Nutrient-rich red yeast rice bran and preparation method thereof

Abstract

The invention relates to nutrient-rich red yeast rice bran and a preparation method thereof.The preparation method comprises the following steps that after rice bran is subjected to enzyme deactivation and sterilization treatment, the moisture is controlled to be 20%-30%; adding a composite enzymatic hydrolysate into the pretreated rice bran, uniformly stirring, and performing enzymolysis to obtain a semi-solid base material; the temperature of the semi-solid base material is controlled to be 36-40 DEG C, and the pH value is adjusted to be 5.0-5.5; inoculating monascus for culturing, turning over the yeast once every 10-12 hours, and culturing for 5-6 days to obtain a yeast material; spreading and culturing the koji material, and controlling the temperature of the koji material to be 30-35 DEG C; after the culture is completed, drying the yeast material until the moisture is below 10% to obtain the nutrient-rich red yeast rice bran; the monascus rice bran with high content of monacolin K can be obtained through the method, the technological operation is simple, the labor intensity of workers is reduced, the production period is short, and the method is suitable for large-scale application and has remarkable economic benefits and social benefits.

Description

Technical Field

[0001] The invention relates to the technical field of rice bran processing, and more specifically to nutrient-rich red yeast rice bran and a preparation method thereof. Background Art

[0002] Red yeast rice is a traditional Chinese fermented food with a long history. It is also called danqu or red yeast rice. It is considered a precious health product by traditional Chinese medicine and is also widely used in food processing and cooking. At present, red yeast rice is mainly produced by fermenting southern crops such as indica rice and rice, but there are the following problems: ① Rice, as a major food crop, is used as a fermentation matrix for red yeast rice enzyme, and the fermentation cost is relatively high, which is not conducive to the large-scale industrial production of red yeast rice; ② The traditional operation method using rice as the fermentation matrix has high operation intensity and long rice pre-treatment time. The process from rice soaking to washing, draining and steaming takes 1-2 days. At the same time, during the fermentation process, the rice matrix is ​​compact, so it is necessary to ensure conditions such as turning over and ventilation; ③ Over-processing of rice removes the bran layer on the surface of rice, resulting in malnutrition. During the rice koji making process, carbon sources (glycerol, soluble starch, glucose, etc.), nitrogen sources (NaNO3, peptone, yeast powder, etc.) and inorganic salts (KH2PO4, MgSO4, etc.) need to be supplemented to regulate the synthesis of the main secondary metabolites of red yeast rice enzyme bacteria; ④ The proportion of open-ring monacolin K fermented by pure rice as a matrix is ​​low.

[0003] Rice bran, also known as rice bran, rice treasure, and oil bran, is a composite powder composed of the seed coat, embryo, endosperm, and a small amount of endosperm collected during the milling of white rice after the husk is removed from the rice husk. As a by-product of rice processing, rice bran can be produced in my country at an annual rate of 16-20 million tons, but most of it has not been deeply processed or reused. According to many domestic and foreign literature reports on grain chemistry, rice bran contains 90% of the nutrients needed by the human body, and the nutrient content accounts for more than 64% of the whole rice grain. Among them, the content of protein, oil, and dietary fiber exceeds 10%, and it is rich in micronutrients. The overall nutritional quality is comparable to that of eggs, and it is called "God-given nutrition source" abroad. Rice bran can be fully utilized for deep processing, such as the Chinese patent CN201910372024.2, which provides a method for making sauce by deep processing of rice bran, using fresh rice bran as raw material, and maximizing the nutritional value of rice bran after decomposition enzyme destruction, sterilization treatment, and step-by-step fermentation, but the processing time of this method is long, the process is complicated, and the processing process is easy to cause pollution to the rice bran, resulting in the failure of making sauce. In CN118546790A, ultraviolet rays are used to induce Monascus to produce Monacolin K, wherein the total amount of Monacolin K detected after 25 days of solid-state fermentation is about 12 mg / g, and the yield of Monacolin K is low. Summary of the invention

