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

• Fresh walnuts were treated with 0, 0.1, 0.5, 1.0, and 5.0 kGy of 60Coγ-ray irradiation.
• Changes of nutrients and sensory quality were studied over time.
• Peroxide value, fat, fatty acids, vitamin E concentrations, and sensory quality were greatly affected by 60Coγ-ray irradiation.
• Optimal irradiation dose of 0.5 kGy for fresh walnut was obtained.

Fresh Liaohe walnuts (Juglans regia cv. Liaoning4) were given 60Coγ-irradiation doses of 0, 0.1, 0.5, 1.0 and 5.0 kGy and stored at 0 ± 1 °C for 120 d. The concentrations of fat, protein, fatty acid, soluble sugar, water and vitamin E (VE), 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 VE content of walnuts during storage. However, an irradiation dose of 0.5 kGy resulted in less oxidative degradation, reduced PV, and maintained a higher VE concentration and better sensory quality of walnuts during the 90 d storage. We conclude that a dose of 0.5 kGy is the optimal dose for the preservation of fresh walnuts over a 90 d storage period.