The induction period or oxidative stability index (OSI) of four parent oils, i.e. palm olein (POo), soyabean oil (SBO), canola oil (CNO) and sunflower oil (SFO) was investigated and to be further compared with that of three binary blends of POo with SBO, CNO and SFO, respectively and one tertiary blend of POo with SBO and CNO. Two oil ratios of 90:10 and 50:50 were prepared for the binary blends of POo + SBO, POo + CNO and POo + SFO while 40:50:10 for POo + SBO + CNO. All the oils were used to fry French fries at 180°C for a total of 72 hr (8 hr daily for nine days) of intermittent frying. The stability of the oil was quantified by using the Rancimat test following the AOCS Official Method Cd 12b-92. Incorporation of POo has generally improved the induction period of the unsaturated oils as compared to their unary forms. Indeed, POo and its blends gave higher induction period after frying for 24 hr. Irrespective of oil types, the induction period was relatively comparable towards the end of frying sessions. The rate of induction period reduction is likely influenced by the presence of tocotrienol homologues in POo and its blends.
* Malaysian Palm Oil Board, 6 Persiaran Institusi, Bandar Baru Bangi, 43000 Kajang, Selangor, Malaysia.
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