A method for evaluating rice eating quality and storage stability based on PRSI

Abstract

The present invention discloses a method for evaluating the storage resistance of rice taste quality based on PRSI, comprising: (1) selecting fresh rice and rice aged for 3 months by an artificial accelerated aging method; respectively measuring the rice appearance and taste scores of polished rice, and the fatty acid value and POD activity value of brown rice; (2) respectively calculating the individual storage resistance coefficients of the rice appearance, taste score, fatty acid value and POD activity value, which are X1, X2, X3 and X4; (3) calculating the rice quality storage resistance index PRSI by the following prediction equation model: PRSI=-0.055+0.367X1+0.502X2+0.003X3+0.254X4; (4) evaluating the storage resistance of the rice taste quality according to the PRSI value. Compared with the rice with a low PRSI value, the rice with a high PRSI value deteriorates faster in taste quality during storage and is less storable. The present invention simplifies the comprehensive trait index of rice taste quality and storage tolerance into a PRSI value, and at the same time constructs a corresponding evaluation method, which is accurate and reliable and can realize the accurate evaluation of the taste quality and storage tolerance of rice of different rice varieties.

Description

Technical Field

[0001] The present invention relates to the field of rice testing and analysis, and in particular to a method for evaluating the storability of rice taste quality based on PRSI. Background Art

[0002] Rice storage tolerance is categorized into seed vigor storage tolerance and eating quality storage tolerance. Seed vigor storage tolerance refers to the viability and germination ability of rice seeds after storage, while eating quality storage tolerance refers to the extent of degradation in the eating quality of rice after storage as a staple food. These two aspects have distinct connotations, and the associated characteristic indicators and genes vary significantly. To date, the evaluation of eating quality storage tolerance has remained elusive due to two key challenges. First, rice eating quality is a comprehensive trait encompassing several aspects, including rice appearance, rice aroma, and rice texture (according to GB / T 15682-2008). Therefore, previous storage tolerance evaluation methods, which used LOX genes (primarily associated with rice aroma after storage) or gelatinization characteristics (primarily associated with rice texture after storage) as single indicators, were unable to effectively identify representative rice varieties with storable eating quality. Second, the storage tolerance of eating quality varies significantly among rice varieties. There are some differences in storage tolerance between indica rice, japonica rice, and indica-japonica hybrid rice. Generally speaking, indica rice has slightly better storage tolerance, while japonica rice has poorer storage tolerance. Therefore, studying storage tolerance based on only a small number of varieties of a single type is not reliable.

[0003] In summary, the existing evaluation methods for rice taste quality and storage stability still have many deficiencies and defects. A more accurate, standardized, and scientifically reasonable evaluation method for rice taste quality and storage stability is urgently needed. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for evaluating the storage resistance of rice taste quality based on PRSI, so that the evaluation is more accurate, more standardized, and more scientific and reasonable, which solves the inaccuracy problem caused by single evaluation in the past, can guide the selection and classification storage of rice taste quality and storage resistance varieties, and achieve grain storage loss reduction and quality improvement.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for evaluating the storage stability of rice taste quality based on PRSI. The method proposes a definition of a rice storage stability index. The Paddy Rice Storability Index (PRSI) refers to the storage stability of the taste quality of rice during storage. A high rice storage stability index indicates that the taste quality of rice deteriorates rapidly during storage; a low rice storage stability index indicates that the taste quality of rice deteriorates slowly during storage. The present invention also provides storage stability levels corresponding to different index ranges. The present invention simplifies the comprehensive trait index of rice taste quality storage stability into a PRSI value, and constructs a corresponding evaluation method, specifically:

[0007] The present invention provides a method for evaluating the storability of rice taste quality based on PRSI, comprising the following steps:

[0008] (1) Fresh rice and rice aged for 3 months by artificial accelerated aging were selected to obtain brown rice and polished rice. The rice appearance score and rice taste score of polished rice, and the fatty acid value and POD activity value of brown rice were measured respectively.

