Thiols

Compounds containing sulfhydryl groups — organic molecules in which the oxygen of an alcohol is replaced with sulfur (–SH). Thiols are among the most potent aroma compounds known: these compounds have extremely unpleasant odours at remarkably low thresholds — the skunky note of light-struck beer, the catty character of blackcurrant, the durian‘s notorious punch. Yet at controlled trace levels, thiols lend desirable tropical, grapefruit, and meaty notes to wines, fruits, and savoury flavourings. Their reactivity — oxidizing to disulfides, binding metals — makes them both analytically elusive and technologically challenging to manage.