OXIDATIVE STABILITY OF MACADAMIA AND PISTACHIO OILS

Abstract

The objective of this work was to evaluate the composition and oxidative stability of macadamia and pistachio oils. Oils from macadamia and pistachio nuts were analyzed for their composition in fatty acids, triacylglycerols and sterols. The Oxidative Stability Index (OSI) of this oils was measured using a Rancimat 679 Metrohm at 98, 110 and 120ºC with air flow of 8.33 and 10.0 L/h. Macadamia and pistachio oils were also added to soybean and sunflower oils (in levels of 5 to 20%) to evaluate a possible oxidative stability increase of the latter. Oil samples of macadamia nuts showed as predominance fatty acids, the oleic acid (63.41 to 67.30%) and  palmitoleic acid (10.32 to 14.27%) however the major fatty acids in  pistachio  nut oil samples were oleic  (53.83% to 56.85%) and linoleic (31.38% to 32.26%) acids. The OSI at 98°C for macadamia nut oil and for pistachio nut oil reached respectively, 93h and higler than 96h, indicating high oxidative stability. Such values are between the highest found in the literature for vegetable oils in this temperature. A reduction of the OSI occurred when the temperature increased, for both oils. There was only a slight increase in the blends of macadamia and pistachio oils and sunflower and soybean oils.