[0009] (2) Calculate the storage coefficients of rice appearance score, rice taste score, fatty acid value and POD activity value respectively. The storage coefficient is the absolute value of the percentage change before and after aging, and is calculated according to the following formula;

[0010] ;

[0011] Among them, A i is the value after aging, CK i is the value of fresh rice before aging; X i is the storage coefficient; the storage coefficients of rice appearance score, rice taste score, fatty acid value and POD activity value are recorded as X1, X2, X3 and X4 respectively;

[0012] (3) The rice storage resistance index (PRSI) is calculated using the following prediction equation model:

[0013] PRSI=-0.055+0.367X1+0.502X2+0.003X3+0.254X4;

[0014] (4) The storage resistance of rice taste quality is evaluated based on the PRSI value. Compared with rice with a low PRSI value, the taste quality of rice with a high PRSI value deteriorates faster during storage and is less storable.

[0015] As a further improvement of the present invention, in step (4), when PRSI ≤ 0.35, the rice taste quality is a storable type; when PRSI ≥ 0.55, the rice taste quality is a non-storable type; when 0.35 < PRSI ≤ 0.45, the rice taste quality is a medium storable type; when 0.45 < PRSI < 0.55, the rice taste quality is a medium non-storable type.

[0016] Furthermore, in step (1), the artificial accelerated aging method is: placing the fresh rice in an incubator at 35°C and a relative humidity of 75% for accelerated aging treatment.

[0017] Furthermore, in step (1), the rice appearance score and rice taste score are measured using a Japanese Satake Taste Analyzer STA1B.

[0018] Furthermore, in step (1), the fatty acid value is determined by extracting the fatty acids in the rice with anhydrous ethanol at room temperature and titrating with potassium hydroxide solution.

[0019] Furthermore, in step (1), the POD activity value is determined using the guaiacol method.

[0020] Furthermore, the guaiacol method comprises the following steps: taking 0.5 g of brown rice, quick-freezing it with liquid nitrogen, grinding it into fine powder, adding guaiacol solution and reacting it in a water bath, recording the absorbance value at 470 nm and calculating the POD activity value.

[0021] Furthermore, after step (4), the method further includes guiding the breeding of rice varieties with good taste and storage resistance based on the evaluation results of the rice taste quality and storage resistance.

[0022] Furthermore, after step (4), the method further includes guiding the classified storage of rice based on the evaluation results of the rice taste quality and storage resistance.

[0023] By adopting the above technical solution, the present invention has at least the following advantages:

[0024] This invention provides a method for evaluating the storage stability of rice flavor quality based on the Rice Preservative Index (PRSI). The method defines a Rice Preservative Index (PRSI), which simplifies the comprehensive trait of rice flavor quality deterioration during storage into a single numerical value. A corresponding evaluation method is also developed to assess the storage stability of rice flavor quality based on the numerical value. Furthermore, based on a large number of rice varieties and parameters, the method identifies core indicators that influence rice flavor quality deterioration during storage: rice appearance score, rice mouthfeel score, fatty acid value, and POD activity value. These indicators are closely related to rice flavor variety, avoiding the inaccuracy caused by previous single-evaluation methods. Furthermore, the equation model evaluation method is more accurate and reliable. The overall evaluation method is more accurate, standardized, and scientifically sound, enabling accurate evaluation of the storage stability of rice flavor quality across different rice varieties. Furthermore, the PRSI is easy to measure, facilitating large-scale testing of rice varieties. This method is of great significance for the identification of flavor-stable varieties and for future high-quality grain storage, providing technical support for future green and quality-preserving grain storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0026] Figure 1 This is a comparison chart of the PRSI values ​​of various rice varieties;

[0027] Figure 2 is the principal component scree plot;

[0028] Figure 3 It is the principal component factor radar chart;

[0029] Figure 4 This is a systematic cluster diagram of rice eating quality and storage stability based on PRSI;

[0030] Figure 5 This is the linear regression analysis chart of the PRSI equation predicted value and actual value. DETAILED DESCRIPTION

[0031] This embodiment takes the production of large-scale planting varieties as an example to illustrate the technical solution of the present invention in detail, which should not be understood as any limitation to the technical solution.

[0032] In this example, indica rice, japonica rice, and indica-japonica hybrid rice varieties with large planting areas (indica rice: Tailiangyouxiang Yazhan, Tailiangyou 217; japonica rice: Jia 67, Zhehexiang 2; indica-japonica hybrid rice: Chunyou 167, Zhehangyou 220) were selected for evaluation and identification. The specific steps are as follows:

[0033] (1) For each rice variety, 600 g of freshly harvested, full-grained, insect-free, and mildew-free rice was selected. 200 g of rice was husked with a rice husker and finely ground with a mill to obtain brown rice and polished rice.

