doi: 10.17113/ftb.54.02.16.4096

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

Doris Kokalj^1*, Janez Hribar¹, Blaž Cigić¹, Emil Zlatić¹, Lea Demšar¹, Lovro Sinkovič², Helena Šircelj³, Grega Bizjak⁴ and Rajko Vidrih¹

¹Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia
²Crop Science Department, Agricultural Institute of Slovenia, Hacquetova 17, SI-1000 Ljubljana, Slovenia
³Department of Agronomy, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia
⁴Department of Power Systems and Devices, Faculty of Electrical Engineering, University of Ljubljana, Tržaška cesta 25, SI-1000 Ljubljana, Slovenia

Article history:
Received  January 30, 2015
Accepted November 30, 2015

Key words:
LED light, antioxidant potential, phenolics, flavonoids, pigments, ascorbic acid, tocopherols

Summary:
The objective of this study is to investigate the eff ects 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 emitt ed 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.

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