Quality evaluation method of monascus rice product based on linkage of ingredient content and in-vitro digestion release characteristics
Patent Information
- Application Number
- CN202611084922.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-21
- Publication Date
- 2026-08-28
Smart Images
Figure CN122651931A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of food quality testing and functional evaluation technology, specifically involving a method for evaluating the quality of red yeast rice products based on a multi-dimensional linkage of the content of acid monacolin K (MKA) and lactone monacolin K (MKL), the color value of red yeast pigment, and the bioavailability of in vitro digestion by INFOOGS. Background Technology
[0002] Red yeast rice (RYR) is a traditional food and medicine product made from rice through fermentation by Monascus fungi. It is widely used in functional foods, health foods, and dietary supplements. Red yeast rice contains various active ingredients, including monacolin compounds and red yeast pigments. Among these, Monacolin K (MK) is the most widely studied core component and is most closely related to its lipid-lowering function. It has the same chemical structure as lovastatin (LOV), meaning they are the same substance, only differing in origin. Red yeast pigments are one of the main metabolic components of red yeast rice fermentation, possessing both coloring and anti-inflammatory properties, as well as auxiliary lipid-lowering activities; it is an important auxiliary parameter for quality control.
[0003] Monacoline K exists primarily in red yeast rice in two forms: MKL and MKA. MKA is the bioactive form that directly inhibits HMG-CoA reductase activity, while MKL requires further ring-opening conversion in vivo to exert its lipid-lowering effect. Therefore, the proportion of MKA is one of the key factors affecting the lipid-lowering activity of the product.
[0004] Currently, my country's quality standards for red yeast rice and related products mainly include QB / T 2847 "Functional Red Yeast Rice" and GB 1886.19 "Food Additive Red Yeast Rice". These standards only use the total MK content or red pigment value as the evaluation basis, which has three major technical defects: (1) Only MK is measured. tol Content, without distinguishing between MKA and MKL, total MK content (MK tol (1) It cannot reflect the true efficacy and is easy to misjudge "high total amount, low activity"; (2) It ignores the influence of red yeast rice matrix on MK stability and bioaccessibility and cannot assess "whether it can be absorbed after ingestion"; (3) The parameters are isolated and the digestion linkage of component color value is not realized, and it is impossible to identify "high dose, low utilization rate" products.
[0005] Therefore, there is an urgent need to establish a comprehensive quality evaluation method that can simultaneously characterize chemical composition, pigment quality, and in vitro digestion dynamics, in order to improve the authenticity, scientific nature, and functional relevance of red yeast rice product quality evaluation and promote the standardized production of red yeast rice. Summary of the Invention
[0006] To address the problems and shortcomings in the prior art, this invention addresses the issue that existing standards only measure MK. tol To address the issue of evaluating red yeast rice products by only measuring color value and ignoring digestive release, which leads to a disconnect between the evaluation results and actual lipid-lowering effects, this paper proposes a quality evaluation method that links component content, pigment quality, and in vitro digestive release. This method enables precise grading, efficient detection, and efficacy prediction, and is applicable to the quality grading, factory inspection, and market supervision of red yeast rice, red yeast rice powder, red yeast functional foods, and red yeast health products.
[0007] The technical solution of the present invention is as follows: (1) The contents of the acid form (MKA, direct active) and lactone form (MKL, prodrug) of monacolin (MK) in red yeast rice products were simultaneously and quantitatively determined by high performance liquid chromatography-photodiode array detector (HPLC-PDA), and the total MK content (MK) was calculated. tol The KMA / MKL ratio can be obtained by further analyzing the KMA / MKL ratio.
[0008] The MKA percentage refers to the proportion of MKA content to the sum of MKA and MKL content, calculated as MKA percentage % = MKA content / (MKA content + MKL content) × 100%, which is the proportion of the acidic substance MKA in the total acidic and lactone substances of Monacoline.
[0009] Step (1) specifically involves simultaneous quantitative detection using high-performance liquid chromatography-photodiode array detector (HPLCPDA). This means that within the same chromatographic detection program and the same injection analysis procedure, the peak areas of the MKA and MKL peaks in the sample are collected separately and substituted into the corresponding standard curves for quantification. The MKL peaks are then calculated. tol Content, MKA / MKL ratio and MKA percentage.