[0034] (2) The rice appearance score and rice taste score, as well as the fatty acid value and POD activity value of the brown rice were measured. The rice appearance score and rice taste score were measured using a Japanese Satake Taste Analyzer (STA1B). The fatty acid value was determined by extracting the fatty acids in the rice with anhydrous ethanol at room temperature and titrating them with potassium hydroxide solution to calculate the fatty acid value. The POD activity was determined using the guaiacol method. 0.5 g of fresh brown rice sample was quickly frozen in liquid nitrogen and ground into fine powder. The guaiacol solution was added and reacted in a water bath. The absorbance at 470 nm was recorded and the POD activity value was calculated in U / g·min. The characteristic parameters of the fresh rice samples are as follows (Table 1).

[0035] Table 1 Characteristic parameters of fresh rice samples

[0036]

[0037] (3) The remaining 400 g of rice sample was artificially accelerated aged and placed in a nylon bag in a constant temperature and humidity chamber (35°C, 75% RH) for 3 months. A 200 g sample of rice was husked with a rice husker and finely ground with a mill to obtain brown rice and polished rice. The rice appearance score, rice taste score, fatty acid value, and POD activity value were determined according to the method in (2). The results are shown in Table 2.

[0038] Table 2 Characteristic parameters of rice samples after storage

[0039]

[0040] (4) The single storage coefficient is calculated based on the changes in the four characteristic parameters before and after rice storage (aging). The storage coefficient is the absolute value of the percentage change before and after aging. The formula is as follows:

[0041]

[0042] Among them, A i is the value after aging, CK i is the value of fresh rice before aging; X i The storage coefficients for rice appearance, rice taste, fatty acid content, and POD activity are denoted as X1, X2, X3, and X4, respectively. The individual storage coefficients for rice after storage are as follows (Table 3).

[0043] Table 3 Single storage coefficient of rice after storage

[0044]

[0045] (5) According to the storage coefficient X of each variety i Substitute into the rice storage resistance index PRSI prediction equation model, PRSI=-0.055+0.367X1+0.502X2+0.003X3+0.254X4. Calculate the PRSI value ( Figure 1 Among them, Tailiangyouxiang Yazhan has the lowest PRSI value, indicating the best storage quality, while Zhehexiang 2hao has the highest value, indicating the least storage quality. Tailiangyouxiang Yazhan is a storage-tolerant variety, while Tailiangyou 217 and Zhehexiang 2 are not storage-tolerant. Jia 67 and Zhehangyou 220 are moderately storage-intolerant varieties, while Chunyou 167 is moderately storage-tolerant.

[0046] (6) To further verify the accuracy of the PRSI value, the six rice varieties mentioned above were taken out after being stored in a grain warehouse for two years. The color, odor, fatty acid value and taste score were measured according to the GB / T 20569 rice storage quality judgment rules. The results are as follows (Table 4). Except for Tailiangyouxiangyazhan, which is suitable for storage, the others are slightly or severely unsuitable for storage, among which Zhejianghangyou 220 and Chunyou 167 are slightly unsuitable for storage. The degree of deterioration of rice taste quality after two years of storage is basically close to the PRSI value, indicating that the PRSI value can be used to better evaluate the storage resistance characteristics of rice taste quality. After harvesting and before storage, rice varieties can be classified and stored according to their PRSI values, and different storage strategies can be formulated, such as low temperature and low humidity or controlled atmosphere, to maximize grain saving, loss reduction, quality improvement and efficiency increase. The results of the rice taste quality storage resistance evaluation can also be used to guide the selection of rice taste quality storage resistance varieties.

[0047] Table 4 Quality indicators of rice after 2 years of storage

[0048]

[0049] It should be noted that the method for selecting characteristic parameters and constructing the PRSI index equation model in this embodiment is as follows:

[0050] Specifically: A total of 42 main rice varieties in the rice-growing areas of the middle and lower reaches of the Yangtze River were collected, including indica rice, japonica rice and indica-japonica hybrid rice as follows (Table 5).

