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Facts on post harvest
storage of watermelons
Grower
Solutions Magazine
Lefroy
Valley Magazine
Dec
2002
Recently I was asked by a grower, what the
optimum storage/transport temperature was for watermelons, since he
was concerned that at 12o C there was condensation on the fruit,
which would be ideal for post harvest disease organisms such as
botrytis to take hold. It was a good question, which prompted me to
research the answer.
 I
was aware that growers from the north, shipping in the cool season,
often do not cool their watermelons, nor do they use refrigerated
transport. Growers that ship in the hot months (October to March)
are using refrigerated transport, with and without precooling,
usually at about 12oC .
On searching the literature available on this subject
the following became evident. Most research has been conducted at
temperatures between 10 and 16o C at a relative humidity between
85-90%.The general consensus is that watermelons will keep for 2-3 weeks if stored at between 12 - 15o C .
Temperatures below 10o C , can result in chilling injury to the
fruit (pitting of the skin, flesh breakdown and blackrot).
Watermelon should be cooled to between 12-15o C
within 24 hours of harvesting, if they are to be stored for long
periods of time. Fruit can get over-ripe fairly quickly if not
cooled. However, watermelon colour will continue to improve for up
to 7 days after harvesting if kept at temperatures of 18-22o C , but
it will actually fade (get lighter) if kept at temperatures of below
12o C for long periods of time. It is important to note that once
harvested the sugar content or sweetness will not improve.
This does give both growers and market agents some
room to move in managing watermelons post harvest.
Watermelons should, ideally not be stored or
transported together with climacteric fruit (those that give off
ethylene) as the ethylene will result in a shortened lifespan and
damage the fruit.
Allan MacKinley
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