NMR-Based Metabolomic Study of Purple Carrot Optimal Harvest Time for Utilization as a Source of Bioactive Compounds

The carrot (Daucus carota L.), one of the most important vegetable crops in the world, is recognized as a source of different compounds with healthy properties. Due to their high content of anthocyanins, purple carrots have been used as a natural colorant source to face the increasing demand of consumers for non-synthetic products. However, the root developmental stage can greatly affect the phytochemical composition and, in this regard, the identification of chemical biomarkers for the optimal harvest time would be of paramount interest both from a nutritional point of view and for the agri-food industry. In the present work, the metabolic profiling of purple carrots was monitored over four months using high-resolution 1H NMR spectroscopy. Several metabolites were identified, and their quantitative variations allowed for the investigation of the carrot development processes. The metabolic profile analysis showed an increase in amino acid, NAD, and caffeic acid levels during carrot development. A more tardive harvest in December entailed an increase in levels of luteolin-7-O-glucoside, chlorogenic acid, falcarinol, and γ-aminobutyrate, and a decrease in carotenoids and ω-6 fatty acid. The results showed how the harvest time affects the composition in terms of flavonoids, phenols, and polyacetylenes, therefore, improving the bioactive compound content.