Abstract:

The green walnut fruits of the cultivar Liaohe No. 2 were subjected to 60Coγ-ray irradiation at 0, 0.1, 0.3, 0.5
and 1.0 kGy, respectively, and then stored at (0 ± 1) ℃ for 60 days firstly and then for another 30 days after the removal of
green husk. Changes in color parameters, browning index, cracking rate, ethylene production, gas composition, the contents
of protein, fat and fatty acids, peroxide value and carbonyl value were monitored during storage. The results showed that
irradiation significantly decreased the cracking rate of walnut fruit and ethylene peak, maintained the peroxide value and
carbonyl value at relatively low levels and also slowed down lipid oxidation. Irradiation at doses of 0.3 and 0.5 kGy had a
good performance on sensory quality, and the optimal dose for retarding fruit senescence was 0.3 kGy. The lowest cracking
rate and ethylene peak were achieved with this dose. Meanwhile, the total essential fatty acids remained at a high level, and
the highest fat content and lowest peroxide value were obtained at the late stage of storage. In conclusion, 0.3 kGy was the
optimal irradiation dose for cold storage of walnut fruit.

Key words: walnut fruit, irradiation, cold storage, physiology, quality