Primary Metabolites and Polyphenols in Rapeseed (Brassica napus L.) Cultivars in China |
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Authors: | Miao Zhang Chang Zheng Mei Yang Qi Zhou Wenlin Li Changsheng Liu Fenghong Huang |
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Affiliation: | 1. Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Xudong 2nd Road, 430062, Wuhan, Hubei, China;2. Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Xudong 2nd Road, 430062, Wuhan, Hubei, China
Oil Crops and Lipids Process Technology National&Local Joint Engineering Laboratory, Xudong 2nd Road, 430062, Wuhan, Hubei, China
Hubei Key Laboratory of Lipid Chemistry and Nutrition, Xudong 2nd Road, 430062, Wuhan, Hubei, China |
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Abstract: | Defatted meals of 10 rapeseed (Brassica napus L.) varieties were investigated for their total phenolic, phenolic acid (free, esterified, and insoluble-bound forms), and tannin contents. The antioxidant capacities (AC) of methanol extracts from samples were assessed using the 2,2′-diphenyl-1-picrylhydrazyl radical (DPPH?), Folin–Ciocalteu method and ferric reducing antioxidant power (FRAP), and β-carotene–linoleic acid tests. In the fraction of free phenolic acids, sinapic, caffeic, ferulic, syringic, gallic, and p-coumaric acids were identified. In the fraction of esterified phenolic acids, sinapine, sinapoyl glucoside, and disinapoyl gentiobiose were identified. After basic hydrolysis, sinapic, ferulic, cinnamic, and 4-hydroxybenzoic acids were identified, and sinapic acid (SA) constituted 98.3% to 99.6% of the total esterified phenolic acids. Eleven components (sinapic, protocatechuic, p-coumaric, syringic, vanillic, gallic, caffeic, ferulic, salicylic, cinnamic, and 4-hydroxybenzoic acids) in the fraction of insoluble-bound phenolic acids were identified. The AC of the samples correlated with the total phenolic content. Overall, the total phenolics showed a better correlation with AC than the individual phenolic compounds. Moreover, SA, sinapoyl glucoside, and disinapoyl gentiobiose showed a highly significant and strong positive correlation with the AC of rapeseed meals, and the derivatives of cinnamic acid showed a higher correlation with AC than the derivatives of benzoic acid. The change in the canolol content in rapeseeds under microwave irradiation is discussed. The correlation of the canolol formed with SA and its derivatives is discussed. |
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Keywords: | Phenolic compounds Antioxidant capacity Correlations Microwave Rapeseed |
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