University of California

Ask the Produce Docs (General)

How can we, and do we need to, increase humidity in cold storage for bananas?

Category
  • Cold Storage
Question

We are a stevedoring company who is receiving bananas in Europe. For a customer of ours we are building a new cold store.  We are now in discussion with this client whether or not to install humidifiers.  The installation of these humidifiers will cost us around 150000 to 200000 €.  You understand that we only want to do this if it is really proven that the bananas will benefit from this investment.  My main problem is why to install humidifiers when all bananas are packed in bags which keep the relative humidity at around 95 to 100% in the bag.  Our present cold stores have a relative humidity of around 65% to 70% at 13°C (measured with an outside humidity of about 79% at 8°C).  The RH measured at that time in the bags was around 95% to 100%.  Thanks for your quick answer (B.M.)

Answer

I agree with you, there is probably no real value in installing humidifiers if the room is going to be used for bananas packed in bags.  High humidity and especially droplets of water reduce the strength of corrugated boxes and may increase damage associated with crushed fruit.  Also humidifiers require maintenance.  If they are not maintained they often drip water and the easiest way to stop this nuisance is to just shut off the water supply to the unit!

However if the cold room is also used for other commodities particularly those that lose water easily, like leafy green vegetables, high humidity is valuable.  The best way to obtain higher levels of RH is to install large evaporators with a suction pressure control system.  This allows the evaporators to operate at high temperatures and condense less water from the room air.  Later on if the commodities handled in the room require even higher humidity than the large coils can provide then humidifiers can be added.  They should always be viewed as the last step to take in obtaining high humidity.  I hope this helps. – Jim Thompson

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