Processing and production factors
Cassava products for animal
feeding
Cassava products have long been used for animal feeding. Large
quantities of cassava roots and cassava waste are utilized in
the cassava-producing countries for this purpose. Imports of
dried cassava roots and meal into European markets for the supply
of the compound feed industry are also increasing.
Processing Cassava Chips
The present method of processing chips in Thailand, Malaysia
and some other countries is very simple, consisting in mechanically
slicing the cassava roots and then sun drying the slices. The
recovery rate of chips from roots is about 20-40 percent. However,
the products are considered inferior in quality by some quality-conscious
feedstuff manufacturers, although many others consider them
satisfactory.
Step 1 Preparation of the roots
When the roots are not sorted, peeled and washed, the chips
are usually brown in color and have a high content of fiber
sand and foreign objects as well as hydrocyanic acid. Trimming,
peeling and washing the roots in a similar manner as for the
processing of cassava flour are recommended in order to produce
white chips of superior quality.
Step 2 Slicing or shredding
The roots are shredded in a special machine, which is usually
made locally. The machine consists of a rotating notched cutting
disk or knife blades mounted on a wooden frame equipped with
a hopper. The cassava roots are cut into thin slices and pieces
as they pass through the machine.
Step 3 Drying
Sun drying is used mostly where the sliced roots are spread
out on drying areas, or concrete floors of various dimensions.
To produce good quality chips the roots must be sliced and dried
as quickly as possible after harvest. The chips should be turned
periodically in the drying period, usually two or three sunny
days, until the moisture content reaches 13-15 percent. The
chips are considered dry when they are easily broken but too
hard to be crumbled by hand. The thickness of the slices also
has an effect on the quality of chips. Thick slices may appear
dry on the surface when their internal moisture content is still
high.
When rain threatens during the drying process, the chips are
collected by hand or by a tractor into piles under a small roof.
Interrupted sun drying affects the quality of the finished chips
and pellets. When the semidried chips are wet again by rain,
they become soggy and upon completion of drying lose their firm
texture. In rainy regions, where continuous sun drying is difficult,
some form of artificial heat drying is required.
Pellets
The production of pelleted chips has recently been increasing
as they meet a ready demand on the European markets. They have
the following advantages over chips: quality is more uniform;
they occupy 25-30 percent less space than chips, thus reducing
the cost of transport and storage; handling charges for loading
and unloading are also cheaper; they usually reach their destination
sound and undamaged, while a great part of a cargo of sliced
chips is damaged in long-distance shipment because of sweating
and heating.
Pellets are produced by feeding dried chips into the pelleting
machine, after which they are screened and bagged for export.
The powdered chips which fall down during pelleting are re-pressed
into pellets and the process is repeated. There is usually about
2-3 percent loss of weight during the process.
Meal
This product is the powdered residue of the chips and roots
after processing to extract edible starch. It is generally inferior
in quality to chips, pellets and broken roots, has a lower starch
content and usually contains more sand. The use of cassava meal
in the European Economic Community has declined with a shift
to the other cassava products during the last few years. However,
there will remain some demand for this product, especially by
small scale farmers who produce their own feedstuffs. Since
it does not require grinding and thus can be readily mixed with
other ingredients.
Residual pulp
During the processing of cassava flour, the residual pulp which
is separated from the starch in the screening process is used
as an animal feed. It is usually utilized wet (75-80 percent
moisture content) in the neighborhood of the processing factory
but is sometimes sun dried before it is sold. This product is
considered a by-product of the cassava starch industry and represents
about 10 percent by weight of the cassava roots.
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