A method for identifying the textural characteristics of cooked rice from small samples of rice populations.

Abstract

This invention provides a method for identifying the textural characteristics of small-sample cooked rice from rice genetic populations. By using centrifuge tubes as the rice cooking vessel and measuring various textural parameters of the rice using a texture analyzer, the amount of each parallel sample is reduced to 0.5 ± 0.03 g. Only 2.5 g is needed to obtain the textural parameters of both fresh and reheated rice, providing a feasible method for identifying the textural phenotype of rice genetic populations, especially those with small seed quantities. Qualitative medium-speed filter paper is used to cover the tube opening, facilitating the exchange of moisture between the inside and outside of the centrifuge tube during cooking and preventing rapid loss of surface moisture during reheating. The sampling process employs whole-grain indiscriminate sampling, effectively avoiding differences in results caused by different sampling locations due to the unevenness of the inner and outer layers of the rice when sampling from a large number of samples after cooking. This invention establishes an objective evaluation method for the textural characteristics of small-sample rice based on a texture analyzer, laying the foundation for genetic research on the textural characteristics of rice.

Description

Technical Field

[0001] This invention belongs to the field of rice quality analysis technology, specifically relating to a method for identifying the textural characteristics of small-sample cooked rice from rice genetic populations. Background Technology

[0002] The breeding of high-quality rice varieties and the analysis of the mechanisms underlying high-quality eating are key areas of research in the genetic improvement of rice quality. Objective and accurate evaluation of rice eating quality is a prerequisite for studying the formation mechanism of high-quality eating and for breeding high-quality rice varieties. In recent years, significant progress has been made in the study of the physicochemical quality of rice and the molecular mechanisms of its formation. Based on the correlation between rice eating quality and physicochemical indicators such as amylose content and gelatinization temperature, a series of genes affecting rice eating quality, including amylose content and gelatinization temperature, have been cloned. However, these physicochemical indicators are mostly indirect evaluations of rice eating quality, and the relationship between them and rice eating quality is not a simple linear one. Rice varieties with the same physicochemical indicators may also have significantly different eating qualities.

[0003] Overall, there is currently very little genetic research on the hardness, stickiness, and other properties directly related to the eating quality of rice. There are two main reasons for this: First, the technology for identifying eating phenotypes is relatively lagging behind. Traditionally, the evaluation of rice eating quality relies on sensory evaluation. In the national standard GB / T 15682-2008, "Sensory Evaluation Method for the Cooking and Eating Quality of Rice and Grain in Grain and Oil Inspection," the tested variety is compared with a reference variety. Hardness, elasticity, and stickiness are graded into seven levels: "best," "good," "slightly better," "same as reference sample," "slightly worse," "poorer," and "worst," with scores of +3, +2, +1, 0, -1, -2, and -3 respectively. Therefore, the final score of the sample is actually a reference score relative to the reference variety, not the actual value. The results offer very limited information for genetic research and lack practical application. Secondly, rice eating quality is a complex biological trait, resulting from the combined effects of multiple gene regulation and environmental factors. Using genetic populations for QTLs and GWAS association analyses would likely be more effective. However, a single rice genetic population contains anywhere from a few hundred to several thousand accessions. In reality, due to the limited planting area in experimental fields, the amount of seeds harvested from each accession is not large, especially in the F2 population, where each plant has different genetic information, and the amount of seeds harvested from a single plant is very limited, sometimes less than 10g, requiring further seed saving for subsequent research. Therefore, there is an urgent need to develop a rice eating quality analysis technique that uses a small amount of seeds (rice) but provides a wealth of accurate information for genetic research.

[0004] Therefore, this invention starts from the study of texture characteristics related to the taste of rice genetic populations, especially the F2 segregating population, and controls the amount of rice used for cooking to establish a relatively comprehensive, objective and accurate identification method for evaluating texture characteristics related to the taste quality of rice, including hardness, stickiness and chewiness, thus laying the foundation for genetic research on traits related to the taste quality of rice. Summary of the Invention

[0005] To address the problems existing in the prior art, the purpose of this invention is to design and provide a technical solution for identifying the textural characteristics of small-sample cooked rice from rice genetic populations. This invention is specifically implemented using the following technical solution:

[0006] A method for identifying the textural characteristics of cooked rice samples from a rice genetic population, comprising the following steps:

[0007] 1) After harvesting, the seeds of rice genetic population materials should be stored at room temperature for more than 3 months and the moisture content should be balanced to 12±1%;

[0008] 2) Remove the husks from the seeds in step 1), mill them, and prepare them into first-grade rice according to national standard GB1354-2009 for later use;

[0009] 3) Take 0.5g of the rice processed in step 2) and grind it into rice flour. Pass the rice flour through a 100-mesh sieve for later use.

