Step 1: Harvesting
Harvesting of cassava is usually
done in the early mornings. The cassava roots are harvested by the used of
mechanical harvesters if available or by uprooting the roots mechanically and
using your cutlass to burrow into the soil in case any of the cassava roots are
still left within the soil to avoid wastage. For accurate record keeping, It is
expected of the farmer to know the total number of stands that is been
harvested and the record kept. After Harvesting of the cassava, they are then
taken to the factor by the use of a transporting wheel that is coupled to a tractor
in a mechanized farm or using other means of transportation.
Step 2: Peeling and washing
cassava roots
Freshly harvested
cassava roots are covered with soil and dirt and some may be damaged or rotten.
Only healthy roots (without rot or other damage) should be transported to the
factory. At the factory, the roots are peeled to remove the outer brown skin and inner thick cream layer and
washed to remove stains and dirt. The water source should be checked regularly
to ensure it is not dirty or contaminated.
Items needed here
are:
·
Fresh,
undamaged cassava roots
·
Source
of clean, good water
·
Source
of assorted clean containers
·
Clean,
Sharp knife
·
Plastic
scourer
When
peeling, Select fresh
cassava roots without rot or damage. Use a sharp knife to peel the roots and
remove the skin. Remove
any damaged or woody parts from the roots. Do not shave the roots
because you will cut off too much and reduce the amount of gari produced.
When Washing, Wash the peeled roots in clean water. Do not use water from unprotected sources
as this could introduce contamination. Gently scrub the roots with the scourer to remove pieces of unpeeled skin and dirt and make sure the washed roots are clean with no
spots.
Step 3: Grating cassava roots
into mash
Cassava roots are
traditionally grated into a mash or pulp as part of the process to remove cyanide and make the roots
safe to eat. Traditional cassava
graters are usually made from perforated metal sheets. These rust quickly and are difficult to keep clean.
They are also very slow and labour intensive to use.
Mechanized graters
are needed to produce a sufficient quantity of cassava mash to meet market demands and standards.
Smallholder processors therefore need to learn how to use and maintain these
machines.
Items needed for
Grating are:
·
Washed
and spotless roots in a clean container
·
A
motorized grater. It is preferred that the grating drum and all the food
contact medium in the grating machine be made or stainless steel as Iron made
one promotes quick rusting and will have a detrimental effect on the quality of
the grated cassava.
·
Clean
woven polythene sacks to hold the cassava mash after grating
When grating, we
load the grater with washed roots while the engine is running to crush the
roots into a mash. It is advisable not to use bare hands in the grating machine
to avoid injury or otherwise, carefully done. After it had been grated, the
mash will then be collected into a clean polythene sack.
Step 4: De-watering and fermenting mash into wet cake
De-watering and
fermenting complete the
process of removing cyanide
from the cassava mash. This is
done traditionally by using stones
or logs as weights to press excess water out of the bags of cassava mash. The
bags are then left to drain and
ferment for a few days.
As with traditional graters, these
methods are slow and unhygienic,
and are therefore not suitable
for a cassava processing business.
Several improved methods are available.
Bagged cassava
mash can be left on the fermentation rack for one or more days before
de-watering. Alternatively, the bags of cassava mash can be pressed for the
required number of days, during which time the mash will ferment. At the end of
the fermentation period, the mash will become a firm, wet cake.
Fermentation
periods of longer than one or two days will produce very sour products.
Consumer tastes and preferences will therefore determine the length of the
fermentation period.
The carotene
cassava was not allowed to undergo fermentation process but the TMS variety was
allowed to undergo fermentation process for up to 3 days before de-watering in
the Hydraulic Press. De-watering of both varieties took about 24 hours.
Items needed in
this step include:
·
A
fermentation rack
·
A hydraulic
press or a screw press depending on the choice of the farmer or what is
available.
De-watering of the
cassava mash in the factory can be done using any of these two methods:
The first is to
load the bags of cassava unto the fermentation rack and allow the milky water
to drain freely from the bags. The fermentation period depends on the choice
and the type of quality product that is envisaged to be achieved by the farmer.
At the end of the fermentation period, remove the bags of mash from the rack and
screw them in a hydraulic press or screw press. This step is carried out in the
Cassava factory in OAU Teaching and research farm in the processing of the TMS
variety of cassava.
