PHYSIOLOGY AND QUALITY CHANGES OF MATURE- GREEN MUME (PRUNUS-MUME SIEB ET ZUCC) FRUITS STORED UNDER SEVERAL CONTROLLED-ATMOSPHERE CONDITIONS AT AMBIENT-TEMPERATURE

Early- and late-hervested mume fruits (Japanese apricot, Prunus mume S ieb, et Zucc. cv. Gojiro) were stored for 3 days at 25-degrees-C under several controlled atmosphere (CA) conditions, and the effects on oxy gen uptake and gas evolution during CA storage and quality changes of fruits in or after CA storage were investigated. 1. Ripening character istics of mume fruits in or after CA storage were much affected by the harvesting time. Volumes of oxygen uptake and ethylene production dur ing 3 days storage were two and five times, respectively, more with la te-harvested fruits exposed to ambient air than there were with early- harvested fruits. Percentages of injured and rotting fruits in or afte r CA storage were higher in late-harvested fruits than in early-harves ted fruits. 2. Compared to fruits in ambient air supply, the volumes o f oxygen uptake and ethylene production of mume fruits decreased when exposed to a gas mixture of 19.8% CO2 and 21%O2; they decreased even m ore when the CA gas contained 5%O2 or 2%O2. However, at 2%O2 and no CO 2, the percentage of physiologically injured fruits increased consider ably in or after the storage. 3. When fruits were exposed to a mixture of high CO2 and low O2, the rates of O2 uptake and productions of CO2 , acetaldehyde, ethyl alcohol, and the percentages of injured brown fr uits increased as the supplying volume of the gas mixture was increase d. Our data indicate that anaerobic respiration and browning injury ar e functions of oxygen and carbon dioxide concentrations. 4. In the inj ured brown fruits, activities of phenol oxidase (PhOD) and peroxidase (POD) and chlorophyll content were lower than those of sound fruits. T herefore, the browning injury was considered to be in consequence of n ecrosis of tissue by accumulation of anaerobic metabolite, such as ace taldehyde, in low concentration of oxygen. 5. These results suggest th at removing ethylene from the storage atmosphere and maintaining the C A storage at approximately 8%CO2 and low O2 of minimum concentration o f 2% are important to retain the quality of mume fruits.