Abstract:

【Objective】The yellow pigment content (YPC) in wheat grain is an important factor affecting the color and nutritional quality of flour end-use products. To quickly, accurately and simply detect YPC in wheat grain, the traditional method for YPC determination, AACC 14-50, was improved, providing a technical support for genetic improvement of the color and nutritional quality of flour end-use products.【Method】In this study, improvements have been made to the AACC 14-50 method using a Multiskan Spectrum microplate reader. The accuracy and stability of the modified method were analyzed, and the influence of extraction time and preservation time on flour YPC was dissected. The YPC of 283 domestic and foreign wheat varieties were determined by the improved method to further verify its effectiveness and explore excellent resources for genetic improvement of the color and nutritional quality of flour end-use products. 【Result】 The results showed that YPC determined by the modified method was significantly and positively correlated with those by the traditional AACC 14-50 method, with a correlation coefficient of 0.994 (P<0.001), and analysis of variance showed that YPC measured by the two methods was significant among varieties. The YPC of 144 wheat varieties were measured repeatedly using the modified method, and the correlation coefficients of YPC among three replicates were 0.997, 0.998 and 0.998, respectively. The flour YPC of Gaoyou 5218, Jishi 02-2 and Zhengmai 366 reached the maximum value (0.93, 1.24 and 1.53 μg·g^-1) at the extraction time of 30 min, and remained stable during 30-120 min (0.94-0.97 μg·g^-1, 1.30-1.33 μg·g^-1 and 1.59-1.62 μg·g^-1). No significant changes were observed in the flour YPC of Gaoyou 5218, Jishi 02-2 and Zhengmai 366 stored at room temperature for 0-20 days (0.93-0.97 μg·g^-1, 1.29-1.33 μg·g^-1 and 1.60-1.64 μg·g^-1; P>0.05). A wide range of YPC variation was identified in 283 domestic and foreign wheat varieties, with correlation coefficients ranging from 0.73 to 0.98 among different environments. Briefly, the mean YPC of varieties in the Huang-Huai wheat region was 1.15 μg·g^-1, ranging between 0.51-2.42 μg·g^-1. The average value of YPC in varieties from the Northern winter wheat region was 1.57 μg·g^-1, ranging from 0.90 to 2.52 μg·g^-1. The average value of YPC in the Middle-Lower reaches of the Yangtze River wheat region was 1.07 μg·g^-1, and the variation ranged from 0.56 to 2.54 μg·g^-1. The average YPC of foreign varieties was 1.61 μg·g^-1, ranging from 0.94 to 2.48 μg·g^-1. Twenty-four varieties with lower YPC and 26 with higher YPC were identified, which can be used as parents in wheat breeding programs to improve the color and nutritional quality of flour end-use products. Compared with the traditional AACC 14-50 method, the modified one reduces the workload, decreases the detection time, and increases the detection efficiency by about 12-15 times, and the consumption of samples and reagents is only 1/16 of those in the traditional method, which greatly reduces the cost. 【Conclusion】 The modified method for determining YPC in wheat grain established in this study is accurate, reliable, economical, efficient and simple, which can replace the traditional AACC 14-50 method for a large-scale determination of YPC.

Key words: Triticum aestivum, color of flour end-used products, nutritional quality, multiskan spectrum microplate reader, genetic improvement