Optothermal window method for on-line monitoring of decay kinetics of trans-beta-carotene in thermally treated vegetable oils

The optothermal window detection method at 488 nm was used to monitor on-line the concentration of trans-beta-carotene that was added to several vegetable oils after treating them at 200 degreesC in the presence of air for varying amounts of time. Results obtained for extra virgin oil show a direct proportionality between the rate constant describing the disappearance of trans-beta-carotene and the duration of thermal treatment. The rate constant for the decay of trans-beta-carotene in oils treated under identical conditions was also dependent on the type of oil. Trends and individual data are discussed in the light of a possible application of the method for the determination of the oxidative stability of vegetable oils.