A liquid rice vinegar brewing method based on dry material gelatinization

Abstract

The application discloses a liquid rice vinegar brewing method based on dry pasting of raw materials. The rice vinegar brewing method improves the existing vinegar brewing method, cancels the steps of rice crushing, liquefaction and saccharification, and performs dry pasting on the rice raw material, so that the rice vinegar product prepared has softer and mellow taste, richer aroma, and the vinegar brewing time is shortened, and the method is more suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of vinegar preparation technology, and in particular to a method for brewing liquid rice vinegar based on dry gelatinization of raw materials. Background Technology

[0002] Vinegar production can be categorized into several types based on different fermentation methods, including solid-state fermented vinegar, liquid-state fermented vinegar, and combined solid-liquid fermented vinegar. Among these, solid-state fermented vinegar is primarily represented by Chinese grain vinegars, such as Zhenjiang vinegar, Shanxi aged vinegar, and Sichuan bran vinegar. In contrast, liquid-state fermented vinegar is more widely distributed globally, including German alcoholic vinegar, British malt vinegar, and Italian grape vinegar. Liquid-state fermented vinegar primarily employs deep-bed aerated fermentation, a method known for its speed and efficiency. Chinese rice vinegar is a typical example of liquid-state fermented vinegar. Its production process involves crushing, liquefying, saccharifying, and fermenting rice into rice wine, followed by inoculation with a single acetic acid bacteria strain for deep liquid fermentation. Compared to traditional multi-strain solid-state fermentation methods, rice vinegar uses relatively simple raw materials and brewing bacteria, resulting in a product dominated by acetic acid, with a relatively bland flavor and simple taste. Due to Chinese dietary habits, people tend to prefer traditional solid-state fermented vinegar, which offers a richer and more diverse flavor, greater nutritional value, and a smoother taste. Therefore, manufacturers urgently need to innovate their liquid rice vinegar production methods to produce liquid rice vinegar that meets consumers' demands for flavor, nutrition, and taste.

[0003] In the current research field, the fermentation process of rice vinegar has been studied to some extent. Specifically, regarding the optimization of methods for liquid fermentation of rice vinegar, the article "Research on the Production of Rice Vinegar by Liquid Deep Fermentation Method" focuses on treating rice through enzyme liquefaction and saccharification. In contrast, another study entitled "Production Method and Physicochemical Index Analysis of Millet Vinegar" treats rice through enzyme liquefaction and saccharification, then uses Daqu (a type of starter culture) for alcoholic fermentation, and employs a solid-state method in acetic acid fermentation.

[0004] In the patent field, Chinese patent 201310252269.1 focuses on the application of dilute-state fermentation in rice vinegar production, which differs from traditional liquid-state fermentation methods. Similarly, Chinese patent 201410257255.6 describes a highly efficient rice vinegar production method, but focuses on improving production efficiency rather than improving the taste and flavor of rice vinegar. Chinese patent 201611129470.3 focuses on adding Daqu (a type of starter culture) to rice wine fermentation after rice liquefaction and saccharification to improve the flavor characteristics of rice vinegar. Patent 201910352472.6 mixes bran extract fermented with Lactobacillus helveticus with rice wine, then inoculates it with Pasteurella acetic acid bacteria for acetic acid fermentation to prepare liquid-state fermented rice vinegar, thereby improving the flavor of liquid-state fermented rice vinegar. In summary, these documents and patents provide detailed introductions to different rice vinegar production methods, including liquid-state fermentation, solid-state fermentation, and dilute-state fermentation. However, it should be noted that there are currently no reports on improving the flavor of liquid rice vinegar from the perspective of pretreatment of the main raw material, rice. This area has considerable room for research and exploration. Summary of the Invention

[0005] Purpose of the Invention: The purpose of this invention is to provide a brewing method for improving the flavor of vinegar through dry gelatinization of raw materials. Technical Solution: This invention provides a method for brewing liquid rice vinegar based on dry gelatinization of raw materials, comprising the following steps:

[0006] (1) Rice is rapidly gelatinized by heating with high-temperature hot air at a temperature of 280-320°C for 45-55 seconds; after gelatinization, it is cooled to room temperature.