[0010] (2) Determine the pigment parameters in red yeast rice products, and then process them to obtain the comprehensive color value of red yeast pigment; (3) Simulate digestion of red yeast rice products and determine the bioavailability in the stomach and intestines; (4) Establish a comprehensive evaluation model based on the parameter results of steps (1) to (3) to carry out quality grading and evaluation of red yeast rice products.
[0011] The red yeast rice products mentioned refer to lipid-lowering functional products fermented by Monascus purpureus, including but not limited to red yeast rice, red yeast rice powder, red yeast functional foods, red yeast health products, and red yeast dietary supplements.
[0012] In step (1), lovastatin lactone (LOVL) is used as the quantitative standard for MKL, and lovastatin acid (LOVA) is used as the quantitative standard for MKA. Quantitative standard curves for LOVL and LOVA are established using the external standard method to quantitatively analyze the content of MKL and MKA in red yeast rice products.
[0013] The specific step (2) involves using ultraviolet spectrophotometry to determine the color values of yellow, orange, and red pigments in red yeast rice products. Red yeast rice pigments include yellow, orange, and red pigments. The comprehensive color value of red yeast rice pigments is then calculated using the color values of yellow, orange, and red pigments.
[0014] Step (3) specifically involves using INFOGEST in vitro gastrointestinal two-step simulated digestion to determine the bioavailability of monacolin MK in the gastric and intestinal phases. INFOGEST is an experimental standard.
[0015] This invention relates to a two-step digestion process involving the stomach and intestines for ingestible red yeast rice products.
[0016] Specifically, step (4) involves converting the total MK content obtained in step (1) into MK. tol The labeling deviation was obtained by comparing the total MK content with the preset MK content set at the factory for red yeast rice products. tol The core parameters are MKA content, comprehensive color value of red yeast rice pigment, labeling deviation, and intestinal MK bioavailability. A multi-parameter linkage comprehensive evaluation model is established using the entropy weight method to complete the quality grading and evaluation of red yeast rice products and achieve quality grading.
[0017] The acidic lovastatin is prepared by alkaline hydrolysis of lactone lovastatin.
[0018] In step (2), red yeast rice products are extracted with anhydrous ethanol, and the absorbance of the extract at wavelengths of 385 nm, 470 nm, and 505 nm is measured to characterize the content of yellow, orange, and red pigments, respectively. The color values of yellow, orange, and red pigments are calculated using formulas. S = (A×V×n) / m In the formula: S is the color value of yellow pigment / orange pigment / red pigment (U / g), A is the absorbance, V is the volume of extraction liquid (mL), n is the dilution factor, and m is the sample mass (g).
[0019] In step (3), the bioavailability of MK in red yeast rice products is obtained through sequential simulated gastric and intestinal digestion assessments: First, the red yeast rice products were subjected to simulated gastric digestion. The simulated gastric digestion conditions were: pH 3.0, pepsin 250 U / mL, and incubation at 37 ℃ for 2 h. Then, the red yeast rice products were subjected to enteric simulated digestion. The enteric simulated digestion conditions were: pH 7.0, pancreatic enzyme 200 U / mL, bile salt 8.17 g / L, and incubation at 37 ℃ for 2 h. The relative bioavailability of intestinal MK was calculated using the following formula: Among them, the total MK content of undigested samples tol The total MK content was determined by measuring the MK content of red yeast rice products that had not undergone gastric and intestinal digestion. tol The results were obtained by measuring the digestive fluids after sequential digestion in the stomach and intestines.
[0020] In step (4), the evaluation model uses the entropy weight method to determine the parameter weights, including: total MK content MK tol The five core parameters are: MKA percentage, MK label deviation, red yeast rice pigment comprehensive color value, and intestinal MK bioavailability.
