Changes in peel surface structures of pomegranate fruit (‘Wonderful’) during storage

Pomegranate fruit is susceptible to water loss despite its thick rind, resulting in financial loss to the industry. The aim of this study was to evaluate changes in peel surface structures of pomegranate fruit during storage, thus aiding the understanding of water loss mechanisms for strategic control techniques. Fruit were kept under cold storage (7°C, 90% RH) for 42 d and thereafter transferred to shelf conditions (23°C and 58% RH) for 8 d. The fruit were monitored for water loss during storage. In addition, peel samples were obtained from the top (near the calyx), mid (equatorial region) and bottom (near the pedicel) locations and were examined for lenticels, micro-cracks, and wax patterns using a scanning electron microscope (SEM). The thickness of waxy cuticles was assessed using confocal laser scanning electron microscopy (CLSEM). Results showed a decreasing waxy cuticle thickness profile, widening and deepening of micro-cracks and noticeable shrivelling during fruit storage. This study established the susceptibility of pomegranate fruit to excessive moisture loss because of the various surface openings. Secondly, the results portray the extent to which water loss affects the general appearance of the fruit and compromises peel integrity. Therefore, these findings are vital in aiding the application of water loss controls such as surface protective coating and waxing.