OXIDATIVE STABILITY OF BLENDS AND INTERESTERIFIED BLENDS OF SOYBEAN OIL AND PALM OLEIN

Improvement of oxidative stability of soybean oil by blending with a m ore stable oil was investigated. Autoxidation of blends and interester ified blends (9:1, 8:2, 7:3 and 1:1, w/w) of soybean oil and palm olei n was studied with respect to fatty acid composition, fatty acid locat ion and triacylglycerol composition. Rates of formation of triacylglyc erol hydroperoxides, peroxide value and volatiles were evaluated. The fatty acid composition of soybean oil was changed by blending. Linolen ic and linoleic acids decreased and oleic acid increased. The triacylg lycerol composition of blends and interesterified blends was different from that of soybean oil. Relative to soybean oil, LnLL, LLL, LLO, LL P, LOO and LLS triacylglycerols were lowered and FOG, POP and PLP were higher in blends and interesterified blends (where Ln, L, O, P and S represent linolenic, linoleic, oleic, palmitic and stearic acids, resp ectively). Interesterification of the blends leads to a decrease in PO O and POP and an increase in LOP Linoleic acid concentration at triacy lglycerol carbon-2 was decreased by blending and interesterification. Rates of change for peroxide value and oxidation product formation con firmed the improvement of soybean oil stability by blending and intere sterification. But, blends were more stable than interesterified blend s. Also, the formation of hexanal, the major volatile of linoleate hyd roperoxides of soybean oil, was decreased by blending and interesterif ication.