[0051] Table 5 Main rice varieties in the middle and lower reaches of the Yangtze River

[0052]

[0053] For each rice variety, 600 g of freshly harvested, plump, insect-free, and mold-free rice grains were selected. 200 g of the rice was husked using a rice husker and finely ground using a rice grinder to obtain brown and polished rice. Indicators related to rice taste quality were measured, including rice appearance value (score), rice mouthfeel value (score), overall taste value, peak viscosity, minimum viscosity, final viscosity, gelatinization temperature, alkali digestion value, gel consistency, fatty acid value, protein content, amylose content, total starch content, α-amylase activity, β-amylase activity, peroxidase (POD) activity, superoxide dismutase (SOD) activity, malondialdehyde (POD) activity, and lipoxygenase activity.

[0054] Subsequently, 400g of rice grains were placed in a nylon mesh bag and placed in a constant temperature and humidity chamber (35°C, 75% RH) for three months. After removal, a 200g rice sample was husked with a rice husker and finely ground with a fine grinder to obtain brown and polished rice. The rising indices were again measured. After these measurements, the individual storability coefficients for each index were calculated (Tables 6-1 and 6-2). Analysis of the individual storability coefficients revealed that indices related to rice flavor quality varied before and after storage, and that these indices influenced each other. Therefore, it is difficult to accurately and objectively evaluate the storability of rice flavor quality using these indices directly. Based on this, principal component analysis (PCA) was used to reduce the dimensionality of the parameters influencing flavor quality.

[0055] Table 6-1 Single storage coefficient of rice parameters before and after storage (1)

[0056]

[0057] Table 6-2 Single storage coefficient of rice parameters before and after storage (2)

[0058]

[0059] Principal component analysis showed that the cumulative contribution of the first six factors in each factor characteristic was 69.46%, and their characteristic roots λ>1 (Table 7). Therefore, by extracting the first six factors and grouping variables with the same nature into one category, the original individual indicators can be converted into six new independent comprehensive indicators (represented by F1, F2, F3, F4, F5, and F6, respectively). F1 had a high loading on rice appearance, taste, and overall score; F2 had a high loading on minimum viscosity, final viscosity, and gelatinization temperature; F3 had a high loading on protein content and SOD activity; F4 had a high loading on α-amylase activity; F5 had a high loading on MDA; and F6 had a high loading on peak viscosity ( Figure 2 、 Figure 3 ).

[0060] Table 7 Principal component eigenvectors and contribution rates

[0061]

[0062] Further, the weight coefficients of the principal component comprehensive index (ω i ), the membership function value of each genotype comprehensive index [μ(x i )] (Table 8) and Paddy Rice Storability Index (PRSI), and cluster analysis was performed using the Euclidean distance weighted pairwise arithmetic mean method for the PRSI values ​​of each genotype to divide the storage resistance level. Where Pi is the contribution rate of the i-th comprehensive index in the principal component analysis, x i 、x imax and x imin They represent the principal component score of the i-th comprehensive indicator and the maximum and minimum values ​​of the principal component score of the i-th comprehensive indicator, respectively.

[0063]

[0064]

[0065]

[0066] Table 8 Membership function values ​​of comprehensive indicators of various varieties

[0067]

[0068]

[0069] At λ=0.2, 42 rice varieties can be divided into 4 categories ( Figure 4 ), of which Category I is the storable type with good taste and quality, represented by Zhongzheyou H7; Category II is the medium storable type, accounting for 52.3%; Category III is the medium storable type, accounting for 28.6%; and Category IV is the storable type with good taste and quality. The PRSI value of Category I is 0.32-0.35, that of Category II is 0.36-0.46, that of Category III is 0.50-0.59, and that of Category IV is 0.64-0.71. Therefore, the storage resistance of rice taste quality is defined according to the PRSI value: when PRSI ≤ 0.35, the rice taste quality is of the storable type; when PRSI ≥ 0.55, the rice taste quality is of the non-storage type; when 0.35 < PRSI ≤ 0.45, the rice taste quality is of the medium storability type; when 0.45 < PRSI < 0.55, the rice taste quality is of the medium non-storage type.

