OLIVE AND AVOCADO OILS AND THEIR BLEND: EVALUATION AND UTILIZATION IN SOME FOODS

Abstract

Olive oil (OO) and avocado oil (AO) along with their blend (OAB) at 1:1 ratio were evaluated in terms of physicochemical properties, polyphenols, oil classes, fatty acids composition, stability and antioxidant activity. Utility of these oils in making cake and oil/butter blend was also investigated. No significant differences could be traced among OO, AO and OAB with respect to saponification value and specific absorbance (K232 ). In contrast, refractive index, specific gravity, free fatty acids iodine value, peroxide value, specific absorbance ( K270 ) and three colour values assessed by Lovibond Tintometer, exhibited significant differences among the aforementioned oils. Fatty acids composition revealed that AO had the highest content of C16:0 (18.63%), followed by OAB (15.23%) while OO tailed behind (13.15%). The highest content (4.01%) of C18:0 was belonging to OO, while OAB had (3.26%) and AO exhibited (2.42%). Content of unsaturated fatty acids of the three oils was higher than their counter parts of saturated ones. The OO possessed the highest content of polyphenols, while AO had the least content but it possessed the highest content of cholorophyll. Direct relationship could be figured out between content of polyphenols and antioxidant activity (68.2%, 61.0% and 53.7% for OO,OAB and AO, respectively). Moreover, polyphenols were separated by TLC into nine bands in OO and OAB while six bands were found in AO. Oil classes which were separated by TLC indicated that triacylglycerols, diacylglycerols, monoacylglycerols and polar compounds were the most abundant compounds in studied oils. Incorporation of OO, AO and OAB in formulation of carrot cake and oil/butter blend was found to be quite accepted by panelists.