Cassava value chain in Tanzania: Post-harvest

Backgrounder

 

Introduction and how to use this issue pack

 
This issue pack is designed to give radio broadcasters the information they need to create effective and entertaining programs on the post-harvest value chain for cassava, a staple food with the scientific name of Manihot esculenta.

The issue pack focuses on cassava in Tanzania, but the information it contains can be adapted to other sub-Saharan African countries where cassava is grown.

Section 2 of this issue pack presents a true story about a Tanzanian cassava grower and processor.

Section 3 presents background information on activities in the cassava post-harvest value chain. Please see Resource Pack 95, Item 9 – An introduction to value chains – for a definition of “value chain” and a better understanding of why value chains are important for both broadcasters and farmers. See also Resource Pack 96, Item1 – Cassava value chain in Tanzania – production for information on cassava production, and on creating effective and entertaining radio programs on cassava production.

In the final section, section 4, we list sources for further information on the post-harvest value chain for cassava in Tanzania. This includes resource organizations, online radio programs, online videos, and online documents.

You might use the information in this issue pack in several ways. For example:
You could use the story in section 2 as a starting point for creating your own local stories. You might start by interviewing cassava processors, traders, and others.

You can use section 3 as background information for any program on post-harvest cassava.
You could contact one or more of the organizations listed in section 4 for information or to interview a cassava expert.
You could use the audio and video resources and online documents in section 4 to help create programs on groundnuts.

Cassava story

 
Mohamed Rajabu is a farmer from the village of Tongwe, about 50 kilometres southwest of the city of Tanga on Tanzania’s Indian Ocean coast. Cassava has transformed Mr. Rajabu’s life and that of his family. He now produces more than enough of the crop to meet his domestic needs, and sells the surplus as cassava flour.

Mr. Rajabu belongs to the Tongwe Farmers Group. The group built a farmer-run cassava processing centre in Tongwe. The centre has both manual and power-operated chippers and graters, and machines for squeezing water from grated cassava. Grated cassava mash and cassava chips are dried and milled into cassava flour before being sold.

Before he started growing cassava, poor harvests caused by low rainfall made it difficult for Mr. Rajabu to support his family. But since he started growing cassava, the increasing demand for the crop assures him of an adequate income.

Because of its expanding production, the Tongwe Farmers Group was able to sign an agreement with a local supermarket chain to sell its members’ processed cassava at market prices.

Cassava has improved Mr. Rajabu’s economic security to the point that he has branched out into other businesses. He invested 3,000,000 Tanzanian shillings [$1,800 U.S.] of the profits from his cassava sales to buy a shop in Tongwe, a store which supplies villagers with basic supplies such as soap, sugar, plastic utensils, salt and cooking oil.

Adapted from Cassava cushions Tanzanian farmers from climate impacts (Trust, July 2012: https://news.trust.org/item/20120711143200-crg2e)

Background information on post-harvest cassava in Tanzania

 

Cassava originated in tropical America and was introduced to Africa in the mid-1500s, arriving in East Africa in the 1700s. Today, it is a staple in much of Africa. Apart from being a food staple, cassava, cassava starch and cassava by-products are used in many types of products: confectioneries, glues, plywood, textiles, paper, and pharmaceutical drugs. Cassava chips and pellets are used as animal feed and in alcohol production.

In sub-Saharan Africa, cassava is a staple food for more than five hundred million people. It is both an important food security crop and an income-generating crop for resource-poor households in many countries. Two-thirds of the more than 18 million hectares of cassava grown worldwide are produced in Africa. About 93 per cent of African cassava is consumed as food.

Tanzania produces an estimated seven million tonnes of cassava, fourth most in Africa, 84% of which is used as human food. Cassava is a main food crop in the coastal areas of Tanzania and the Lake Zone. It is grown in all regions of Tanzania, but the main growing areas are the Lake Victoria zone (Mwanza, Mara, Kagera and Shinyanga regions), the Southern zone (Lindi and Mtwara regions and Tunduru district in Ruvuma region), the Eastern zone (Morogoro, Tanga, Coast, and Dar es Salaam regions) and Zanzibar (Pemba and Unguja islands).

