Superficial scald, a functional disorder of stored apples. I.—The rôle of volatile substances

The effect of 19 volatile products on the development of superficial scald was investigated. These included formic, acetic, butyric and caproic acids and their ethyl esters; methanol, ethanol, butanol, and hexanol; butyl and hexyl acetates; acetaldehyde, propionaldehyde, hexanal, and acetone; and ethylene. At a concentration of one mole in 10,000 moles of air only butyric and caproic acids and butyl and hexyl acetates significantly increased scald in oil-wrapped apples, and the level in all cases was below that of unwrappped untreated fruit. The concentration of volatile acids, alcohols and esters in the scald-liable tissue was unaffected by storage in oil wraps. Crude ‘hexane’ at a concentration of one mole in 150 moles of air gave excellent control, which was reduced by purification of the ‘hexane’. The volatile theory of scald, the nature of the causal factor, and the mechanism of control by oil wraps is discussed.