Hans J. Rosenfeld

Carrots were grown in controlled climate chambers at 9, 12, 15, 18 and 21 °C 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 21 °C) led to higher contents of terpenoid volatiles in carrots. A high positive correlation between terpenes (α‐terpinene, β‐myrcene, trans‐caryophyllene, farnesene, α‐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.© 2002 Society of Chemical Industry

Summary Data from experiments with carrots grown in phytotrons under different day and night temperatures at two locations in Norway and three harvesting dates were treated by means of Principal Component Analysis (PCA). No effect of the single temperature amplitudes were found, the significant main effects were due to the mean temperature levels of 12 and 188C, location and harvest date. The PCA visualized the effect of mean temperature level on sensory, chemical and physical variables. Differences between the two groups were mainly caused by variation in sensory variables, the first group being characterized by high score for whiteness, sweetness, acidic taste, crispness, juiciness, glucose, fructose and root length. The other group had a high score for colour, odour, overall taste and flavour parameters, firmness, dry matter, sucrose, a and b-carotene, root weight and root diameters.

The study describes the variation in physical and chemical data from a trial with carrots grown outdoors and in plastic greenhouses during two years at three geographical locations in Norway, 59°40’N, 63°28’N and 69°39’N, and analysed by principal component analysis (PCA), partial least square and multiple linear regression (MLR). The most important principal component (PCI) to describe the total variation was the root weight, root diameters, and the carotene content. PCI described 53–65% of the total variation. Further 13–17% of the variation could be explained by a second component which included the air temperature a fortnight prior to harvest, and the sugar content of the roots. PLS and MLR revealed relationships between chemical and physical variables. Physical variables were able to predict 55% of the variation in chemical variables by the first two PLS components. The biological development of the carrot roots was best described by the root weight and a computed variable containing root dry weight and cylindricity of the carrot roots.

The carrot cv. Panther FT grown in phytotrons at 9,12 15,18 and 21°C constant diurnal temperatures at two locations, Ås (59°40’N) and Tromsø (69°39’N), and harvested at two dates was evaluated for sensory attributes, chemical composition and morphological variates. Significant temperature effects were detected for most sensory, chemical and physical variables. High growing temperatures (18 and 21°C) favoured colour, bitter tasting flavour components, firmness and the dry matter, sucrose and carotene content of the roots, whereas low growing temperature (9 and 12°C) heightened sweet taste, acidic taste, crispness, juiciness, and the fructose and glucose content. The longest roots were obtained at 9 and 12°C, the highest root weights at 12 and 15°C. Principal component analysis (PCA) revealed clear differences in the sensory profile of carrots grown at high and low temperatures, expressed by the first three principal components which together explained 81% of the variation in sensory variables. PCA of chemical and physical variables explained 90% of the variation, variables to describe the variation in PCI were root diameters, 3-carotene and sucrose, while root length, dry matter and fructose contributed to describe the variation in PC2.