Cassava is a tuberous edible plant of the Spurge Family that originated in tropical America. It is cultivated throughout the tropical regions worldwide for its tuberous roots from which many products can be derived. The Federal Institute of Industrial Research Oshodi, FIIRO, has developed long shelf-life products from cassava and gari is one of them as it is a good source of energy.
It is the most popular cassava food in West Africa due to its convenience and multiplicity of use. The product is currently produced in West, Central Africa, East, and Southern Africa largely through the work of international agricultural development organizations like the International Institute of Tropical Agriculture (IITA) and the United States Agency for International Development (USAID) to increase food security. As an institution committed to ensuring food security, sustainability and job creation, FIIRO has also worked extensively in developing and adding value to the cassava tuber.
Gari is made from freshly harvested roots of cassava varieties with good gari making characteristics. Cassava roots must be produced using safe agricultural inputs and practices. Cassava varieties with good quality gari are selected. The roots are harvested at maturity when the dry matter and starch contents are high and no lignification of the roots have occurred. Cassava roots are transported from farms in sacks to prevent health hazards due to contamination and good hygiene must be maintained during harvesting, transportation, handling, production and storage. Gari can be eaten in granular form as snack, soaked in cold water with sugar, milk and/or salt or groundnut. When mixed with hot water, gari (eba) can be eaten with soups.
The production starts by peeling fresh cassava roots, then washing and grating, fermenting, dewatering or pressing, breaking of the cake, sifting, roasting or frying and then, packaging (James et al 2012). The quality of gari depends mostly on the cassava variety and how adequate the processing steps were taken.
Gari Processing Steps
Peeling: Freshly harvested cassava roots are peeled latest a day after harvesting. Peeling must be thorough to avoid the presence of peel fragments in the final product. Manual peeling with a knife is most common but mechanical peelers have recently become available. Mobile Cassava Processing Unit (MOCAPI) is one of FIIRO'S fabrications that has cassava peelers as part of its mechanism. The practical significance of peeling is the removal of brown peel which might affect the colour of the gari and increase fiber content.
Washing: Peeled roots are washed thoroughly in portable water to remove sand particles and dirt that can mar the quality of the final product.
Grating: Clean roots are grated to obtain a mash. Grating is carried out by a motorized cassava grater but hand graters, made by fastening the perforated grating sheets on wooden planks, are still used in some rural villages. A grating plate is made of a perforated metal sheet and with a sharp extruding face as the grating zone. The sharpness of the extruding zone determines the efficiency of subsequent operations such as fermentation and detoxification and the final product such as fineness (Oguntimein et al. 1995). Grating disintegrates the cassava tissue and frees up the moisture so that mechanical dewatering can be done easily. Cassava starch granules are also partially released due to grating.
Fermentation: Grated cassava mash is loaded either into a polypropylene bag or basket (lined with polypropylene sack) and left for 1-5 days to ferment, depending on the taste preferences of the target consumer. Fermentation of cassava is an important operation in terms of taste, aroma, safety and general quality of gari. The acceptability of gari is influenced by its sourness which is related to the amount of lactic acid or length of fermentation. Cassava fermentation for gari production occurs through the activities of endogenous microorganisms, mostly lactic acid bacteria, producing lactic acid that reduces the pH of the fermenting mash. The longer the fermentation period, the lower the pH of the marsh or more sour the gari becomes. Cassava detoxification during gari processing may start from grating and continue simultaneously with fermentation until after roasting.
Dewatering: The fermented mash is featured inside a polypropylene sack by pressing with a manual screw or hydraulic press. Pressing is done principally to reduce moisture content of the grated marsh to 40‐50%. The dewatering operation contributes to cassava detoxification by eliminating cyanogen and cyanohydrins in particular, with the waste effluent.
Disintegration and Sieving: The cake formed after dewatering is disintegrated or granulated by a hand-held motorized cassava grater. The cake can also be broken up by hand and sieved with a manual woven sieve or rotary sieve to remove fibre and lumps. Sieving reduces the formation of lumps during roasting.
Roasting: The roasting process, otherwise known as "garification" is done immediately after sieving. An earthenware stove and a frying pan made of molded aluminum or stainless steel are used, often on a wood fire. In some communities, the roasting pan is smeared with a small amount of shea fat or palm oil prior to roasting. The granules are fed in bits into the hot pan and stirred until an adequate quantity has been fed in. Stirring during roasting continues with intermittent short breaks which allows gelatinization to properly occur. The gari collected is dry and creamy in colour. Gelatinization improves the digestibility of gari while the level of dryness determines the crispiness and storability. The final moisture content of gari should be 8-10%.
Cooling: Roasted gari is allowed to cool for 4-6 hours in clean containers. As the gari cools, it loses moisture and becomes drier and crisper.
Sieving (grading): This may depend on consumer preference. The Roasted gari may be sieved to remove big lumps and obtain uniform particle sizes.
Packaging: The final package is packed based on distribution outlets. Packaging is done soon after the gari is significantly cooled. When properly packaged, gari can be stored for at least a year.
Processing Machinery: New and more efficient machines are now available for processing cassava into gari. Such as:
- High-capacity cassava graters.
- Hydraulic operated dewatering machines (pressers).
- Earthenware stoves with stainless steel fryers and chimneys.
- Fresh cassava peelers.
The availability of these machines has increased the efficiency of mechanized gari processing operations.
Gari processing plants must be located close to the source of fresh cassava tubers, water, labour, electricity. Quality and safety measures must be put in place for gari production suitable for human consumption.
FIIRO has added value to gari in its research and development activities that the gari processed end product ready for the market is fortified with necessary vitamins and minerals. The Institute also has a collection of Machinery, like the Mobile Cassava Processing Unit (MOCAPI), a cassava Processing unit that sits on a tricycle. It eases gari processing at the farms, thereby eliminating the stress and cost of moving raw materials. A larger version of MOCAPI for larger output is also available and sits on a truck.
FIIRO's research on gari processing is quite extensive covering a range of end products like:
- The fortified gari for soaking (in local parlance) i.e., ready for instant consumption with cold water.
- Fine textured gari as 'eba', usually prepared with hot water and eaten with soups.
- Coarse textured gari also made with hot water as 'eba' to be eaten with soups.
- Soy-Garri is nutritionally boosted garri, to increase the protein content of garri.