Effect of Postharvest LED Application on Phenolic and Antioxidant Components of Blueberry Leaves

Light from red (661 nm) and blue (417 nm) LEDs were applied for 12, 24, and 48 h on freshly harvested blueberry leaves of different cultivars mixed together. The extracts obtained through microwave extraction of these leaves were analysed in terms of total phenolic content, total monomeric anthocyanin content, and antioxidant activity as measured by % scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and ferric reducing antioxidant potential (FRAP). It was observed that although the content of total phenolic content was high in the untreated leaves, there was an increase in the phenolic content and monomeric anthocyanin content of the leaves treated with blue light. DPPH inhibition activity and FRAP for all the samples were high; however, there was an increase in the FRAP of samples treated with light for different durations, which varied with type of light and the time of application of the LED light.