Compositional analysis and roasting behaviour of gevuina and macadamia nuts

P>This study compares the composition of macadamia and gevuina nuts following natural abscission and air-drying of intact nuts and compares chemical and sensory properties on roasting gevuina nuts using a reported macadamia roasting process. The markedly higher fat content of macadamia (75% vs. 43%) reflected a higher percentage of protein, moisture, ash and carbohydrate in gevuina nuts. Gevuina nuts also had lower energy and pH values than macadamia. Water activities were similar. Both oils were around 80% monounsaturated, but differed widely in positional isomerism. On roasting, macadamia nuts developed sweet, nutty, buttery notes along with brown colour development (measured using L*, a*, b* values) after 20 min at 135 degrees C while gevuina nut colour and aroma took at least 30 min, where the aroma was more hazelnut-like. Extractable volatiles were significantly higher for macadamias following roasting.