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Some treatments were examined to prolong freshness in green-mature Yuzu (Citrus junos Tanaka) fruits stored in polyethylene (a type of linear low density plastic) bags.1. Degreening of fruits had already begun on the 35th day of storage at 5°C, but no chilling injury occurred over a period of 110 days. All injuries occurred on the 35th day of storage at 0°C. There was not a great difference between a 20μm and a 30μm thick film in the degreening index and the percent of injury.2. The thickness of polyethylene film was 30μm in the case of storage at 2°C. The storage with a freshening agent prolonged the period for reaching 100% chilling injury for 1 to 3 months longer than that without it. The period without injury lasted at least 6 months when the fruits were stored with a freshening agent after they had been preliminarily dipped in hot water at 50°C for 2 to 5min. These storage conditions did not affect the degreening of fruits, since there was no significant difference between initial values and those of 6-months later for the color indexes (a and b) based on the L-a-b system. The fruits pretreated with water at 30°, 40°and 20°C (as a control), however, suffered chilling injury in 3 to 4 months, even though accompanied with a freshening agent.

The fruits of Yamamomo, ‘Kamezo’ and ‘Kanton’ (cultivars of Myrica rubra Sieb. et Zucc.) packaged in polyethylene bags (30μm thick) were stored at 20 or 2°C, using an ethylene removing agent (E.A.), nitrogen or a water-absorbing mat.1. Fruits produced about 3μl/kg/h of ethylene at the peak. The fruits at the breaker stage became full-ripe within two days after harvest, but neither endogenous nor exogenous ethylene stimulated pigmetation in immature yellow-green fruits.2. The firmness of ‘Kamezo’ decreased to less than 60% of initial firmness (220g/cm2) after 3 days at 20°C, but the use of E. A. resulted in retention of 80% of the initial firmness for 7 days. Nitrogen had no effect on keeping quality. The carbon dioxide level reached 10 to 13% at 20°C, but only 2 to 3% at 2°C. There were no physiological disorders such as chilling or carbon dioxide injury during cold storage.3. The initial firmness of ‘Kanton’ was 265g/cm2, but was reduced to 60% of this after 4 days. It seems that the shelf life of ‘Kanton’ would be one or two days longer than that of ‘Kamezo’. The rating of firmness remained at more than 80% of the initial value after 10 days at 2°C, and more than 90% after 6 days when E. A. was applied, or after 8 days when the water-absorbing mat was used together with E. A.4. The level of water-soluble pectins increased remarkably in the two cultivars at 20°C. Although it increased 2-fold in 7 days in ‘Kamezo’ at 2°C, there was no increase in ‘Kanton’ throughout 8 days.5. There were great differences between the ratios of reducing sugar (glucose+fructose) to sucrose in the two cultivars: 6.7 in ‘Kamezo’ and 0.21 in ‘Kanton’, measured in fresh materials. It was presumed that these differences related to the storage quality of the fruits.