Prestorage ultraviolet-white light irradiation alters apple peel metabolome

Abstract

Global metabolic profiling of 'Granny Smith' apple peel was employed for evaluating metabolomic alterations resulting from prestorage UV-white light irradiation. Apples were bagged midseason to restrict sunlight, harvested at the preclimacteric stage prior to bag removal, treated with fluorescent UV-white light for 0-48.5 h, and stored for 6 months at 0 degrees C. Trimethylsilyl (oxime) derivatized or underivatized aliquots of methanolic extracts from peel samples collected immediately after irradiation or following cold storage were evaluated using GC-MS and LC-UV/vis-MS, respectively. The profile, including more than 200 components, 78 of which were identified, revealed changes in the metabolome provoked by UV-white light irradiation and cold storage. Analyses of individual components selected using principal component analysis (PCA) models showed distinct temporal changes, before and after cold storage, related to prestorage irradiation in a diverse set of primary and secondary metabolic pathways. The results demonstrate metabolic pathways associated with ethylene synthesis, acid metabolism, flavonoid pigment synthesis, and fruit texture, are altered by prestorage irradiation, and many of the alterations are detectable after 6 months of cold storage in air.