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

Winny Routray,Valerie Orsat,Mark Lefsrud

doi:10.3390/chemengineering2040056

Winny Routray, Valerie Orsat + Show 1 more

Open Access

https://doi.org/10.3390/chemengineering2040056

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Journal: ChemEngineering	Publication Date: Nov 20, 2018
Citations: 9	License type: CC BY 4.0

Affiliation: McGill University

Abstract

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.

Highlights

Blueberry leaves have been considered as an important source of phenolic compounds [1,2], which can be processed using several postharvest applications, including extraction, separation, purification, and encapsulation leading to viable product development and commercialisation of different blueberry phenolic compounds or for application in nutraceutical purposes and as food additives
Several reports have mentioned the increase in the total content of phenolic compounds and anthocyanins in plant material due to the abiotic stress
The application of blue light for 12 h increased the concentration of total phenolics as compared to extract obtained from untreated leaves and the application of up to 24 h increased, maintained, or decreased the phenolic concentration, the application for 48 h led to deterioration of the compounds in all observed cases

Summary

Introduction

Blueberry leaves have been considered as an important source of phenolic compounds [1,2], which can be processed using several postharvest applications, including extraction, separation, purification, and encapsulation leading to viable product development and commercialisation of different blueberry phenolic compounds (chlorogenic acid [3], catechin, epicatechin, caffeic acid, and different anthocyanins [4]) or for application in nutraceutical purposes and as food additives. Blueberry leaves have been reported to have antioxidant activities comparable or higher than the fruits [1,2,5] and several other health beneficial effects including antidiabetic [6] and antibacterial effects [7]. Postharvest processing methods affect the concentration of these compounds in the plant sources. In the past few decades, research on postharvest application of different abiotic sources of stress has been increasingly conducted. Abiotic stress application has been reported to affect the pathways for biosynthesis of some groups of secondary metabolites including terpenes, phenolics, and nitrogen containing compounds (polyamines and glycine betaine [9,10]). UV-B and UV-C has been observed to have a significant positive effect on phenolic compounds concentration in various fruits including blueberries, apples, and elderberries [11,12]

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