Characterization of macadamia oil (Macadamia integrifolia) obtained under different extraction conditions

Abstract

The aim of this study was to evaluate how the pretreatment of macadamia nuts, with oven or microwave, followed by oil extraction by mechanical press (screw or hydraulic) affect the yield and chemical characteristics of macadamia oil. The combination of the pretreatments and mechanical oil extractions was done as follows: oil extract only by screw press, only by hydraulic press, heating by microwave followed by screw press, heating in oven followed by screw press, heating by microwave followed by hydraulic press, and heating in oven followed by hydraulic press. To characterize the oils, the following analyzes were performed: yield, peroxide value, free acidity, iodine and saponification value, fatty acid composition and oxidative rancidity. The oils extracted by hydraulic press combined with microwave had the highest yield, the best oxidative stability and lowest peroxide value. The results suggest that the combination of microwaves and hydraulic press extract oils with quality superior to the other treatments studied.