[0007] (2) Mix the dry gelatinized rice, water and active dry yeast and inject them into an alcohol fermentation tank. Add saccharifying enzyme, mix thoroughly and carry out alcohol fermentation to obtain mature mash.

[0008] (3) Mix the dry gelatinized rice with water and pour it into a lactic acid fermentation tank. Add saccharifying enzyme and lactic acid bacteria liquid, mix thoroughly and carry out lactic acid fermentation to obtain lactic acid fermentation liquid.

[0009] (4) Mix the lactic acid fermentation liquid with the mature mash, add a filter aid, and filter through a plate and frame filter to obtain a clear liquid;

[0010] (5) Inoculate the clear liquid with acetic acid bacteria and carry out acetic acid liquid fermentation to obtain rice vinegar.

[0011] Further, in step (2), the solid-liquid ratio of rice to water is 1:2.5 to 3.5; the amount of saccharifying enzyme added is 100 to 200 U per gram of rice; the weight of active dry yeast added is 0.05 to 0.2% of the weight of rice; and the alcoholic fermentation cycle is 5 to 7 days.

[0012] Further, in step (3), the solid-liquid ratio of rice to water is 1:14 to 20; the amount of saccharifying enzyme added is 100 to 200 U per gram of rice.

[0013] Furthermore, the lactic acid bacteria liquid mentioned in step (3) is Lactobacillus fermentum.

[0014] Further, the inoculation amount of the lactic acid bacteria solution in step (3) is 5-15% v / v, and the lactic acid bacteria concentration of the lactic acid bacteria solution is 10. 7 ~10 8 CFU / mL, lactic acid fermentation cycle is 1-3 days.

[0015] Furthermore, the alcohol content of the solution after mixing the lactic acid fermentation liquid and the mature mash in step (4) is controlled at 9-11% v / v.

[0016] Furthermore, the filter aid mentioned in step (4) is diatomaceous earth.

[0017] Furthermore, the amount of filter aid added in step (4) is 1 to 2% of the weight of the rice.

[0018] Furthermore, the acetic acid bacillus mentioned in step (5) is Acetobacter pasteurianus, and the inoculation amount is 0.1 to 0.2‰ of the weight of the clear liquid.

[0019] Further, the fermentation conditions described in step (5) are an aeration rate of 0.10–0.20 vvm, a fermentation temperature of 28–32°C, and a fermentation cycle of 4–6 days.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following outstanding advantages: The rice vinegar brewing method of this application improves the existing vinegar brewing method, eliminates the steps of rice crushing, liquefaction and saccharification, and performs dry gelatinization of rice raw materials. The rice vinegar product prepared has a more mellow and rich taste and a more intense aroma. In addition, the pretreatment time of raw materials is shortened from 3-4 hours to about 0.5 hours, which is more suitable for industrial production. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to specific technical solutions.

[0022] Example 1

[0023] (1) Dry gelatinization of raw materials: The air in the hot air furnace is heated to 280℃ using a gas burner; hot air is sent into the fluidization chamber using a high-temperature blower; the fluidization time is controlled to 45s by adjusting the motor speed; rice raw materials are continuously and evenly added to the fluidization chamber using a quantitative feeder, so that the rice raw materials come into contact with the hot air and achieve rapid gelatinization; after gelatinization, the rice raw materials are discharged from the discharge pipe and cooled to room temperature by air; after the hot air passes through the fluidization chamber, it enters the cyclone separator, where dust is removed, and then it enters the hot air furnace through the air duct for reheating and recycling. Dust is discharged through the dust exhaust and airlock.