[0070] After defining the meaning of the PRSI value and its corresponding distribution range, how to quickly determine the PRSI value becomes a subsequent issue. After determining the PRSI values ​​of the above varieties, the gray correlation analysis method was used to rank the correlation of 19 taste quality related indicators (Table 9). The top 5 indicators were rice appearance, taste, comprehensive value, POD activity and fatty acid value. Among them, the comprehensive value is the weighted value of rice appearance and taste. Therefore, the rice appearance, taste, POD activity and fatty acid value were selected for partial least squares regression analysis with the PRSI value, and the regression equation model PRSI=-0.055+0.367X1+0.502X2+0.003X3+0.254X4 was obtained. The coefficient of determination R 2 =0.835, F value is 46.66, and both the coefficient of determination and F value are at extremely significant levels, indicating that the model has good fitting, strong explanatory power and high prediction accuracy.

[0071] Table 9 Correlation and ranking between quality-related indicators and PRSI

[0072]

[0073] The PRSI prediction value of each breed was calculated based on the equation model, and regression analysis was performed using the PRSI prediction value and the actual PRSI value ( Figure 5 ), further verification showed that the PRSI value prediction equation model has high prediction accuracy and strong feasibility. It can be used to quickly calculate the evaluation and identification of rice taste quality and storage stability.

[0074] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Those skilled in the art can make some simple modifications, equivalent changes or modifications based on the technical content disclosed above, which all fall within the scope of protection of the present invention.

Claims

1. A method for evaluating the storage stability of rice based on the PRSI rice storage stability index, characterized in that: The steps include: (1) Fresh rice and rice aged for 3 months by artificial accelerated aging were selected to obtain brown rice and polished rice. The rice appearance score and rice taste score of polished rice, and the fatty acid value and POD activity value of brown rice were measured respectively. (2) Calculate the individual storage coefficients of rice appearance score, rice taste score, fatty acid value, and POD activity value respectively. The storage coefficient is the absolute value of the percentage change before and after aging, and is calculated according to the following formula; Among them, A i is the value after aging, CK i is the value of fresh rice before aging; X i is a single storage coefficient; the storage coefficients of rice appearance score, rice taste score, fatty acid value and POD activity value are recorded as X1, X2, X3 and X4 respectively; (3) The rice storage resistance index (PRSI) was calculated using the following prediction equation model: PRSI = -0.055 + 0.367X1 + 0.502X2 + 0.003X3 + 0.254X4; The method for constructing the prediction equation model comprises: measuring indicators related to rice taste quality before and after storage, calculating individual storage coefficients of the indicators, analyzing the correlation between the indicators, reducing the dimension of the indicators affecting rice taste quality by principal component analysis, further calculating the rice storage resistance index (PRSI) by membership function, performing cluster analysis on the rice storage resistance index (PRSI) values ​​to divide the storage resistance grades, and constructing the prediction equation model by grey correlation analysis and regression analysis; (4) The storage resistance of rice taste quality was evaluated according to the PRSI value. Compared with the rice with low PRSI value, the rice taste quality with high PRSI value deteriorated faster during storage and was less storable. When PRSI ≤ 0.35, the rice taste quality was storable; when PRSI ≥ 0.55, the rice taste quality was not storable; when 0.35 < PRSI ≤ 0.45, the rice taste quality was medium storable; when 0.45 < PRSI < 0.55, the rice taste quality was medium not storable.

2. The method for evaluating the storage stability of rice taste quality based on the PRSI rice storage stability index according to claim 1, wherein In step (1), the artificial accelerated aging method is: placing the fresh rice in an incubator at 35°C and a relative humidity of 75% for accelerated aging treatment.

3. The method for evaluating the storage stability of rice taste quality based on the PRSI rice storage stability index according to claim 1, wherein: In step (1), the fatty acid value is determined by extracting the fatty acids in the rice with anhydrous ethanol at room temperature and titrating with potassium hydroxide solution.

4. The method for evaluating the storage stability of rice taste quality based on the PRSI rice storage stability index according to claim 1, wherein: In step (1), the POD activity value is determined using the guaiacol method.

5. The method for evaluating the storage stability of rice taste quality based on the PRSI rice storage stability index according to claim 4, wherein: The guaiacol method comprises the following steps: taking 0.5 g of brown rice and freezing it in liquid nitrogen, grinding it into fine powder, adding guaiacol solution and reacting in a water bath, recording the absorbance at 470 nm and calculating the POD activity value.

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