Cassava tuber has the following composition: The Nutritive, Environmental and Economic values of Traditional Fermented Cassava Products in Rwanda. NKUBANA Andrew PhD, Punjab Agricultural University, College of Agriculture, Department of Food Science and Technology, Ludhiana, India E-mail: andex2006@gmail.com Tel: +91-9915210474 Abstract: Fresh cassava roots and leaves cannot be stored for long because they rot within 3-4 days after harvest. Being bulky with about 70 percent moisture content, transportation of the roots and leaves from rural to urban areas for marketing is very difficult and expensive. Both root and leaf contain varying amounts of cyanide that is toxic to humans and mammals; additionally, they are not palatable. Thus there is a need to process cassava into various products that have increased shelf-life, are easier to transport and market, cost less to transport, contain less cyanide and have improved palatability and nutritional value. Several traditional fermented foods and beverages are produced at the household level in Rwanda and create local employment opportunity and income generation. The cassava-based fermented foods include; cassava flour & cassava leaf flour (isombe). Literature on Rwanda fermented cassava foods is non-existent. Therefore, the objective of this review is to document the methods by which these Rwandan fermented foods are produced and to advise scientific means to improve their quality and optimize their production methods. INTRODUCTION Cassava (Manihot esculenta), sometimes also called manioc, is the third largest source of carbohydrates for human consumption in the world, with an estimated annual world production of 208 million tons. In Africa, which is the largest centre of cassava production, it is grown on 7.5 million ha and produces about 60 million tons per year. It is a major source of low cost carbohydrates and a staple food for 500 million people in the humid tropics. On infertile land where the cultivation of other crops is difficult, unless considerable inputs are applied, cassava still has a reasonable yield. The crop is highly efficient in producing starch, it is year-round available, it is tolerant to extreme stress conditions and it fits nicely within traditional farming systems. Fresh roots contain about 30% starch. Cassava starch is one of the best fermentable substances for the production of ethanol. At the moment sugar cane is the most widely used crop for bio-ethanol in the Tropics, but sugar cane requires a lot of water. The plant grows tall, some reaching 15 feet, with leaves varying in shape and size. The edible parts are the tuberous root and leaves. The tuber (root) is somewhat dark brown in color and grows up to 2 feet long. Cassava is the third largest source of carbohydrates for human consumption in the world, due to its efficient growth, year round availability, its tolerance to extreme stress and its suitability to be incorporated into traditional low input farming systems, which predominate in Africa. Recently, the cultivation of cassava for the production of ethanol has been intense field. In situations where water availability is limited (i.e. not enough for the cultivation of sugar cane), cassava is the preferred feedstock for ethanol production. Fresh cassava roots and leaves cannot be stored for long because they rot within 3-4 days after harvest. Being bulky with about 70 percent moisture content, transportation of the roots and leaves from rural to urban areas for marketing is very difficult and expensive. Roots contain varying amounts of cyanide that is toxic to humans and mammals; additionally, they are not palatable. Thus there is a need to process cassava into various products that have increased shelf-life, are easier to transport and market, cost less to transport, contain less cyanide and have improved palatability and nutritional values. Several traditional fermented foods are produced at the household level in Rwanda and create local employment opportunity and income generation. The cassava-based fermented foods used as whole: roots, peels, stem, leaves and then cassava flour & cassava leaf flour (isombe) as sources of nutritional several kinds of daily consumable foods. Ecofys has selected the topic “Bio-ethanol from cassava”. Cassava is grown in many countries with a warm and moist tropical climate. Cassava yields well on soils of relatively low fertility where the cultivation of other crops would be uneconomical. Such growth conditions are widely available throughout the Tropics, especially in Africa. Figure 1: Flow chart of Cassava ethanol production Methodology The separation of the starch granules from the tubers/roots in as pure a form as possible is essential in the manufacture of cassava flour. The granules are locked in cells together with all the other constituents of the protoplasm (proteins, soluble carbohydrates, fats and so on), which can only be removed by a purification process in the watery phase. Processing the starch can therefore be divided into the following stages Preparation and extraction Purification and Substitution Gelatinization Removal of water by centrifuging and drying. Grinding, bolting and other finishing operations. IMPORTANCE OF QUICK PROCESSING In the processing of cassava starch it is very vital to complete the whole process within the shortest time possible, since as soon as the roots have been dug up, as well as during each of the subsequent stages of manufacture, enzymatic processes are apt to develop with a deteriorating effect on the quality of the end product and it involves the following Peeling and washing Rasping or pulping Screening Settling and purification Drying Finishing and packaging GENERAL APPLICATION & BENEFITS Applied in Food industry & dietary supplement Bio-ethanol & Bio-fuel (Biomass/Biogas) Rich source of Vitamin A & other traces of nutritional values Cosmetic, Neutraceutical and Pharmaceutical industries Human disease prevention (immune system) Source of Employment at household level Paper & poly wood industries Potential source of human energy Biodegradable plastics Mammal and Poultry Feeds Textile industry Drilling industry Income generation Figure 3: Cassava drying Figure 2: Cassava tubers and its cultivation This new use to make bio-fuels from cassava may affect the development of rural Africa both in a positive and in a negative way, which was the main reason why this quick-scan report looks at cassava cropping and utilization from different angles: general agronomy, suitability as a feedstock for ethanol production, use of co-products, current status and markets, its economic feasibility in comparison with other ethanol crops and aspects of sustainability. It is the result of a limited quick can performed by 6 members of the Bio Energy group at Ecofys, which implies that just an overview of the main issues is presented, without going into much detail. CONVERSION FACTORS Because of the high starch content cassava is a high yielding ethanol crop. However, distinction has to be made between yields from dried cassava chips and fresh cassava roots. For one kilogram of cassava chips, approximately two kilograms of fresh cassava roots are required. One litre of ethanol can be produced from: 5 - 6 kg of fresh roots (containing 30% starch) 3 kg of cassava chips (14% moisture content ) On a per tonne cassava basis: 1 tonne of fresh cassava roots yields 150 litres of ethanol 1 1 tonne of dry cassava chips yields 333 litres of ethanol Cassava tuber has the following composition: Peel 10-20% Cork layer 0.5-2% Edible portion 80-90%, of which: Water 62% Carbohydrate 35% Protein 2% Fat 0.3% Fiber 1% Ash 1% Conclusion Several traditional fermented foods are produced at household level in Rwanda. The presence of unspecified microorganisms complicates the control of fermented process and gives products of variable quality. The microbiology and biochemistry of these traditionally fermented foods need to be fully understood before the prominent microorganisms fermentations are isolated, identified, character sized and used in development. These together with improved processing and use of quality raw materials for fermentation could be used in the establishment of small–scale industry of fermented foods. Further research should be directed towards identifying the benefits and risks associated with fermenting and possible contamination. Therefore this Literature on Rwanda fermented cassava has the objective to document the methods by which these Rwandan fermented foods/products are produced and to advise scientific means to improve their quality and optimize their production methods.