Influence of Yellow Light-Emitting Diodes at 590 nm on Storage of Apple, Tomato and Bell Pepper Fruit.

Emil Zlatić,Rajko Vidrih,Blaž Cigić,Doris Kokalj,Grega Bizjak,Helena Šircelj,Lovro Sinkovič,Lea Demšar,Janez Hribar

doi:10.17113/ftb.54.02.16.4096

Abstract

The objective of this study is to investigate the effects of irradiation from light-emitting diodes (LEDs) on several fruits during storage. To improve storage and increase the contents of some bioactive compounds, apple, tomato and red bell pepper fruits were exposed to yellow light emitted from the diodes at 590 nm. The contents of ascorbic acid, total phenolics, total flavonoids and several pigments were investigated, along with the antioxidant potential. The colour parameters (L*, a* and b*) and firmness of the fruit were also determined. After 7 days of LED light irradiation, there was significantly higher total phenolic content and antioxidant potential in apple peel extracts. The irradiated fruit of tomato had significantly higher levels of total phenolic compounds, and the fruit of red bell pepper had significantly higher antioxidant potential. LED light had no effects on the colour parameters, although there was a tendency to accelerate colour development. Apple fruit irradiated with LED light was significantly less firm. Among twelve analysed pigments, significantly more β-carotene was detected in LED light-irradiated apple and bell pepper fruit, more α-tocopherol and γ-tocopherol in bell pepper fruit, and more lutein in apple peel and bell pepper fruit. The applied LED light slightly accelerated the ripening of the studied fruit, and affected the synthesis of some of the secondary metabolites.

Highlights

The human body produces reactive oxygen species (ROS), such as superoxide anion radicals, hydroxyl radicals and hydrogen peroxide, which can be beneficial in small amounts, but can lead to oxidative stress in larger amounts
We investigated the effects of yellow light-emitting diodes (LEDs) light (590 nm) on several biochemical compounds and quality parameters of apple, tomato and red bell pepper fruit
The mechanisms of the influence of LED light on plant metabolism have been well studied in the plants grown in glasshouses, but they have not been studied in any great extent during fruit storage after harvest

Summary

Introduction

The human body produces reactive oxygen species (ROS), such as superoxide anion radicals, hydroxyl radicals and hydrogen peroxide, which can be beneficial in small amounts, but can lead to oxidative stress in larger amounts. As a strong scavenger activity against free radicals is found in many plants worldwide, the intake of fruit and vegetables is associated with a lower risk of cancer and cardiovascular disease [2]. Sumption of natural exogenous antioxidants, such as polyphenols, has protective effects against these diseases, which can be partly attributed to several specific components: vitamins, flavonoids, anthocyanins and other phenolic compounds [1]. Polyphenols are secondary metabolites that have aromatic rings and hydroxyl groups, and these compounds can be divided into phenolic acids, stilbenes, flavonoids and lignans. Flavonoids are a group of polyphenolic antioxidants that have the capacity to transfer electrons to free radicals, to activate antioxidant enzymes, and to reduce α-tocopherol radicals. Previous studies have confirmed that there are high levels of phenols and flavonoids in the fruit of apple (Malus domestica ‘Granny Smith’) [5,6], tomato (Solanum lycopersicum L.) [7,8] and sweet pepper (Capsicum annuum) [9,10]

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