Cassava production requires less labour than other staple crops (only one-fifth of the working days of maize, yam or rice). But cassava requires considerable post-harvest labour because the roots are highly perishable and must be processed into a storable form within one or two days after harvest.

Storage

Farmers often store fresh cassava roots in the ground and harvest them as needed. Harvested roots can be stored in sacks on a short-term basis only, since deterioration starts two days after harvest.

After home processing, dried cassava chips are often stored in traditional storage facilities in sacks, or in large woven round baskets (vihenge in Kiswahili) on the floor of the house, or in the attic. When cassava chips are stored in the house on raised platforms above the cooking area or in the attic, they are smoked, which preserves the chips longer. Chips can be stored for two to three months before insect damage, but for one year after being smoked. Dried cassava chips are more easily marketed and can fetch a higher price because traders find it easier to transport them. High quality cassava flour (HQCF) can be stored for up to one year.

Processing

After harvest, farmers transport cassava roots to processing areas by bicycle, small tractor, or by carrying the roots. Some processing is done on the farm, some in the home, and some at smaller or larger processing plants.

Post-harvest processing of cassava greatly increases its commercial value. HQCF has great potential as a commercial product. Cassava flour, cassava starch, and cassava chips have potential as substitutes for imported wheat, as an ingredient in adhesives, and as animal feed, respectively. (Brazil incorporates 2% cassava flour in wheat flour bread and Nigeria has recently made it a requirement to include 10% cassava flour in bread.) In addition, cassava-producing countries import many starch-based products that could be produced from cassava starch.

The major processed products include milled products such as flour, bread, confectionaries and biscuits; animal feed for poultry, pigs, and cows; beer and other beverages; sweets and snacks. Cassava starch is used in a wide variety of industrial products, including textiles, paper, glue, paint, and pharmaceuticals. Fermented cassava starch can also be used to create ethanol for biofuel.

Effective processing, for example, soaking and grating, remove naturally-occurring toxins in the roots, reduce the product’s weight for transport, decrease post-harvest losses resulting from root breakage, and extend shelf life.

Cassava roots contain a substance called hydrogen cyanide which is toxic to human beings. Bitter cassava contains up to 50 times the cyanide content of sweet cassava. Processing greatly reduces the cyanide content in the roots, making them safe for human consumption.

Making High Quality Cassava Flour (HQCF)

The following is a nine-step process for processing HQCF from raw cassava roots.

Step 1: Selecting roots

Use healthy, mature, firm, unbruised, freshly harvested cassava roots. The flesh should be white (for white varieties) with no cracks and few fibrous roots.

Step 2: Peeling

Peel with a sharp knife, removing the stalk, woody tips and fibrous roots. After it is dried, cassava peel can be used for animal feed or making compost. Peelers and graters should be washed before and after use.

Step 3: Washing

Wash peeled cassava roots with clean water twice to remove dirt, sand, soil, leaves or other impurities.

Step 4: Grating

Use a mild steel or stainless steel grater to turn cassava roots into a fine mash.

Step 5: Pressing

Pack the grated cassava mash into a clean bag such as a jute or sisal sack that will allow extra water to escape. Press the sack using a screw press, hydraulic jack or other process to remove excess water until the cassava is crumbly.

Step 6: Drying

Spread the pressed cassava mash thinly on a clean black plastic sheet on a gentle slope in full sun. Ideally, the plastic sheet should be raised off the floor. Dry until the moisture level is below 12%. At this level of moisture, cassava chips will crack when handled. Cover with netting to keep away flies and birds. Solar, stove and hot-air dryers are more expensive, but the drying process is more reliable and higher quality.

Step 7: Milling

Mill the dried cassava mash with a hammer mill (village posho/kinu mill) to make flour.

Step 8: Sifting

Use a sieve to sift the milled flour to remove fibrous materials and lumps. This is important to obtain high-quality free-flowing flour, free of fibre and with a good particle size.

Step 9: Packaging and storing

Pack sifted cassava flour in airtight moisture-proof black plastic bags. Seal the bag using a burning candle and label with date of manufacture and expiry date (after twelve months). Pack bags in a carton to protect them from light. Store the cartons in a well-ventilated, cool, dry place. The packaged flour will keep for about twelve months.

