2.3.1. Extraction of carotenoids
The carotenoid content in the samples were extracted using the method of Olives Barba, Cámara Hurtado, Sánchez Mata, Fernández Ruiz, and López Sáenz de Tejada (2006). A sample (2 g) was placed in a vessel, protected from light, and mixed with 100 ml of extraction solvent (hexane/acetone/ethanol: 50:25:25 v/v/v). The mixture was magnetically stirred during 30 min; then 15 ml of water were added. The upper layer was placed in a round-bottomed flask, and an aliquot of 10 ml of the extract was evaporated to dryness. The residue was dissolved to a final volume of 4 ml. The final solution was filtered through 0.45 lm membrane filters and 20 ll were injected for HPLC analysis