Effect of Blue and Red Light-Emitting Diodes on Haskap (Lonicera caerulea L.) Postharvest Storage

Light-emitting diodes (LEDs) have been applied to many fruits and vegetables during postharvest storage; however, their effects on haskap storage remain unknown. This research aims to identify the impact of red and blue LEDs on haskap postharvest storage. By analyzing physical parameters (weight loss and firmness) as well as physicochemical factors (soluble solid content, pH, and acids), in addition to color parameters, microbial populations, total phenolic quantifications, and antioxidant capacity, the effects of red LED, blue LED, and darkness treatments were compared. The results indicated that red and blue LEDs significantly increased weight loss in haskap compared to the dark treatment. LEDs did not influence SSC, pH, or acids on any sampling day; however, pH showed significant changes throughout the storage period. Both red and blue LEDs affected color parameters, resulting in lower a* and higher L*, suggesting that LEDs may influence anthocyanin content in the fruit skins. With similar preservation effects, haskap treated by LEDs exhibited firmer berries during storage. The assessment of secondary metabolism indicated that total phenolics and flavonoids remained unchanged, while anthocyanins significantly increased throughout storage. Haskaps under both LEDs also displayed higher antioxidant capacities without significantly affecting microbial populations or ascorbic acid content during storage. This study demonstrated that red and blue LEDs positively affected the preservation of haskap, considering the assessment of firmness, color, anthocyanin content, and antioxidant capacities. However, the weight loss under LEDs needs to be addressed with adjustments of irradiation intensity or duration in the future.