Estimation of walnuts oxidative stability using an accelerated shelf-life testing approach

An accelerated shelf-life test using elevated temperatures 62، 72 and 82 C was conducted to predict the oxidation progression of walnuts over a long-term storage. Oxidation parameters including values of conjugated dienes (CD) and trienes (CT) values and thiobarbituric acid (TBA) value were employed to evaluate the oxidation processes. Changes followed an apparent first-order kinetic. Walnuts and walnut kernels were also kept in normal condition (20-30 С; RH، 35-45%) for 12 months in order to validate the approach. A maximum of energy (62. 24-75. 67 kJ mol-1 K-1) needed for formation of primary oxidation products and a minimum of energy (35. 65 kJ mol-1 K-1) to generate secondary oxidation products were calculated. Formation of oxidation products in walnut kernels was found to be a temperature-dependent reaction، with Q10 =1. 44- 2. 1. The results showed that CD and CT values could provide a proper estimation for oxidative stability of the nuts stored in ordinary condition، with an average error of approximately 12. 9%.