| Bread wheat(Triticum aestivum L.) is a major crop worldwide, and carotenoids in wheat are an important criterion in the assessment of colorful and nutritional values of end-use products, with little information available about carotenoids. Carotenoids are diverse groups of lipid-soluble organic pigments, which have several functions in improving human health and nutrition. The objective of the present study was to develop an optimal procedure for extraction and establish a method for separation of carotenoids compositions extracted from flours using ultra performance liquid chromatography(UPLC). Subsequently, 305 bread wheat cultivars were investigated to analyze their genetic variation. The main results obtained in this study are summarized below:1. Carotenoids from the flours were extracted using solvent extraction based on the report as described by previous research with modification. The following experiments, n-hexane/acetone(8:2, v/v, 0.1% BHT w/v) and oscillation were chosen for carotenoids extraction. The separation was achieved using YMC Carotenoid column(100 × 4.6 mm, 3 μm) with photodiode array(PDA) detector, and the column was thermostated at 35 °C. Under a gradient system consisting of acetonitrile/methanol/water/triethylamine(81:14:5:0.05, v/v/v/v)(A) and methanol/ethyl acetate/triethylamine(68:32:0.05, v/v/v)(B) at a constant flow rate of 0.4 m L/min, the carotenoids of bread wheat flour samples can be well separated in less than 25 min. The gradient was programmed as follows:(1) initial conditions of 100% solution A and 0% solution B,(2) a 0.3 min linear gradient with 100% solution A and 0% solution B,(3) a 11.7 min linear gradient with solution A from 100% to 0% and solution B from 0% to 100%,(4) a 8 min linear gradient with 100% solvent B and 0% solvent A,(5) a 3 min linear gradient with solution A from 0 to 100% and solution B from 100 to 0%, and(6) a 2 min linear gradient with 100% solvent A and 0% solvent B. Carotenoids were detected at 450 nm.2. The contents of carotenoids were investigated among 305 bread wheat cultivars from three wheat regions Genotype contributed the majority of variation in carotenoids contents, followed by environment and interaction between genotype and environment. The contents of lutein, zeaxanthin, and β-carotene ranged from 20.63 to 102.54 μg/100 g, 4.10 to 14.98 μg/100 g, 1.23 to 85.29 μg/100 g in wheat flour with an average of 43.51 μg/100 g, 7.49 μg/100 g, and 19.26 μg/100 g, respectively. Lutein was the main compound of carotenoids accounting for 62% of three carotenoids compositions, followed by β-carotene and zeaxanthin, sharing 27% and 11%, respectively, while no α-carotene was detected in all samples. Among three wheat regions, the highest average lutein content was 48.01 μg/100 g, from Northern Winter Wheat Region. Zeaxanthin and β-carotene of cultivars from Yellow and Huai River Valleys had the highest average contents, which were 7.90 and 20.56 μg/100 g, respectively. The total carotenoids, lutein, and zeaxanthin contents of cultivars from foreign countries were higher than Chinese cultivars. The contents of total carotenoids, lutein, zeaxanthin, and β-carotene were higher in 1BL.1RS than non-1BL.1RS cultivars. This work will be useful for quality breeding of bread wheat. |
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