[0024] (2) Alcoholic fermentation: Dry gelatinized rice is mixed with water and active dry yeast in a certain proportion and then injected into an alcoholic fermentation tank. 100 U / g rice saccharifying enzyme is added and the mixture is thoroughly mixed before alcoholic fermentation. The ratio of rice to water is 1:2.5; the weight of active dry yeast is 0.05% of the weight of rice. Alcoholic fermentation is completed in 7 days.

[0025] (3) Lactic acid fermentation: Dry gelatinized rice is mixed with water and poured into a lactic acid fermentation tank. 100 U / g of rice saccharifying enzyme is added, and the mixture is thoroughly mixed before lactic acid fermentation. The rice-to-water ratio is 1:20. A 5% (v / v) culture of *Lactobacillus fermentum* (China General Microbiological Culture Collection Center, accession number CGMCC 12934) is inoculated, resulting in a lactic acid bacteria concentration of 4.2 × 10⁻⁶. 7 CFU / mL, fermentation ends in 1 day.

[0026] (4) Mix the lactic acid fermentation liquid with the mature mash, and control the alcohol content of the mixture at 10.2% (v / v). Add 1% of the weight of rice as a filter aid, diatomaceous earth, to the clear liquid, and then filter it through a plate and frame filter to obtain the clear liquid.

[0027] (5) Inoculate the clear liquid with 0.1‰ of the clear liquid with Acetobacter pasteurianus (China General Microbiological Culture Collection Center, accession number CGMCC12930) and carry out acetic acid liquid fermentation. The fermentation conditions are: aeration rate of 0.20 vvm, fermentation temperature of 28-32℃, and fermentation is completed in 6 days.

[0028] (6) The fermented rice vinegar is filtered and sterilized to obtain the rice vinegar product.

[0029] Example 2

[0030] (1) Dry gelatinization of raw materials: The air in the hot air furnace is heated to 300℃ using a gas burner; the hot air is sent into the fluidization chamber using a high-temperature blower; the fluidization time is controlled to 50s by adjusting the motor speed; the rice raw material is continuously and evenly added to the fluidization chamber using a metering feeder, so that the rice raw material comes into contact with the hot air and achieves rapid gelatinization; after the gelatinized rice raw material is discharged from the discharge pipe, it is cooled to room temperature by air; the hot air enters the cyclone separator after passing through the fluidization chamber, and after the dust is removed in the cyclone separator, it enters the hot air furnace through the air duct for reheating and recycling. The dust is discharged through the dust exhaust and airlock.

[0031] (2) Alcoholic fermentation: Dry gelatinized rice is mixed with water and active dry yeast in a certain proportion and then injected into an alcoholic fermentation tank. 150 U / g rice saccharifying enzyme is added and the mixture is thoroughly mixed before alcoholic fermentation. The ratio of rice to water is 1:3; the weight of active dry yeast is 0.12% of the weight of rice. Alcoholic fermentation is completed in 6 days.

[0032] (3) Lactic acid fermentation: Dry gelatinized rice is mixed with water and poured into a lactic acid fermentation tank. 150 U / g of rice saccharifying enzyme is added, and the mixture is thoroughly mixed before lactic acid fermentation. The rice-to-water ratio is 1:17. A 10% (v / v) culture of *Lactobacillus fermentum* (China General Microbiological Culture Collection Center, accession number CGMCC 12934, derived from patent CN110093285B) is inoculated, resulting in a lactic acid bacteria concentration of 5.6 × 10⁻⁶. 7 CFU / mL, fermentation ended in 1.5 days.

[0033] (4) Mix the lactic acid fermentation liquid with the mature mash, and control the alcohol content of the mixture at 10.1% (v / v). Add 1% of the weight of rice as a filter aid, diatomaceous earth, to the clear liquid, and then filter it through a plate and frame filter to obtain the clear liquid.

[0034] (5) Inoculate the clear liquid with 0.1‰ of the clear liquid with Acetobacter pasteurianus (China General Microbiological Culture Collection Center, accession number CGMCC12930, derived from patent CN108441435A) and carry out acetic acid liquid fermentation. The fermentation conditions are: aeration rate of 0.17 vvm, fermentation temperature of 28-32℃, and fermentation is completed in 5 days.

