Saffron yellow: characterization of carotenoids by high performance liquid chromatography with electrospray mass spectrometric detection.

Saffron is one of the oldest natural dyestuffs and is obtained from the dried stigmata of Crocus sativus L. Nowadays, saffron is considered as an invaluable spice of golden-yellow hue, a precious ingredient in the Eastern and Mediterranean cuisines. It is characterized by a bitter taste that is caused by the chemical properties of its constituents. The yellowness of saffron results from the presence of crocins (glycosyl esters of crocetin), its main color compounds, which are examined in the present study in the crude methanol extracts by high performance liquid chromatography (HPLC) coupled with spectrophotometric and electrospray mass spectrometric detection (HPLC-UV-Vis-ESI MS). This technique allowed the separation and identification of trans- and cis-isomers of crocins. Their mass spectra registered in the negative ion mode comprised the quasi-molecular and fragment ions, as well as a range of other ions. Doubly charged ions were found for trans-isomers only, due to the high symmetry of their molecules. Modification of the eluent allowed the identification of several signals corresponding to adduct ions of crocins with the used additives.