The composition of polar compounds formed during frying was analysed using HPSEC (Table 2). Heating increased the concentration of polar compounds in the palm oil. This is in accordance with previous work that was conducted on several types of oil (Arroyo,Cuesta, Garrido-Polonio, López-Varela, & Sánchez-Muniz, 1992). In our study, the predominant polar fraction in fresh oil was diacylglycerols (97%), with presence of small amounts of free fatty acids (1.7%) and oxidised triacylglycerols (1.5%). During frying, new polar compounds were formed, including oligomers, which was at the highest level in oils used for frying at the highest temperatures (180 C).