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

Abstract

Carrots are one of the highest dietary sources of beta-carotene and are naturally high in the (all-E)-beta-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 degrees C to simulate long-term storage or 20 degrees C to simulate marketing practices resulted in increases in (all-E)-beta-carotene of 20.3% after 3 days at 4 degrees C and 34.4% after 14 days at 20 degrees C, respectively. The levels of Z isomers in raw carrots were low with (13Z)-beta-carotene and (9Z)-beta-carotene accounting for less that 1.8% of the total beta-carotene present. Levels of (9Z)-beta-carotene decreased during storage at either temperature, whereas storage at 4 degrees C resulted in a 109% increase in (13Z)-beta-carotene after 56 days. Cooking significantly increased the levels of (13Z)-beta-carotene and (9Z)-beta-carotene and resulted in the production of (15Z)-beta-carotene, which was absent in raw carrots. Storage at 4 degrees C for 15 days or more prior to cooking reduced the susceptibility of (all-E)-beta-carotene to thermal isomerization during cooking, resulting in lower levels of all three Z-beta-carotene isomers being generated, while storage at 20 degrees C for up to 21 days resulted in significantly higher levels of (all-E)-beta-carotene before and after cooking but had no effect on Z-isomer production during cooking. Consequently, we conclude that, for the greatest health benefit, fresh carrots can be stored for up to 21 days at 20 degrees C or at 4 degrees C for up to 56 days without significant reduction in (all-E)-beta-carotene and should be consumed raw or boiled for less than 15 min to limit Z-beta-carotene isomer formation.

Stability of color, β‐carotene, and ascorbic acid in thermally pasteurized carrot puree to the storage temperature and gas barrier properties of selected packaging films

“…In our study for a given type of pouch, the temperature effect was significantly ( p < 0.05) higher at 13 °C than for the other two temperatures. This may be attributed to more efficient extraction of carotene after storage due to cell wall softening and membrane destabilization (Imsic, Winkler, Tomkins, & Jones, ). Imsic et al () reported a 25 and 34% increase in all‐trans‐β‐carotene in raw carrots stored at 4 and 20 °C, respectively, followed by a gradual reduction to level similar to the initial value.…”

Variation of bioactive compounds in dried seaweedHimanthalia elongatasubjected to different culinary processes

“…A possible explanation of the higher content of β-carotene after boiling treatment could be the formation of Z (cis) isomers generated during the cooking from the degradation of the all-trans isomers. Recently, Imsic, Winkler, Tomkins, and Jones (2010) have observed that the cooking of carrots has produced (15 Z)-β-carotene isomers, a fact which was not observed in raw carrots. This isomerization occurs when the temperature employed is high enough to induce the dissolution of the crystal structure of the β-carotene (Imsic et al, 2010).…”

“…Recently, Imsic, Winkler, Tomkins, and Jones (2010) have observed that the cooking of carrots has produced (15 Z)-β-carotene isomers, a fact which was not observed in raw carrots. This isomerization occurs when the temperature employed is high enough to induce the dissolution of the crystal structure of the β-carotene (Imsic et al, 2010). It is well reported that after boiling, β-carotene content shows an increase (Azizah, Wee, Azizah, & Azizah, 2009;Bernhardt & Schlich, 2006;Hwang & Kim, 2013;Kidmose, Christensen, Agili, & Thilsted, 2007).…”

Carrot β-Carotene Degradation and Isomerization Kinetics during Thermal Processing in the Presence of Oil

“…After the thermal treatments, 13-Z-β-carotene was formed in the highest amount, followed by 15-Z-and 9-Z-β-carotene, except for the treatment at 130°C, at which 9-Z-β-carotene became more important than 15-Z-β-carotene after long treatment times. Similarly, Imsic et al 25 found that 13-Z-β-carotene was predominantly formed in carrots after boiling for 15 min, followed by 15-Z-β-carotene and with 9-Z-β-carotene being the least abundant isomer. After 60 min at 85°C, 67.9% of all Z-isomers in the oil/carrot emulsion was present as 13-Z-β-carotene, whereas 15-Z-β-carotene accounted for 32.1% of the total Z concentration and 9-Z-β-carotene was still not formed.…”