Total carotenoids were extracted using a solution of acetone with 20% (v/v) water (Lichtenthaler, 1987). After 30 min in the dark, the samples were centrifuged using a BECKMAN JA-21 at 13,000g for 15 min at 10 °C and subsequently spectrophotometrically analyzed by a 25 UV-Vis (Perkin Elmer Instruments Ltd., Seer Green, Beaconsfield, U.K.)