[0010] 4) The amylose content of the rice flour obtained in step 3) is determined according to the industry standard NY / T 2639-2014;

[0011] 5) The protein content of the rice flour obtained in step 3) is determined according to the industry standard GB 5009.5-2016.

[0012] 6) From the rice processed in step 2), select whole rice grains with a length ≥ 3 / 4 of the grain length, weigh 0.5 ± 0.03 g of whole rice and put it into a 2.0 mL round-bottom centrifuge tube with the cap cut off beforehand. Record the accurate weight A of the centrifuge tube after the cap is cut off and the accurate weight B of the whole rice weighed.

[0013] 7) Wash the rice grains in the centrifuge tube from step 6). After washing, use absorbent paper to dry the water on the outer wall and the inner wall of the centrifuge tube above the rice grains.

[0014] 8) Add water to the rice grains washed in step 7). After adding water, cover the centrifuge tube opening with a 5cm diameter qualitative medium-speed filter paper with the cap cut off, and secure the edge of the filter paper to the outer wall of the centrifuge tube with a rubber band.

[0015] 9) Place the centrifuge tubes from step 8) into a 24-well 2.0mL stainless steel centrifuge tube rack, and then place them in a constant temperature and humidity incubator at 25℃ and 70% humidity to soak the rice sample for 15 minutes.

[0016] 10) Place the centrifuge tubes, along with the tube rack, after soaking the rice samples in step 9) into a steamer for steaming;

[0017] 11) After taking out the sample obtained in step 10), place it in a constant temperature and humidity incubator at 25°C and 70% humidity. Two tubes are placed for 10 min for the texture determination of fresh rice, and two tubes are placed for 24 h for the texture determination of refrigerated rice.

[0018] Further, in step 6), weights A and B are accurate to 0.1 mg, and each material is repeated 4 times.

[0019] Further, the cleaning in step 7) specifically involves: spraying water onto the rice grains in the centrifuge tube using a pointed washing bottle, stirring clockwise twice and counterclockwise twice with a 200μL pipette tip to wash away the aleurone layer powder and dust remaining on the surface of the rice grains during the milling process, and pouring out the rice washing water as cleanly as possible. Repeat the washing and pouring process twice in total. During the pouring process, use the pipette tip to block the rice grains to prevent them from being poured out.

[0020] Further, in step 8), the amount of water added is calculated according to the formula Y = 0.024X1 + 0.037X2 + 0.574, where Y is the water-to-rice ratio, X1 is the amylose content (%) on a dry basis, X2 is the protein content (%) on a dry basis, and the total weight is W = A + YB.

[0021] Furthermore, in step 10), the steaming time is 30 minutes and the heat preservation time is 20 minutes.

[0022] Furthermore, the samples obtained in step 11) are sampled using the whole grain indiscriminate sampling method. For each tube of rice sample, without stirring, blunt-tipped tweezers are used to sample sequentially from top to bottom in the centrifuge tube. Broken rice grains are not taken. Three whole rice grains are taken each time and placed parallel to each other on the platform below the test probe. Each tube is sampled 5 times.

[0023] Further, the test conditions for the samples in step 11) are as follows: the FTC texture analyzer is in secondary extrusion mode, the cylindrical probe is 2.5 cm in diameter and 3.5 cm in height, the force sensor is 100 N, the initial force is 0.15 N, the test speed is 30 mm / min, the deformation is 60%, the elastic recovery time is 2 s, each tube is measured 5 times, and each sample is measured 2 tubes. The hardness, viscosity, chewiness and other texture parameters are obtained by removing one minimum value and one maximum value, and the average value of the remaining 8 measurements is taken as the final value of the sample.

