The Effect Of Irradiation On Sprout Inhibition In Fresh Walnut Nuts And Preservation Of Green Walnut

Walnut(Juglans regia L.)as common nut in our life, is rich in protein and unsaturated fatty acids. Has broad market prospect. Dried walnut was always dominated in walnut sales, fresh walnuts has advantage in keeping nutritional value and good taste. However, fresh walnut is easy to germinate in room temperature, the high content of moisture and fat in fresh walnut cause mold and rancid smell, preservation techniques of fresh walnuts are becoming hotspots. In this paper,we select walnut fruits of Liaohe No.2 as the test materials, and this test concluding 2 parts, and main achieved the following results.(1)Effects of irradiation on sprout inhibition and physiology in fresh walnut nut during room temperature sand storageThe fresh walnut fruits of Liaohe No. 2 were subject to 60Coγ-ray irradiation at 0, 0.030, 0.050, 0.075,0.100 and 0.300 k Gy, then stored in sand at(25±1) ℃. The indices, including respiration rate, germination index, soluble sugar, starch, soluble protein, LOX, POD, IAAO, CAT, amylase, protease and G6 PDH were monitored during sand storage. For investigating the influence of different doses on physiological indicators of fresh walnut during sand storage. The results showed that during sand storage under normal temperature, irradiation can significantly inhibit respiration strength of fresh walnuts, lower respiratory metabolism, respiration rate was negatively correlated with radiation dose; Irradiation can effectively inhibit the germination of fresh walnuts, 0.050 k Gy can effectively postpone germination of fresh walnuts, the greater the dose, the effect is more obvious; 0.100 k Gy and 0.300 k Gy unmalted throughout the whole process; Irradiation as a means of coercion, can increase total content of soluble sugar and fat, can reduce protein degradation; To a certain extent, irradiation can reduce the LOX, CAT, G6 PDH, amylase, protease activity, strengthen IAAO, POD enzyme activity.(2)Effects of irradiation on postharvest physiology and quality in walnut fruit during cold storageThe green walnut fruits of Liaohe No. 2 were subject to 60Coγ-ray irradiation at 0, 0.100, 0.300, 0.500 and 1.000 k Gy, then stored at(0±1) ℃ by two-step way of first walnut fruit for 60 d then nuts in-shell for 30 d. The indices, including color, browning index, cracking rate, ethylene production, gas composition, contents of fat, fatty acid, peroxide value and carbonyl value were monitored during storage. The results showed that irradiation significantly decreased the cracking rate of walnut fruit and ethylene production, maintained the peroxide value and carbonyl value at relatively low levels and slowed down the lipid oxidation. The doses of 0.300 k Gy and 0.500 k Gy had a good performance on sensory quality, but the property in physiological and quality and at 0.300 k Gy was the most optimal, with the lowest ethylene production and higher content of essential fatty acids during storage, meanwhile the highest fat content, and the lowest peroxide value at the late stage of storage. In conclusion, 0.300 k Gy was the optimal irradiation does for walnut fruit during cold storage.