Onions, leek, shallots and other Alliaceae-varieties are important and widespread culinary ingredients as vegetables and spices in numerous processed foods all over the world. Among various sulfur compounds mainly characterizing the overall aroma of raw and processed onions (Allium cepa L.), several chiral, heterocyclic alkyl-substituted sulfur compounds, cis-/trans-3,5-diethyl-1,2,4-trithiolan, cis-/trans-3,6-diethyl-1,2,4,5-tetrathian and cis-/trans-4,6-diethyl-1,2,3,5-tetrathian, were identified as characteristic and important aroma compounds in cooked onions and were also reported in other Alliaceae-varieties. Due to the well-known aroma properties of sulfur compounds, they often hold a special position as potent aroma compounds with characteristic odor qualities. Furthermore, the stereochemistry is a well-known aspect influencing their sensory properties. Up to now, no comprehensive qualitative and quantitative data are available on the amounts of cis-/trans-3,5-diethyl-1,2,4-trithiolan, cis-/trans-3,6-diethyl-1,2,4,5-tetrathian and cis-/trans-4,6-diethyl-1,2,3,5-tetrathian. Hence, the concentrations of the above mentioned odorants were investigated after cooking of commercial white and red onions, leek, shallots, chives and spring onions. In connection with method development for enantiomer separation, all target compounds were identified in comparison to authentic reference compounds combining gas chromatography with mass spectrometry and sensory techniques. Afterwards, a stable isotope dilution assay (SIDA) was developed for quantitation purposes applying multidimensional GC-MS techniques. Finally the target compounds were synthesized and their sensory properties were evaluated with special emphasis on odor-thresholds of the isomers in air and odor qualities.

Quantitation of chiral heterocyclic key aroma compounds in cooked Alliaceae varieties using a stable isotope dilution assay

250th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.