2005-2-28
I'm Gwen Outen with the VOA Special English Agriculture Report.
Drying food is a simple, low-cost way to keep food safe for
eating. Drying removes water that small organisms use to break down
food into other substances. Some of these substances may be
poisonous to humans.
A device that uses the sun is a good way to dry food. There are
several kinds of solar dryers. The easiest to build is called the
direct dryer. The sun shines directly on the food being dried. The
direct dryer is a box with holes in it so that air can enter and
leave the box. It has a cover made of clear glass or plastic. When
the sun shines into the box, heat is produced. The heat is trapped
inside the box and cannot escape back through the cover. The heat
dries the food.
The solar dryer works better if the sides of the box are black.
This is because dark colors hold heat while light colors reflect it.
One way to make the sides black is to use wood that has been
blackened by fire.
If you use black paint instead, be sure the paint contains no
lead. Lead is poisonous to people, especially children.
The box can be made of almost any material such as wood, concrete
or sheet metal. The dryer should be two meters long, one meter wide
and twenty-three to thirty centimeters deep. The sides and bottom
should have additional material, called insulation, to keep the heat
from escaping.
The surface on which the food is placed should permit air to
enter from below and pass through to the food. A surface made of
wires with small square openings works very well. You should use
wire with the largest openings or squares that do not allow the food
to fall through. Air that comes in from below the wire surface will
also carry away water evaporated from the food as it dries.
A direct dryer will dry most vegetables in two-and-one-half to
four hours at temperatures from forty-three to sixty-three degrees
Celsius. Fruits take longer, from four to six hours at the same
temperatures.
Solar food drying is fast, safe and low-cost. It is also healthy
because nutrients such as vitamin C are kept in the food. Solar
dried food also tastes and looks good.
You can get more information about solar food dryers from the
group Volunteers in Technical Assistance. VITA is on the Internet at
v-i-t-a dot o-r-g. (vita.org.)
This VOA Special English Agriculture Report was written by Gary
Garriott. I'm Gwen Outen.