Why Humidify... For Crop and Produce Storage


Food depends on moisture, just like people do.  Produce contains up to 50% water and if products are stored too dry and too warm, vaporization increases.  This means that the produce dries out, just as humans might dehydrate in dry and warm surroundings.

Longer Lasting Produce

When crops, particularly salad vegetables, are harvested in the summer months, the crops are at whatever temperature pertains on that day. For the crop to reach the customer it has to be kept fresh and, in order to do this, the crop is cooled very rapidly to between 2 and 4°C. If the crop has been harvested at >20°C, the degree of cooling required to bring the crop to storage temperature will damage the crop.

To counter this, moisture is added during the chill down period. However it is not possible to humidify during the whole chilling period as the duty requirement would be so high that it is not commercially viable. 

The humidification is therefore timed to operate when the cooling is off, to give a fog in the store so that the crop can reabsorb moisture from the air and also to provide residual moisture to prevent moisture loss from the crop during the next chill cycle.

The normal cycle is 15 minutes of cooling followed by 5 minutes of fogging, this cycle being repeated until the crop is down to temperature. There is no humidity control for this process and control is achieved by using a timing circuit in the plant control panel that runs the humidifier. It is critical that the fans from the chiller plant run all the time during this process so that the air distribution paths are maintained.

Facts About Storing Produce

Your produce can last for a long time, but it depends on how you store it. See below for information about the best way to store certain products.
LETTUCES should be stored in a plastic bag in the refrigerator and will keep longer if carefully rinsed. Dip the lettuce leaves in water and drain thoroughly before storing.
TOMATOES lose their flavor and won’t ripen if they are stored in the refrigerator. It is therefore a good idea to put them in a bowl on the kitchen counter together with other fruits that also need to ripen – e.g. avocados or bananas.
HERBS in pots can last for a long time if they are generously watered. It is a bit more difficult with herbs in bundles. They should be kept in a plastic bag in the refrigerator with a few drops of water to keep the whole bundle moist. They only last a few days if you rinse them before storage.

APPLES & PEARS do not keep very long at room temperature. If you don’t have room in the refrigerator, put them in a polystyrene box in a cool, dark place to slow the ripening process. 
MELONS keep well at room temperature and lose their flavor if stored in the refrigerator. Once you have cut them, however, they must be stored in the refrigerator.

Benefits of Nortec humidification in crop storage include:

  • Improved productivity through reduced product weight loss
  • Extended potential storage duration and longer shelf life
  • Extensive expertise around the world in many agricultural applications
  • Comprehensive product range to precisely meet customers' requirements
  • Low energy systems to reduce operating costs and improve humidity control
  • Comprehensive service of advice, design, supply, installation, commissioning, maintenance and spares supply

Other industries where Nortec delivers vital humidity control