[0004] Based on the above technical problems existing in the prior art, the present invention provides a method for preparing nutrient-rich red yeast rice bran. The method uses enzymatically hydrolyzed rice bran as a base material, inoculates Monascus at high temperature and cultures at low temperature to obtain red yeast rice bran with a high monacolin K content.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] A method for preparing nutrient-rich red yeast rice bran, characterized in that it comprises the following steps:

[0007] S1. Rice bran pretreatment: After the rice bran is sterilized and treated with enzyme inactivation, the moisture content is controlled at 20-30%;

[0008] S2, semi-solid enzymolysis: adding the composite enzymolysis liquid to the pretreated rice bran, stirring evenly and then performing enzymolysis to obtain a semi-solid base material; S3, high temperature inoculation: controlling the temperature of the semi-solid base material at 36-40°C, adjusting the pH to 5.0-5.5; inoculating Monascus for cultivation, turning the koji every 10-12 hours, and culturing for 5-6 days to obtain the koji material;

[0009] S4, low temperature culture: the koji material is flattened and cultured, and the temperature of the koji material is controlled at 30-35°C;

[0010] S5, drying: after the culturing is completed, the koji material is dried until the moisture content is below 10% to obtain nutritious red yeast rice bran;

[0011] The composite enzymatic hydrolysate comprises cellulase, phytase and lipase; based on the mass fraction of rice bran powder, the added amount of cellulase is 1-2‰, the added amount of phytase is 3-4‰, and the added amount of lipase is 1-2‰.

[0012] In some embodiments, in step S3, during the high temperature inoculation process, the ambient temperature is controlled at 42-45°C, the humidity is 65-75%, and the air volume is 1800-2400m 3 / h.

[0013] In some embodiments, in step S3, 1.0-3.0% acetic acid is added to adjust the pH of the semi-solid base to 5.0-5.5.

[0014] In some embodiments, in step S2, the glycerol content is controlled to be 1-2% after enzymatic hydrolysis, and the phytic acid degradation rate is above 50%.

[0015] In some embodiments, in step S2, the temperature is controlled at 50-55° C. and the pH is controlled at 6-7 during the stirring process.

[0016] In some embodiments, in step S4, the ambient temperature is controlled at 28-32°C, the humidity is 55-65%, and the air volume is 4200-4600m3 / h.

[0017] In some embodiments, in step S4, the culturing time is 20-40 days.

[0018] In some embodiments, the composite enzymatic hydrolysate consists of cellulase, phytase, lipase and sterile water.

[0019] In some embodiments, in step S2, the enzymatic hydrolysis time is 2-8 hours.

[0020] In some embodiments, the preparation method comprises the following steps:

[0021] S1. Rice bran pretreatment: After the rice bran is sterilized and treated with enzyme inactivation, the moisture content is controlled at 20-30%;

[0022] S2, semi-solid enzymolysis: adding a composite enzymolysis liquid to the pretreated rice bran, stirring evenly and then performing enzymolysis to obtain a semi-solid base material; during the stirring process, the temperature is controlled at 50-55° C., the pH is 6-7, and after enzymolysis, the glycerol content is controlled at 1-2%, and the phytic acid degradation rate is above 50%;

[0023] S3, high temperature inoculation: the temperature of the semi-solid base material is controlled at 36-40°C, the ambient temperature is controlled at 42-45°C, the humidity is 65-75%, and the air volume is 1800-2400m 3 / h, add 1.5% acetic acid to adjust the pH to 5.0-5.5, and inhibit the contamination of foreign bacteria during the culture process. Inoculate Monascus for cultivation, turn the koji every 10-12 hours, and cultivate for 5-6 days to quickly accumulate a large number of bacteria until the spores on the surface of rice bran germinate normally, the mycelium is evenly distributed, there is no odor, and there is no foreign bacteria contamination, and the koji material is obtained;

[0024] S4, low temperature culture: the koji material is flattened and cultured, the thickness of the koji material is 30-35cm, during the culture process, ventilation is carried out and the temperature of the koji material is controlled at 30-35℃, the ambient temperature is 28-32℃, the humidity is 55-65%, and the air volume is 4200-4600m 3 / h;

