Vapour heat treatment of Sultanina table grapes. II: Effects on postharvest quality

Abstract

Abstract Vapour heat treatments have been found to be effective for the postharvest control of Botrytis cinerea (grey mould) on table grapes. In the current research, the effect of such treatments on the quality of table grapes (Vitis vinifera L. cv. Sultanina) has been evaluated. Individual berries or bunches of grapes were subjected to a range of temperatures (52.5–58 °C) for various time intervals (18–30 min). Following heat treatment, the fruit was stored at 20 °C and various quality parameters were measured over a 7 day period. Treatments at temperatures of 52.5 or 55 °C for times ranging from 18 to 27 min were found not to significantly affect bunch weight loss, berry firmness, berry colour, total soluble solids or acid concentrations. At higher temperatures (58 °C) or for extended time periods (e.g. 55 °C for 30 min), some negative effects were observed, namely increased weight loss and berry colour darkening compared with control bunches. In most of the treatments, the commercially significant quality defects of berry shatter and stem browning were reduced. It is concluded that vapour heat treatments can be applied to ‘Sultanina’ table grapes for disease control without compromising fruit quality.