Another way to make cassava flour is to incorporate a fermentation stage which produces a slightly sour product known in West Africa as gari. The fermentation can occur either during the dewatering stage or by soaking whole or cut roots in water for three to five days until the root has fermented. The process of fermentation should be carefully monitored to ensure that the process of releasing the poisonous cyanide gas from the roots is complete and the product has an acceptable flavour and texture.

Processing roots into cassava chips

The first three stages of making cassava chips – selecting the roots, peeling and washing – are identical to processing cassava flour. But instead of grating the roots into a fine mash, the roots are chipped with a mechanical or powered chipper.

After chipping, the chips are dried, either in the sun or with a mechanical dryer. Drying platforms should be raised off the ground. Because cassava chips are often infested by insects during the drying process, it is important to minimize the drying time. The smaller the chips, the faster they will dry.

Cassava chips must be dried to the point where they break easily without crumbling. After drying, the chips should be packaged.

Making cassava starch

Cassava starch is traditionally used to make foods such as biscuits, bread, and puddings. It is also used as an ingredient in non-food items such as paper, pharmaceuticals and textiles.

The first stages of making starch are peeling, washing and grating the roots. Then you add three times as much clean water as cassava to a bucket and let the mixture sit for 30-45 minutes.

Next, you pour the mixture through a clean piece of cloth and leave it to sit for an hour or more. Then, pour the water off and break the settled pieces at the bottom of the bucket into smaller pieces. Dry the pieces in the sun or by artificial drying for six hours or more. Then mill your cassava and you have starch.

Processing tools

Simple machines and tools can reduce processing time and labour, reduce losses by 50 per cent, and reduce labour hours by 75%. Cassava products can be made with manual or powered graters and chippers. Grating reduces the cyanide content of bitter cassava varieties to an acceptable level. But if graters are unavailable, the roots can be kept in water for four days before further processing. This allows the cyanide gas to be released safely, reducing any health hazard. Processors must carefully dispose of the water used to soak bitter cassava.

Mechanized graters, pressers, and mills are common in villages in Ghana, Nigeria, and Uganda. But in Tanzania, only a small percentage of villages have access to mills. Many villages lack electricity and petroleum.

Animal feed

There may be increased opportunities for small-scale producers and processors to supply higher quality cassava chips (“improved” makopa) to the steadily growing livestock feed industry, especially for poultry feed.

But the success of replacing maize with cassava chips in feed depends on the price of maize: Lower maize prices make cassava uncompetitive. And if maize prices rise too high, the profitability of the whole animal feed sector is depressed and many firms will downscale their operations.

Other products

There may be opportunities to supply cassava for traditional and clear beer, and for the cassava-based snack sector.

Waste products of processing

Cassava processing can lead to an accumulation of waste, mainly cassava peels. Cassava peels are often consumed by animals such as cows, goats and pigs. The peels and leaves are a useful supplement to animal feeds, rather than depending solely on grass and other fodders. Cassava peels are also used to make compost to restore soil fertility.

Processing challenges

Availability of clean water: Water is needed to wash the roots and to make starch. In Tanzania, there is often insufficient clean water because water infrastructure is inadequate. Processors use water from wells and rivers as well as rainwater, piped water and water from boreholes, though some of these sources are unavailable during the dry season. Without clean water, the quality of cassava products will be low.

Inadequate harvests: It is difficult for larger cassava processors to obtain a sufficiently large and continuous supply of roots because of the unpredictable harvest in Tanzania. While cassava can be harvested throughout the year, it is best harvested during the dry season so it can dry by sunlight. Thus, cassava is normally sun-dried between June to October and between January and February. This makes it difficult for processors to continuously operate processing factories or make plans to expand their operations.

Shortage of processing machines: There are several reasons why processing machines are not widely used in Tanzania: processors have no incentive to use them because of the small volume of cassava production; there are only a few processing equipment manufacturers; processors are short of money; and financing for investment in machinery carries high interest rates. In addition, large parts of rural Tanzania lack electricity.

