Nondestructive Raman Analysis of Polyacetylenes in Apiaceae Vegetables

Food plants from the Apiaceae family have been found to demonstrate health-promoting properties. Polyacetylenes are bioactive compounds that are considered to contribute substantially to the beneficial properties of Apiaceae plants. This study applied a Raman mapping technique in the investigation of polyacetylene spatial distribution in fresh roots of some Apiaceae species. Fresh root sections were measured directly without any preliminary preparation. For three Apiaceae species, that is, parsnip ( Pastinaca sativa L.), celeriac ( Apium graveolens var. rapaceum L.), and parsley ( Petroselinum crispum ), the presence of polyacetylenes was confirmed due to the detection of strong and well-separated Raman signals of symmetric -C ≡ C-C ≡ C- stretching vibration in the range of 2200-2300 cm(-1). The spectra were used for generation of two-dimensional maps applying the integration and cluster analysis methods. The Raman maps visualized the distribution of total polyacetylenes as well as individual compounds. Heterogeneous and tissue-specific occurrence of polyacetylenes in roots is shown.