Effects of Simulated Digestion on the Bioaccessibility of Phenolic Compounds and Antioxidant Activity of Dehydrated Bignay [Antidesma bunius (L.) Spreng]

Bignay is a Philippine indigenous berry rich in phenolic compounds with antioxidant activity. This can be dehydrated and used as a functional ingredient, but dehydration followed by digestion results to changes in the bioactive compounds modifying their bioaccessibility. Most bioaccessibility studies are on different fresh berries and fruits while very limited on dried or processed fruits. Thus, this study investigated the effect of simulated digestion on the bioaccessibility of phenolic compounds and antioxidant activity of freeze dried, oven dried, and spray dried bignay as well as cookies with added dehydrated bignay. Total phenolic content (TPC), total flavonoid content (TFC), total anthocyanin content (TAC), and antioxidant activity using 1,1-diphenyl-2-picryl hydrazyl (DPPH) scavenging activity, ferric reducing antioxidant power (FRAP), and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays were determined. The TPC, TFC, TAC, and antioxidant activity of the dehydrated bignay and cookies showed significant differences (p <= 0.05) at the end of each digestion stage. Among the dehydrated samples, the freeze dried bignay had the highest TPC, TFC, TAC and antioxidant activity after the gastric and intestinal stages resulting in a bioaccessibility of 66.39 % for TPC, 78.93 % for TFC, and 70.43 % for TAC along with a bioaccessibility of 81.45 % for DPPH, 82.28 % for FRAP, and 75.64 % for ABTS. Furthermore, the cookies with the added freeze dried bignay had the highest TPC, TFC, TAC and antioxidant activity at the end of both gastric and intestinal stages. This resulted in a bioaccessibility of 48.85 % for TPC, 47.26 % for TFC, 33.16 % for TAC, 62.60 % for DPPH, 64.39 % for FRAP, and 36.39 % for ABTS. Simulated digestion favored the release of phenolic compounds with antioxidant activity, although the contents were lower than that obtained before the simulated digestion. The total phenolics, flavonoids, anthocyanin, and antioxidant activity were better preserved by freeze drying then followed by oven drying and least by spray drying.