Grasas y Aceites, Vol 56, No 1 (2005)

The influence of natural tocopherols during thermal oxidation of refined and partially hydrogenated soybean oils


https://doi.org/10.3989/gya.2005.v56.i1.133

C. J. Steel
Laboratório de Óleos e Gorduras, Departamento de Tecnologia de Alimentos, Faculdade de Engenharia de Alimentos, Universidade Estadual de Campinas (UNICAMP), Brazil

M. C. Dobarganes
Instituto de la Grasa (CSIC), Spain

D. Barrera-Arellano
Laboratório de Óleos e Gorduras, Departamento de Tecnologia de Alimentos, Faculdade de Engenharia de Alimentos, Universidade Estadual de Campinas (UNICAMP), Brazil

Abstract


Samples of refined and partially hydrogenated soybean oils, with iodine values between 60 and 130, tocopherol-stripped or not by aluminium oxide treatment, were submitted to thermal oxidation, at 180 °C (during) for 10 hours. Samples were collected at 0, 2, 5, 8 and 10 hours, for the determination of dimers and polymers (degradation compounds) and tocopherols. The relation of iodine value to the formation of dimers and polymers and the role of originally present tocopherols in the protection of fats and oils against thermal degradation was verified. The degradation curves for tocopherols showed that α and γ -tocopherols were destroyed faster than β and δ -tocopherols. In addition, the degradation rate of tocopherols was greater in the more saturated fats. The formation of dimers and polymers was greater in the oil than in the hydrogenated samples and in the samples treated with aluminium oxide with respect to the original, untreated samples.

Keywords


Hydrogenated fats; Oils; Soybean; Thermal degradation; Thermal oxidation; Tocophero

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