Title: Pre-storage UV-White Light Irradiation Alters Apple Peel Metabolome Authors
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 29, 2007
Publication Date: January 1, 2008
Citation: Rudell Jr, D.R., Mattheis, J.P., Curry, E.A. 2008. Pre-storage UV-White Light Irradiation Alters Apple Peel Metabolome. Journal of Agricultural and Food Chemistry. 56:1138-1147. Interpretive Summary: Sunlight can positively or negatively alter apple fruit appearance and enhance or reduce fruit marketability. How sunlight impacts other characteristics of apple fruit, particularly eating quality, has not been extensively characterized. The impacts of light after harvest on fruit characteristics after extended storage are also unknown. Extensive characterization of apple fruit constituents after light treatment at harvest indicates changes in compounds that contribute to eating quality and nutritive value are present following light exposure and subsequent long-term cold storage. These results demonstrate the role of light in stimulating specific changes in apple fruit components that may be of use in development of postharvest storage protocols.
Technical Abstract: Global metabolic profiling of ‘Granny Smith’ apple peel was employed for evaluating metabolomic alterations resulting from pre-storage UV-white light irradiation. Apples were bagged mid-season to restrict sunlight, harvested at the pre-climacteric stage prior to bag removal, treated with fluorescent UV-white light for 0-48.5h, and stored for 6 months at 0°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 264 total 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 pre-storage irradiation in diverse 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 pre-storage irradiation and many of the alterations are detectable after 6 months cold storage in air.