A simple pretreatment with low O 2 to alleviate superficial scald in Granny Smith apples

Sealing Granny Smith apples in a low‐O 2 atmosphere for 7 days at 20 °C (LO 2 ‐20C) prior to cold storage reduced superficial scald development after 6 and 8 months at 0 °C plus 10 days at 20 °C. This LO 2 ‐20C treatment reduced the O 2 levels that induce endogenous production of significant amounts of CO 2 , acetaldehyde and ethanol, and thereby reduced ethylene production in cold storage, which in turn reduced scald development. Treatment with ethanol vapour (20 mL L −1 ) for 1 day at 20 °C plus 6 days at 1 °C or with low O 2 for 1 day at 20 °C plus 6 days at 1 °C (LO 2 ‐1C) did not reduce scald effectively. 1‐Methylcyclopropene (1‐MCP) treatment at 0.5 µL L −1 was the most efficient at reducing scald development. In all treatments, superficial scald development proceeded from the distal blossom end towards the proximal stem end of fruits. After 6 months of cold storage at 0 °C, peel browning and membrane leakage, measured as electrical conductivity in situ , were greater at the blossom end than at the stem end of control, ethanol‐ and LO 2 ‐1C‐pretreated fruits. In LO 2 ‐20C‐ and 1‐MCP‐pretreated fruits, colour indices (hue angle, lightness and chroma) and electrolyte leakage were similar at both the stem and blossom ends and were associated with less scald development after 6 months at 0 °C. The reduction in scald development was also associated with lower peroxidase and polyphenol oxidase activities in the peel of LO 2 ‐20C‐ and 1‐MCP‐pretreated fruits. A simple treatment at 20 °C (LO 2 ‐20C) prior to regular cold storage could also be suitable for organically grown apples that cannot be treated with diphenylamine or 1‐MCP. Copyright © 2007 Society of Chemical Industry