Effects of Microwave Roasting on Physicochemical Properties of Pistachios (Pistaciavera L.)

Abstract

Effects of 480 and 640 W power levels and 2, 3 and 4 min for roasting of pistachios using microwaves (MW) on the physicochemical properties of pistachios in comparison with an Iranian traditional method of soaking in salty water and drying under hot-air at 135o C for 20 min were investigated. MW roasting of pistachios decreased water activity values, producing a softer nut. Twenty one volatile compounds were identified in roasted pistachios using GC-MS. The highest volatile concentration and sensory odor intensity scores were observed for hot air roasted pistachios and MW at 640 W for 4 min. Roasting reduced the force needed to cut pistachios. Unsaturated fatty acid contents in MW roasted pistachios were higher (82.0%) than in hot-air produced nuts (74.7%). Total phenolic content values increased with roasting time and with the MW power level. Pistachios can be successfully roasted using microwaves as a fast and economical method.