Stability of thiols in an aqueous process flavoring.

The flavor stability of an aqueous solution of a savory model process flavoring based on ribose and cysteine was investigated during accelerated storage at 50 degrees C. Of the three sulfur-containing flavor-impact components investigated, 2-methyl-3-furanthiol was found to be the least stable (59% decrease/24 h), and it was followed by 2-furfurylthiol (28% decrease/24 h), 2-mercapto-3-butanone (14% decrease/24 h), and 2,5-dimethyl-4-hydroxy-3(2H)-furanone (max. 10% decrease/24 h). Both cysteine and ribose were found to affect the stability of various flavor compounds. A mechanism for the instability of 2-methyl-3-furanthiol is proposed, and was confirmed by H-D exchange experiments.