RESPIRATORY PHYSIOLOGY OF MATURE-GREEN MU ME (PRUNUS MUME SIEB ET ZUCC) FRUITS IN 4 CULTIVARS HELD UNDER VARIOUS CONTROLLED ATMOSPHERES AT AMBIENT-TEMPERATURE

The respiratory physiology of mature-green mume (Japanese apricot, Pru nus mume Sieb. et Zucc.) fruits was investigated using four cultivars (Gojiro, Nankou, Hakuoukoume, Shirakaga); fruits were held for 7 days at 25 degrees C under various controlled atmospheres (CA). 1. Changes in respiration rates were similar in four cultivars; those held in 3% O-2 or higher attained climacteric maximum of O-2 uptake and CO2 produ ction rates almost concurrently up to the 3rd day. O-2 uptake and CO2 production rates in the fruits depended on the CA conditions, decreasi ng as the O-2 concentration was lowered, or conversely, as the CO2 con centration was increased. Anaerobic respiration of mume fruits occurre d at O-2 concentration of up to 2% at 25 degrees C. 2. Ethyl alcohol a nd acetaldehyde production rates increased from the 4th day of CA stor age. Fruits held at O-2 concentration of up to 1% developed browning i njury and produced ethyl alcohol at a high rate; the percentage of fru its with water-core injury was high in the CA condition of low O-2 in the absence of CO2. 3. Ethylene production rates were suppressed under high CO2 concentrations or O-2 levels less than 5%. In 3% O-2 or high er, ethylene production rates reached the peak half or one day after t he respiratory climacteric peak. However, in all CA conditions, the vo lume of ethylene produced was highly correlated with that of O-2 uptak e during the 7-day storage. 4. These results indicate that maintaining mume fruits in about 10% CO2 and 3 similar to 4% O-2 may help to reta in optimum quality at 25 degrees C, but that such CA conditions delaye d the respiratory climacteric rises just slightly and increased ethyl alcohol production after the 3rd day of storage. Therefore, under thes e conditions, the storage period of mume fruits at ambient temperature may be limited to 3 days.