Determination of the oxidative stability by DSC of vegetable oils from the Amazonian area

Abstract

Differential scanning calorimetry (DSC) and a Rancimat method apparatus were applied to evaluate the oxidative stability of buriti pulp oil ( Mauritia flexuosa Mart), rubber seed oil ( Hevea brasiliensis), and passion fruit oil ( Passiflora edulis). The Rancimat measurements taken for the oxidative induction times were performed under isothermal conditions at 100 °C and in an air atmosphere. The DSC technique involved the oxidation of oil samples in an oxygen-flow DSC cell. The DSC cell temperature was set at five different isothermal temperatures: 100, 110, 120, 130 and 140 °C. During the oxidation reaction, an increase in heat was observed as a sharp exothermic curve. The value T 0 represents the oxidative induction time, which is determined from the downward extrapolated DSC oxidative curve verses the time axis. These curves indicate a good correlation between the DSC T 0 and oxidative stability index (OSI) values. The DSC method is useful because it consumes less time and less sample.