Cassava

 

Introduction

Given that cassava represents a valuable subsistence and cash crop in many countries, its agricultural potential in South Africa needs to be fully exploited. Cassava was introduced into Africa by sixteenth century Portuguese slave traders and has been cultivated in the rest of Africa for several hundred years. While cassava has had a long history in the rest of Africa, cassava is not a well-known crop in South Africa.

Importance of cassava in the world Cassava is the most important tropical root crop. Its starchy roots are a major source of dietary energy for more than 500 million people. It is known to be the highest producer of carbohydrates among staple crops. According to the United Nations Food and Agriculture Organization (FAO), cassava ranks fourth as a food crop in the developing countries, after rice, maize and wheat. The leaves are relatively rich in protein and can be consumed. Cassava can be stored in the ground for several seasons, thereby serving as a reserve food when other crops fail. Cassava is also increasingly used as an animal feed and in the manufacture of different industrial products. It is also used in industrial processes.   According to FAO estimates, 172 million tonnes of cassava was produced worldwide in 2000. Africa accounted for 54%, Asia for 28%, and Latin America and the Caribbean for 19% of the total world production. In 1999, Nigeria produced 33 million tonnes, making it the world ’s largest producer. A total of 16.8 million hectares was planted with cassava throughout the world in 2000; about 64% of which was in sub-Saharan Africa.   The average yield in 2000 was 10.2 tonnes per hectare, but this varied from 1.8 tonnes per hectare in Sudan to 27.3 tonnes per hectare in Barbados. In Nigeria the average yield was 10.6 tonnes per hectare. World cassava production is projected to increase to 209 million tons (fresh weight) by 2005 or 2.2 per cent annually as in the past, reflecting both yield improvements and area expansion. World utilization is projected to increase by 2.3 per cent annually to 209 million tons. Sixty per cent of the total demand is for food, the remainder for other uses.

Global cassava trade is projected to increase by 1.6 per cent by 2005, that is, from the 4.8 million tons produced from 1993-1995 to 5.8 million tons (dry weight) in 2005, reflecting moderate growth in import demand for cassava feed and other novel cassava food and non-food products. However, cassava for feed is projected to continue to account for over three-quarters of the world cassava trade and flours and starches for food and industrial uses for the remainder.

Cassava products

Cassava is the basis of a multitude of products, including food, flour, animal feed, alcohol, starches for sizing paper and textiles, sweeteners, prepared foods and bio-degradable products. The products are derived from a number of forms of cassava, ranging from fresh leaves and roots to modified cassava starch. The degree of processing and the technical requirements tend to increase from the fresh form to the modified starch form.

All of the above products represent potential market development opportunities for cassava. While some cassava is sold as fresh roots or leaves, even these products usually receive some special post-harvest handling or treatment before they are consumed. As cassava normally requires some form of processing before it can be consumed or sold, processing is of central importance in the future of the crop. While the market potentials are great, it must be remembered that these opportunities are location and time specific. Because of the specificity of market opportunities it is impossible to compile a list of priority market opportunities. The following section, however, does attempt to highlight some the benefits and challenges that might be encountered when attempting to develop different types of cassava markets.

Products from leaves and roots

Fresh roots and leaves are used primarily as human food. Because of their perishability, most roots are usually consumed or marketed close to the centres of production. Traditional methods for preserving fresh roots include packing roots in moist mulch or removing leaves two weeks prior to harvest to increase root shelf life to two weeks. In Colombia, CIAT researchers found that preservative treatments such as dipping fresh roots in wax or paraffin and storing them in plastic bags reduced vascular streak and prolonged storage for 3 to 4 weeks. Roots can be peeled, chopped into chunks and frozen for specialized markets. Cassava leaves can be eaten as a fresh vegetable, ground fresh and frozen in plastic bags, or dried and ground for sale in plastic bags. The leaves are more nutritionally balanced than the roots and can help to prevent certain deficiency diseases. Leaves, however, may be high in hydrocyanic acid (HCN), but the HCN can be reduced to safe levels in most cases when the liquid is squeezed out after grinding and through evaporation during cooking.

Potential for fresh cassava

Higher incomes and urbanization are associated with greater consumption of convenience foods and foods that are perceived as more desirable foods. In cassava-producing countries, urbanization represents an opportunity for producers to produce cassava for a larger consuming population. The implication is that cassava markets for fresh cassava can grow if the cassava products are convenient and in a more desirable form. Costa Rica has demonstrated that there is a growing export market for fresh cassava - if it is packaged in an attractive and useful manner. The potential for fresh cassava in producing countries represents growth, firstly through concentration, although competition and innovation are important factors as well. The potential for fresh cassava in non-producing countries represents growth through concentration and innovation.