[0021] In step (4), the multi-parameter linkage comprehensive scoring model is as follows: Where Q represents the comprehensive scoring parameter, and X1 represents the normalized total MK content MK tol X2 represents the normalized MKA percentage, X3 represents the label bias after logarithmic compression and negative normalization, X4 represents the normalized red yeast rice pigment comprehensive color value, and X5 represents the normalized intestinal bioavailability.
[0022] The quality evaluation and grading results of red yeast rice products are obtained by comprehensively evaluating the scoring parameter Q based on at least one preset threshold. In specific implementation, the products can be divided into grades A (excellent), B (good), C (medium), and D (unqualified) according to the Q value.
[0023] The method described above can simultaneously identify three types of substandard products: high content with low activity, high color value with no function, and high dosage with low utilization rate, thus achieving a dual evaluation of efficacy authenticity and label authenticity.
[0024] This invention addresses the issue that existing standards only measure MK. tol The content of MKA, which is the direct active form, can easily lead to biased evaluation of high content and low activity. In addition, the detection of a single parameter cannot correlate the composition of MK, the color value of red yeast rice pigment and bioavailability, making it difficult to identify the pain points of high-dose, low-utilization products. This invention uses HPLC-PDA to simultaneously quantify MKA and MKL in red yeast rice products, combined with ultraviolet spectrophotometry to determine the color value of red yeast rice pigment, and relies on the INFOGEST in vitro simulated digestion model to analyze the bioavailability of MK in the gastrointestinal two-phase system, thus constructing a comprehensive quality evaluation system with multiple parameters.
[0025] Compared with the prior art, the present invention has the following beneficial effects: (1) Achieve multi-dimensional integrated evaluation: This invention integrates quantitative analysis of MK (MKA, MKL), color value analysis of red yeast rice pigment, and in vitro digestion model into the same evaluation process, so as to achieve simultaneous evaluation of the chemical composition, pigment quality and digestion dynamic behavior of red yeast rice products and avoid misjudgment of single parameters.
[0026] (2) Stronger correlation with efficacy: Intestinal bioavailability of MK is positively correlated with lipid-lowering activity, but not positively correlated with the MK content of the product, which can effectively identify products with "high content and low utilization". Compared with traditional methods that only detect MK... tol The content method of this invention can better reflect the true utilization value of the product.
[0027] (3) Effectively identifies false labeling: This invention can simultaneously evaluate MK tol Content, MKA / MKL ratio, and digestion-release behavior. Therefore, this can strengthen quality control of red yeast rice products, urge manufacturers to improve product stability and authenticity, and enhance market supervision efficiency.
[0028] (4) It can be used to guide process optimization: This invention can evaluate the effects of different fermentation processes, extraction processes and refining processes on MK release behavior, and can be used to guide enterprises to optimize fermentation conditions and improve intestinal release rate and effective exposure level.
[0029] (5) Easy to promote and apply: The HPLC, spectrophotometer and INFUGEST digestion model used in this invention are all conventional experimental equipment and mature methods. No special instruments are required, the detection cost is low, and it has good industrial promotion value.
[0030] This invention can effectively identify products with high content and low release and high utilization, greatly improve the authenticity and functional relevance of quality evaluation, and is applicable to the procurement, quality control, process optimization and market supervision of red yeast rice raw materials, providing key technical support for the standardized evaluation of food and medicine homology functional foods. Attached Figure Description
[0031] Figure 1 Chromatogram for HPLC-PDA detection of a mixed standard of LOVA and LOVL; Figure 2 The quantitative standard curves for LOVA and LOVL are shown, where (a) is the acid form and (b) is the lactone form. Figure 3 Chromatograms showing the MK content and composition analysis of 10 commercially available red yeast rice products. Detailed Implementation
[0032] To enable those skilled in the art to better understand the technical solution of the present invention, the method provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.
[0033] The embodiments of the present invention are as follows: Example 1: (1) Sample pretreatment: After pulverizing and mixing the red yeast rice product sample, weigh 0.3000 g of the sample and add 25 mL of 75% ethanol solution. Extract the sample by ultrasonication at 30 ℃ for 1 h. This step ensures high and stable extraction efficiency of MK from red yeast rice with minimal error. After extraction, centrifuge at 10000 r / min for 5 min and collect the supernatant as the sample solution to be tested.
