Effect of 60Co-γ-irradiation doses on nutrients and sensory quality of fresh walnuts during storage

Fresh Liaohe walnuts (Juglans regia cv. Liaoning4) were given Co-60 gamma-irradiation doses of 0, 0.1, 0.5, 1.0 and 5.0 kGy and stored at 0 +/- 1 degrees C for 120 d. The concentrations of fat, protein, fatty acid, soluble sugar, water and vitamin E (Vs), peroxide value (PV) and the sensory quality were determined at regular intervals during storage. Irradiation at 0.1, 1.0 and 5.0 kGy accelerated lipid oxidation, increased the PV, and decreased the sensory quality and V-E content of walnuts during storage. However, an irradiation dose of 0.5 kGy resulted in less oxidative degradation, reduced PV, and maintained a higher Vs concentration and better sensory quality of walnuts during the 90d storage. We conclude that a dose of 0.5 kGy is the optimal dose for the preservation of fresh walnuts over a 90d storage period. (C) 2013 Elsevier B.V. All rights reserved.