Oxidation products of alpha-farnesene associated with superficial scald development in d'Anjou pear fruits are conjugated trienols

Conjugated triene (CT) oxidation products of the acyclic sesquiterpene (E,E)-alpha-farnesene are thought to induce development of the physiological storage disorder superficial scald in apple and pear fruits of susceptible cultivars. CTs that accumulate in peel tissues of Granny Smith and Delicious apples after several weeks of cold storage are known to be conjugated trienols (CTols) rather than the corresponding hydroperoxides produced by in vitro autoxidation of alpha-farnesene. Here, it is shown that CTols are also the predominant in vivo oxidation products of alpha-farnesene in cold-stored pear fruit of the highly scald-susceptible d'Anjou cultivar. Analysis by octadecylsilane reversed phase high-performance liquid chromatography with diode array detection, gas chromatography with flame ionization detection, gas chromatography-mass spectrometry, and proton nuclear magnetic resonance spectroscopy identified 3,7,11-trimethyldodeca-1,3(E),5(E),10-tetraen-7-ol as the major CT in hexane extracts of peel tissue from d'Anjou pears stored for 3-5 months in air at -1 degrees C. The possible origins of CTols in apples and pears and the hypothesized role of these oxidation products of alpha-farnesene in the induction of scald are discussed. .