Maintain Your Grain
The cooling process pertains to
temperature regulation of post-harvest
crops, which is critical because it directly affects metabolism. Plants start preparing for death long before harvest, but live
for some time after. Metabolic processes
do not cease until the food source
(water, carbohydrates and minerals)
is no longer available. The harvested commodity is inherently
susceptible to the elements after
harvest, because without roots it
can no longer self-regulate temperature or humidity.
With regard to the temperature of harvested plants you have
to consider not only the ambient temperature of the environment where they are stored but also the heat given off by the
harvested commodity itself. All living cells respire, producing
heat by using sugar and releasing carbon dioxide. Most people
think plants only take in CO2 and give off oxygen, but the truth
is most plants actually respire and give off CO2 as well, during
the night. Metabolic processes like respiration produce heat and
once harvested, most crops should be moved to an area with a
lower temperature. This is especially true for leafy crops, where
the heat of respiration is considerable. Case in point—if you
harvest basil plants and place them directly into a garbage bag
and wait 20 minutes, when you reach into the bag again you
will notice a dramatic increase in temperature. This is due to the
plant’s respiration, resulting in an increase in heat and humidity.
Humidity is closely linked to temperature during post-harvest
processes. Leafy plants left to be dehydrated should have plenty
of air circulation and a moderately low humidity, which will
slow the metabolism of the plants. Once the metabolism slows,
lowering the humidity until the moisture content is below 15
per cent will keep the product from molding
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