Preparation process of red yeast rice

Abstract

The invention provides a preparation process of red yeast rice, which is characterized by comprising the following steps: (1) preparing rice koji juice; (2) blending rice koji juice and mature vinegar liquid; (3) selection of red yeast seed koji; (4) preparing wine mother liquor; (5) preparing kojic rice; (6) culturing in a koji room; (7) drying in the sun; aiming at the defects in the prior art, the invention provides the red yeast rice wine which is higher in productivity, more stable in quality and beneficial to enriching the flavor of the red yeast rice wine.

Description

Technical Field

[0001] The invention relates to the field of microbial fermentation, in particular to a red yeast rice production process. Background Art

[0002] Red yeast rice (hongqu) is a special type of koji used in the brewing of Chinese rice wine. Made from rice, it is inoculated with koji mother. Rich in active ingredients such as red yeast pigments, monacolin K, and gamma-aminobutyric acid (GABA), it possesses potential health benefits, including antioxidant, antibacterial, and lipid-lowering properties. Wine brewed with this type of koji, known as red yeast rice wine, is characterized by its vibrant color and rich flavor. Existing red yeast rice production methods suffer from numerous drawbacks that require improvement and optimization. First, the red yeast is susceptible to contamination by bacteria. The presence of highly infectious molds and acid-producing microorganisms in the air creates demanding production environments and leads to inconsistent quality. Second, because the growth temperature of the red yeast requires 30-40°C, production can only be done once or twice a year, depending on the season. This results in low yields and a long production cycle, failing to meet market demand. Third, the flavor of red yeast rice wine produced with this method is relatively monotonous, lacking the rich, complex taste of wheat koji rice wine. Therefore, improving the red yeast rice production process, increasing its production capacity and production quality, and enriching the flavor of red yeast rice wine are the key research directions that the red yeast rice brewing industry needs to focus on at this stage. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the present invention provides a method with higher production capacity, more stable quality and helps to enrich the flavor of red yeast rice wine.

[0004] To achieve the above object, the present invention provides a red yeast rice production process, characterized in that it includes the following steps: (1) Preparation of rice koji juice: soak glutinous rice, steam it, and cool it down, then inoculate Aspergillus niger and culture it, then add clean water and mix it, and finally filter it to obtain rice koji juice; (2) Preparation of rice koji juice-aged vinegar liquid: Select red yeast rice vinegar, add rice koji juice and stir evenly, and control the pH value of the stirred rice koji juice-aged vinegar liquid to 4.4-5.3, and the reducing sugar content to 90-110g / L; (3) Selection of red yeast rice: The yellow rice wine lees squeezed from the yellow rice wine mash are selected and separated by dilution and coating, and continuously subcultured to screen out the red yeast with strong vitality and rich enzyme system. The strain is then confirmed by PCR and sequencing technology, and then expanded and cultured in the first-level seed liquid and the second-level liquid culture medium, and used as the seed rice for subsequent red yeast rice inoculation; (4) Preparation of yeast liquor: Grind the selected red yeast rice into powder with a grinder, add the prepared rice yeast juice and aged vinegar solution, stir into a paste, control the room temperature at 25-30℃ and culture for 108-132 hours. The yeast liquor has a saccharification power of ≥200u / ml, a liquefaction power of ≥500u / ml, and a yeast count of ≥10 8 / ml, and when used later, add hot water cooled to 30℃ to dilute it into the yeast liquor; (5) Preparation of koji rice: soak early indica rice in room temperature water for 6 hours, drain and steam, cool to 40°C by air cooling, and then control the temperature at 32-38°C before adding diluted yeast liquor; (6) Entering the koji room for cultivation: The inoculated koji rice is transported to the koji room for heat preservation. The rice is naturally heated up in the first 20 to 24 hours. When a small amount of white spots appear on the surface of the koji rice and the temperature reaches 39-41°C, the rice is evenly spread out. The koji rice is cultivated for about 6 to 8 days. During this period, the temperature is controlled at 28 to 34°C. When the temperature exceeds the above range, the koji needs to be turned over and cooled. Starting from the third day, when the moisture in the koji dissipates to dryness, clean water is sprayed appropriately and the water temperature is controlled at 28-30°C. It takes 1 to 2 days. After 7 days of cultivation, when the surface of the rice grains is completely covered with red mycelium, the culture is mature. (7) Drying the koji: When the koji is red inside and out and has a special red koji aroma, it can be transferred to the oven and dried at 28℃ for 24 hours to obtain the finished red koji. It is then stored in clean PE bags. The surface of the finished koji is purple-red, the cross section is semi-pink, and the center is slightly white. The moisture content is 10-15%, the saccharification power is ≥1000u / g, the liquefaction power is ≥1000u / g, and the yeast count is ≥10. 8 pcs / ml; Furthermore, the reducing sugar content of the rice koji juice is ≥200 g / L; Furthermore, red yeast rice vinegar needs to be aged vinegar with a total acidity of ≥5.00g / 100mL; Furthermore, the coarseness of the red yeast rice powder needs to pass through a 40-mesh sieve.

