Characterization of the Aldehydes and Their Transformations Induced by UV Irradiation and Air Exposure of White Guanxi Honey Pummelo (Citrus Grandis (L.) Osbeck) Essential Oil

Aldehydes are key aroma contributors of citrus essential oils. White Guanxi honey pummelo essential oil (WPEO) was investigated in its aldehyde constituents and their transformations induced by UV irradiation and air exposure by GC-MS, GC-O, and sensory evaluation. Nine aldehydes, i.e., octanal, nonanal, citronellal, decanal, trans-citral, cis-citral, perilla aldehyde, dodecanal, and dodecenal, were detected in WPEO. After treatment, the content of citronellal increased, but the concentrations of other aldehydes decreased. The aliphatic aldehydes were transformed to organic acids. Citral was transformed to neric acid, geranic acid, and cyclocitral. Aldehyde transformation caused a remarkable decrease in the minty, herbaceous, and lemon notes of WPEO. In fresh WPEO, β-myrcene, d-limonene, octanal, decanal, cis-citral, trans-citral, and dodecenal had the highest odor dilution folds. After the treatment, the dilution folds of decanal, cis-citral, trans-citral, and dodecenal decreased dramatically. This result provides information for the production and storage of aldehyde-containing products.