Variation in Carotenoid Composition in Carrots during Storage and Cooking

High-performance liquid chromatography (HPLC) was applied to determine the carotenoid composition of carrots during storage and cooking. Analyses were conducted immediately after harvest and 1, 2, 4, and 8 weeks after harvest. During the course of the storage, the carotenoid levels generally decreased, and this decrease was found to be greater during the first week for $\beta$-carotene (all-trans-$\beta$-carotene) and lutein, and during the second week for $\alpha$-carotene. Additionally, the amount of the $\alpha-$ and $\beta$-carotenes in carrot leaves changed slightly within the first 2 weeks of harvest when stored at $4^{\circ}C$. Specifically, the level of lutein, the main component of carrot leaves, increased from 233.8$\pm$11.7 to $346.2\pm26.7{\mu}g$/g DW during the first 2 weeks. In addition, the change in carotenoid contents was observed during the home-processing of one Korean cultivar. Carrots fried in oil showed the highest amount of $\beta$-carotene ($164.3\pm6.6{\mu}g$/g DW) and $\alpha$-carotene ($50.1\pm0.4{\mu}g$/g DW), while carrots that were prepared by sauteing, pressure-cooking in water and microwaving had the second highest levels. The greatest loss of in carotenoids occurred in response to boiling in water containing 1% NaCl, braising and baking. The content of lutein increased slightly after boiling in water containing 1% NaCl ($9.3\pm0.4{\mu}g$/g DW), while a loss in lutein occurred after preparation using other home-processing methods. A cis-isomer of all-trans-$\beta$-carotene, 13-cis-$\beta$-carotene, was present in detectable amounts in all processed samples, but not in raw roots. Another isomer, 9-cis-$\beta$-carotene, was detected in carrots that were prepared by boiling, frying and pressure-cooking.