[0005] The advantages of adopting the above technical solution are: the present invention uses rice koji juice instead of glutinous rice as the carbon source for the early expansion of red yeast rice, and simultaneously produces red yeast rice seed koji, and grinds the red yeast rice seed into powder, thereby expanding the contact area between the monascus and the culture solution, which is conducive to promoting the growth and reproduction of microorganisms in the red yeast rice and reducing the amount of seed koji used. In addition, red yeast rice vinegar is added to adjust the pH of the culture solution, thereby avoiding contamination by miscellaneous bacteria during the yeast culture process and stabilizing the quality of the red yeast rice seed. It also provides a richer flavor for the subsequent production of red yeast rice wine, making the red yeast rice wine soft and rich in flavor, and highlighting the characteristics of softness, mellowness, fragrance, mellowness, smoothness and saturation. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 A schematic diagram of a flow chart of an embodiment of the present invention; DETAILED DESCRIPTION

[0007] The present invention is a method for producing red yeast rice. Figure 1 The specific process is as follows: Step 1, preparation of rice koji juice: soak glutinous rice for 24 minutes and then drain it. Put the rice into the steamer and steam it for about 30-40 minutes, until the rice grains are fully cooked but not too soft. It means that the rice has reached the proper degree of maturity and the starch is fully gelatinized. At this time, there is no hard part inside the rice grains, but it has not become too soft and loose due to long cooking time or other reasons, and has lost the shape and elasticity of the rice grains. The rice grains still maintain a certain integrity and texture. The moisture content is 50-55%. After steaming, air cool and spread to 35-40℃. Then, sprinkle 0.1% Aspergillus niger spores evenly on the cooled rice and stir gently to evenly distribute the spores. Put the rice into the fermentation container and spread it into a thin layer, roughly 2-3 cm thick. Cultivate it in a well-ventilated environment at a temperature of 30-35°C. Turn the rice over every 12 hours to ensure uniform fermentation and prevent the temperature from being too high. The fermentation process takes 48-72 hours, until the surface of the rice is covered with mycelium and emits a sweet aroma. Finally, add the cultured rice koji to clean water and mix evenly. Heat the mixture to 60-70°C and keep it for 1-2 hours to allow the enzyme in the rice koji to decompose starch and protein, releasing sugar and amino acids. Filter the mixture. The filtrate obtained is the rice koji juice. When used later, it needs to be diluted with water to a total sugar of 100-120g / L and sterilized at high temperature.