[0035] (6) The fermented rice vinegar is filtered and sterilized to obtain the rice vinegar product.

[0036] Example 3

[0037] (1) Dry gelatinization of raw materials: The air in the hot air furnace is heated to 320℃ using a gas burner; the hot air is sent into the fluidization chamber using a high-temperature blower; the fluidization time is controlled to 55s by adjusting the motor speed; the rice raw material is continuously and evenly added to the fluidization chamber using a metering feeder, so that the rice raw material comes into contact with the hot air and achieves rapid gelatinization; after the gelatinized rice raw material is discharged from the discharge pipe, it is cooled to room temperature by air; the hot air enters the cyclone separator after passing through the fluidization chamber, and after the dust is removed in the cyclone separator, it enters the hot air furnace through the air duct for reheating and recycling. The dust is discharged through the dust exhaust and airlock.

[0038] (2) Alcoholic fermentation: Dry gelatinized rice is mixed with water and active dry yeast in a certain proportion and then poured into an alcoholic fermentation tank. 200 U / g of rice saccharifying enzyme is added, and the mixture is thoroughly mixed before alcoholic fermentation. The ratio of rice to water is 1:3.5; the weight of active dry yeast is 0.2% of the weight of rice. The alcoholic fermentation cycle is 5 days.

[0039] (3) Lactic acid fermentation: Dry gelatinized rice is mixed with water and poured into a lactic acid fermentation tank. 200 U / g of rice saccharifying enzyme is added, and the mixture is thoroughly mixed before lactic acid fermentation. The rice-to-water ratio is 1:14. A 15% (v / v) culture of *Lactobacillus fermentum* (China General Microbiological Culture Collection Center, accession number CGMCC 12934) is inoculated, and the lactic acid bacteria concentration is 3.8 × 10⁻⁶. 7 CFU / mL, fermentation ends in 3 days.

[0040] (4) Mix the lactic acid fermentation liquid with the mature mash, and control the alcohol content of the mixture at 9.2% (v / v). Add 1% of the weight of rice as a filter aid, diatomaceous earth, to the clear liquid, and then filter it through a plate and frame filter to obtain the clear liquid.

[0041] (5) Inoculate the clear liquid with 0.1‰ of the clear liquid with Acetobacter pasteurianus (China General Microbiological Culture Collection Center, accession number CGMCC12930) and carry out acetic acid liquid fermentation. The fermentation conditions are: aeration rate of 0.14 vvm, fermentation temperature of 28-32℃, and fermentation is completed in 5 days.

[0042] (6) The fermented rice vinegar is filtered and sterilized to obtain the rice vinegar product.

[0043] Comparative Example 1

[0044] The other steps were the same as in Example 2. Comparative Example 1 used Lactobacillus plantarum (purchased from China Industrial Microbiology Preservation Center, accession number CICC 24828) for lactic acid fermentation.

[0045] Comparative Example 2

[0046] The other steps are consistent with those in Example 2. In Comparative Example 2, the rice pretreatment does not use the dry gelatinization method. Instead, the same weight of rice raw material is crushed to 80 mesh, mixed with water at a ratio of 1:3, an appropriate amount of liquefying enzyme is added, heated to 90°C, and maintained for 2 hours for liquefaction. The liquefied liquid is used for alcoholic fermentation and lactic acid fermentation in steps (2) and (3). The fermentation conditions are the same as in Example 2.

[0047] Comparative Example 3

[0048] The other steps are consistent with those in Example 2. In Comparative Example 2, the rice pretreatment does not use the dry gelatinization method. Instead, the same weight of rice raw material is crushed to 80 mesh, mixed with water at a ratio of 1:3, an appropriate amount of liquefying enzyme is added, heated to 90°C and maintained for 2 hours for liquefaction. The liquefied liquid is used for alcoholic fermentation in step (2) and lactic acid fermentation is not performed. After alcoholic fermentation, the alcohol content is diluted with tap water.

