A lactone aroma compound with an intense peach-like odour, one of the key character-impact compounds of peach, apricot, and strawberry flavour. It occurs naturally in these fruits and in dairy products, where it contributes to the creamy, fruity notes of heated milk and some cheeses. Flavourists use it widely in fruit flavourings, beverages, confectionery, and dairy flavours to impart ripe peach character, and it can be produced biotechnologically by yeast fermentation of ricinoleic acid from castor oil, allowing a natural label. Its odour threshold is extremely low, so tiny amounts shape the whole flavour profile. It exemplifies how a single molecule can define a fruit’s identity.