[0024] This invention reduces the amount of rice used, requiring only 2.5g per sample to determine the hardness, stickiness, chewiness, and other textural parameters of fresh and cooked rice, as well as physicochemical indicators such as amylose content and protein content. It is particularly suitable for genetic populations with small seed yields. By using 2.0mL centrifuge tubes as the steaming vessel and replacing the caps with quantitative medium-speed filter paper to seal the tube openings, this invention facilitates the mutual balance of moisture inside and outside the centrifuge tube during steaming, effectively preventing moisture condensation on the caps and walls after cooling and dripping into the sample, thus affecting the measurement results. Furthermore, the use of 2.0mL centrifuge tubes as the steaming container results in a small sample volume and limited internal space, promoting sample homogeneity. Additionally, the whole-grain indiscriminate sampling method in this invention effectively avoids the differences in results caused by different sampling locations due to the unevenness of the inner and outer layers of rice during steaming when sampling from large quantities of cooked samples.

[0025] In summary, the beneficial effects of this invention are as follows: 1) It requires a small sample size, providing a feasible method for identifying the texture phenotype of rice genetic populations, especially those with small seed quantities; 2) The 2.0 mL centrifuge tube, used as a cooking container, has a small internal space, which is more conducive to sample uniformity. Furthermore, the whole-grain sampling method from top to bottom avoids the problems of uneven sampling and weak sample representativeness caused by differences between the inner and outer layers of rice when using a large number of samples; 3) It establishes an objective evaluation method for the texture characteristics of small-sample rice based on a texture analyzer. Compared with the qualitative reference scores given by the control samples in the sensory evaluation method of manual tasting, it can provide more specific numerical information, laying the foundation for genetic research on the texture characteristics related to the eating quality of rice. Attached Figure Description

[0026] Figure 1 To compare the texture determination results of rice cooked with 0.5g of rice in a 2.0mL centrifuge tube and rice cooked with 20g of rice in a 50mL aluminum box under suitable water conditions;

[0027] Figure 2 To compare the texture determination results of rice made from 0.5g of rice in a 2.0mL centrifuge tube and rice made from 20g of rice in a 50mL aluminum box under different water-to-rice ratios;

[0028] Figure 3 The frequency distribution of hardness, stickiness, and chewiness of fresh and retrograded rice from the Asominori×IR24 recombinant inbred line population is shown. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments in order to better understand the technical solution.

[0030] Experimental Example 1

[0031] Three different rice varieties, Nanjing 46, Ningjing 7, and Zhongjiazao 17, were selected, and their amylose and protein contents were determined. The amylose contents (%) were 9.6, 16.2, and 27.3, respectively, and the protein contents (%) were 6.3, 7.3, and 9.8, respectively. Substituting these values ​​into the water-to-rice ratio calculation formula Y = 0.024X1 + 0.037X2 + 0.574 (Y, water-to-rice ratio, X1, amylose content, dry basis; X2, protein content, dry basis), the suitable water-to-rice ratios for Nanjing 46, Ningjing 7, and Zhongjiazao 17 were calculated to be 1.04, 1.23, and 1.59, respectively. Two groups were prepared for each variety. One group consisted of 0.5 ± 0.03 g of whole rice grains placed in a 2.0 mL round-bottom centrifuge tube with the cap removed beforehand. After washing the rice sample, water was added and weighed to the appropriate water-to-rice ratio. A 5 cm diameter qualitative medium-speed filter paper was used to cover the opening of the centrifuge tube with the cap removed, and the edges of the filter paper were securely tied to the outer wall of the centrifuge tube with a rubber band. Four tubes were prepared for each variety: two tubes were used for the texture determination of fresh rice, and two tubes were used for rice that had been aged for 24 hours. For the determination of rice texture, another group used 20g ± 0.03g of whole rice grains placed in a cylindrical aluminum box with a bottom diameter of 5.5cm and a height of 3.2cm. After washing the rice sample, water was added and the weight was weighed to the appropriate water-to-rice ratio. A 9cm diameter qualitative medium-speed filter paper was used to cover the top of the aluminum box, and the edges of the filter paper were secured to the outer wall of the aluminum box with rubber bands. Four boxes were prepared for each variety, two for the determination of texture of fresh rice and two for the determination of texture of rice that had been stored for 24 hours. The soaking, steaming, and heat preservation methods for the rice in the centrifuge tubes and aluminum boxes were the same: soaking in a constant temperature and humidity incubator at 25℃ and 70% humidity for 15min, steaming in a steamer for 30min, and heat preservation for 20min.

