STORAGE CONDITIONS AND WAXING AFFECT WATER STATUS AND QUALITY OF MANGO

Abstract

The study determined the effect of storage conditions and waxing on the water status and postharvest quality of mango fruits (Mangifera indica L.) cv. Keitt. Hydrothermal treated fruits were divided on two sets: one waxed with a commercial wax (Britex®), and the other unwaxed as control. Waxed and unwaxed fruits were stored under three different water vapor pressure deficits (VPD) conditions, 1.52, 1.14 and 0.22 kPa, during 10 d at 24 ± 1 °C. Daily and cumulative weight loss, firmness, relative water content (RWC), water potential (Ψw), osmotic potential (Ψ_s), pressure potential (Ψ_p) and soluble solid content (°Brix) were determined. Weight loss increased directly proportional to VPD. Wax application was effective in reducing by 30 % the weight loss, but only at high VPD. Using daily weight loss and DPV conditions, empiric models were generated to predict shelf life on control and waxed fruits (r² =0.90). When fruits reached 89 % RWC and Ψ_p = 0 (cellular plasmolysis), the commercial quality was still unaffected. Fruits with 84 % of RWC, Ψ_p < 0, and firmness = 20 N, defined the beginning of commercial quality loss. Ψw was reduced during storage from -1.0 to -2.8 MPa, depending on VPD conditions and wax application; this reduction was partially due to solute accumulation (°Brix) that modified Ψ_s. As °Brix increased, Ψ_s descended in a lineal relation, a relation that can also be used for prediction.