Evaluation of the Effectiveness of Light Emitting Diodes in Post-harvest Shelf Life Extension of Blueberries

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Sandhu, Ramandeep Kaur

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University of Guelph


Light emitting diodes (LEDs) are being used as a cost-effective alternative light source during plant growth to regulate the overall quality of fruits and vegetables; however, they have been used infrequently at the post-harvest stage. Their capability of narrow bandwidth emission and controllable spectral distribution holds a potential to help food producers and distributors in reducing wastage incurred during the post-harvest activities. LEDs can potentially help in regulating senescence, ripening and nutritional attributes in fruits and vegetables. The objective of the thesis is to develop a LED post-harvest system for fresh fruits and vegetables and evaluate the effect of LED lights of different wavelengths and photon flux intensities on nutritional content and shelf life of fruits and vegetables at different temperatures and treatment times. Blueberries were measured for change in weight, diameter, colour, TSS and anthocyanin content to evaluate the effect of LED lights on ripening. Phenolic compounds were estimated and quantified using Folin-Ciocalteau reagent and HPLC assays and Antioxidant activity was determined using scavenging activity on DPPH radicals and FRAP. The results suggest that under some conditions of illumination with LEDs, the nutritional content enhanced, and ripening was delayed. The results from this thesis will help researchers to identify optimal LED treatment parameters for post-harvest enhancement of the overall quality of fruits and vegetables. This will also help in determining the potential applications of LEDs in various post-harvest management operations of food to reduce losses and help in building the competence of the food supply system.



Light emitting diodes, soluble sugars, phenolics, antioxidant, anthocyanin, post-harvest