辐照对核桃果实冷藏生理与品质的影响

Effects of Irradiation on Postharvest Physiology and Quality in Walnut Fruit during Cold Storage

以‘辽核2号’核桃果实为材料,经0(对照)、0.1、0.3、0.5、1.0 k Gy不同剂量^(60)Coγ射线辐照处理后,采用青皮果实60 d+脱皮鲜坚果30 d两步法贮藏于(0±1)℃的冷库中,监测其在贮藏期间色差、褐变指数、裂果率、乙烯释放量、气体成分、蛋白质含量、脂肪含量、脂肪酸含量、过氧化值与羰基价的变化。结果表明,辐照处理显著降低了核桃果实贮藏期间的裂果率和乙烯峰值,保持了较低的过氧化值和羰基价,延缓了脂肪氧化速度;0.3 k Gy和0.5 k Gy处理的感官品质较好,以0.3 k Gy延缓核桃果实衰老的作用突出。该剂量条件下核桃果实裂果率和乙烯峰值最低,必需脂肪酸总量维持在较高水平,贮藏末期脂肪含量最高,过氧化值最低,确定0.3 k Gy为核桃果实冷藏适宜辐照剂量。

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