[0032] For texture testing, whole-grain indiscriminate sampling was used for rice in centrifuge tubes without stirring. Tweezers were used to sample from top to bottom, excluding broken grains. Three whole grains were sampled each time, placed parallel to the test probe, and repeated five times per tube for a total of ten times across two tubes. For rice in aluminum boxes, the top surface layer was scraped off with tweezers, and samples were taken from the central area away from the inner wall of the box. Three whole grains were sampled each time, placed parallel to the test probe, and repeated ten times per box. Texture testing of both centrifuge tube and aluminum box samples was performed using a two-stage extrusion mode on an FTC texture analyzer. The cylindrical probe was 2.5 cm in diameter and 3.5 cm in height. A 100 N force sensor was used, with an initial force of 0.15 N, a testing speed of 30 mm / min, a deformation of 60%, and an elastic recovery time of 2 seconds. The minimum and maximum values ​​for hardness, viscosity, and chewiness were removed, and the average of the remaining eight measurements was taken as the final value for the sample.

[0033] The results for hardness, viscosity, and chewiness are as follows: Figure 1As shown in A, B, and C, under suitable water conditions, a comparison of the texture measurements of different varieties of rice steamed in a 2.0 mL centrifuge tube with 0.5 g of rice versus rice steamed in a 50 mL aluminum box reveals that, for all three texture parameters—hardness, stickiness, and chewiness—the rice steamed in a 2.0 mL centrifuge tube with 0.5 g of rice, regardless of whether it is fresh or reheated rice, is consistently lower than the rice steamed in a 50 mL aluminum box with 20 g of rice. This correlation is quite pronounced. Regarding hardness, the hardness of rice cooked with 0.5g of rice in a 2.0mL centrifuge tube, regardless of whether it was fresh or reheated rice, was approximately 72.5±0.6% of that of rice cooked with 20g of rice in a 50mL aluminum container. Regarding stickiness, the stickiness of rice cooked with 0.5g of rice in a 2.0mL centrifuge tube, regardless of whether it was fresh or reheated rice, was approximately 64.5±0.8% of that of rice cooked with 20g of rice in a 50mL aluminum container. Regarding chewiness, the chewiness of rice cooked with 0.5g of rice in a 2.0mL centrifuge tube, regardless of whether it was fresh or reheated rice, was approximately 57.5±1.7% of that of rice cooked with 20g of rice in a 50mL aluminum container.

[0034] In summary, for different rice varieties, the ratios of hardness, stickiness, and chewiness parameters measured by steaming 0.5g of rice in a 2.0mL centrifuge tube to those measured by steaming 20g of rice in a 50mL aluminum box are relatively fixed. That is, the data obtained from steaming 0.5g of rice in a 2.0mL centrifuge tube can be considered as a proportional conversion of the data from steaming 20g of rice in a 50mL aluminum box. This also applies to rice genetic populations containing multiple families. Based on this conversion ratio, the texture determination of rice obtained from steaming 0.5g of rice in a 2.0mL centrifuge tube will not affect the genetic mapping results of the texture characteristics of the rice population compared to the texture of rice obtained from steaming 20g of rice in a 50mL aluminum box.

[0035] Experimental Example 2

[0036] High amylose content rice variety Zhongjiazao 17 was selected, and three gradient water-to-rice ratios were set at 1.3, 1.4, and 1.5. Two sets were prepared for each water-to-rice ratio. One set consisted of 0.5 ± 0.03 g of whole rice grains placed into 2.0 mL round-bottom centrifuge tubes with the caps removed. Water was added according to the appropriate water-to-rice ratio. A 5 cm diameter qualitative medium-speed filter paper was used to cover the opening of the centrifuge tube, and the edges of the filter paper were securely tied to the outer wall of the centrifuge tube with rubber bands. Four tubes were prepared for each variety, with two tubes used for... For the textural determination of fresh rice, two tubes were used for the textural determination of rice that had been stored for 24 hours after reflux. The other group consisted of 20g ± 0.03g of whole rice grains placed in a cylindrical aluminum box with a bottom diameter of 5.5cm and a height of 3.2cm. Water was added according to the appropriate water-to-rice ratio described above. A 9cm diameter qualitative medium-speed filter paper was used to cover the top of the aluminum box, and the edges of the filter paper were secured to the outer wall of the aluminum box with rubber bands. Four boxes were prepared for each variety: two for the textural determination of fresh rice and two for the textural determination of rice stored for 24 hours after reflux. The soaking, steaming, and heat preservation methods for the rice in the centrifuge tubes and aluminum boxes were the same: soaking for 15 minutes in a constant temperature and humidity incubator at 25℃ and 70% humidity, steaming for 30 minutes in a steamer, and heat preservation for 20 minutes.