[0025] S5, drying: After the cultivation is completed, the koji material is dried until the moisture content is below 10% to obtain nutritious red yeast rice bran.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The invention uses rice bran as a raw material, pre-treated and semi-solid enzymolysis as a fermentation matrix raw material, inoculates Monascus and ferments under specific conditions to obtain nutrient-rich Monascus rice bran; specifically, the rice bran is pre-treated to prevent the rice bran from becoming rancid and deteriorating, and to avoid the generation of volatile carbonyl low-molecular compounds such as hexanal, valeraldehyde and amyl alcohol during the enzymolysis process to produce rancid smell; an enzymolysis solution with a specific composition is added during the semi-solid enzymolysis process, which, on the one hand, releases nutrients such as minerals, proteins, fats and the like in the rice bran, which is beneficial to the absorption of Monascus; on the other hand, the addition of lipase further decomposes the fat to decompose fatty acids, glycerol and glycerol monoesters or diesters, especially glycerol, so that the Monascus does not need to replenish water and moisture or add an external carbon source during the fermentation process; the purpose of the semi-solid enzymolysis is to ferment the Monascus under suitable temperature and humidity conditions, which is beneficial to the generation of open-ring monacolin K. In the present invention, the antioxidant activity of the inoculated Monascus is high by utilizing the rich antioxidant active substances in rice bran itself, and the functional substance ferulic acid ester (4-hydroxy-3-methoxycinnamate) in the rice bran has a similar function to lovastatin fermented by Monascus, and the two act synergistically, so that the Monascus rice bran has excellent anti-aging, anti-lipid oxidation and blood lipid lowering effects. The Monascus rice bran obtained by the method of the present invention has a monacolin K content of up to 32.21‰ and an open loop of more than 71%, thereby maximizing the nutritional value of the rice bran.

[0028] In addition, the processed rice bran can provide rich carbon sources (glycerol), nitrogen sources and inorganic salts for the secondary metabolism of Monascus. There is no need to supplement the nutrients required by Monascus during the koji making process, which reduces the process flow and avoids the problem of introducing harmful components due to the continuous addition of nutrients.

[0029] The preparation method of the invention adopts three-step cultivation of rice bran pretreatment-semisolid enzymolysis-inoculation cultivation, has simple process operation, reduces manual labor intensity, has a short production cycle, is suitable for large-scale application, and has significant economic and social benefits.

[0030] In addition, the solution of the present invention also has the following advantages:

[0031] (1) Conventional culture media are composed of a variety of artificially prepared compounds, while rice bran can be used as a culture medium to give full play to the advantages of rice bran as a natural nutrient treasure house. The high-quality nitrogen source (protein) and carbon source of rice bran are more conducive to the absorption and growth of bacterial strains than artificially prepared culture media. Through the enzymatic hydrolysis process, the nutrients in rice bran are more conducive to the absorption and utilization of microorganisms, and the culture time is greatly shortened.

[0032] (2) The variable temperature culture method is used to make the rice bran culture medium contain a higher content of monacolin, a higher ring opening rate, a higher red yeast rice yield, and a lower level of citrinin.

[0033] (3) The final product can be used for both medicinal and edible purposes, and can be made into different dosage forms such as tablets and granules by adding different excipients. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a 5000x electron microscope image of rice bran before enzymatic hydrolysis;

[0035] Figure 2 This is a 2000x electron microscope image of rice bran before enzymatic hydrolysis;

[0036] Figure 3 This is a 5000x electron microscope image of rice bran after enzymatic hydrolysis;

[0037] Figure 4 This is a 2000x electron microscope image of rice bran after enzymatic hydrolysis;

[0038] Figure 5 The effect of different fermentation temperatures on the yield of monacolin K. DETAILED DESCRIPTION

[0039] Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar modifications without violating the connotation of the present invention, so the present invention is not limited to the specific implementation disclosed below.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0041] Example 1 Effect of enzymatic hydrolysis conditions on monacolin K production

