Effect of roasting conditions on pigment composition and some quality parameters of pistachio oil.

Pistachio roasting before oil extraction increases consumer preference but may cause changes in the oil composition. In this work, the effect of different roasting conditions on the physical parameters, oxidative stability, and pigment composition of pistachio oil extracted by pressure was studied. Density value of pistachio oil was reduced with severe roasting conditions (125 °C), while viscosity increased slightly. This adverse effect was compensated by a significant increase in both oxidative stability and, especially, in the content of chlorophyll and carotenoid pigments. Pistachio roasting temperature had a clear impact on the color of the pistachio oils, changing from yellow in oils from raw or minimally roasted pistachios (50-75 °C) to brilliant green in oils from pistachios subjected to higher temperature treatments (100-125 °C). An increase in temperature favored the pigment transfer to the oil. The green oils had a total pigment content between 2.3 and 4 times higher than the yellow oils.