Influence of temperature and plant density on sensory quality and volatile terpenoids of carrot (Daucus carota L.) root

Carrots were grown in controlled climate chambers at 9, 12, 15, 18 and 21 degreesC and at two plant densities. Descriptive sensory analysis was performed and terpenes were assessed by means of a dynamic headspace technique. The highest score for sweet taste was obtained in carrots grown at the lowest temperature, while bitter taste, terpenes and sugars showed increasing values with increasing growth temperature. Plant density had little or no effect on sensory quality or terpenoid volatiles. Higher temperatures (18 and 21degreesC) led to higher contents of terpenoid volatiles in carrots. A high positive correlation between terpenes (alpha-terpinene,beta-myrcene, trans-caryophyflene, farnesene, alpha-humulene) and sensory variables (terpene flavour, green flavour, earthy flavour, bitter taste, aftertaste) was found: 83% of the variation in terpenes was able to predict 82% of the sensory variables by means of partial least squares regression (PLS2). It was concluded that these terpenes were responsible for bitter taste and thus suppressed the perception of sweet taste in carrots. Terpinolene decreased with increasing growth temperature and probably plays only a minor role in masking sweet taste in carrots. (C) 2002 Society of Chemical Industry.