Determination of the Chemical Structure of the Intense Roasty, Popcom-like Odorant 5-Acetyl-2,3-dihydro-l,4-thiazine

The chemical structure of a novel intense popcorn-like odorant isolated from the reaction of cysteine and ribose was studied by one- and two-dimensional NMR spectroscopy and high-resolution mass spectrometry, and the structure elucidation was confirmed by synthetic experiments. Thus, the odorant was identified as 5-acetyl-2,3-dihydro-l,4-thiazine (ADT). A sensory study including 5-propionyl-(PDT) and 5-butanoyl-2,3-dihydro-l,4-thiazine (BDT) revealed that also PDT and BDT elicited roasty, popcom-like odors. However, the odor threshold of the BDT was by a factor of 50 000 higher than those of ADT and PDT (0.06 and 0.1 ng/L of air, respectively).