The second step
involves loading the cassava bags directly on to a hydraulic press or screw
press. Lift and press the jack handle up and down until it is hard to move for
the hydraulic press. For the screw press, turn the handle clockwise to force
the water out of the bag.
When a press is
used on bare ground, the waste water will not get drained properly and the area
will be dirty. The bags of cassava mash could also get contaminated with dirt.
It is advisable to place the press on a raised platform.
When water stops
dripping from the bags and the surface of the bag is still moist, you can
remove the firm wet cake from the press. Ensure sufficient water has been
removed, otherwise the garri will form into lumps during roasting. But, if too
much water is removed, the garri will not cook properly during roasting, but
become floury instead.
Step 4: Sieving wet cake into grits and roasting grits into gari
Gari is made by
sieving the wet cake into small pieces - known as grits - and then roasting or
frying the grits in a hot frying tray or pan to form the final dry and crispy
product. Gari is normally white or cream, but will be yellow when made from yellow cassava roots
or when fried with palm oil. It is important to make sure the taste and smell is acceptable to local
consumers. Yellow cassava roots and palm oil are rich in vitamin A and therefore make nutritious gari.
The product should
be free from mould, insects (dead or alive), dirt and any other material that
could be hazardous to
health.
Gari is usually
classified by its particle size:
• Extra-fine: passes through 0.25 mm to 0.5 mm
aperture sieve
• Fine: passes through 0.5 mm to 1 mm aperture
sieve
• Coarse: passes through 1 mm to 1.25 mm
aperture sieve
• Extra Coarse: passes through 1.25 mm to 2.0
mm aperture sieve.
Items needed here
are:
·
Garri
sieve. It could be a type that is made from stainless sieve mesh, or the
traditional sieve made from wooden materials.
·
A garri
roasting bay with a shallow stainless steel tray or a molded aluminum pot. The
tray should be mounted on mud bricks rather than cement bricks since clay is
more heat efficient when compared to cement.
In breaking and sieving
of the cassava mash, we need to:
·
Firstly
remove the wet cake from the bag
·
Break
the wet cake into small pieces (grits) using a grater or a sieve with an
aperture size of 1.5 – 2.0mm. This can also be done by hand.
·
Sieve
the pieces of wet cake to remove any fibrous material.
In roasting:
·
Clean
the surface of the roasting tray and smear it with a thin layer of edible
oil(e.g. palm oil or cooking oil)
·
In the
improved garri roasting bay, fuel wood, wood shavings, charcoal or other
readily available suitable material is lit through a fireplace on the outside
of the factory wall from direct contact with the processor.
·
The
fire heat the stainless steel tray sitting on a raised platform above the
fireplace inside the factory providing the heat for roasting the garri. Heat
the tray and load it with a batch of grits. Stir the batch with a wooden spatula. The gari is ready when
it turns into dry, creamy granules. Smoke generated from the fire underneath
the tray escapes through a
galvanized steel chimney pipe to the top of the roof.
·
Traditional
garri bay exposes the processor to direct heat, smoke and fumes, and this may
affect the health of the processor and their family over the long run.
·
Do not
also use mild steel tray for roasting garri. This will rust and contaminate the
garri.
·
Collect
the garri from the roasting pan when it is dry, leaving a small amount if garri
in the tray. This will help to roast the next batch.
·
Note
that; if the fire is not hot enough, the garri will not cook properly and will
become white. If it is too hot, the garri will burn. Normal required heat will
ensure the garri is well roasted.
Step 5: Bagging and storing the
gari
The product is hygroscopic (it absorbs moisture from the air) and
should be packed in airtight and moisture-proof bags, especially in areas of
high humidity, to prevent mold growth.
This step can be highlighted as follows:
Ø Remove the gari from the roasting tray and
spread it thinly on a raised platform in the open
air to cool and dry. Several
batches can be put on the cooling tray.
Ø Sieve the gari with a standard size sieve to produce fine
granules, which are collected in a plastic bowl.
Ø Use a grinder to break the large granules into smaller ones
Ø When the gari granules are all the same size, pour the gari into a plastic lining
inside a woven polythene sack
Ø Weigh the sack of gari to make sure it is the correct
weight, as required by the market: e.g. 1kg, 5kg, 10kg, 25 kg, 50 kg or 65 kg. Seal the sack manually or with a bag sealer (if available) to
keep the gari clean and fresh during storage.
Pile the sacks on pallets or a raised platform and keep them in a cool, dry place; the gari will keep for up to a year in these conditions
