Chemical Composition and Antioxidant Activity of Mexican Opuntia Peel Fruit Polyphenols and Their Maltodextrin Microencapsulates

Abstract

The cladodes and fruits of many Opuntia species that grow in the wild and are cultivated in México are consumed fresh or after processing in the form of jams and juices. Although the peels that result from this processing can be used as livestock feed, a large amount of this byproduct is discarded. In order to explore the possibility that this peel byproduct may represent a source of functional components, the polyphenol composition and antioxidant activity of the peels from the fruits of six Mexican Opuntia species (O. ficus-indica, O. megacantha, O. robusta, O. albicarpa, O. undulata, and O. joconostle) have been determined. Ferulic, protocatechuic, gallic, sinapic, and p-coumaric acids were the most abundant polyphenols. The main phenolic acid, ferulic acid, ranged from 30.5% to 41.5% in the extracts and from 23.2% to 40.9% in the encapsulated. The original polyphenol extracts exhibited higher antioxidant activity than the corresponding encapsulated extracts as determined using the ABTS, DPPH, and ORAC assays, but the antioxidant activity was higher in the encapsulate extracts when determined using the Caco-2/DCFH assay. O. ficus-indica polyphenol extracts showed the highest ABTS and DPPH scavenging activities with 59.4 and 41.2 μM Trolox equivalents/gdw, while O. robusta-encapsulated polyphenols showed the highest ABTS and DPPH scavenging activities with 39.7% and 36.0% μM Trolox/gdw, respectively. The encapsulated extracts from O. undulata and O. joconostle yielded the highest cell antioxidant activity at all the concentrations that were assayed. These results highlight the important effect that encapsulation has on the antioxidant activity and support the potential use of the Opuntia peel byproduct as a source of health-promoting components.