260with the screw press was darker than the oil extracted with the hydraulic press in all types of pistachios used. No significant differences were found in the acidity, K 270 , and K 232 values when high quality pistachios were used. When lower quality pistachios (smaller pistachios) were used, the values of these three parameters increased in comparison with larger pistachios. On the other hand, oil samples from lower quality pistachios obtained by the screw press showed the highest values. The oxidative stability was higher in the samples of oil from high quality pistachios, with no differences in regard to the extraction system. When lower quality pistachios were used, the oxidative stability was significantly lower.
KEY-WORDS:Oil -Oxidative stability -PistachioPistacia vera -Quality.
INTRODUCTIONNuts are nutrient dense foods rich in unsaturated fatty acids and other bioactive compounds like tocopherols, phytosterols, and phenolic compounds, with wide-ranging cardiovascular and metabolic benefits (Ros, 2010). Among these nuts, the pistachio (Pistacia vera L.) is an increasingly important crop, and one of the favourite nut trees in the world. It is widely cultivated in arid zones of the eastern Mediterranean and the US, and recently it is being introduced successfully in hot dry regions of Spain. Pistachios contain about 45-57% oil, with a high proportion of unsaturated fatty acids like oleic, linoleic and linolenic acids (Arena et al., 2007;Tavakolipour et al., 2010;Tsantili et al., 2010). In addition, pistachios are a rich source of phytosterols and phenolic compounds (Phillips et al., 2005;Tomaino et al., 2010). These components have beneficial effects on human health, as phytosterols have been shown to reduce blood cholesterol and decrease the risk of certain types of cancer (Awad and Fink, 2000;Ostlund, 2004), whereas the phenolic compounds show antioxidant properties (Gentile et al., 2007).Edible oils play an important role in the food industry due to their nutritional properties and their influence on the taste and smell of food. The oils extracted from different seeds or nuts are an interesting culinary addition to provide new
RESUMEN Efecto del sistema de extracción por presión en los parámetros de calidad de diferentes aceites vírgenes de pistacho (Pistacia vera L. var. Larnaka).El pistacho es una magnífica fuente de aceite, puesto que a su alto contenido en materia grasa se añaden una elevada proporción de ácidos grasos insaturados y otros compuestos bioactivos como los polifenoles o los compuestos fenólicos. Se ha analizado el rendimiento y los parámetros de calidad del aceite extraído de cuatro tipos de pistacho de diferente calidad, usando dos tipos de prensas (hidráulica y de tornillo). El rendimiento de la extracción fue mayor cuando se empleó la prensa de tornillo, especialmente cuando los pistachos de mayor calidad (pistachos más grandes) se emplearon para la extracción del aceite (40 2,12%). Con la prensa hidráulica, el rendimiento fue de alrededor del 30% para todos los tipos de pistacho...