[0037] For texture testing, whole-grain indiscriminate sampling was used for rice in centrifuge tubes without stirring. Tweezers were used to sample from top to bottom, excluding broken grains. Three whole grains were sampled each time, placed parallel to the test probe, and repeated five times per tube for a total of ten times across two tubes. For rice in aluminum boxes, the top surface layer was scraped off with tweezers, and samples were taken from the central area away from the inner wall of the box. Three whole grains were sampled each time, placed parallel to the test probe, and repeated ten times per box. Texture testing of both centrifuge tube and aluminum box samples was performed using a two-stage extrusion mode on an FTC texture analyzer. The cylindrical probe was 2.5 cm in diameter and 3.5 cm in height. A 100 N force sensor was used, with an initial force of 0.15 N, a testing speed of 30 mm / min, a deformation of 60%, and an elastic recovery time of 2 seconds. The minimum and maximum values ​​for hardness, viscosity, and chewiness were removed, and the average of the remaining eight measurements was taken as the final value for the sample.

[0038] The results for hardness, viscosity, and chewiness are as follows: Figure 2As shown in A, B, and C, under different water conditions, the texture test results of rice made from 0.5g of rice steamed in a 2.0mL centrifuge tube and rice made from 20g of rice steamed in a 50mL aluminum box are compared. It can be seen that, for the three texture parameters of hardness, stickiness, and chewiness, whether it is fresh rice or reheated rice, the rice made from 0.5g of rice steamed in a 2.0mL centrifuge tube is lower than that made from 20g of rice steamed in a 50mL aluminum box, and the regularity is obvious. Regarding hardness, regardless of whether it was fresh or reheated rice, under different water conditions, the hardness of rice cooked with 0.5g of rice in a 2.0mL centrifuge tube using Zhongjia Early 17 was approximately 72.0±0.7% of that cooked with 20g of rice in a 50mL aluminum container. Regarding stickiness, regardless of whether it was fresh or reheated rice, the stickiness of rice cooked with 0.5g of rice in a 2.0mL centrifuge tube using different varieties was approximately 63.7±1.2% of that cooked with 20g of rice in a 50mL aluminum container. Regarding chewiness, regardless of whether it was fresh or reheated rice, the chewiness of rice cooked with 0.5g of rice in a 2.0mL centrifuge tube using different varieties was approximately 57.0±1.0% of that cooked with 20g of rice in a 50mL aluminum container.

[0039] In summary, for the same variety, even with different amounts of water, the ratios of hardness, stickiness, and chewiness parameters measured from 0.5g of rice steamed in a 2.0mL centrifuge tube to those measured from 20g of rice steamed in a 50mL aluminum box remain relatively constant. This means the data obtained from 0.5g of rice steamed in a 2.0mL centrifuge tube can be considered a proportional conversion of the data from 20g of rice steamed in a 50mL aluminum box, and this conversion ratio remains relatively constant under different water amounts. This further demonstrates that the genetic mapping results of the textural characteristics of rice populations are not affected when comparing the texture of rice steamed from 0.5g of rice in a 2.0mL centrifuge tube to that of rice steamed from 20g of rice in a 50mL aluminum box.

[0040] Example

[0041] 1) A population of recombinant inbred lines (RIL) derived from Asominori×IR24, comprising 180 lines, whose seeds were stored at room temperature for more than 3 months after harvest and whose moisture content was balanced to 12±1%;

[0042] 2) Remove the husks from the seeds obtained in step 1), grind them into fine rice of first-grade quality according to national standard GB1354-2009, and prepare about 5g for later use;

[0043] 3) Take 0.5g of the rice obtained in step 2), grind it into powder, and pass it through a 100-mesh sieve for later use;

[0044] 4) Determine the amylose content of the rice flour obtained in step 3) according to the industry standard NY / T 2639-2014;

[0045] 5) Determine the protein content of the rice flour obtained in step 3) according to the industry standard GB 5009.5-2016;

[0046] 6) Select whole rice (length ≥ 3 / 4 grain length) from the rice obtained in step 2), weigh 0.5 ± 0.03 g of whole rice and put it into a 2.0 mL round bottom centrifuge tube with the cap cut off beforehand. Record the accurate weight A of the centrifuge tube with the cap cut off and the accurate weight B of the whole rice weighed, accurate to 0.1 mg. Repeat each material 4 times.

