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Low temperature injuries
Majority of tropical horticultural produce are injured when stored at very low temperatures due to chilling injury. However, the optimum low temperature for storage should be above freezing temperature and also not to cause chilling injury.
Chilling injury occurs when commodities of tropical and subtropical origin, such as mango, banana and tomato are held at temperatures above their freezing point and below 5 to 15°C depending on the commodities. Chilling injury is manifested in a variety of symptoms, which are listed below. Symptoms of chilling injury 1. Surface of pitting 2. Discolouration – browning, blackening, etc of the external or/and internal tissues. 3. Appearance of water soaked areas 4. Development of necrotic areas 5. Failure of mature fruits to ripen 6. Increased susceptibility to decay 7. Reduction in storage life 8. Loss of characteristic flavour 9. Increase in certain physiological activities like increase in respiration rate, ethylene production, etc. The symptoms of chilling injury occurs while the produce is stored at lower temperature for comparatively longer time, but sometimes will only appear when the commodity is removed from the chilling temperature to a high temperature. Reduction / alleviation of chilling injury Storing at optimum temperature or above the critical temperature for particular commodity is the safest method to avoid chilling injury. Several treatments have been shown to alleviate or at least reduce the chilling injury on some commodities, if they are to be stored at lower temperature. Treatments to reduce/alleviate chilling injury A. Treatments before storage
1. Temperature conditioning – gradual lowering of storage temperatures
2. Ethylene treatment of fruits 3. Exposure to elevated CO2 4. Modified atmosphere packaging B. Treatments during storage
1. Intermittent exposure to higher temperatures 2. Holding under modified atmosphere/controlled atmosphere 3. Holding under low pressure(Hypobaric storage) 4. Maintenance of high RH Chilling sensitive (susceptible to chilling injury) commodities
Non-Chilling sensitive (not susceptible to chilling injury) commodities
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Last modified: Thursday, 15 December 2011, 5:54 AM