The pH effect on the volatile components in the thermal degradation of cysteine was studied at pH's 2.2, 5.1, and 7.1, representing the pH values below, around, and above the isoelectric point of cysteine, with a Parr bomb model system. A vigorous degradation occurred at pH 5.1 and a very mild one at pH 7.1. At pH 2.2 the major components formed are l,2,3-trithia-5-cycloheptene and 2-thiophenethiol. The trithiacycloheptene compound was evaluated as roasted onion and roasted meat odor and was found for the first time in a model system. The mechanism of formation of these two major compounds is proposed. At pH's 5.1 and 7.1, 3,5-dimethyl-1,2,4-trithiolanes possessing a roasted odor are the major components.
All Science Journal Classification (ASJC) codes
- Agricultural and Biological Sciences(all)