The natural skin coating of the apple and its influence on scald in storage II.—Free fatty acids and carbonyl compounds

Analytical results suggest that the free acids of the waxy coating of the apple have no influence on the incidence of superficial scald in cold‐stored fruit. Treatment of fruit with various free and esterified acids had no marked influence on scald, which suggests that oxidation products of these acids are also unconnected with scald. A long‐chain fatty aldehyde was found to be present in the wax. Two methods of scald prevention, wrapping in oiled paper and dipping in diphenylamine solution, were found to reduce the accumulation of this aldehyde in the waxy coating during storage. The evidence suggests that the scald‐promoting factor is formed in the waxy coating of the fruit by an oxidative process during storage, rather than by direct natural synthesis.