[0034] (2) Monacoline K component analysis: High-performance liquid chromatography-photodiode array detector (HPLC-PDA) was used to quantitatively analyze MKA and MKL in the sample solution. The chromatographic conditions were as follows: C18 column, column temperature 30 ℃, mobile phase 25% phosphoric acid aqueous solution (0.3%)-75% methanol, isocratic elution, flow rate 1.0 mL / min, injection volume 10 μL, detection wavelength 238 nm, and analysis time 25 min.
[0035] Since MK and LOVA are the same substance (only from different sources), the quantification of MKL in red yeast rice is often performed using commercially available LOVL standards for equivalent analysis. However, there are no commercially available standards for LOVA. Therefore, LOVL standards were prepared by alkaline hydrolysis to quantify LOVA. First, quantitative standard curves for lovastatin lactone (LOVL) and lovastatin acid (LOVA) were established using the external standard method. Given the current lack of directly available LOVA standards, this study converted LOVL to LOVA through alkaline hydrolysis. LOVL standards were dissolved in 75% ethanol, and an appropriate amount of 0.2 M NaOH was added. The mixture was sonicated at room temperature for 1 h to promote the ring-opening reaction of the lactone. After the reaction, a trace amount of 1 M HCl solution was added to adjust the pH of the system to neutral to terminate the hydrolysis reaction. The resulting mother liquor was stored at -20 °C for later use. Alkaline conditions can effectively promote the conversion of the lactone structure to the hydroxy acid form. The chromatograms obtained by HPLC-PDA detection of the acid and lactone forms of lovastatin mixed standards are shown below. Figure 1 .
[0036] The red yeast rice product test solution was further analyzed using HPLC-PDA, and quantitative standard curves were established based on LOVA and LOVL. Figure 2 ), calculate MKA, MKL and MK in the sample tolContent, and further calculate the MKA / MKL ratio or MKA / MK tol ratio.
[0037] (3) Analysis of the color value of red yeast rice pigment: Weigh 3 g of sample, add 50 mL of anhydrous ethanol, and extract by ultrasonication at 30 °C for 1 h. After centrifugation, collect the supernatant for testing. In this step, a relatively large amount of red yeast rice sample should be weighed to avoid insufficient target compound, which may lead to detection difficulties.
[0038] The absorbance of the test solution at wavelengths of 385 nm, 470 nm, and 505 nm was measured using ultraviolet-visible spectrophotometry to characterize the yellow, orange, and red pigments, respectively. The overall color value was calculated using the following formula: S = (A×V×n) / m In the above formula, S is the color value (U / g); A is the absorbance of the diluted sample solution; V is the volume of the sample extract (mL); n is the dilution factor of the extract; and m is the sample mass (g).
[0039] (4) INFUGEST in vitro simulated digestion assessment of MK bioavailability: The release behavior of MK in samples was evaluated using the INFOKE standard in vitro digestion model. This method, with red yeast rice capsules as the primary analytical target, omits the oral digestion process, thus reducing the cost of pilot-scale testing.
[0040] First, a simulated gastric digestion was performed. 3.000 g of sample was weighed and mixed with 20 mL of pure water. Stomach mimicry solution (SGF, formulation shown in Table 1) was added, the pH was adjusted to 3.0, and the volume was brought to 40 mL. Pepsin was then added, and the mixture was incubated at 37 ℃ with shaking for 2 h. Next, a simulated intestinal digestion stage was performed. Intestinal mimicry solution (SIF, formulation shown in Table 1) was added to the gastric digestion system; the pH was adjusted to 7.0; and the volume was brought to 80 mL. Bile salts and pancreatic enzymes were added, and the mixture was incubated at 37 ℃ for another 2 h.
