Briefely, carotenoids were released from the rice samples (0.6 g) by adding
3 mL of ethanol containing 0.1% ascorbic acid (w/v), vortex mixing for
20 s, and placing in a water bath at 85C for 5 min. The carotenoid extract
was saponified with potassium hydroxide (120 μL, 80%, w/v) at the 85 C
water bath for 10 min. After saponification, samples were placed immediately on ice and cold deionized water (1.5 mL) was added. β-Apo-80-
carotenal (0.05 mL, 25 μg/mL) was added as an internal standard. Carotenoids were extracted twice with hexane (1.5 mL) by centrifugation at
1200g to separate the layers. Aliquots of the extracts were dried under
a stream of nitrogen and redissolved in 50:50 (v/v) dichloromethane/
methanol before analysis by HPLC.