Inhibitory effect of black tea, lemon juice, and other beverages on salivary and pancreatic amylases: What impact on bread starch digestion? A dynamic in vitro study

Certain food properties (ex.: pH, polyphenolic composition) can inhibit digestive amylases and thereby slowdown starch digestion. Our aim was twofold. (1) To determine the impact of 21 beverages and condiments(coffees, teas, wines, vinegars and lemon juice) on salivary and pancreatic amylolysis: inhibition ranged from10% to 100% in our experimental conditions. (2) To investigate the effect of one black tea and lemon juice(selected for their strong inhibitory capacity) on starch hydrolysis during dynamic oro-gastro-intestinal digestionof bread. Compared to water (control), the effect of black tea was limited to a ≈20% reduction of releasedoligosaccharides during the intestinal phase. Lemon juice had a remarkable effect, completely interruptinggastric amylolysis by salivary amylase via a preliminary acidification of gastric contents. These results provide astrong biochemical rationale for the development of dietary strategies to improve the glycaemic impact ofstarch-rich meals which could be tested in vivo