Sulfury aroma notes are prevalent in tropical fruits. The elucidation of their molecular background, however, is often challenging. The crucial substances are all too often highly sensitive to degradation and frequently present in rather small amounts. Mild work-up conditions are, therefore, essential to recover the genuine aroma compounds and sophisticated enrichment approaches are necessary before mass spectral data allow unequivocal structural assignment. Chiral compounds additionally require the elucidation of the enantiomeric distribution, because optical isomers often show different sensory properties in terms of odor quality and/or odor threshold. The talk will exemplify the identification of aroma-active sulfur compounds using the molecular sensory science approach through data on guava (Psidium guajava L.), durian (Durio zibethinus L.), and cempedak (Artocarpus integer (Thunb.) Merr.). While the sulfury, grapefruit-like note of guavas is caused by thiols (3-sulfanyl-1-hexanol and 3-sulfanylhexyl acetate), the intense onion-like odor of durian is associated with dithioacetals and dithiohemiacetals such as 1-(ethylsulfanyl)ethanthiol. The characteristic aroma of cempedak, on the other hand, could be attributed to 2-(methylsulfanyl)alkanes. All these compounds are chiral. Results on the enantiomeric distribution of the compounds and their role in the aroma of the fruits will be detailed in the talk.

Chiral sulfur compounds and their role in the aroma of tropical fruits

248th National Meeting (2014)

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