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Thermal Stability Of Tomato Lycopene In Vegetable Oils

Roberto Lavecchi, Antonio Zuorro

The thermal stability of lycopene in vegetable oil extracts was investigated in the temperature range 60-75°C. Extracts were prepared by contacting ripe tomato skins with three commercial vegetable oils: rice bran oil (RBO), grape seed oil (GSO) and sunflower seed oil (SSO). The results obtained indicate that the stability of lycopene in all three oils is extremely low. A kinetic analysis of degradation rate data showed that thermal degradation follows first-order kinetics, with apparent activation energies varying from 59.6 kJ mol-1 (in SSO) to 108.9 kJ mol-1 (in RBO). At 60°C lycopene degrades more slowly in RBO, the oil with the lower degree of unsaturation and the higher content of antioxidants, while at higher temperatures differences among RBO, GSO and SSO tend to disappear. This could be the result of the combined influence of unsaturated triacylglycerols, tocopherols and tocotrienols on the anti-oxidant/pro-oxidant properties of the oil.