Abstract
A study to determine the postharvest loss and evaluate the effects of different treatments on reduction of postharvest losses and extension of shelf life of four varieties of mangoes, namely, Gopalbhog, Khirsapat, Langra and Fazli was conducted from June, 1997 to August, 1999 at the Mango Research Station, Chapai Nawabganj and the Department of Horticulture, Bangladesh Agricultural University, Mymensingh. The study consisted of two sets of experiments, (a) a survey to determine the extent of postharvest losses of mango in Bangladesh until marketing and (b) studies on the effects of different postharvest treatments on the storage life of mango. The survey indicated that the total postharvest loss of mango in Bangladesh was 27.16%. In the second sets of experiments, the attributes such as total weight loss, total soluble solids, total sugar, reducing sugar, non-reducing sugar and β-carotene contents increased while, titratable acidity and vitamin C contents declined with increase in the duration of storage. Wax coating and fruits sealed in polybag exhibited minimal weight loss during storage. The results revealed that prematurely harvested fruits exhibited longer shelf life than fruits harvested at optimum maturity stage. The shelf life gradually decreased as the fruits advanced towards optimum maturity stage. Highly significant differences in respect of shelf life among the varieties was observed in the investigation. The longest shelf life was observed in cv. Fazli and the shortest in cv. Gopalbhog. Further, wax coating of mangoes appeared to be the best for extending shelf life (21.07, 21.65 days in cv. Khirsapat and Fazli, respectively), followed by KMnO₄ treatment (17.42, 18.38 days in cv. Khirsapat and Fazli, respectively). But these two treatments caused a kind of off-flavour which made the fruits inedible. Hot water treatment was the third best means for increasing the shelf life of mangoes. It also caused a significant improvement in skin colour of the fruits. Among the hot water treatments, dipping the mangoes in water at 55°C for 5 to 10 min was found to be the best by most considerations (16.73, 16.22, 15.36 and 14.93 days in cv. Gopalbhog, Khirsapat, Langra and Fazli, respectively). Dipping in water at 57°C for 10 min resulted in blackening of skin in case of cv. Fazli, but not in Khirsapat. Dipping of mangoes in water at 55-57°C up to 10 min may be recommended for Khirsapat, but temperature above 55°C appeared to be risky for Fazli. Treatments with fungicides and CaCl₂ were significantly better than control, but were inferior to hot water treatments.