Differential scanning calorimetric analysis for monitoring the oxidation of heated oils

Abstract

A simple and reliable differential scanning calorimetric (DSC) method was developed for monitoring the oxidation in heated oils. Three different types of edible oils, namely, corn oil (CO), refined, bleached and deodorised palm olein (RBDPO) and soybean oil (SO) were used in this study. The DSC method was based on the cooling thermogram of oil samples at a scanning rate of 1°C/min from −30 to −85°C. The cooling thermogram of oil showed a well-defined single crystallisation peak. Two DSC parameters of this single crystallisation peak, namely peak temperature and enthalpy were determined. In addition to the DSC method, the deterioration of heated oils was also quantified by means of seven chemical methods. A statistical comparative study was carried out on the DSC and chemical methods. The results show that there is good correlation between the DSC method and other standard chemical methods. In conclusion, the DSC method offers an alternative for the monitoring of the oxidation of heated oil due to its appreciable time-saving, use of small samples with minimal preparation, and absence of toxic chemicals.