[0042] S1. After sterilizing and inactivating enzymes in rice bran, the rice bran was cooled to 50°C, 10-40 mesh rice bran was taken, and a mixed enzymolysis solution containing 1.5‰ cellulase, 3.5‰ phytase and 2‰ lipase was added according to the weight fraction of the rice bran, and a blank sample (without enzymolysis solution) was prepared for comparison, the water content was controlled at 28%, the pH was adjusted to 6.5, and the enzymolysis was performed for 6h; after the enzymolysis, the temperature of the rice bran was controlled at 38°C, the ambient temperature was controlled at 42-45°C, the ambient humidity was controlled at 65-75%, and the air intake was 1800-2400m 3 / h, add 1.5% acetic acid to adjust the pH to 5.0, inoculate Monascus (commercially purchased, Gutian County Shenghua Monascus Co., Ltd.) with an inoculum amount of 2%, turn the koji once every 12h, and culture for 5-6 days until the surface of the rice bran is evenly distributed with no odor and no contamination by other bacteria, spread the koji material to a thickness of 32-35cm, control the temperature of the koji material to 32°C for low-temperature culture, and control the ambient temperature to 28-32°C, the ambient humidity to 55-65%, and the air intake to 4200-4600m 3 / h, and then cultured for 42 days and dried to 8% moisture to obtain nutrient-rich red yeast rice bran.

[0043] The enzymatically hydrolyzed and non-enzymatically hydrolyzed rice bran and the obtained red yeast rice bran were tested, and the results are shown in Table 1 and Figure 1-Figure 4 shown.

[0044] Table 1 Effect of enzymatic hydrolysis conditions on monacolin K production

[0045] No enzymatic hydrolysis Enzymatic hydrolysis glycerin 0.2％ 1.8％ Inorganic phosphorus 0.30％ 1.21％ Phytic acid degradation rate 0％ 67.83％ Monacolin K (mg / g) 22.41 31.68

[0046] Depend on Figure 1-Figure 4 As shown in Table 1, after enzymatic hydrolysis of rice bran by cellulase, phytase and lipase, the fiber layer is fully opened, and the minerals chelated by phytic acid are also partially released, such as inorganic phosphorus, which has a positive effect on maintaining the cell structure of microorganisms, promoting energy metabolism and growth, and other physiological functions. The glycerol released by lipase supplements the carbon source for Monascus and plays a moisturizing role. After enzymatic hydrolysis, monacolin K increased by 41.37%.

[0047] Example 2 Selection of culture medium

[0048] The rice bran and rice are mixed evenly in a weight ratio of 1:0, 1:1, 2:1, 1:2, 0:1, and 20-30% water is added after mixing to condition the mixture, and then the mixture is passed through a single screw extruder for enzyme inactivation, sterilization and maturation to obtain a culture medium raw material; then the temperature is lowered to 50°C, a mixed solution containing 1.5‰ cellulase, 3.5‰ phytase and 2‰ lipase is added according to the weight fraction of amorphous aggregates, the pH is adjusted to 6.5, and enzymolysis is performed for 6 hours; after enzymolysis, a culture medium is obtained, and the culture medium temperature is controlled at 38°C, the ambient temperature is controlled at 42-45°C, the ambient humidity is controlled at 65-75%, and the air intake is controlled at 1800-2400m 3 / h, add 1.5% acetic acid to adjust the pH to 5.0, inoculate Monascus, turn the koji every 12h, and culture for 5-6 days until the surface of the culture medium is evenly distributed with no odor and no contamination by other bacteria; spread the koji material to a thickness of 30-35cm, control the temperature of the koji material to 32℃ for low-temperature culture, and control the ambient temperature to 28-32℃, the ambient humidity to 55-65%, and the air intake to 4200-4600m 3 / h, and then cultured for 42 days and dried to 8% moisture to obtain nutrient-rich red yeast rice bran.

[0049] The yields of monacolin K prepared by co-culturing with different culture medium ratios for 42 days are shown in Table 2.

