To identify the predominant odorants responsible for the off-notes in thermally processed muskmelon juice (MJ), odor profiles and odor-active compounds in fresh and heated MJ were comparatively studied by combined use of sensory evaluation, GC-olfactometry (GC-O) analysis, and comprehensive two-dimensional gas chromatography with quadrupole-time-of-flight mass spectrometry (GC×GC-QTOF-MS). “Fermented” and “sulfurous” were revealed as the two major offensive odor notes of heat-treated MJ in quantitative descriptive sensory analysis, and fundamental heat-induced alterations in potent odorant compositions of MJ was demonstrated by GC×GC-QTOF-MS. Comparative static headspace dilution analysis (SHDA) and aroma extract dilution analysis (AEDA) showed that the odor profile of heated MJ is mainly characterized by newly formed compounds possessing extremely low odor threshold and unpleasant smell, including volatile sulfur compounds with rotten cabbage-like odors, Strecker aldehydes having fermented, dark chocolate-like notes, and heterocyclics exhibiting roasted, cooked-rice like smells. Specifically, dimethyl sulfide, methional, furaneol, methanethiol, acetaldehyde, eugenol, <i>E,E,Z</i>-2,4,6-nonatrienal, trans-4,5-epoxy-(<i>E</i>)-2-decenal, 3-(methylthio)-propan-1-ol, 2-acetyl-1-pyrroline, 2-acetyl-2-thiozole were identified as the predominant off-notes contributors due to they showed higher FD factors. The coupling use of GC-O and GC×GC-QTOF-MS is a powerful tool for location and reliable identification of trace and predominant flavor compounds in complex food matrix. Results of this study will provide useful information for further exploration of the pathway (s) involved in the formation of the off-note as well as the development of potential solutions to minimize or prevent the heat-induced off-note generation.

Identification of predominant contributors to off-odors in thermally processed muskmelon juice using multidimensional gas chromatography techniques and comparative aroma extract dilution analysis

2019 Fall National Meeting

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