Abstract: 【Objective】 Fresh walnut fruit easily appears decay and browning, its kernel easily becomes mildewed and dehydrated during storage. The supply period of fresh walnut fruit is short and walnut used in production is often conserved by dry. The objective of this study is to provide a theoretical basis and technical method for prolonging the supply period of fresh walnut through studying its postharvest physiology and storage technology. 【Method】 ‘Xiang ling’ walnut variety was used as raw material in this study, air flow method was used to analyze the respiratory intensity of fresh walnut with husk and fresh walnut without husk. Moreover, the respiration type was also studied. Before storage under the condition of temperature (1.0±0.5)℃, RH 90%-95%, the materials were subjected to storage in vacuum-package with plastic bag, modified atmosphere package with plastic bag, controlled atmosphere storage of text box, respectively. A contrast was prepared without any treatment. To study the effect of gas composition on postharvest physiology and storage technology of fresh walnut fruit, moisture content, reducing sugar content, lipid content, protein content, MDA content and oil acid value, iodine value, peroxide value of fresh walnut kernel were measured during storage. Related enzymes of fresh walnut kernel such as LOX activity, SOD activity and CAT activity were determined, too. Moreover, green husk browning index of fresh walnut fruit was evaluated in different periods of storage. After storage for 120 d, walnut shell color, endotesta color, kernel flavour of total fresh walnut fruit were evaluated, respectively. Then, the appearance of fresh walnut husk, shell and kernel were taken photo. 【Result】 The results showed that the fresh walnut fruit with green husk is respiration climacteric fruit and fresh walnut without green husk is non-respiration climacteric fruit. The content of moisture, lipid, and oil iodine value presented a reduced trend, but the acid value, peroxide value, LOX activity, and MDA content of fresh walnut kernel showed a increased trend and SOD activity, CAT activity, reducing sugar content, protein content showed no visible change. The contrast treatment showed the worst preservation effect and green husk browning index reached 0.27 after storage for 40 d. However, the green husk browning index of vacuum-package with plastic bag storage was only 0.18 after storage for 120 d. The result also showed that the treatment of vacuum-package with plastic bag could effectively prevent browning of green husk, maintain the moisture of kernel, slow down the change rate of oil acid value, iodine value and peroxide value, keep the activities of SOD and CAT at a high level, inhibit the generation of MDA. By evaluating the sensory quality after storage for 120 d, the treatment of vacuum-package with plastic bag gained the highest score in every single project. 【Conclusion】 The lower the concentration of O₂ in storage circumstances, the better the effect of conservation. After plucked with carpopodium in walnut commercial mature period, pre-cooled at 4.0℃ for 3 d, and vacuumed with LDPE plastic bag using vacuum pack machine, the storage life of walnut could reach 120 d at（1.0±0.5)℃ and RH 90%-95%. Its pericarp browning index of fresh walnut was low, and the color, aroma, taste and shape remained good.

Key words: fresh walnut fruit, controlled atmosphere storage, postharvest physiology, quality change