Screw press extraction of almond (Prunus dulcis (Miller) D.A. Webb): Oil recovery and oxidative stability

Abstract

The objectives of this work were to study the combined effects of seed moisture content and pressing temperature on oil recovery and quality parameters of almond oil (AO) and to evaluate the effectiveness of natural (rosemary extract and ascorbyl palmitate) and synthetic antioxidants (TBHQ) on the oxidative stability of AO analyzing chemical changes during an accelerated thermo-oxidation assay. A factorial arrangement was conducted, in pressing experiments, in order to study the combined effects of seed moisture content (4, 6, 8, 10 and 12% (w/w)) and pressing temperature (20, 40 and 60 C) on oil recovery and quality parameters. Oil recovery increased significantly as moisture content raised. The highest oil recovery (79.3%) was obtained at 8% (w/w) seed moisture content and 40 C pressing temperature. All extraction conditions employed were compatible with an acceptable chemical oil quality. Although in the accelerated assay of thermo-oxidation, the TBHQ became the most effective antioxidant, considering natural alternatives, rosemary extract and ascorbyl palmitate combination showed additional protective effect on the AO preservation.