Quantitative Raman Spectroscopy for the Analysis of Carrot Bioactives

Rapid quantitative near-infrared Fourier transform Raman analyses of the key phytonutrients in carrots, polyacetylenes and carotenoids, are reported here for the first time. Solvent extracts of 31 carrot lines were analyzed for these phytonutrients by conventional methods, polyacetylenes by GC-FID and carotenoids by visible spectrophotometry. Carotenoid concentrations were 0-5586 mu g g(-1) dry weight (DW). Polyacetylene concentrations were 74-4846 mu g g(-1) DW, highest in wild carrots. The polyacetylenes were falcarinol, 6-1237 mu g g(-1) DW; falcarindiol, 42-3475 mu g g(-1) DW; and falcarindiol 3-acetate, 27-649 mu g g(-1). Strong Raman bands for carotenoids gave good correlation to results by visible spectrophotometry. A chemometric model capable of quantitating carotenoids from Raman data was developed. A classification model for rapidly distinguishing carrots With high and low polyacetylene (limit of detection = 1400 mu g g(-1)) concentrations based on Raman spectral intensity in the region of 2250 cm(-1) was produced.