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Changes in quality and phytochemical contents of avocado oil under different temperatures

Resende, Lívia Maria Braga, de Souza, Vanessa Rios, Ferreira, Guilherme Max Dias, Nunes, Cleiton Antônio
Journal of food science and technology 2019 v.56 no.1 pp. 401-408
activation energy, ambient temperature, avocado oil, carotenoids, chlorophyll, cooking, extinction, monounsaturated fatty acids, oxidation, peroxide value, photochemistry, phytosterols, salads
Avocado oil, which has a high content of monounsaturated fatty acid and health-beneficial phytochemicals, is consumed in salads and also can be used for cooking. Therefore, is essential to study its oxidative and photochemical stability under different temperatures. So this work aimed to evaluate the oil oxidation and the phytochemical degradation of avocado oil under three different temperatures: room, 100 °C and 180 °C. The oil oxidation was evaluated by peroxide value and specific extinction in ultraviolet. The phytochemical degradation was evaluated for phytosterol, chlorophylls, and carotenoids contents. The temperature was found to significantly influence the oil oxidation and phytochemical stability, with the oxidation/degradation rate constants increasing with temperature. At room temperature, all oxidative parameters increased linearly with time, indicating a zero-order kinetic. At 100 and 180 °C, peroxide value, K232 and K270 increased linearly at a higher rate, becoming constant or decreasing after a short reaction time. The activation energy from specific extinction at 270 nm curves was 17.74 kcal mol⁻¹ for oil degradation. For phytochemical compounds, the mechanism of reactions depended on the temperature, in which the reaction orders increased with heating. The activation energies for carotenoids, chlorophylls and sterols degradations at high temperatures were 5.00, 6.93, and 4.48 kcal mol⁻¹, respectively. In this way, we found that avocado oil has its stability and quality affected by temperature, and, therefore, is not indicated for use in long and/or successive heating processes.