Effects of Reaction Time and Temperature on the Formation of Volatiles from l-Cysteine and Propanal Heated in a Triglyceride–Water System

The effects of reaction time and temperature on the volatile compounds formed from l-cysteine and propanal were studied in model systems heated in triglyceride–water (75:25). The volatile compounds, flavor profiles and yields formed in these model systems varied according to the reaction conditions. At 90 and 110°C, 2-methyl-2-pentenal was the most predominant component formed. Its maximum proportion occurred after heating for 1.5 hr at 110°C, and markedly decreased with temperatures over 110°C. 2-Ethylthiazolidine was the major product in the system heated at 140°C for 1.5 hr. 2-Ethylthiazolidino [3,4-b] thiazolidine could be detected in the system heated at 90°C for 1.5 hr. At 170°C, the profile of the volatile products was very complex, higher temperatures favoring the formation of nitrogen- and sulfur-containing compounds, including pyrrole, pyridines, thiophenes, thiazolidines, 1,2,4,-trithiolanes and 1,2,4-trithianes.