Effects of Temperature and Relative Humidity on Pistachio Quality Factors during Storage Time

In this research، the effects of storage temperature and relative humidity were studied on quality factors of pistachio nuts including moisture content، peroxide value and free fatty acids. The required experiments were carried out in form of 4*4 factorial experiments in a completely randomized design (CRD) and repeated 4 times. Storage conditions were simulated in temperatures of 5، 15، 25، and 35C، and relative humidity in range of 11 to 87%. Determination of quality factors were carried out at the startup and with 15 days intervals during storage time. Statistical analysis was done and changes of pistachio quality aspects were presented as variation intensity curves versus storage time. By using kinetic analysis of oxidation for pistachio lipids، the reaction rate of oxidation was modeled as a first order differential equation. The constants of oxidation rate in storage temperature of 5 to 35 C were in range of 145/ to 567/. /month. By using Arrhenius relationship، Activation energy for oxidation reaction of pistachio''s lipid was equal to Ea =31/459 kJ/mol.