Inhibition of phenolics on the in vitro digestion of noodles from the view of phenolics release

The inhibition mechanism of buckwheat phenolics on in vitro starch digestion was investigated using extruded noodles with buckwheat starch and phenolic extract (0.50%-2.00%). The cooking quality and reducing sugar released during in vitro digestion were studied, and the extractable phenolic content along digestion was also monitored to reveal a dose-effect relationship between reducing sugar released and the release of phenolics. Noodles containing increased phenolics released less reducing sugar (230-188 mg g(-1)) during digestion. Cooking and digestion made phenolics more extractable, and most of the phenolics were released at the end of the gastric phase (85.6%-94.8%) compared with during the small intestinal digestion. The IC50 of buckwheat phenolic extract (0.102 mg mL(-1)) was four times that of acarbose (0.032 mg mL(-1)). The inhibitory mechanism was further analysed using molecular docking, in which the activity of alpha-amylase was inhibited by phenolics that bind with active sites of alpha-amylase through hydrogen bonds and hydrophobic interaction. Phenolics interacting with starch and the released phenolics can both explain the reduction in starch digestion.