Phenolics and enzymes of phenol metabolism in ‘Seedless’ and ‘Calcuttia’ cultivars of litchi grown in North India

Abstract

Present investigation reports the variability in phenolics and activities of some enzymes involved in their metabolism in pericarp tissue of 'Calcuttia' and 'Seedless' cultivars harvested at one week interval after fruit set. Total phenolics, fl avonols, and phenolic acid contents in litchi fruit pericarp increased after 49 days following fruit set (DAFS), while proanthocyanins showed a small increment initially and then decreased signifi cantly up to maturity. Polyphenol oxidase, phenylalanine ammonia lyase, and cinnamate-4-hydroxylase activities followed the similar trend as observed in phenolic content at respective developmental stages, while peroxidase activity in pericarp was low at initial stages and increased gradually with fruit development. Higher phenolic content with low polyphenol oxidase activity in pericarp during initial stages of fruit development in 'Seedless' as compared to 'Calcuttia' cultivar suggests the slow ripening. A negative correlation between anthocyanin content and anthocyanase activity was recorded. Total phenolic constituents, ferric reducing antioxidant power (FRAP), and 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging activity showed positive correlation with higher values of these parameters in 'Seedless' as compared to 'Calcuttia' cultivar. Knowing the phenolic profi les, antioxidant activity, and activity of related enzymes during fruit development gives the insights into its potential application to reduce the post-harvest browning of litchi.