In this study, emission characteristics of odorants from boiled egg samples were measured through time between fresh and decayed status. Air samples released from boiled egg were collected and analyzed five different periods during the whole experimental period set for 9 days. The concentrations of reduced sulfur compounds (RSC), carbonyl compounds (CC), and NH₃ were generally higher than others like volatile organic compounds over the entire period. Among target compounds, the concentration of H₂S recorded the maximum value of 3.65 ppm immediately after boiling which indicates its maximum contribution as odorant in fresh stage. In addition, some odorants (i.e. CH₃SH, AA, PA, BA, and VA) were detected in the range of 7.52 to 50.8 ppb. Emission of most odorants generally decreased after 1 day of boiling, although their concentrations increased again after 3 days to reach the peak values after 6 days. The dilution-to-threshold (D/T) ratio measured by air dilution sensory test samples between fresh and decayed egg showed patterns similar to H2S. In addition, the result of correlation analysis indicated that there is a strong relationship (p＜0.01) between complex odor and H₂S.

In this study, the emission characteristics of reduced sulfur compounds (RSC) were investigated under decaying conditions using 3 food types with strong odor properties: (1) Kimchi (KC), (2) Fresh fish (FF), and (3) Salted fish (SF). The concentrations of RSC from food decaying samples were measured 5 times during the full study period over 15 days. All the analysis of RSC were made by gas chromatography/pulsed flame photometric detector (GC/PFPD) combined with air server/thermal desorber (AS/TD). According to our analysis, CH₃SH recorded the highest mean concentration (53.8 ppb) out of all RSCs investigated concurrently. Comparison between 3 food types showed that KC had the highest odor strength in primary stage, although it showed a notable decrease through time. On the other hand, FF and SF maintained generally low RSC concentrations in the beginning stage, but they showed large increases in emission concentrations with time. Thus, the results indicate that the relative pattern of RSC emissions tends to vary greatly with food types rather than RSC type.

In this study, odorous emissions from decaying foods were investigated with respect to trimethylamine and ammonia. To this end, three food types (egg, mackerel, and cuttlefish) were used for decaying experiments in which food samples were preserved in throwaway syringes (weight for each sample of 5 g). All decaying experiments advanced for one month under the normal temperature and ventilation. The average concentrations of TMA from egg, mackerel, and cuttlefish samples were measured as 0.6, 5.8 and 130 ppm, respectively, while those of NH₃ as 554, 385, and 531 ppm, respectively. According to our experiments, the concentrations of TMA and NH₃ increased with the progress of corruption. The release of malodor compounds tend to vary sensitively with the changes in temperature and humidity. In case of TMA, a strong correlation with temperature was observed on the order: mackerel ＞ egg ＞ cuttlefish. However, in the case of NH₃, strong correlations were seen to exist with humidity. Changes of TMA concentration were accompanied by changes of pH, especially from mackerel and cuttlefish. NH₃ also showed a similar trend of pH change from samples. When the results of TMA measurements were evaluated in terms of odor intensity, egg, mackerel, and cuttlefish are recorded as 4.36, 5.25 and 6.46, respectively. Likewise, odor intensity of NH₃ measurements was found as 6.96, 6.7 and 6.93, respectively. The results of our odor study suggest that a unique pattern of odor release is developed from decaying food samples.