It would be a huge advantage if we could predict whether lines of fruit were going to become greasy before they were put in storage. One way of predicting potential greasiness is to determine the levels of farnesyl ester on the fruit. In an experiment where the surface waxes of the fruit were extracted and place in a chamber with iodine vapour for 5 minutes, the iodine staining was greatest on the wax from the greasy fruit. There was only a slight iodine staining on the wax from non-greasy fruit. The iodine will stain the wax before the fruit even feels greasy.
Further work needs to be done to refine the test using a range of cultivars and locations.
References Burmeister, D.M. 1997. Detection of skin greasiness in 'Granny Smith' apples with I 2 -staining. New Zealand Journal of Crop and Horticultural Science. Richardson, N. and Phelps T. 1996. Consumer evaluation of the tactile properties of Royal Gala apples varying in skin grease.