[0050] Table 2 Changes in mass fraction of monacolin K under different culture medium ratios (mg / g)

[0051] Rice bran: rice 1:0 2:1 1:1 1:2 0:1 MKA 22.87 16.35 12.14 7.40 3.98 MK 9.34 15.10 18.22 19.02 15.92 MKA+MK 32.21 31.45 30.36 26.42 19.9 Open loop rate 71％ 52％ 40％ 28％ 20％

[0052] Note: MKA is acid type / open-ring monacolin K, and MK is lactone type / closed-ring monacolin K.

[0053] As shown in Table 2, the monacolin K obtained by fermentation of pure rice bran is mainly acidic / open-ring, with a proportion of up to 71%. As the amount of rice increases, the total amount of monacolin K decreases, and the proportion of acidic / open-ring monacolin K decreases.

[0054] Example 3 Effect of different fermentation temperatures on monacolin K and citrinin

[0055] After the rice bran was sterilized and pretreated by enzyme inactivation, the temperature was lowered to 50°C, and a mixture containing 1.5‰ of cellulase, 3.5‰ of phytase and 2‰ of lipase was added according to the weight fraction of the rice bran. The water content was controlled at 45%, and the pH was adjusted to 6.5. The enzymolysis was performed for 6 hours. After the enzymolysis, the rice bran was cultured at 38°C and 32°C, respectively, with a pH of 5.0, and Monascus was inoculated. The koji was turned over every 12 hours. After 5 days of culture, the koji was spread to a thickness of 32-35cm, and the temperature of the koji was controlled at 32°C for low-temperature culture. After 10 days, 15 days, 20 days, 25 days, 30 days, 35 days and 40 days of culture, the koji was dried to a moisture content of 9%, and the changes of monacolin K and citrinin were observed. The results are shown in Table 3 and Figure 5 shown.

[0056] By observing, Figure 5 As shown in Table 3, variable temperature culture, i.e., inoculation at 38°C for 5 days followed by low temperature culture at 32°C, is more suitable for high production of monacolin K by Aspergillus flavus than single temperature culture. At the same time, the content of citrinin under different temperature conditions was detected, as shown in Table 3. The content of citrinin was lower than 50 μg / kg, while the content of commercial red yeast rice was much higher than 50 μg / kg.

[0057] Table 3 Changes in citrinin content under different temperature conditions (μg / kg)

[0058] Time / d Inoculation and culture at 32℃ Inoculation and culture at 38℃ After 5 days at 38℃, transfer to 32℃ 10 Not detected Not detected Not detected 15 Not detected Not detected Not detected 20 Not detected Not detected Not detected 25 Not detected Not detected Not detected 30 Not detected 27 Not detected 35 32 40 27 40 45 43 38

[0059] The red yeast rice bran obtained through the case study has a monacolin K content of 32.21‰, of which the ring opening amount is 71%, and the citrinin content is relatively low. The red yeast rice prepared from pure rice has a monacolin K content of 19.9‰, a ring opening amount of about 20%, and a relatively high citrinin content.

[0060] The culture time and monacolin K yield of the present invention have obvious advantages over traditional solid-state fermentation culture, as shown in the following figure.

[0061] Table 4 Changes in monacolin K production during culture time under different processes

[0062] Process steps The present invention Traditional solid-state fermentation Raw material pretreatment 1h 12-24h (soak rice-steam rice) Semi-solid enzymatic hydrolysis 4-6h / Inoculation 30-35d 35-40d Add additional nutrient solution unnecessary need Monaclin K 32.21‰ 16.75‰

[0063] In summary, considering the most nutritious ingredients and the content of citrinin, the optimal preparation process and conditions of red yeast rice bran are as follows:

[0064] S1. Rice bran pretreatment: After the rice bran is sterilized and treated with enzyme inactivation, the moisture content is controlled at 25-30%;

[0065] S2, semi-solid enzymolysis: adding a composite enzymolysis liquid to the pretreated rice bran, stirring evenly and then performing enzymolysis to obtain a semi-solid base material; during the stirring process, the temperature is controlled at 50° C. and the pH is 6.5. After enzymolysis, the glycerol content is controlled at 1.5-2%, and the phytic acid degradation rate is controlled to be above 65%;

