraction vessel and the separation vessel. A first pressure regulating valve is provided on the connecting pipe, and a second pressure regulating valve is provided on the inlet pipe.

9. The apparatus for preparing Sichuan peppercorn rice vinegar according to claim 8, characterized in that: A second heater is also installed on the connecting pipe.

10. The apparatus for preparing Sichuan peppercorn rice vinegar according to claim 8, characterized in that: The gas outlet pipe, connecting pipe, and gas inlet pipe are respectively equipped with a first one-way valve, a second one-way valve, and a third one-way valve. The first one-way valve is located between the carbon dioxide storage tank and the delivery pump. The second one-way valve is located between the extraction vessel and the first pressure regulating valve. The third one-way valve is located at the rear end of the second pressure regulating valve.

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