Effect of Storage and Cooking on β-Carotene Isomers in Carrots (Daucus carota L. cv. ‘Stefano’)

Carrots are one of the highest dietary sources of β-carotene and are naturally high in the (all-E)-β-carotene isomer, which has higher bioavailability, provitamin A activity, and antioxidant capacity compared to Z (cis) isomers. The objectives of the present study were to investigate the effects of storage temperature, time, and cooking (boiling for 15 min) on the levels of carotene isomers in ‘Stefano’ carrots. Storing carrots at either 4 °C to simulate long-term storage or 20 °C to simulate marketing practices resulted in increases in (all-E)-β-carotene of 20.3% after 3 days at 4 °C and 34.4% after 14 days at 20 °C, respectively. The levels of Z isomers in raw carrots were low with (13Z)-β-carotene and (9Z)-β-carotene accounting for less that 1.8% of the total β-carotene present. Levels of (9Z)-β-carotene decreased during storage at either temperature, whereas storage at 4 °C resulted in a 109% increase in (13Z)-β-carotene after 56 days. Cooking significantly increased the levels of (13Z)-β-carotene and...