[0047] 7) Spray water into the centrifuge tube using a pointed wash bottle. Use a 200μL pipette tip to stir clockwise twice and counter-clockwise twice to wash away any aleurone powder and dust remaining on the surface of the rice grains from the milling process. Pour out as much of the washing water as possible. Repeat the washing and pouring process twice. During pouring, use the pipette tip to block the rice grains to prevent them from being poured out. After the second washing and pouring out of the washing water, use absorbent paper to dry the outer wall of the centrifuge tube and the inner wall above the rice grains.

[0048] 8) Calculate the amount of water to add according to the formula Y = 0.024X1 + 0.037X2 + 0.574 (Y, water-to-rice ratio; X1, amylose content, dry basis; X2, protein content, dry basis). Add the corresponding amount of water to the centrifuge tube containing rice in step 7), so that the total weight W = A + YB. To allow water to interact inside and outside the centrifuge tube during the rice cooking process, and to avoid excess water remaining inside the centrifuge tube affecting the measurement results, this invention abandons materials that prevent water evaporation and interaction, such as centrifuge tube caps, tin foil, and sealing films. Instead, it uses 5cm diameter qualitative medium-speed filter paper to cover the centrifuge tube opening (outer diameter of the centrifuge tube opening is 1.3cm ± 0.1cm) after the cap has been cut off, and secures the edge of the filter paper to the outer wall of the centrifuge tube with a rubber band.

[0049] 9) Place the centrifuge tubes containing the sample and water obtained in step 7) into a 24-well 2.0mL stainless steel centrifuge tube rack and immerse them in a constant temperature and humidity incubator at 25℃ and 70% for 15 minutes.

[0050] 10) To prevent the centrifuge tubes from tipping over during the steaming process, place the centrifuge tube rack into the steamer, steam for 30 minutes, and keep warm for 20 minutes.

[0051] 11) After taking out the sample obtained in step 9), place it in a constant temperature and humidity incubator at 25℃ and 70% humidity. Place 2 tubes for 10 min to start the texture determination of fresh rice, and place 2 tubes for 24 h to use for the texture determination of reheated rice.

[0052] 12) The whole grain indiscriminate sampling method is used to sample the samples obtained in step 10). Each tube contains about 25 grains of rice. Without stirring, use tweezers to take samples from top to bottom in the centrifuge tube. Do not take broken rice grains. Take 3 whole rice grains each time and place them parallel under the test probe. Take 5 times per tube.

[0053] 13) The testing conditions for the samples in step 11) were as follows: FTC texture analyzer, secondary extrusion mode; cylindrical probe diameter 2.5cm, height 3.5cm; force sensor 100N; initial force 0.15N; testing speed 30mm / min; deformation 60%; elastic recovery time 2s; 5 measurements per tube; 2 measurements per sample. The minimum and maximum values ​​for the obtained hardness, viscosity, and chewiness parameters were removed, and the average of the remaining 8 measurements was taken as the final value for the sample. The results for hardness, viscosity, and chewiness are as follows: Figure 3 As shown, the hardness of freshly cooked rice in the population of 180 strains ranged from 9.2 to 19.3 N, with the most common being around 14 N (62 strains); the hardness of retrograded rice ranged from 10.4 to 21.4 N, with the most common being around 20 N (63 strains); the stickiness of freshly cooked rice ranged from 26.7 to 396.8 μJ, with the most common being around 260 μJ (68 strains); the stickiness of retrograded rice ranged from 6.4 to 152.3 μJ, with the most common being around 40 μJ and 70 μJ (126 strains combined); the chewiness of freshly cooked rice ranged from 0.5 to 4.5 J, with the most common being around 1.6 J (117 strains); the chewiness of retrograded rice ranged from 1.1 to 8.1 J, with the most common being around 4.0 J (72 families). Figure 3 The frequency distribution of the three traits—hardness, stickiness, and chewiness—shows a continuous distribution, suggesting that these traits are quantitative traits controlled by multiple genes. The textural phenotypic identification results obtained using this invention lay the foundation for further genetic analysis of textural properties.

