Sample preparation for carotenoids was based upon Mejia and
others (1988) with modifications. Two grams of carrots were homogenized with 25 mL of tetrahydrofuran (THF) containing 0.025%
butylated hydroxytoluene (BHT). The homogenate was spun at 5000
× g for 15 min (Beckman Coulter centrifuge, Allegra 64R). One
milliliter of supernatant was clarified by centrifugation at 10000 × g
for 15 min (Eppendorf centrifuge, model 5415c, Brinkmann Instruments Inc.) and filtered through a 0.22-µm filter. The analysis was
performed by HLPC (Varian 9012), using an analytical column Microsorb RP-C18 (4.6 × 100 mm, 3 µm). The mobile phase was acetonitrile:methanol:tetrahydrofuran HLPC grade (58:35:7 v/v), and