In vitro release and antioxidant activity of Satsuma mandarin (Citrusreticulata Blanco cv. unshiu) peel flavonoids encapsulated by pectin nanoparticles

The flavonoids of citrus peel extracts (CPE) were encapsulated by pectin nanoparticles (PNs), in an attempt to control the releasing property and improve their antioxidant activity. The physiochemical properties of the obtained PNs were characterised. Flavonoid composition in CPE before and after encapsulation were determined. In vitro release profiles and antioxidant activity of CPE were further evaluated. Results showed the size of spherical PNs obtained was 271.5 +/- 5.3nm. Interestingly, in simulated gastric fluid (SGF), 73% flavonoids were released from the naked CPE after 2h, while only 28.78% from the CPE-loaded PNs (E-PNs). The releasing rate of flavonoids reached 91.47% from E-PNs after 24h in the simulated intestinal fluid (SIF). Moreover, DPPH and ABTS assay revealed that E-PNs showed higher antioxidant activity than blank PNs and free CPE. These data showed that the controlled release of CPE might potentially increase its bioaccessibility and there was a synergistic effect between citrus PNs and CPE on the antioxidant activity.