Model Studies on the Oxidative Stability of Odor-Active Thiols Occurring in Food Flavors

Abstract

Dilute ethereal solutions of mercaptoacetone (MA), 2-mercapto-3-butanone (MB), 3-mercapto-2pentanone (MP), 2-methyl-3-furanthiol (MFT), and 2-furfurylthiol (FFT), either alone or in pairs, were stored at 6 °C. During a period of 10 days the oxidation of the thiols to the corresponding disulfides or mixed disulfides was followed by high-resolution gas chromatography/mass spectrometry. In diethyl ether MFT showed the highest oxidation rate, which decreased in the order MFT . MA > MB ) MP ) FFT. After 1 day, mixed disulfides (e.g. MFT-FFT, FFT-MB) were detectable when pairs of the five thiols dissolved in diethyl ether were stored at 6 °C. MFT oxidized more slowly in dichloromethane than in diethyl ether, and it was stable in pentane. However, a heat treatment increased the oxidation rate of MFT dissolved in dichloromethane or pentane.

Comparative evaluation of potent odorants of boiled beef by aroma extract dilution and concentration analysis

“…Thiol no. 3 is easily oxidized to its disulphide [14], which was also detected in both screening procedures (no. 31 in Table 1).…”

“…Pure compounds, corresponding to those in Table 1, were obtained commercially: nos. 1-3, 5, 7, 9, 11, 13, 18-20, [11], (Z)-2-nonenal [12], (E,Z)-2,4-decadienal [13], bis(2-methyl-3-furyl)disulphide [14] and (Z)-1,5-octadien-3-one [15] were synthesized according to the cited literature.…”

Development of stable isotope dilution assays for the quantitation of the food odorants hydrogen sulphide, methanethiol, ethanethiol, and propane-1-thiol and application to durian (Durio zibethinus L.) pulp

“…Simultaneous quantitation of hydrogen sulphide and short-chain alkane-1-thiols can be accomplished by gas chromatography with PLOT columns and sulphur-sensitive detectors such as a flame photometric detector (FPD) or a sulphur chemiluminescence detector (SCD) [32]. However, the high volatility of hydrogen sulphide and short-chain alkane-1-thiols and their tendency towards the oxidative formation of disulphanes [2,33,34] may lead to substantial losses during the analytical workup. To compensate for such losses, the application of stable isotope dilution assays (SIDA) has been suggested [30,35].…”

“…4-Vinylpyridin in combination with SIDA has been successfully used to quantitate 2-methyl-3-furanthiol, a compound extremely sensitive to oxidation [33], but also to quantitate methanethiol, e.g. in stewed beef juice [37].…”

Formation by yeast of 2-furanmethanethiol and ethyl 2-mercaptopropionate aroma compounds in Japanese soy sauce

“…Furfural has also been reported to play an important role in the formation of 2FM in that reaction, 23,24) but 2FM is an unstable compound that readily oxidizes to a disulfide. 25) Kumazawa and Masuda 26) have reported that the residual ratio of 2FM in a citric/Na 2 HPO 4 buffer solution decreased with increasing pH values after heating. In addition, Muench et al 27) have reported that the formation concentration of 2FM from glucose and cysteine showed a maximum at pH 5.0.…”