Claims

1. A method for identifying the textural characteristics of small-sample cooked rice from a rice genetic population, characterized in that, Includes the following steps: 1) After harvesting, the seeds of rice genetic population materials should be stored at room temperature for more than 3 months, and the moisture content should be balanced to 12±1%; 2) Remove the husks from the seeds obtained in step 1), mill them, and prepare them into first-grade rice according to national standard GB1354-2009 for later use; 3) Take 0.5g of the rice processed in step 2) and grind it into rice flour. Pass the flour through a 100-mesh sieve for later use. 4) The amylose content of the rice flour obtained in step 3) is determined according to the industry standard NY / T 2639-2014; 5) The protein content of the rice flour obtained in step 3) is determined according to the industry standard GB 5009.5-2016. 6) From the rice processed in step 2), select whole rice grains with a length ≥ 3 / 4 of the grain length, weigh 0.5 ± 0.03 g of whole rice and put it into a 2.0 mL round-bottom centrifuge tube with the cap cut off beforehand. Record the accurate weight A of the centrifuge tube after the cap is cut off and the accurate weight B of the whole rice weighed. 7) Wash the rice grains in the centrifuge tube from step 6). After washing, use absorbent paper to absorb the water on the outer wall and the inner wall of the centrifuge tube above the rice grains. 8) Add water to the rice grains washed in step 7). After adding water, cover the centrifuge tube opening with a 5cm diameter qualitative medium-speed filter paper with the cap cut off, and secure the edge of the filter paper to the outer wall of the centrifuge tube with a rubber band. During this process, it is necessary to prevent the water inside the centrifuge tube from being shaken onto the filter paper. 9) Carefully place the centrifuge tubes from step 8) onto a 24-well 2.0mL stainless steel centrifuge tube rack, and then place them in a constant temperature and humidity incubator at 25℃ and 70% humidity to soak the rice sample for 15 minutes. 10) Place the centrifuge tubes, along with the tube rack, after soaking the rice samples in step 9) into a steamer for steaming; 11) After taking out the samples obtained in step 10), place them in a constant temperature and humidity incubator at 25℃ and 70% humidity. Two tubes are placed for 10 min for the texture determination of fresh rice, and two tubes are placed for 24 h for the texture determination of refrigerated rice. The specific test conditions are as follows: FTC texture analyzer in secondary extrusion mode, cylindrical probe with a diameter of 2.5 cm and a height of 3.5 cm, force sensor of 100 N, initial force of 0.15 N, test speed of 30 mm / min, deformation of 60%, elastic recovery time of 2 s, 5 measurements per tube, 2 measurements per sample. Remove the minimum and maximum values ​​of the obtained hardness, viscosity, and chewiness texture parameters, and take the average value of the remaining 8 measurements as the final value of the sample.

2. The method for identifying the textural characteristics phenotype of small-sample cooked rice from rice genetic populations as described in claim 1, characterized in that... In step 6), weights A and B are accurate to 0.1 mg, and each material is repeated 4 times.

3. The method for identifying the textural characteristics phenotype of small-sample cooked rice from a rice genetic population as described in claim 1, characterized in that... The cleaning process in step 7) involves spraying water onto the rice grains in the centrifuge tube using a pointed washing bottle, stirring clockwise twice and counterclockwise twice with a 200μL pipette tip to wash away the aleurone layer powder and dust remaining on the surface of the rice grains during the milling process. The rice washing water should be poured out as cleanly as possible. This washing and pouring process is repeated twice. During the pouring process, the pipette tip should be used to block the rice grains to prevent them from being poured out.

4. The method for identifying the textural characteristics phenotype of small-sample cooked rice from a rice genetic population as described in claim 1, characterized in that... In step 8), the amount of water added is calculated according to the formula Y=0.024X1+0.037X2+0.574, where Y is the water-to-rice ratio, X1 is the amylose content (%) on a dry basis, and X2 is the protein content (%) on a dry basis, so that the total weight W=A+YB.

5. The method for identifying the textural characteristics phenotype of small-sample cooked rice from a rice genetic population as described in claim 1, characterized in that... In step 10), the steaming time is 30 minutes and the heat preservation time is 20 minutes.

6. The method for identifying the textural characteristics phenotype of small-sample cooked rice from a rice genetic population as described in claim 1, characterized in that... The samples obtained in step 11) were obtained by whole grain indiscriminate sampling. For each tube of rice sample, without stirring, blunt-tipped tweezers were used to take samples from top to bottom in the centrifuge tube. Broken rice grains were not taken. Three whole rice grains were taken each time and placed parallel under the test probe. Five samples were taken from each tube.

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