| As the largest country in the production and consumption of legumes,legumes are widely planted in China,including 11 genera and 17 species.Legumes are not only rich in protein,starch,dietary fiberand fat,but also contain phytochemicals that are beneficial to human health(such as polyphenols).Although there has been many published researches on the phenolic compounds and antioxidant activities of legumes,they are mostly focused on the antioxidant activity of legume extracts.As far as we know,little has been reported on the distribution of phenolic compounds in legume and effects of human digestion processing on the phenolic compounds composition and their antioxidant activity.In this study,the composition of phenolic compounds and their antioxidant acitivities in six legumes(soybean,adzuki bean,chickpeas,kindy bean,faba bean and lentil),were determined;The composition and distribution of phenolic compounds in six legumes were analyzed,and the quantification of phenols were analyzed.In vitro gastrointestinal digestion model was conducted to examine the bioaccessibility of legume phenolic compounds in the human intestinal tract during digestion.The human colony fermentation experiment was conducted to study the changes of phenolic compounds in the human colon.The main results are as follows:1.Soluble phenolics composition in six legumes.The content of phenolic acids and flavonoids were s positively correlated with their antioxidant capacity.The soluble phenolics in adzuki bean had the highest phenolic acid,flavonoids content and antioxidant capacity.Seventy five phenols were identified in soluble extraction.The contents of phenolic acids and flavonoids,and their antioxidant capacity in the free,ester-bonded,glycosidically bonded phenolic fractions varied significatly among different legumes,and hydroxybenzoic acid,protocatechucin,and coumaric acid were widely present in six legumes.The anthocyanins in black lentils were mainly delphinidin-3-O-(2-O-?-D-glucopyranosyl-?-L-arabinopyranoside)and cyanidin derivatives.2.Bound phenolics composition in six legumes.There were significant difference in bound phenolic acid and flavonoid contents among selected legumes,and the efficiency of alkaline hydrolysis in the release of bound phenolics was better than that of acid hydrolysis.UPLC-QTOF-MS was used to identify 53 phenolic compounds in the bound phenolic extracts of the legumes.Quantitative determination of 20 phenolic compounds was performed by HPLC-QQQ,including 7 phenolic acids,13 flavonoids.p-Hydroxybenzoic acid,protocatechue,gallic acid,and catechin are abundant in the six selected legumes.3.Simulation of gastrointestinal digestion in vitro.The in vitro simulated digestion was conducted in legumes with higher bound phenolic contents(soybean,kindy bean and faba bean,2.27±0.30 mg GAE/g DW,2.07±0.09 mg GAE/g DW,1.79±0.12 mg GAE/g DW,respectively).Results showed that the contents of the released bound phenols in oral,stomach and small intestine phase were extremely low,only accounts for 3.25-14.64 % of the amounts of alki hydrolysis releasing.4.Simulation of human colon microbial fermentation.Results indicated that under the action of microorganisms,bound phenolics were released from the legume matrix,increasing the phenolic acid contents in the fermentation broth,but at the same time,microorganisms may also degrade phenolics to other substances,for which the phenols contents decrease,the pH of the solvent changed with the fermentation time. |
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