[0041] Gastric and intestinal digestive fluids were collected separately and centrifuged at 10,000 r / min for 10 min, repeated twice. 40 mL of supernatant was collected, and MK was extracted with 1:3 (v / v) 75% ethanol. After centrifugation again, the supernatant was collected, and the contents of MKA and MKL were detected by HPLC-PDA. The relative bioavailability of MK in vitro was calculated according to formula (2): Table 1 Digestive fluid formulation (5) Overall quality evaluation: According to MK tolBased on parameters such as content, MKA ratio, comprehensive color value of red yeast rice pigment, label MK deviation, and intestinal MK bioavailability, an entropy weight method was used to establish a comprehensive quality evaluation system for red yeast rice, and to classify red yeast rice products according to quality.
[0042] This embodiment further details the present invention by combining the above process with parameter measurement and evaluation of 10 commercially available red yeast rice (powder) products: (1) HPLC-PDA detection of MKA and MKL in the sample, such as Figure 3 As shown in Table 2: Table 2 shows the results for different products using MK. tol The content varied significantly (not detected to 30.79 mg / g), with MKA accounting for only 9.65% to 36.21%. The MKA / MKL ratio ranged from 0.10 to 0.56, indicating that the MK in the red yeast rice (powder) samples was mainly in the lactone form. High MK content did not necessarily mean high MKA content; for example, R10 had the highest total MK, but its MKA content was only 9.65%, indicating extremely low levels of active form. R5 had only 2.43 mg / g of total MK, but its MKA content was 36.21%, indicating the best proportion of active form. Furthermore, the total MK content of some products differed significantly from the label value. For example, R9's label indicated 50 mg / g of MK, but it was not detected in actual testing, resulting in a label deviation of 99.42%.
[0043] Therefore, measuring total MK alone cannot determine the true activity; MKA and MKL must be measured simultaneously.
[0044] Table 2. Analysis of MK content in 10 commercially available red yeast rice (powder) samples. (2) Analysis of the color value of red yeast rice pigment, as shown in Table 3: The color value of 10 samples was tested using step (3) of the technical solution. Table 3 shows that the overall color value of different samples varied significantly, with the lowest being 101.46 U / g and the highest being 2444.58 U / g. For example, sample R9 had the highest overall color value at 2444.58 U / g, but contained almost no MK and had no lipid-lowering function; R6 had the lowest overall color value (101.46 U / g), but had a MK intestinal release rate of 51.88% (see Table 4), indicating a high bioavailability; R4 and R10 had color values > 1000 U / g, and possessed both high MK content and release performance. Color value is not necessarily related to lipid-lowering function; it only reflects the fermentation level and coloring ability and cannot represent the function; it must be linked to MK parameters.
[0045] Table 3. Color and Value Analysis of 10 Commercially Available Red Yeast Rice (Powder) Samples (3) Analysis of MK in vitro digestion and release behavior, as shown in Table 4: The in vitro bioavailability of MK in the product is evaluated using the technical solution step (4).
[0046] Table 4 shows that in the gastric phase, the overall bioavailability of MK in RYR samples was low, ranging from only 0.81% to 3.07%; while the bioavailability of LOV powder in the gastric phase was as high as 81.93%. In the intestinal phase, the bioavailability of MK in RYR samples increased significantly, reaching 9.08% to 57.49%, but the bioavailability of LOV powder decreased significantly. At the same time, the proportion of MKA increased significantly. Specifically, the intestinal bioavailability of R5 sample reached 57.49%, while that of R10 sample was only 9.08%. This indicates that products with high MK content do not necessarily have high bioavailability.
[0047] Further observation revealed that the proportion of MKA in the RYR sample significantly increased during digestion; the proportion of MKA in the intestinal phase could rise to 60.14%–79.05%, significantly higher than that in the LOV powder group. This indicates that the red yeast rice natural matrix not only reduces MKA loss but also promotes the conversion of MKA to its active acidic form. Excluding the digestion release would inevitably lead to the serious misjudgment of "qualified content but ineffective efficacy."
[0048] Table 4. MK in vitro digestibility analysis of 10 commercially available red yeast rice (powder) samples. Note a: Acid content indicates the content of MKA or LOVA after digestion; lactone content indicates the content of MKL or LOV after digestion; total content indicates the content of MK. tol or LOV tol That is, acid form + lactone form; b: * indicates a significant difference compared with the LOV group (P < 0.05), ** indicates an extremely significant difference (P < 0.01), and *** indicates an extremely significant difference (P < 0.001).
