Spatial distribution of sugars, organic acids, vitamin C, carotenoids, tocopherols, 6-methoxymellein, polyacetylenic compounds, polyphenols and terpenes in two orange Nantes type carrots (Daucus carota L.)

Abstract

In this study, the main primary and secondary metabolites were analyzed in various parts of two orange carrots. Results clearly indicate levels vary considerably between tissues and sections, and also highlight the importance of adopting standardized sampling methods when determining quality attributes in carrot. Peel was richer in citric acid, γ-tocopherol, 6-methoxymellein, falcarindiol, and most polyphenols and terpenes than other tissues, and poorer in sugars, α-tocopherol and falcarinol. Phloem was richer in falcarindiol acetate, but poorer in malic acid. Contrary to α- and β-carotene, lutein was mainly localized in xylem. Sucrose, carotenoids, α-tocopherol and falcarindiol acetate significantly decreased from the top sections of tissues to the bottom ones. Citric acid, 6-methoxymellein, falcarindiol and most terpenes showed similar trends in peel. In contrast, reducing sugars showed an increasing profile in tissues with highest levels in the bottom sections. Most polyphenols showed similar patterns in peel, and malic acid in phloem. Falcarinol contents decreased from the top sections of phloem to the bottom ones but increased in xylem. No clear trend was observed for γ-tocopherol and ascorbic acid.