Yujiao Cheng,Guijie Li,Houjiu Wu,Linhua Huang,Hua Wang
Light-induced off-flavor compounds in Ponkan mandarin juice were investigated during its shelf-life by headspace solid-phase microextraction multidimensional gas chromatography–mass spectrometry/olfactometry (MDGC-MS/O) and a GC–MS/pulsed flame photometric detector (GC–MS/PFPD). A total of 34 aroma-active compounds with flavor dilution (FD) factors from 2 to 128 were tentatively identified by aroma extract dilution analysis-MDGC-MS/O. Among them, a light-induced off-flavor compound with a high FD factor, methional (cooked potato), was positively identified in the Ponkan mandarin juice at the end of the shelf-life. In addition, 11 volatile sulfur compounds (VSCs), including 6 screened shelf-markers (variable identification, VID > 0.80), were identified in Ponkan mandarin juice by a sulfur detector (PFPD). Four VSCs exhibited odor activity values exceeding 1. Three VSCs (methanethiol, dimethyl trisulfide, and methional) were confirmed as key light-induced off-flavor compounds in Ponkan mandarin juice based on addition/omission experiments. Furthermore, light irradiation accelerated the degradation of sulfur precursors (methionine and MMS) and the formation of these VSCs leading to an increase in off-flavor intensity.
Yujiao Cheng,Guijie Li,Houjiu Wu,Guolu Liang,Hua Wang
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.
Yujiao Cheng,Leng Han,Linzi Shao,Hua Wang,Zheng Guo,Guijie Li
Pomelo flowers emit a strong fragrance and give aromatic odors. Volatile compounds from pomelo flowers were analyzed at three developmental stages and in the main organs by molecular sensory science. A total of 134 volatiles including 25 odorants, were analyzed by gas chromatography–mass spectrometry/pulsed flame photometric detector (GC–MS/PFPD) and multidimensional GC–MS/olfactory (MDGC–MS/O). The total volatile content varied among pomelo flowers at different developmental stages (stage-III > stage-II > stage-I) and among different organs of pomelo flowers (petal > pistil > stamen). Linalool was an important odorant with a high OAV, and floral/fruity comprised the predominant aroma profile. Four odorants, ethyl 2-methylbutanoate, linalool, β-myrcene, and 2-butenal, were selected based on variable importance in projection (VIP) values and contributed mainly to the discrimination of pomelo flowers at three different developmental stages. Linalool, β-myrcene, d -limonene, and ethyl hexanoate were potential markers for evaluating flavor differences in pomelo floral organs.
危险品化学品经营许可证（带存储）