[0049] Comparison of the quality of balsamic vinegar obtained in the examples and comparative examples:

[0050] Table 1 Scoring Criteria for Color, Appearance, Aroma, and Taste of Balsamic Vinegar

[0051]

[0052]

[0053] Table 2 Comparison of sensory indicators of the balsamic vinegar produced in each embodiment and comparative example

[0054]

[0055] Table 3 Comparison of physicochemical properties of the balsamic vinegar produced in each embodiment and comparative example

[0056]

[0057] As can be seen from Tables 2 and 3, the rice vinegar obtained in the comparative example has a less desirable flavor and taste than that of the example. The present invention can significantly increase the content of non-volatile acids and lactic acid in rice vinegar, making the rice vinegar product more mellow and rich in flavor and aroma.

Claims

1. A liquid rice vinegar brewing method based on dry material gelatinization, characterized by, Comprising the following steps: (1) rapidly dry gelatinize the rice by high-temperature hot air heating, the heating temperature is 280~320℃, and the heating time is 45~55s; after gelatinization, it is cooled to room temperature; (2) mix the dry gelatinized rice, water and active dry yeast, then inject into the alcohol fermentation tank, add saccharifying enzyme, mix well, then perform alcohol fermentation to obtain mature mash; (3) mixing the dry-gelatinized rice and water, then injecting into a lactic acid fermentation tank, adding saccharifying enzyme and lactic acid bacteria liquid, mixing thoroughly, then carrying out lactic acid fermentation to obtain lactic acid fermentation liquid; the lactic acid bacteria is Lactobacillus fermentum (CGMCC 12934) Lactobacillus fermentum) CGMCC 12934; The solid-liquid ratio of the rice and water is 1:14~20; the addition amount of saccharifying enzyme is 100~200 U per g of rice; The inoculation amount of the lactic acid bacteria solution is 5-15% v / v, the lactic acid bacteria concentration of the lactic acid bacteria solution is 10 7 ~10 8 CFU / mL, and the lactic acid fermentation period is 1-3 days. (4) mix the lactic acid fermentation liquor with the mature mash, add filter aid, perform plate and frame filtration to obtain clear liquid; (5) inoculate Acetobacter into the clear liquid to perform acetic acid liquid state fermentation, and rice vinegar is obtained.

2. The raw material dry-pasting-based liquid rice vinegar brewing method according to claim 1, characterized by, In step (2), the solid-liquid ratio of the rice and water is 1:2.5~3.5; the addition amount of saccharifying enzyme is 100~200 U per g of rice; the addition weight of active dry yeast is 0.05~0.2% of the weight of the rice; and the alcohol fermentation period is 5~7 days.

3. The raw material dry-pasting-based liquid rice vinegar brewing method according to claim 1, characterized in that, In step (4), the alcohol content of the solution after mixing the lactic acid fermentation liquor with the mature mash is controlled to be 9~11% v / v.

4. The raw material dry-pasting-based liquid rice vinegar brewing method according to claim 1, characterized in that, In step (4), the filter aid is diatomite.

5. The raw material dry-pasting-based liquid rice vinegar brewing method according to claim 1, characterized in that, In step (4), the addition amount of filter aid is 1~2% of the weight of the rice.

6. The raw material dry-pasting-based liquid rice vinegar brewing method according to claim 1, characterized in that, The acetic acid bacteria in step (5) is Acetobacter pasteurianus. Acetobacter pasteurianus) The inoculation amount is 0.1-0.2‰ of the mass of the supernatant.

7. The raw material dry-pasting-based liquid rice vinegar brewing method according to claim 1, characterized in that, In step (5), the fermentation conditions are as follows: aeration amount 0.10~0.20 vvm, fermentation temperature 28~32℃, and fermentation period 4~6 days.

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