Control of black rot caused by Alternaria alternata in yellow pitahaya (Selenicereus megalanthus) through hot water dips

Abstract

Black rot by Alternaria alternata causes the majority of losses in yellow pitahaya (Selenicereus megalanthus) during postharvest period. Leading strategy for decay control is the use of synthetic fungicides, but constraints associated with the use of this kind of products have led to the search for alternative methods to reduce fungal infections. The efficacy of hot water dips at different temperatures and times (40 °C for 1 min; 40 °C for 2 min; 50 °C for 1 min and 50 °C for 2 min) for controlling black rot on yellow pitahaya was evaluated by measuring disease severity on fruit pre-inoculated with A. alternata. The results showed that both treatments, 50 °C for 2 min and the imazalil fungicide (0.4 g L−1), significantly reduced lesion diameter (63.1 and 70.5%, respectively) after 21 days at 12 °C compared with non-treated control fruit. Hot water dips at 50 °C for 2 min before cold storage maintained firmness, reduced weight loss, slowed the changes in fruit skin color, soluble solid content (SSC) and titratable acidity (TA) and did not affect sensory quality of yellow pitahaya. These results showed that dips in hot water may provide a postharvest alternative treatment to control or reduce black rot caused by A. alternata in yellow pitahaya.