| Lignans are the important active substances in sesame seeds with great nutritionaland medicinal values. The purpose of this study was to provide a theoretical basis andtechnical support for screening sesame germplasm with high lignan content, breeding new cultivar, further research and full development and utilization of sesame lignans. Sesame lignans are commonly divided as lignans and lignan glucosides in terms of their solubility. Sesaminol triglucoside as the main theme in this paper, a HPLC method for determination of major water-soluble phenolic lignans sesaminol triglucoside content in sesame seeds and the optimum extraction process were established. The effects of growing environment, post-ripening and roasting on lignan contents of sesame seeds were explored. The correlation of lignans with lignan glucosides was also analyzed. The major results are summarized as follows.(1) The purity of sesaminol triglucoside purified from sesame seeds was 98.22%. And based on this a HPLC method for determination of sesame seeds major water-soluble phenolic lignans sesaminol triglucoside content was established. According to the external standard method to detection the content of sesaminol triglucoside, the target peak could be well separated from other impurities and the baseline stable. And the optimal extracting parameters were obtained through single factor design and orthogonal experiment, and it can be used as a pretreatment method of the quantitative method for sesaminol triglucoside in sesame seeds.The optimum conditions for sesaminol triglucoside extraction were the concentration of ethanol 70%, the solid/liquid ratio 1:40, the temperature of ultrasound 20 ℃ and the time of ultrasound 20 min. This method was confirmed convenient, accurate and reliable for the determination of sesaminol triglucoside content in sesame seeds.(2) 212 of representative materials were screened from total 3800 accessions and planted in four different ecological zones, in order to explore the relationship among different origin, seed weight, seed coat color with sesamin and sesamolin content.The results showed that the sesame lignans content increases with latitude upward; sesame seeds color L value was significantly positively correlated with sesamin content(r = 0.2966, ɑ = 0.01), but not significantly with sesamolin content; seed weight was significantly negatively correlated with content of sesamin(r =-0.2603, ɑ = 0.01), but significantly positively correlated with sesamolin content(r = 0.2279, ɑ = 0.01). The 15 samples of representative materials were screened in the following study, and their contents of sesamin, sesamolin, sesaminol triglucoside were measured and analysied. We found that sesaminol triglucoside has no significant correlation with sesamin and sesamolin in sesame seeds.(3) The moisture content and acid value in sesame seeds were decreased during sun-drying, while fat content increased. And all those became stable over 20 days. According to their change tendency, post-ripening had been completed within 20 days after harvest. During this period, post-ripening had little influence on sesamin and sesamolin,but marked influence on sesaminol triglucoside.The content of sesaminol triglucoside firstly increased and then decreased, tending to stable after 15 days. Compared with the newly harvested seame seeds, the sesaminol triglucoside content of test materials SO1, SO3 and SO4 increased, but the sesaminol triglucoside content of SO2 decreased slightly.(4) The effect of roasting temperature and time on sesamin, sesamolin, sesamol and sesaminol triglucoside in this study was extremely significant overall(P<0.01). At temperature of above 200 ℃, the contents of sesamin, sesamolin and sesaminol triglucoside began to significantly decrease in the different rosting time of 30 min, 20 min, 10 min, respectively, and the time needed for roasting became lesser with the temperature rises. And this proved that sesamolin was converted into sesamol. |
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