Comparative study on phenolic profiles and antioxidant activity of litchi juice treated by high pressure carbon dioxide and thermal processing

Abstract

The present study compared physicochemical parameters, total phenolic and total flavonoid contents, individual phenolics, and antioxidant activity of litchi juice processed by high pressure carbon dioxide (HPCD), high temperature and ultra high temperature treatments. The results showed that HPCD can retain color of litchi juice better than thermal processing ( p < 0.05), while three processing methods had no influence on pH and total soluble solid in litchi juice. Compared to thermal processing, HPCD processed litchi juice had more total phenolics, total flavonoid and individual phenolics including rutin, (-)-epicatechin and chlorogenic acid ( p < 0.05). Furthermore, the antioxidant activity of litchi juice was analyzed by 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) assays. The result indicated that HPCD processing can preserve the antioxidant activity better than thermal processing ( p < 0.05). This study suggested that HPCD could be used as an alternative of traditional thermal processing to produce more fresh fruit juice.