| Abstrakt: |
The thermal and oxidative degradation of carotenoids was studied in an oil model system to determine their relative stabilities and the major ß-carotene isomers formed during the reaction. All-transß-carotene, 9-cisß-carotene, lycopene, and lutein were heated in safflower seed oil at 75, 85, and 95°C for 24, 12, and 5 h, respectively. The major isomers formed during heating of ß-carotene were 13-cis, 9-cis, and an unidentified cisisomer. The degradation kinetics for the carotenoids followed a first-order kinetic model. The rates of degradation were as follows: lycopene>all-transß-carotene˜9-cisß-carotene>lutein. The values for the thermodynamic parameters indicate that a kinetic compensation effect exists between all of the carotenoids. These data suggest that lycopene was most susceptible to degradation and lutein had the greatest stability in the model system of the carotenoids tested. Furthermore, there was no significant difference in the rates of degradation for 9-cisand all-transß-carotene under the experimental conditions. |
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