The novel esters farnesyl oleate and farnesyl linoleate are prominent in the surface wax of greasy apple fruit

Abstract

ABSTRACTThin-layer chromatography was used to screen neutral and acidic fractions of surface waxes from cv. Royal Gala (Malus × domestica Borkh.) apple fruit from known stages of maturity and after postharvest storage with measured variation in skin greasiness. Changes in the amounts and presence of several compounds were observed, with the dominant change occurring in the neutral fraction. A smeary spot on our chromatograms of greasy fruit was analysed by further chromatography and mass spectrometry and found to contain large amounts of novel long-chain unsaturated fatty acid esters of farnesol. Greasy fruit contained 66 µg/cm2 peel of oleyl, linoleyl and linolenyl farnesol esters. These compounds, absent from early-harvest non-greasy apples, are liquid at sub-zero temperatures and appear to be the major contributing component to apple skin greasiness. An observed increase in farnesene, itself a liquid at ambient temperatures, in the peel of greasy apples is also likely to contribute to apple skin greasiness.