Sulfur-containing volatiles arising by thermal degradation of alliin and deoxyalliin
1997
Kubec, R. | Velisek, J. | Dolezal, M. | Kubelka, V.
Alliin (S-allyl-L-cysteine sulfoxide) and its biochemical precursor deoxyalliin (S-allyl-L-cysteine) were heated in a closed model system at different temperatures (from 80 to 200 degrees C) in the presence of variable amounts of water (0-98%) for 1-60 min. The arising volatile compounds were isolated by extraction, analyzed, and identified by means of GC and GC/MS. The major volatile compounds generated by thermal degradation of these amino acids were diallyl sulfides (mono-, di-, tri-, and tetrasulfide) and allyl alcohol. Other important degradation products (arising especially at temperatures higher than 140 degrees C) were sulfur-containing cyclic compounds, namely 2,5-dimethyl-1,4-dithianes, 2-methyl-1,4-dithiepane, and dimethyl-1,2,5-trithiepanes. It was found that the typical garlic aroma can be formed nonenzymatically during the thermal treatment of either alliin or deoxyalliin. The major precursor of this aroma was alliin, while deoxyalliin was much more stable. The contribution of the individual volatiles to the resulting aroma with regard to their sensory properties is discussed.
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