Effects of Intermittent Warming on Chilling Injury and Respiratory Rate of Cucumber Fruits during Cold Storage

Abstract

1. In order to alleviate chilling injury of cucumber fruits during the storage at 5°C, the effects of intermittent warming on the respiratory rate (CO₂ production) and the appearance of chilling injury of the fruits were investigated in relation to the time, duration and temperature of warming.
2. Warming treatment at 18°C for 7h after 3 days in storage reduced considerably the respiratory rates and markedly the chilling injury as compared with the control. These effects were reduced as the time of warming was delayed. Repeated warming at 2-days intervals was much more effective than a single warming.
3. The longer the duration of warming at 18°C applied after 4 days in storage, the greater the reduction of subsequent respiratory rate at 5°C and the delay of the appearance of chilling injury. The pronounced effects were obtained by warming for more than 24h.
4. When warming treatments above 18°C for 24h were performed after 4 days in storage for the fruits harvested in April, the respiratory rates decreased and the appearance of chilling injury was delayed gretatly with increase in the warming temperature. Chilling injury was evaluated 3 days after transfer of the fruits to room temperature at the end of 13 days in storage at 5°C. The fruits which had been warmed at 18 to 30°C showed only a slight injury and those at 36 to 40°C retained good eating quality although 60-90% of the control fruits decayed. However, warming at 42°C slightly caused a high temperature injury on the fruits. Essentially the same effects of warming were obtained for the fruits harvested in July, although on the control fruits chilling injury was found severe as compared with those harvested in April.