A thorough study of the surface wax of apple fruits.

The composition of the surface waxes of three apple ( Malus domesticaL.) cultivars ("Florina", "Golden B" and "Ozark Gold") has been studied by means of spectroscopic and GC-MS analysis of the class-fractionated mixture of components. Odd n-alkanes, mainly C(27) and C(29) molecules, are prevalent in the saturated fraction. Small concentrations of alkenes were also found; the C(28:1) component is strongly (72%) in excess over the other 1-alkenes. Straight-chain esters (mainly of palmitic acid) of saturated primary alcohols (C(18)-C(30)) were also detected; whereas the acyl moiety is made up essentially of an even number of carbons, the alcohol counterpart does not exhibit this characteristic. Aldehydes are present (C(20)-C(30)) with the homologue patterns C(26)-C(30) most strongly represented. Straight-chain free secondary alcohols characterize the waxes of "Florina" and "Ozark Gold"; the hydroxy function is located far from the extremity of the carbon framework. Outstanding is the presence of three alcohols with 29 carbon centres. These alcohols are accompanied by free straight-chain primary alcohols, mainly with even-numbered carbon chains in the range C(26)-C(30). Free fatty acids are present; all of have a framework of even-numbered carbon chains mainly in the range C(16)-C(20). C(18:1) (oleic acid) is well represented.