Carrot flavour – acceptance, sweetness and bitterness

The carrot (Daucus carota L.) is one of the best liked and is in addition the predominant vegetable grown in Switzerland. However, occurrence of bitterness is one of the main factors diminishing its popularity. The causative compound is isocoumarin a phenolic. Any kind of preharvest or postharvest stress may induce its synthesis and thus bitterness in carrots. Its biosynthesis occurs via the acetate-malonate pathway and not via the shikimate-pathway as common for phenolics. Consumer tests combined with sensory tests by trained panelists and chemical analysis showed that isocoumarin exceeding 10 mg/kg diminished eating quality. Carrots grown under optimal conditions and stored optimally contain trace amounts of isocoumarin and are characterized by sweet taste and absence of bitterness.