R. Kubec et al., SULFUR-CONTAINING VOLATILES ARISING BY THERMAL-DEGRADATION OF ALLIIN AND DEOXYALLIIN, Journal of agricultural and food chemistry, 45(9), 1997, pp. 3580-3585
Alliin (S-allyl-L-cysteine sulfoxide) and its biochemical precursor de
oxyalliin (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 c
ompounds were isolated by extraction, analyzed, and identified by mean
s of GC and GC/MS. The major volatile compounds generated by thermal d
egradation of these amino acids were diallyl sulfides (mono-, di-, tri
-, and tetrasulfide) and allyl alcohol. Other important degradation pr
oducts (arising especially at temperatures higher than 140 degrees C)
were sulfur-containing cyclic compounds, namely 2,5-dimethyl-1,4-dithi
anes, 2-methyl-1,4-dithiepane, and dimethyl-1,2,5-trithiepanes. It was
found that the typical garlic aroma can be formed nonenzymatically du
ring the thermal treatment of either alliin or deoxyalliin. The major
precursor of this aroma was alliin, while deoxyalliin was much more st
able. The contribution of the individual volatiles to the resulting ar
oma with regard to their sensory properties is discussed.