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Extending the frying-life of oils is of commercial and economic importance. Due to this fact, assessment on the thermal stability of frying oils could provide considerable savings to the food processors. In this study, the physico-chemical properties of five palm products mainly palm oil, single-fractionated palm olein, double-fractionated palm olein, red palm olein and palm-based shortening during 80 hours of heating at 180 were investigated. Heating properties of these products were then compared with that of high oleic sunflower oil, which was used as reference oil. The indices applied in evaluating the quality changes of oils were free fatty acid, smoke point, p-anisidine value, tocols, polar and polymer compounds. Three palm products i.e. palm oil, single-fractionated palm olein and double-fractionated palm olein were identified to be the most stable in terms of lower formation of free fatty acid, polar and polymer compounds as well as preserving higher smoke point and tocols content compared to the other three oils. The low intensity of hydrolytic and oxidative changes due to prolonged heating, suggests that these palm products are inherently suitable for frying purposes.

Solid fat from fractionation of palm-based products was converted into cake shortening at different processing conditions. High oleic palm stearin with an oleic content of 48.2 % was obtained from fractionation of high oleic palm oil which was produced locally. Palm product was blended with different soft oils at pre-determined ratio and further fractionated to obtain the solid fractions. These fractions were then converted into cake shortenings named as high oleic, N1 and N2 blends. The physico-chemical properties of the experimental shortenings were compared with those of control shortenings in terms of fatty acid composition (FAC), iodine value (IV), slip melting point (SMP), solid fat content (SFC) and polymorphic forms. Unlike the imported commercial shortenings as reported by other studies and the control, experimental shortenings were trans-free. The SMP and SFC of experimental samples, except for the N2 sample, fell within the ranges of commercial and control shortenings. The IV was higher than those of domestic shortenings but lower when compared to imported and control shortenings. They were also observed to be b tending even though a mixture of b and b was observed in the samples after 3 months of storage. The shortenings were also used in the making of pound cake and sensory evaluation showed the good performance of high oleic sample as compared to the other shortenings.

Commercial oil D 0.06±0.00 f 3.0±0.0 a 5.83±0.05 c 2.66±0.31 c 2.59±0.18 c 1.20±0.10 b 0.76±0.03 d Commercial oil E 0.20±0.00 b 2.3±0.0 c 5.82±0.06 c 3.30±0.13 b 0.84±0.02 f 0.38±0.00 d 2.85±0.02 b Mean of triplicate analysis±SD Values within a column with different superscript letters are significantly different (p < 0.05)

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