Postharvest diseases are limiting factors to the storage of many crops. There is a growing interest in alternative methods to control postharvest diseases. Pre-storage heat treatment seems to be one of the most promising rot control methods, associated with other alternative methods. The objective of this work was to verify the effects of immersion and spraying heat treatment on the cuticle of Fuji and Gala apples (Malus domestica Borkh.) right after treatment and a short storage period. This experiment consisted of six treatments, three replications of three fruits each: no treatment; hot water immersion at 58ºC for 30 s, 1 and 2 min.; hot water spraying at 58º C for 30s; chloroform immersion for 30s. Samples were excised to visualize on scanning electron microscope at onset and after three weeks storage at 0ºC. During the storage period, cracks of the cuticle layer got wider. Heat acts melting the crystalloids on the cuticle layer, and the melting forms a more homogeneous covering pattern on the apple surface. Heat caused occlusion of fractures by melting waxes, showing this is one of the probable effects of heat on the fruit, which could be acting as a physical barrier to avoid the entrance of pathogen in the apple, as well as reducing fresh weight loss.
thermoterapy; epicarp; Malus domestica
