A method of producing a more intense flavorant. Trans-4,5-epoxy-(E)-2-decenal is enriched to contain at least 90% of the (-) isomer and is added to a product in an amount sufficient to flavor the product. The product may be a foodstuff, such as a food or beverage. Addition of the substantially pure (-) isomeric form of trans-4,5-epoxy-(E)-2-decenal achieves enhanced product taste and/or aroma, and provides increased economy and efficiency in its production.