Characterization of key off-odor compounds in thermal duck egg gels by GC-olfactometry-MS, odor activity values, and aroma recombination

Characterization of volatile off-odor compounds in thermal duck egg gels was investigated by gas chromatography-olfactometry-mass spectrometry (GC-O-MS), odor activity values (OAVs) and aroma recombination. The results demonstrated that the off-odor of thermal duck egg mainly came from egg yolk (EY), and content of aldehydes was the highest in EY. Anaerobic treatment in nitrogen contributed to decreased off-odor sensory scores and volatile components of the heated egg gels. Aerobic EY gels (treated in air) were determined to contain eight volatile compounds with OAVs greater than 1, such as hexanal, nonanal, benzaldehyde, ( E )-2-octenal, ( E )-2-nonenal, ( E, E )-2,4-decadienal, 1-octen-3-ol and 2-pentylfuran. However, three key volatile components (nonanal, benzaldehyde and ( E )-2-nonenal) with OAVs greater than 1 were found in anaerobic EY gels. Moreover, on the basis of results of recombination and omission experiments, hexanal, ( E )-2-octenal, ( E, E )-2,4-decadienal, 1-octen-3-ol and 2-pentylfuran were identified as key off-odor components in thermal EY gels. Sensory evaluation of the recombination model with five aroma compounds scored 4.38 out of 5 points. The major aroma profile of the off-flavor from egg EY gels included strong fatty, nutty, and mushroom aromas.