[0066] S3, high temperature inoculation: the temperature of the semi-solid base material is controlled at 38°C, the ambient temperature is controlled at 42-45°C, the ambient humidity is 65-75%, and the air volume is 1800-2400m 3 / h, adding 1.5% acetic acid to adjust the pH to 5.0, and inhibiting the contamination of foreign bacteria during the culture process; inoculating Monascus for cultivation, turning the koji every 10-12h, culturing for 5-6 days, rapidly accumulating a large number of bacteria until the Monascus spores on the surface of rice bran germinate normally, the mycelium is evenly distributed, has no peculiar smell, and is free of foreign bacteria contamination, thereby obtaining koji material;

[0067] S4, low temperature culture: the koji material is flattened and cultured, the thickness of the koji material is 30-35cm, during the culture process, ventilation is carried out and the temperature of the koji material is controlled at 32°C, the ambient temperature is 28-32°C, the ambient humidity is 55-65%, and the air volume is 4200-4600m 3 / h;

[0068] S5, drying: After the cultivation is completed, the koji material is dried until the moisture content is below 10% to obtain nutritious red yeast rice bran.

[0069] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0070] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing nutrient-rich red yeast rice bran, characterized in that: The following steps are involved: S1. Rice bran pretreatment: After the rice bran is sterilized and treated with enzyme inactivation, the moisture content is controlled at 20-30%; S2, semi-solid enzymolysis: adding a composite enzymolysis solution to the pretreated rice bran, stirring evenly and performing enzymolysis to obtain a semi-solid base material; S3, high temperature inoculation: the temperature of the semi-solid base material is controlled at 36-40°C, and the pH is adjusted to 5.0-5.5; Monascus is inoculated for cultivation, and the koji is turned every 10-12 hours, and the koji material is obtained after culturing for 5-6 days; S4, low temperature culture: the koji material is flattened and cultured, and the temperature of the koji material is controlled at 30-35°C; S5, drying: after the culturing is completed, the koji material is dried until the moisture content is below 10% to obtain nutritious red yeast rice bran; The composite enzymatic hydrolysate comprises cellulase, phytase and lipase; based on the mass fraction of rice bran powder, the added amount of cellulase is 1-2‰, the added amount of phytase is 3-4‰, and the added amount of lipase is 1-2‰.

2. The preparation method of nutrient-rich red yeast rice bran according to claim 1, wherein In step S3, during the high temperature inoculation process, the ambient temperature is controlled at 42-45°C, the humidity is 65-75%, and the air volume is 1800-2400m 3 / h.

3. The preparation method of nutrient-rich red yeast rice bran according to claim 1, characterized in that, In step S3, 1.0-3.0% acetic acid is added to adjust the pH of the semi-solid base to 5.0-5.

5.

4. The preparation method of nutrient-rich red yeast rice bran according to claim 1, characterized in that, In step S2, after enzymatic hydrolysis, the glycerol content is controlled to be 1-2%, and the phytic acid degradation rate is above 50%.

5. The preparation method of nutrient-rich red yeast rice bran according to claim 1, characterized in that, In step S2, the temperature is controlled at 50-55° C. and the pH is controlled at 6-7 during the stirring process.

6. The preparation method of nutrient-rich red yeast rice bran according to claim 1, characterized in that, In step S4, the ambient temperature is controlled at 28-32°C, the humidity is 55-65%, and the air volume is 4200-4600m 3 / h.

7. The preparation method of nutrient-rich red yeast rice bran according to claim 1, characterized in that, In step S4, the culture time is 20-40 days.

8. The preparation method of nutrient-rich red yeast rice bran according to claim 1, characterized in that, The composite enzymatic hydrolysate consists of cellulase, phytase, lipase and sterile water.

9. The method for preparing nutrient-rich red yeast rice bran according to claim 1, wherein In step S2, the enzymatic hydrolysis time is 2-8 hours.

10. A nutritious red yeast rice bran, characterized in that: Prepared by the preparation method according to any one of claims 1 to 9.

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