Abstract
Despite a plethora of studies over the years, the physiological post-storage disorder superficial scald remains enigmatic. Various efforts to control the disorder have been tested, among them, the development of tailor-made storage technologies such as the dynamic controlled atmosphere by means of chlorophyll fluorescence (DCA-CF), allowing to handle the problem to a certain extent. To date, it has not been possible to unequivocally reveal the underlying etiology and biochemical mechanisms leading to superficial scald. The appearance of the disorder is likely triggered by a chilling induced process in the fruit’s epidermis. One of the earliest and most widely accepted theories on superficial scald development is related to the auto-oxidation products of α-farnesene, grouped as CT trienols, which injure the cell membranes, leading to disruption of the organelles in the outer cell layers, ultimately resulting in the occurrence of brown patches on skin i.e., typical scald symptoms. Recent research increasingly confers the crucial role in this process to the oxidation of phenolic compounds. At present different efforts are being made to predict scald susceptibility of the fruits already at harvest or at an early stage of storage. In the present work the potential of near-infrared spectroscopy (NIRS) for predicting superficial scald susceptibility in apples was investigated, applying PLS regression to model the information from the obtained NIR spectra (1,000-2,500 nm). The conducted partial least squares (PLS) regression provided a limited prediction performance for superficial scald development in apples, resulting in correlation coefficients of validation (rval) of 0.5. Much better rval were achieved when predicting the hypothetical scald precursors α-farnesene and CTols in apple skin, reaching in the case of CTols an rval >0.8.