ITDG 
Interdev Agroalimentaire  

Production of gari

	Type de fiche	Techniques/Technologies
	Mise en œuvre	ITDG(Royaume Uni)
	
	Zone géographique	Afrique; 
	Mots clés	GARI; FARINE; MANIOC; GRILLAGE; AMIDON

	Echelle d’action	Village
	Public(s) cible(s)	Small- and medium-scale food processors

Contexte
Gari is a creamy-white granular flour with a slightly fermented flavour and a slightly sour taste.  It is produced from cassava tubers and eaten as a main meal with soup or stew.  It is also consumed as a drink with sugar and milk. When properly stored it has a shelf life of six months or more.

Fresh cassava deteriorates very rapidly after harvest and needs to be processed to preserve it for consumption.  There are several traditional methods of preservation that vary from country to country.  Production of gari is one method of preservation.  This product is popular as a convenience-type of food since the starch in the cassava is pre-cooked and therefore the gari does not take long to cook.

Preservation of gari is achieved by a combination of fermentation to reduce the pH, heating to drive off moisture and to deactivate enzymes and micro-organisms and a final low moisture content.  It is packaged in moisture proof material to prevent the uptake of moisture.

Problématique / Objectifs
  The fresh cassava should be free form microbial or insect damage and without serious bruising or cuts. It should be processed within two days of harvest to prevent deterioration and loss of quality of the gari.
  Washing should be carried out thoroughly to avoid contamination of the final prouct with peels, sand and so on. 
  As with all cassava products, especially the bitter varieties, it is essential to detoxify the cassava by removing cyanide from the cyanide-containing compounds. This is achieved by fermentation to hydrolyse the cyanide-containing compounds, followed by heating to drive off the cyanide gas. This is an essential part of the process and should be properly controlled.
  Fermentation must be properly controlled as to short a period will result in incomplete detoxification and a bland product.  Too long a period will result in a strong sour taste.  Both over- and under-fermentation also badly affect the texture of the gari.
  The pressing stage is important.  If too much liquid is removed from the cassava during pressing, the gelatinisation of starch during roasting is affected and the product is more white.  If too little liquid is removed, the formation of granules during roasting is affected and the dough will form into lumps.  The ideal moisture content is 47-50%.  With experience, gari processors can visually determine the correct amount.
  Sieving is important to obtain a high quality product that is free from fibrous particles and has granules of about the same size.
  The granule must be roasted to about 80 C to achieve partial gelatinisation of the starch. If lower temperatures are used, the product simply dries and produces a dry white powder. Too high a temperature will cause charring of the product and make it stick to the roasting pan.
  Gari is very hygroscopic, that is it readily picks up moisture from the air. It should be packed in airtight and moisture-proof bags, especially in areas of high humidity, to prevent the growth of mould.

Description/Mise en oeuvre
Gari is prepared from cassava according to the following method:

  Selection
  Peeling
  Washing
  Grating
  Fermentation
  Pressing
  Sieving
  Heating
  Cooling
  Sieving
  Packaging and storage

A process flow sheet outlines the method (ref link)

Selection
Select fresh, mature tubers that are free from rot, disease and discoloration.

Peeling
Peel by hand and remove the woody tips.
Washing
Wash the peeled tubers in clean water to remove pieces of peel, sand and dirt.

Grating
Use a manual or motorised cassava grater

Fermentation
Pack the grated cassava into baskets made from cane, bark or palm branches and leave for 24-48 hours at room temperature.

Pressing
Fill the fermented paste into hessian or polypropylene sacks and place in a manual screw press or weigh down with rocks. If the rocks are used, they are often applied to the grated cassava while it is fermenting, thus carrying out the fermentation and the pressing at the same time. Press until the moisture content is between 47-50%.

Sieving
Use a wooden sieve to separate out the fibrous particles and to control the size of the pieces.

Heating
Roast the fermented cassava in a large, shallow cast iron pan over a fire, with constant stirring for about 20-30 minutes.  Stirring is necessary to prevent sticking and burning of the gari. The temperature should be about 80 C to ensure the starch is partially gelatinised.

Cooling
Cool to room temperature.

Sieving
Sieve again to obtain granules of a uniform size. Larger granules of gari that are separated out can be sold as a cheaper grade.

Packaging and storage
Pack in polythene bags and seal to prevent the entry of moisture and air. Store in a cool dry place, away from direct sunlight and out of the reach of animals and rodents. If dried and stored properly, gari has a shelf life of six months or more.

Résultats/Eléments chiffrés
The following equipment is required:

Cassava press
Grater
Wash tank
Sieves
Roasting pan
Heat sealer

Enseignements
  Fresh cassava is a moist, low-acid food that is susceptible to bacterial and fungal growth.  It is important to follow strict hygienic practices during the early stages of processing to ensure that contamination is minimised.
  Fermentation (by lactic acid bacteria) reduces the pH to create a more acidic environment. This is essential for the hydrolysis of the cyanide-containing compounds.
  If the fermentation is inadequate, the cyanide level of the gari can remain dangerously high, especially if bitter cassava varieties are used.  The amounts of cyanide remaining are rarely high enough to be fatal, but long-term consumption of low levels of cyanide can lead to disease and disability.
  Commercialisation of the gari process needs to ensure that the various stages of the process are all adequate to reduce the final cyanide content to acceptable levels.
  Before producing gari for sale, the processor must carry out a market survey to determine demand for the product.

Auteur : Sue Azam Ali
Saisie le : 05/12/2001
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