[0008] Step 2, selection of red yeast rice: select yellow rice wine lees squeezed from yellow rice wine mash with good yellow rice wine flavor and high alcohol content, separate them by dilution and coating, continuously cultivate, screen out red yeast with strong vitality and rich enzyme system, and then confirm the strain by PCR and sequencing technology, and then expand the culture through the first-level seed liquid and second-level liquid culture medium. The specific culture process is as follows: add 3% red yeast vinegar and 0.2% yellow rice wine special yeast to the second-level liquid culture medium and inoculate it into steamed indica rice, cover it with a sterilized wet cloth, and culture it in an incubator at a temperature of 32-36℃ and a humidity of 65-75% for 2 days. 4h, white spots will appear on the surface of the rice, gently turn the rice over, during which the temperature of the rice is controlled at 35-40℃, and after another 24h, the surface of the rice will turn light pink, put the rice into a fine filter bag, soak it in 32-36℃ sterile water for 2-3 seconds, and put it back into the incubator for cultivation. This practice continues for 2-3 days, during which the rice needs to be turned over once every morning and evening. On the 10th day of cultivation, the red yeast rice culture is completed and dried in a 40℃ oven. The cultured red yeast rice has a moisture content of ≤10%, a saccharifying power ≥1500u / g, a liquefying power ≥1500u / g, and a yeast count ≥10 8 pcs / ml.

[0009] Step 3: Pour 8kg of diluted rice koji juice and 0.5kg of red yeast vinegar into a ceramic jar and stir evenly. The temperature of the mixture is controlled at 28-32°C, the pH is 4.4-5.3, and the reducing sugar is 90-110g / L.

[0010] Step 4: Grind the selected red yeast rice into powder with a grinder, pour 1.3 kg of red yeast rice powder into a ceramic jar, and stir it evenly with the rice yeast juice-aged vinegar mixture to form a paste. Incubate it at a temperature of 25-30 ° C and a humidity of 65-75% for 5 days. During this period, stir the yeast liquor once in the morning and once in the evening. The yeast liquor at the end of the incubation period has a saccharification power of ≥ 200u / ml, a liquefaction power of ≥ 500u / ml, and a yeast count of ≥ 10 8 pcs / ml.

[0011] Step 5: Take 7.5 kg of the finished yeast liquor, add 3.5 L of red yeast rice vinegar, and add water to 60 L. The liquid temperature is controlled at 28-32 ° C.

[0012] Step 6: soak 1500 kg of indica rice in room temperature water for 6 hours, drain, and use a horizontal rice steamer to steam at a pressure of 0.6-0.8 MPa until the rice grains have no white core, and then cool them with air cooling. After soaking, the rice has a moisture content of about 50% and a temperature of 40-45° C.

[0013] Step seven, while the rice is being conveyed through the rice steamer transmission system, the mixed yeast liquor is evenly mixed with the rice, ensuring that the Monascus is evenly distributed throughout all the steamed rice.

[0014] Step eight, the inoculated koji rice is transported to the koji room and covered with clean straw for insulation. The rice is naturally heated for the first 20 to 24 hours. When a small amount of white spots appear on the surface of the koji rice and the temperature reaches about 40°C, the rice is evenly spread out. The koji rice is cultured for about 6 to 8 days, during which the temperature is controlled at 28 to 34°C. When the temperature is too high, the koji needs to be turned over and cooled in time. On the third day, the moisture in the koji is dissipated to dryness, and clean water is sprayed appropriately. The water temperature is controlled at 28-30°C for 1-2 days. After 7 days of culture, the surface of the rice grains is completely covered with red mycelium and the culture is mature.

[0015] Step nine, when the koji is red inside and out and has a special red koji aroma, it can be transferred to the drying room and dried at 28℃ for 24 hours to obtain the finished red koji. It is then stored in clean PE bags. The surface of the finished koji is purple-red, the cross section is semi-pink, and the center is slightly white. The moisture content is 10-18%, the saccharification power is ≥1000u / g, the liquefaction power is ≥1000u / g, and the yeast count is ≥10 8 pcs / ml.

[0016] The above example is only one preferred specific example of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention are all included in the protection scope of the present invention.

