Lipid Oxidation Kinetics of Pistachio Powder During Different Storage Conditions

The effects of storage temperatures (15, 25, 35, and 40 degrees C) and relative humidity (11, 33, 73 and 87%) on peroxide value, lipid oxidation and shelf life of stored pistachio powder studied in this project. Results showed that the changes in lipid oxidation follow zero-order reaction kinetic. Additionally, the highest inhibition (or activation) energy (E-a) for oxidation of fatty acid molecules and forming hydro-peroxides reached to approximate to 50 kJ/mol at relative humidity of 33%, which corresponds to monolayer moisture content of pistachio powder. Thermodynamic analysis of these reactions indicated that these reactions are endothermic (H++>0) and nonspontaneous (G(++)>0) processes. Practical ApplicationsPistachio nut (Pistachia vera L.) is one of the most popular nuts in the world with its high nutritional value and unique flavor as a snack and a food ingredient (as powder or kernel). It is also used as a main part of many traditional Persian foods such as Gaz, Baghlava and Ghotab. Fat oxidation is one of the main factors for quality loss in pistachio, i.e., changes in nutritional and organoleptic properties of this product during storage period. The main object of this research is the kinetic effects of different storage temperature and RH on auto-oxidation of pistachio powder's lipid during storage period. Generally, the results are applicable by pistachio powder's workstations and their producing factories during processing and storage for controlling the shelf life.