Effects of starch on nitrous acid-induced oxidation of kaempferol and inhibition of α-amylase-catalysed digestion of starch by kaempferol under conditions simulating the stomach and the intestine

► Nitrite oxidised kaempferol under the conditions of the stomach. ► The oxidation resulted in the formation of nitric oxide. ► Kaempferol bound to starch. ► Starch (10 and 100 mg mL−1) enhanced and inhibited the oxidation, respectively. ► Kaempferol inhibited amylose digestion more strongly than amylopectin digestion.