Ethanol vapour—a new anti-scald treatment for apples

Abstract

Superficial scald was controlled on highly susceptible Granny Smith apples, grown in New South Wales, by exposing the fruit to evaporating ethanol at 0 or 20 °C. To avoid cross contamination of ethanol, the fruit were stored in sealed polyethylene bags (0.05 mm thickness). The ethanol was added at the rate of 0, 0.25, 0.5 or 1.0 g fruit−1 to five small cups each containing 10 g vermiculite. The bags were then sealed and the fruit held at 0 or at 20 °C for four days before storage at 0 °C. The addition of 0.5 or 1.0 g ethanol fruit−1 completely controlled scald in four of the five experiments carried out during three seasons. These levels of ethanol substantially reduced scald in the fifth experiment. Scald was also greatly reduced when 0.25 g ethanol fruit−1 was used. 90–100% of untreated fruit in all five experiments were affected with scald. There was no fruit injury or apparent off-flavour after several months storage. Superficial scald was also significantly reduced when fruit was injected, twice, early in storage with 0.3 ml ethanol. In a second experiment scald was reduced with a single injection of 0.25 ml ethanol.