In vitro gastrointestinal release profiles and antioxidant capacity of bound polyphenols from soluble and insoluble dietary fiber of jackfruit pulp.

Abstract

Jackfruit (Artocarpus heterophyllus Lam.) pulp dietary fiber contains abundant bound polyphenols, but their gastrointestinal release remains unclear. This study examined polyphenol release, bioaccessibility, and antioxidant capacity of soluble dietary fiber (SDF) and insoluble dietary fiber (IDF) during simulated digestion. Total phenolic content showed phase-dependent changes: SDF peaked in the intestinal phase, whereas IDF peaked earlier in both gastric and intestinal phases. Phenolic bioaccessibility was higher in the gastric than intestinal phase for both fibers. DPPH scavenging activity and FRAP values were mainly enhanced during gastric digestion, while ABTS scavenging activity showed fiber-dependent changes, including higher intestinal-phase activity in SDF and a secondary rebound in IDF. Catechin was the dominant phenolic compound throughout digestion. Gaussian modeling captured the dynamic release profiles of total phenolics and catechin (R2 = 0.69-0.99). These findings clarify the digestive behavior of jackfruit fiber-bound polyphenols and support their use in functional foods.