The natural skin coating of the apple and its influence on scald in storage. I.—fatty acids and hydrocarbons

The way in which oiled wraps reduce the incidence of superficial scald in cold‐stored apples has been studied by determining the composition of the skin coating of the apple and that of the lipid material that is transferred to the wrap during storage. The skin coating of apples treated with diphenylamine, another scald inhibitor, was also analysed. In the fatty acid fraction from the apple, the C 18 group of acids predominated, followed by C 16 and C 20 . Other odd‐ and even‐numbered acids from C 9 to C 22 were found. The principal hydrocarbon was the normal C 29 , followed by the C 27 , C 25 and C 28 normal hydrocarbons. Other odd‐ and even‐numbered members of the series between C 10 and C 31 were also found. The fatty acid fraction absorbed by the wrap was about 10% of that of the unwrapped apple. Its composition approximated to that of the apple except that it was deficient in linoleic, linolenic, arachidic and behenic acids. The effect of diphenylamine was to reduce the total yield of carbon straight‐chain compounds but the acid and hydrocarbon composition was substantially unaltered. The results suggest that neither fatty acids nor hydrocarbons are involved in the protectant action of oiled wraps or of diphenylamine.