Flavor deterioration of Mandarin juice during storage by MDGC-MS/O and GC-MS/PFPD

Commercial mandarin juice often exhibits flavor deterioration during storage. The changes in volatile flavor profiles were investigated in mandarin juice stored under three different temperature conditions (4 °C, 25 °C, and 40 °C). The application of multidimensional gas chromatography-mass spectrometry/olfactometry (MDGC-MS/O) coupled with aroma extract dilution analysis (AEDA) identified 31 odorants in stored mandarin juice, including seven off-flavor contributing compounds: methanethiol (unpleasant, repulsive), dimethyl sulfide (sulfur, cabbage), methional (cooked potato), p-cymene (solventy), 4-vinylguaiacol (medicine), terpinen-4-ol (wood), and α-terpineol (floral, mint). 4-Vinylguaiacol was also identified in mandarin juice for the first time. In addition, 64 volatile compounds determined by GC-MS/pulsed flame photometric detector (GC-MS/PFPD) were classified as alcohols, terpenes, volatile sulfur compounds (VSCs), aldehydes, esters, ketones, and phenols. Volatile compound differences were observed in mandarin juice under different storage conditions by heat-map generation and principal component analysis (PCA). The results revealed that high-temperature storage led to a rapid increase in the concentration of total alcohols and VSCs. Furthermore, the flavor deterioration markers α-terpineol and dimethyl sulfide were identified based on off-flavor contribution and variable importance in projection (VIP) (score >1) values in the PLS-DA model. These two compounds are valuable for marker-assisted flavor deterioration analysis in mandarin juice during storage.