Products from dried roots

In many countries of Africa and Latin America, cassava is processed at home or at village level to produce toasted flour (farinha in Brazil, gari in West Africa), or to make flat bread (casabe in the Caribbean). Farinha and gari etc. can be produced in both small- and large-scale operations. Dried cassava has been a major success as an animal feed ingredient in Europe and as an export product in Thailand and Indonesia. Thailand, China, Brazil and Paraguay are also reportedly using a substantial proportion of their cassava for non-intensive swine, poultry and fish production. In most of the other countries of LAC, about 20 % is used for animal feeds. On-farm feeding of fresh or dried cassava has been practised for a long time, and its use in balanced rations is increasing, because it adds value and results in more marketable livestock products. Technical details for using dried cassava in rations are well established in milling and blending and in animal nutrition. FAO estimates that from 1992-1994 about 25% of world cassava output was devoted to feed in the form of pellets and chips, which represents a 2% increase over the 1970s. Trade development by the EEC at global level and in such non-cassava-producing countries as Japan and the Republic of Korea is helping to promote the use of cassava as a feed.

Potential for dried cassava:

In general, urbanization and rising incomes have reduced the market for fresh roots. Housewives seek convenience foods that are easy to buy, store and prepare. Thus, packaged cassava and cassava flour and breads are gaining greater acceptance in some markets. Farinha and gari in particular could be considered as convenience foods because they are easy to buy, store and prepare. These possibilities should be explored further, particularly with the increase in the African, Latin American and Caribbean populations in the Western world. Cassava flour has potential in many developing countries, particularly in Africa (and, to a lesser extent, in Asia) where there is a large consumption of bread made from 100 per cent imported wheat. The degree of replacement can lead to different grades of breads and pastry products and different prices for the consumer. Research will be needed to evaluate the different proportions of cassava/wheat flour and this research will have to be done in partnership with the bakery industry. Dried cassava in the form of meal, chips and pellets is an important animal feed ingredient. As livestock production and meat consumption become more important in cassava-producing countries, the need for animal feed rations is expected to increase. Finally, dried and fresh cassava can be used to produce glues and alcohol (both hydrous and anhydrous). These markets, especially those for glue and anhydrous alcohol, represent new opportunities for the use of cassava in many countries. These potentials represent growth through concentration, innovation, and competition. The combination of the growth factors will be site specific.

Products from cassava starch

Cassava starch is used directly in different ways or as a raw material for further processing. Special features of cassava starch are its viscosity, resistance to shear stress and resistance to freezing. The main classes of starch-based products are:

• unmodified or native starch;
• modified (physical, chemical, biological) starches for industrial purposes;
• sweeteners, including high-fructose syrup and glucose (dextrin, monosodium glutamate, pharmaceuticals, etc.).
  

Development of communities

Projects focused on development

Cassava became a staple food in many rural communities because of its tolerance of drought and poor soil conditions and because it can be cultivated in generally difficult crop environments. Traditionally, cassava production is labour-intensive and cassava is generally cultivated as a subsistence crop on a small scale by peasant farmers. Surplus production is generally marketed and sold by the informal sector throughout Africa, South America and South-East Asia. Once subsistence production becomes established, there will be economic incentives to produce surpluses. Once thought to be resistant to pests and diseases, the crop can be improved genetically to increase its resistance to severe pest infestations and serious diseases. Cassava yields can be quite high, as high as 25 to 40 tons/ha, although national yields are often well below these levels. The world average is about 10 tons/ha.

Although it was long considered a smallholder subsistence crop, cassava can be grown in large plantations or under more favourable conditions to produce raw materials for industrial processing. It must be remembered that the supply chain for cassava products tends to begin with small-scale production units, followed by small-scale processing units for the drying and/or milling of cassava. These steps are often carried out at the home and village/local level. As the product moves through the supply chain, activities like marketing, processing and packaging are done by fewer larger-scale units, which then distribute the final product to a larger number of consumers. This hourglass supply chain differs from the supply chain of many established agricultural products. The existence of the hourglass supply chain does suggest that the growth and development of cassava product markets will benefit the large number of resource-poor farmers located on poor lands as well as the local processing units. The challenge is how to equip these farmers and processors with the knowledge and tools needed to provide the products that meet the requirements of growth markets. There is also the challenge of how to deal with growth markets that lead to an altered supply chain - one with fewer large-scale producers. The potential structural change of the supply chain will, therefore, have to be evaluated when marketing opportunities are assessed.

Current practices and acceptability of the crop

Cassava can grow and produce high yields in areas where maize and other crops will not grow or produce well. It can tolerate drought and can be grown on soils with a low nutrient capacity, but responds well to irrigation or higher rainfall regions and to the use of fertilizers. Cassava is highly flexible in its management requirements, and has the potential of high-energy production per unit area of land. The crop has long been used as a famine reserve and food security crop. Because cassava has no definite maturation point, harvesting may be delayed until market, processing or other conditions are more favourable; this flexibility means cassava may be field stored for several months or more. Cassava is, therefore, highly acceptable in the rural areas.​