[0049] (4) Comprehensive quality evaluation analysis: According to MK tol A comprehensive scoring model was established based on the content, MKA percentage, red yeast rice pigment color value, labeling bias, and intestinal bioavailability of MKA. The original values of each indicator were set as A. i MK tol The four indicators—content, MKA percentage, red yeast rice pigment color value, and intestinal MK bioavailability—were all normalized using positive indicators. Label deviation A3 calculation method: In the formula, C' is the measured MK of the sample. tolContent, C indicates the MK content as indicated on the product label.
[0050] To reduce the impact of extreme deviation values on the overall evaluation results, the label deviation is logarithmically compressed and then normalized according to the negative index: in, This represents the label bias obtained after logarithmic compression of all samples participating in the evaluation. Maximum value This indicates that among all samples participating in the evaluation The minimum value; This represents the dimensionless standardized index value of the label bias obtained after logarithmic compression and negative normalization. The larger the value, the more consistent the measured MK content is with the label value; When the product does not indicate the MK content and label deviation cannot be calculated, take... = 0.
[0051] The weights of each parameter are shown in Table 5, the product grading standards are shown in Table 6, and the grading results of 10 commercially available red yeast rice products are shown in Table 7.
[0052] Table 5 Entropy weights for each parameter of the evaluation model The evaluation model is as follows: Table 6 Product Classification Table Table 7. Grading Results of 10 Commercially Available Red Yeast Rice Products Key comparisons: According to the old standard (total MK only): R10 is of superior quality; according to the present invention: R10 release is poor, only grade B; According to the old standard (color price only): R9 is a superior grade; according to the present invention: R9 has no MK and is rated as D grade; According to the old standard: R6 is unqualified; according to the present invention: R6 releases excellently and has good absorption potential. It can be upgraded to Grade C.
[0053] In summary, only by linking multiple parameters such as MK form, color value, gastrointestinal release, and label deviation can the quality of red yeast rice products be objectively, truthfully, and reproducibly evaluated, thus solving the industry problems of "high content but low activity, high color value but no function, and high dosage but low utilization rate".
[0054] As demonstrated by the above implementation examples, the quality evaluation method for red yeast rice products proposed in this invention, based on the linkage between component content and in vitro digestion and release characteristics, integrates multiple dimensions such as simultaneous quantification of MK acid / lactone forms, characterization of red yeast pigment color value, and INFOOGS in vitro gastrointestinal digestion and release characteristics, avoiding efficacy misjudgments caused by single-parameter evaluation. It utilizes intestinal MK bioavailability to reflect the true usable activity of the product, establishing a standardized evaluation system strongly correlated with lipid-lowering efficacy. Furthermore, the entire testing process can be completed with standard laboratory equipment, making it simple to operate, yielding stable results, and providing strong comparability. This method can overcome the deficiencies of existing standards, and can be used for process optimization and quality control in production enterprises, as well as supporting market supervision and product grading, possessing strong practicality and promotional value. Therefore, this method is expected to become a universal standardized means for quality evaluation of red yeast rice and related products, showing good application prospects and broad market space in improving the quality of medicinal and edible functional foods and promoting industry standardization.
[0055] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the method of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for quality evaluation of red yeast rice products based on the linkage between component content and in vitro digestion release characteristics, characterized in that, The method includes the following steps: (1) Simultaneously, the content of the acidic and lactone forms of monacolin in red yeast rice products was quantitatively determined, and the total MK content and the proportion of MKA were calculated. (2) Determine the pigment parameters in red yeast rice products, and then process them to obtain the comprehensive color value of red yeast pigment; (3) Simulated digestion of red yeast rice products was performed to determine the bioavailability in the gastric and intestinal phases; (4) Establish a comprehensive evaluation model based on the parameter results of steps (1) to (3) to carry out quality grading and evaluation of red yeast rice products.
2. The method for quality evaluation of red yeast rice products based on the linkage between component content and in vitro digestion release characteristics as described in claim 1, characterized in that: The red yeast rice products mentioned refer to lipid-lowering functional products fermented by Monascus purpureus.
