EXTENDING STORAGE LIFE OF COMMERCIALLY IMPORTANT TROPICAL FRUITS USING BIO-WAXES

Commercial storage of papaya and mango is restricted by postharvest diseases caused by fungi. The use of bio-waxes on storage life extension and quality retention of these commodities was investigated. Three different bio-waxes (chitosan, ITI wax 1 and ITI wax 2) formulated from locally available ingredients were used in this study. Papaya and mango harvested at commercial maturity were dipped in wax formulations and stored at low temperature at 13°C and 80% relative humidity for 7, 14 and 21 days. Since, chitosan is reported as an antifungal compound, an in vitro antifungal assay was also conducted for disease causing fungi, Colletotrichum spp. and Botryodiplodia spp. isolated from fruit prior to in vivo assay. In vitro studies on chitosan revealed significant inhibition on radial mycelial growth of the disease causing organisms isolated from these commodities at treatments of 1% chitosan and above. Significant changes were observed in all bio-wax coated fruits compared with non-treated controls with respect to peel colour, firmness, internal CO2 concentration and respiration rate while other organoleptic characteristics of fruit were not affected. Both papaya and mango coated with 1% chitosan and ITI wax 1 showed improved keeping quality with high marketability throughout the storage period of 14 days at 13±1°C plus 2 days at 28±2°C. Mangoes coated with the ITI wax 1 formulation showed storage life extension of 17 days at the same temperature. Significant increase in the activity of plant defense enzymes, chitinase and AŸ, 1-3, glucanase were observed in the papaya peel samples of chitosan coated fruits compared to controls. The results of this study confirmed that the storage life of these tropical fruits could be extended using bio-waxes without detrimental effects on external and internal quality of fruit.