Effect of digestion on bound phenolic content, antioxidant activity and hypoglycemic ability of insoluble dietary fibre from four Triticeae crops.

To assess the physiological functions of bound phenols in insoluble dietary fiber (IDF) from different Triticeae crops, bound phenols in IDF were extracted from wheat, triticale, barley and quinoa. In addition, model in vitro was established and used in evaluating the release of bound phenols and changes in their physiological functions after simulated digestion. Results showed that bound phenol content in IDF from Triticeae crops before digestion was higher than which during digestion, and its physiological functions were also better (p < .05). Moreover, barley extracted before digestion, its bound phenolic content in IDF was higher than those in other three Triticeae crops, besides,its bound phenol also showed better antioxidant ability. Before digestion, bound phenols in IDF from triticale showed the best hypoglycemic ability (the inhibition rate of α-glucosidase was 95%; the inhibition rate of α-amylase was 97%). In the simulated digestion model, the bound phenols were mainly released during the intestinal digestion stage, they showed better physiological functions than which released at the gastric digestion stage. The bound phenol content in triticale was higher and its physiological functions was better than those in the other crops. PRACTICAL APPLICATIONS: The results of this experiment showed that the release of bound phenols measured by chemical extraction (i.e., before digestion) was higher than that by simulated gastrointestinal digestion. Compared with the chemical extraction method, in vitro gastro-intestinal digestion simulates the pH value and enzyme environment of food in the human body gastrointestinal digestion process more effectively. This study can provide reference for selecting Triticeae crops feeding in the future. To be more precise, bound phenol content in the insoluble dietary fiber of barley was the highest before digestion. The bound phenol in the insoluble dietary fiber of triticale had the best hypoglycemic ability. The bound phenolic compounds are mainly released during intestinal digestion, and their physiological functions are better than that in gastric digestion.