Changes in phytochemical compositions, antioxidant and α-glucosidase inhibitory activities during the processing of tartary buckwheat tea

This study focused on the evaluation of changes in phytochemical compositions, antioxidant and α-glucosidase inhibitory activities during the processing of tartary buckwheat tea. Soak-treating tartary buckwheat significantly decreased the contents of total starch and rutin, whereas significantly increased the contents of quercetin, kaempferol, total flavonoid, and total phenolic compounds. In steam-treating soaked tartary buckwheat for 40–60 min, the contents of total starch, protein, crude fat, isoquercitrin, quercetin, kaempferol, total flavonoid and total phenolic compounds significantly decreased, whereas the content of rutin significantly increased. The reaction of rutin degrading might be catalyzed in soaking processing, and a catalytic reverse shift reaction of rutin-synthesizing might take place in steaming processing. The process of drying and roasting significantly decreased the contents of total starch, rutin, total flavonoid, and total phenolic compounds. The total phenolic content of collected tartary buckwheat materials positively correlated with the antioxidant and α-glucosidase inhibition activities.