Claims

1. A red yeast rice production process, characterized in that: The following steps are included: (1) Preparation of rice koji juice: soak glutinous rice, steam it, and cool it down, then inoculate Aspergillus niger and culture it, then add clean water and mix it, and finally filter it to obtain rice koji juice; (2) Preparation of rice koji juice-aged vinegar liquid: Select red yeast rice vinegar, add rice koji juice and stir evenly, and control the pH value of the stirred rice koji juice-aged vinegar liquid to 4.4-5.3, and the reducing sugar content to 90-110g / L; (3) Selection of red yeast rice: The yellow rice wine lees squeezed from the yellow rice wine mash are selected and separated by dilution and coating, and continuously subcultured to screen out the red yeast with strong vitality and rich enzyme system. The strain is then confirmed by PCR and sequencing technology, and then expanded and cultured in the first-level seed liquid and the second-level liquid culture medium, and used as the seed rice for subsequent red yeast rice inoculation; (4) Preparation of yeast liquor: Grind the selected red yeast rice into powder with a grinder, add the prepared rice yeast juice and aged vinegar solution, stir into a paste, control the room temperature at 25-30℃ and culture for 108-132 hours. The yeast liquor has a saccharification power of ≥200u / ml, a liquefaction power of ≥500u / ml, and a yeast count of ≥10 8 / ml, and when used later, add hot water cooled to 30℃ to dilute it into the yeast liquor; (5) Koji rice inoculation: soak early indica rice in room temperature water for 6 hours, drain and steam, cool to 40°C by air cooling, then control the temperature at 32-38°C, and then add diluted yeast liquor; (6) Entering the koji room for cultivation: The inoculated koji rice is transported to the koji room for heat preservation. The rice is naturally heated up in the first 20 to 24 hours. When a small amount of white spots appear on the surface of the koji rice and the temperature reaches 39-41°C, the rice is evenly spread out. The koji rice is cultivated for about 6 to 8 days. During this period, the temperature is controlled at 28 to 34°C. When the temperature exceeds the above range, the koji needs to be turned over and cooled. Starting from the third day, when the moisture in the koji dissipates to dryness, clean water is sprayed appropriately and the water temperature is controlled at 28-30°C. It takes 1 to 2 days. After 7 days of cultivation, when the surface of the rice grains is completely covered with red mycelium, the culture is mature. (7) Drying the koji: When the koji is red inside and out and has a special red koji aroma, it can be transferred to the oven and dried at 28℃ for 24 hours to obtain the finished red koji. It is then stored in clean PE bags. The surface of the finished koji is purple-red, the cross section is semi-pink, and the center is slightly white. The moisture content is 10-15%, the saccharification power is ≥1000u / g, the liquefaction power is ≥1000u / g, and the yeast count is ≥10. 8 pcs / ml.

2. A red yeast rice production process according to claim 1, characterized in that: In the step (1), the glutinous rice is soaked for 24 hours and then drained. The rice is placed in a steamer and steamed for about 30-40 minutes until the rice grains are fully cooked and the moisture content is 50-55%. After steaming, the rice is air-cooled and spread to cool to 35-40°C.

3. A red yeast rice production process according to claim 1, characterized in that: In the step (1), Aspergillus niger is inoculated and cultured: 0.1% Aspergillus niger spores are evenly sprinkled on the cooled rice and gently stirred to evenly distribute the spores. The inoculated rice is placed in a fermentation container and spread into a thin layer 2-3 cm thick. The rice is cultured in a well-ventilated environment at a temperature of 30-35°C. The rice is turned over every 12 hours to ensure uniform fermentation and temperature control. The fermentation process lasts for 48-72 hours until the surface of the rice is covered with mycelium and emits a sweet aroma.

4. A red yeast rice production process according to claim 1, characterized in that: In the step (1), the rice koji juice is prepared by adding the cultured rice koji to clean water and mixing evenly, heating the mixture to 60-70°C and maintaining it for 1-2 hours to allow the enzyme in the rice koji to decompose starch and protein, releasing sugar and amino groups, filtering the mixture, and obtaining the filtrate, which is the rice koji juice. When used, it needs to be diluted with water to a total sugar content of 100-120 g / L and sterilized at high temperature.

5. A red yeast rice production process according to claim 1, characterized in that: In the step (1), the reducing sugar content of the rice koji juice is ≥200 g / L.

6. A red yeast rice production process according to claim 1, characterized in that: In the step (2), the red yeast rice vinegar needs to be aged vinegar with a total acid content of ≥5.00 g / 100 mL.

7. A red yeast rice production process according to claim 1, characterized in that: In the step (4), the coarseness of the red yeast rice powder needs to pass through a 40-mesh sieve.

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