Effect of simulated gastrointestinal digestion on the phenolic composition and biological activities of guava pulp and processing by-products.

Powdered samples of guava pulp and processing by-products (single fraction containing crushed seeds, peels, and residual pulp) are rich sources of polyphenols with antidiabetic, anti-obesity, cardioprotective, and anticancer potential. However, post-digestion retention of these bioactivities remains unclear. Therefore, these samples were subjected to in vitro digestion simulating oral, gastric, small intestine, and large intestine phases. Phenolic bioaccessibility was highest upon large intestinal digestion for pulp (62.04 %) and waste (22.49 %), while the lowest occurred in the oral and small intestinal phases. Digestion reduced their antiradical activity and ability to inhibit α-glucosidase (42.42-55.84 %) but enhanced pancreatic lipase inhibition (up to 82.82 %). Digested samples could better suppress oxidative damage to LDL-cholesterol and supercoiled DNA. Phenolic acids and ellagitannins were released after gastric digestion, while proanthocyanidins predominated in intestinal phases. Digestion altered the phenolic composition of samples, positively affecting several bioactivities. Further research should investigate metabolization of polyphenols across intestinal cells to establish bioavailability.