Studies on the Degradation Mechanisms of Proteins and Their Derivatives in the Foods

Part IV The Decompositions of Several Mercaptals and Mercaptoles of Cysteine in Aqueous Solutions

Abstract

Cysteine mercaptals and mercaptoles were prepared by the reactions of L-cysteine with formal-dehyde, acetaldehyde, n-butyraldehyde, benzaldehyde, furfural, pyruvic acid and levulinic acid in 6 N hydrochloric or sulfuric acid. Hydrogen sulfide released from cysteine mercaptals and mercaptoles in heated aqueous solutions (oil bath:120°C) was determined. Although a small amount of hydrogen sulfide was liberated from L-cystine on one hour heating, its amount increased suddenly after three hours. Among these compounds L-cysteine mercaptal of furfural was most unstable and a large amount of hydrogen sulfide was produced.