Antioxidant Capacity and Bioaccessibility of Synergic Mango (cv. Ataulfo) Peel Phenolic Compounds in Edible Coatings Applied to Fresh-Cut Papaya

Edible coatings (EC) applied to fresh-cut fruits are used to increase their shelf-life and to deliver antioxidant bioactives such as phenolic compounds (PC) that reduce their oxidative damage while enhance their functional value. However, the combination of different PC may have synergetic, additive or antagonic effects on the final antioxidant capacity (AOXC). The aim of this study was to examine the AOXC of binary combinations of selected PC from mango peel and their bioaccessibility from 6% alginate-based EC applied to fresh-cut papaya, under simulated gastrointestinal conditions. Among equimolar (0.1 mM) combinations, gallic + protocatechuic acids (AB) were synergic in radical scavenging activity (RSA) as assayed by DPPH (90% RSA) and FRAP (0.39 mg TE/mL) methods; when assayed in 6% alginate-based EC, their RSA increased (117.85% RSA, 0.88 mg TE/mL). The application of EC + AB to papaya cubes and further in vitro digestion decreased their AOXC probably due to interactions between EC and papaya’s matrix. Therefore, further studies are needed in order to evaluate the effect of combination of phenolic and EC applied in other fruits matrix on antioxidants bioaccessibility.