Assessing Types and Variation of Vitamin E (tocochromanol) Compounds throughout the Carrot Life Cycle

Carrot roots produce vitamin E (tocochromanol) compounds but little is known about their kinds and amounts. We are seeking to classify and quantify tocochromanols present in carrot root. Vitamin A (carotenoid) compounds are an important and well-studied nutritional component of carrots. Carotenoids and tocochromanols share a common biochemical precursor. However, despite the nutritional importance of tocochromanols, they have not been well classified in carrot root and variation among germplasm accessions has not been studied. We are interested in: 1) determining which of the eight tocochromanols (α-, ß-, γ-, and δ- tocopherols and tocotrienols) are present; 2) if there is variation across germplasm accessions; 3) if there is a relationship between quantity of tocochromanols and carotenoids; and 4) what portion of the recommended daily intake value for vitamin E is satisfied by a serving size of carrot. Twelve germplasm accessions including commercial carrot cultivars and breeding lines were grown in field conditions in Markesan, WI, in Summer 2011. Carrots were harvested and analyzed for the levels of individual tocochromanols and carotenoids. To assess changes in tocochromanols throughout the life cycle, carrots from this harvest were vernalized for 3 months at 5 °C and planted in the greenhouse. Roots were sampled at flowering and seed maturity. In order to analyze changes in these compounds over storage life, another set of roots were placed in cold storage and sampled in November, January, and March. Samples were analyzed for tocochromanol and carotenoid compounds simultaneously using HPLC with fluorescent and UV detections, for tocochromanols and carotenoids, respectively. Of the eight tocochromanol compounds, we detected α-, and the combined peak for ß- and γ- forms of tocopherols and tocotrienols. Both δ- tocopherol and tocotrienol were below our detection limit. Variability among germplasm accessions and throughout the vernalization period and life cycle will be discussed.