3. The method for quality evaluation of red yeast rice products based on the linkage between component content and in vitro digestion release characteristics as described in claim 1, characterized in that: In step (1), lovastatin lactone is used as the quantitative standard for MKL, and lovastatin acid is used as the quantitative standard for MKA. Quantitative standard curves for LOVL and LOVA are established using the external standard method to quantitatively analyze the content of MKL and MKA in red yeast rice products.
4. The method for quality evaluation of red yeast rice products based on the linkage between component content and in vitro digestion release characteristics as described in claim 1, characterized in that: The specific step (2) involves using ultraviolet spectrophotometry to determine the color values of yellow, orange, and red pigments in red yeast rice products, and then using the color values of yellow, orange, and red pigments to calculate and process the comprehensive color value of red yeast rice pigments.
5. The method for quality evaluation of red yeast rice products based on the linkage between component content and in vitro digestion release characteristics as described in claim 1, characterized in that: The specific step (3) involves using INFOGEST in vitro gastrointestinal two-step simulated digestion to determine the bioavailability of Monacolin MK in the intestinal phase.
6. The method for quality evaluation of red yeast rice products based on the linkage between component content and in vitro digestion release characteristics as described in claim 1, characterized in that: Specifically, step (4) involves converting the total MK content obtained in step (1) into MK. tol The labeling deviation was obtained by comparing the total MK content with the preset MK content set at the factory for red yeast rice products. tol The core parameters are MKA content, comprehensive color value of red yeast rice pigment, labeling deviation, and intestinal MK bioavailability. A multi-parameter linkage comprehensive evaluation model is established to complete the quality grading and evaluation of red yeast rice products.
7. The method for quality evaluation of red yeast rice products based on the linkage between component content and in vitro digestion release characteristics as described in claim 6, characterized in that: The acidic lovastatin is prepared by alkaline hydrolysis of lactone lovastatin.
8. The method for quality evaluation of red yeast rice products based on the linkage between component content and in vitro digestion release characteristics as described in claim 1, characterized in that: In step (2), red yeast rice products are extracted with anhydrous ethanol, and the absorbance of the extract at wavelengths of 385 nm, 470 nm, and 505 nm is measured to characterize the content of yellow, orange, and red pigments, respectively. The color values of yellow, orange, and red pigments are calculated using formulas. S = (A×V×n) / m In the formula: S is the color value, A is the absorbance, V is the volume of the extract, n is the dilution factor, and m is the sample mass.
9. The method for quality evaluation of red yeast rice products based on the linkage between component content and in vitro digestion release characteristics as described in claim 1, characterized in that: In step (3), the bioavailability of MK in red yeast rice products is obtained through sequential simulated gastric and intestinal digestion assessments: First, the red yeast rice products were subjected to simulated gastric digestion. The simulated gastric digestion conditions were: pH 3.0, pepsin 250 U / mL, and incubation at 37 ℃ for 2 h. Then, the red yeast rice products were subjected to enteric simulated digestion. The enteric simulated digestion conditions were: pH 7.0, pancreatic enzyme 200 U / mL, bile salt 8.17 g / L, and incubation at 37 ℃ for 2 h. The relative bioavailability of intestinal MK was calculated using the following formula: Among them, the total MK content of undigested samples tol The total MK content was determined by measuring red yeast rice products that had not undergone gastric and intestinal digestion. tol The results were obtained by measuring the digestive fluids after sequential digestion in the stomach and intestines.
10. The method for quality evaluation of red yeast rice products based on the linkage between component content and in vitro digestion release characteristics as described in claim 1, characterized in that: In step (4), the multi-parameter linkage comprehensive scoring model is as follows: Where Q represents the comprehensive scoring parameter, and X1 represents the normalized total MK content MK tol X2 represents the normalized MKA percentage, X3 represents the label bias after logarithmic compression and negative normalization, X4 represents the normalized red yeast rice pigment comprehensive color value, and X5 represents the normalized intestinal bioavailability. The quality evaluation and grading results of red yeast rice products are obtained by comprehensively judging the scoring parameter Q based on the preset threshold.