EFFECT OF STORAGE CONDITIONS AND WAXING ON WATER STATUS AND POSTHARVEST QUALITY OF CUCUMBER

Abstract

Storage conditions and waxing can affect water status and postharvest quality of cucumber fruits (Cucumis sativus L.) cv. Conquistador. The factors were studied in order to develop empirical models for quality and shelf-life prediction. Fruits were stored under six different vapor pressure deficit conditions (VPD), from 0.19 to 1.26 kPa. Daily and cumulative water losses; firmness, water (Ψw), osmotic (Ψs) and pressure (Ψp) potentials, total soluble solids and relative water content (RWC) were measured. First symptoms of detrimental quality (shriveling) were observed when the fruits reached 6 % of weight loss, regardless of VPD conditions or wax application. Wax application reduced weight loss in all storage conditions as compared with non-waxed fruits. Daily weight loss on waxed and nonwaxed fruits as a function of storage conditions (VPD) allowed to develop models for weight loss prediction. Waxed fruits under low relative humidity condition (VPD=1.26 kPa) reached 6 % of weight loss after six days; under a high relative humidity (VPD=0.2 kPa) fruits (waxed and non-waxed) did not reach those losses.. Initial water, osmotic and pressure potentials values were -0.4 MPa, -0.6 MPa, and +0.2 MPa, respectively. During storage, fruit values of Ψw and Ψs were reduced, especially under low humidity conditions. Relative water content (RWC) decreased more than 10 % during storage. Values below 88 % of RWC indicated cell plasmolysis caused by a reduction of Ψp values to cero or less.