3 Temperature, humidity and ventilation

A plant product after harvest is still living. The most important physiological functions affecting product quality during storage are the rates of respiration and transpiration. To extend storage life, respiration and transpiration should be reduced as much as possible. This is often done by controlling, individually or in combination

  • temperature
  • humidity
  • ventilation
  • atmospheric composition
  • Temperature. Reducing the temperature reduces the rate of respiration, which delays ripening and thus extends storage life. Optimum storage temperature for plantain and banana is 13-14 °C. At this temperature, storage life of mature, ripe fruit is 1-2 weeks. Below
    11 °C, stored fruit develops chilling injuries, and peel turns gray.

    Fruit should be harvested early in the day, when the temperature is low. Immediately after harvest, fruits are cooled to the storage temperature. This stage, called precooling, should be rapid.

    Fruit can be cooled using cold air (room cooling, forced air cooling), cold water (hydro-cooling), direct contact with ice, or evaporation of water from the fruit (evaporative cooling, vacuum cooling). Plantain and banana are usually cooled with cold air, to prevent temperatures becoming too low, which can cause chilling injury.

    Humidity. High humidity reduces water loss, and increases storage life. However, high humidity also encourages fungal growth. A relative humidity of 90% provides the best compromise for storing plantain and banana.

    Humidity can be raised in a container or room by spraying water in a fine mist. Humidity is reduced by venting. Humidity can be controlled with the help of a humidistat.

    Traditional methods for increasing the storage humidity include spraying fruit intermittently with water, storing fruit on wet sacking, and storing fruit in boxes filled with moist coir or sawdust. Although effective, these methods can cause excessive wetting, which leads to fruit splitting and reduces market quality.

    Ventilation. Air circulation is an effective method used to reduce temperature in storage rooms. However, ventilation also increases water loss from fruit, by removing the saturated layer of air that surrounds the fruit.

    If ventilation is used to reduce temperature, water loss can be reduced by

  • covering fruit with tarpaulins
  • packing fruit into bags, boxes, or cartons
  • wrapping fruit in polyethylene bags or heat shrink plastic films
  •  

      Objectives, Study materials, Practicals
      Questions
       
      1 Storing plantain and banana
      2 Improving storage life
      3 Temperature, humidity and ventilation
      4 Atmospheric composition
      5 Treatment of fruit
      6 Improving postharvest handling
      7 Bibliography
      8 Suggestions for trainers
         
      Credits

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