Gender issues

 
Cassava is not a men’s crop or a women’s crop. Both men and women are involved, though they tend to specialize in different tasks. Men are ordinarily responsible for land clearing, ploughing and planting, while women specialize in weeding, harvesting, transporting, storage and processing.

But men may be attracted to processing and marketing cassava because of the potential to earn income. Traditionally, male household heads decide how cassava products are to be sold and how the resulting cash will be spent. Smaller cassava sales are controlled by women, who mostly use the income for domestic necessities such as soap, matches, salt, and school supplies.

Marketing
 
Most cassava farmers in Tanzania sell at least some cassava as well as using it for home consumption. A 2013 survey of 600 households conducted by Farm Radio International in two Tanzanian areas – Tanga and Mtwara – found that more than 90% of male and female cassava farmers were involved in selling as well as growing for domestic consumption.

The main forms of processed cassava in Tanzania are cassava chips and cassava flour, though most Tanzania farmers sell raw cassava tubers, which decreases their potential income. In rural cassava-growing areas, cassava is grown as a staple food security crop. In urban areas, HQCF and chips are convenient and compete with food grains in the markets.

Farmers normally sell their cassava as individuals rather than through groups, which lessens their bargaining power. Focus groups in Tanga and Mtwara suggest that the main reason for this is the desire to meet immediate needs such as food, medical services and school supplies. Farmers say that, though they receive a better price with collective bargaining, it takes a long time to receive payment.

Both male and female farmers say that middle people and vendors exploit them by offering very low prices for cassava. In the Tanga focus groups, farmers reported that vendors organized harvesting, sorting, grading and packing. There were no weigh scales and vendors packed bags of up to one and a half times normal size, largely due to farmers’ lack of bargaining power.

Farmers often have little knowledge of local markets. Most wait for middlemen to visit their farms, making the farm gate price very low. Limited transport and storage facilities also make marketing more difficult. Because cassava is a bulky crop, farmers are often obliged to sell their cassava to middlemen or at nearby markets at low prices. Roads to cassava-producing areas are generally poor. The majority of farmers who do receive market information access it through vendors and fellow farmers. Farm Radio International’s household survey in Tanga and Mtwara showed that no-one receives market information through the radio because there are few farming programs and none that focus on cassava.

Opportunities for processed cassava

 

There may be possibilities to supply HQCF to bakeries for inclusion in wheat flour. HQCF is cheaper than wheat flour, which is 100% imported in Tanzania. Several bakeries in Mtwara are currently adding 10% HQCF to their wheat flour, partially because of the high cost of transporting wheat flour from the port of Dar es Salaam. The Tanzanian national standard for wheat bread allows the inclusion of up to 30% other flours.

There are several other possible opportunities for cassava flour, including:
Supplying bulk HQCF to biscuit manufacturers;
Supplying mixed wheat and HQCF flours to millers for home baking chapattis, mandazis, doughnuts and cakes; and
Supplying blended maize and HQCF flour to millers for making ugali.

Marketing challenges in Tanzania

 
Farmers who want to process and market value-added cassava products face a variety of challenges. The majority of both female and male cassava farmers surveyed by Farm Radio International in Tanga and Mtwara identified their main marketing difficulties as not having a guaranteed market, and not having access to current market prices. The following are some of the other main marketing challenges in Tanzania. (Most cassava-producing countries face some of these same challenges.)

Narrow sales channels: Flour processing facilities in Tanzania face a variety of problems related to sales, including: lack of distribution channels for their product, lack of distributors and wholesalers, and lack of sales representatives.

Poor transportation infrastructure: Road conditions make transport and distribution of cassava products difficult. The difficulties and costs of internal transportation and distribution are such that big markets like Dar es Salaam find it cheaper to import products than purchase them domestically.

Low prices: Rural farmers have little information on market prices. As a result, farmers often sell their cassava at very low prices. Mobile phones are making price information more widely available, but most farmers are not well enough organized to negotiate with merchants or processors on price. The fact that harvest and sales are confined to the dry season means that farmers have weaker bargaining power.

Inadequate financing: Investing in processing machines and developing new products requires financing. But private banks are very careful about financing cassava-related businesses, as the image of cassava is not very positive. Also, high interest rates on loans can severely limit processors’ earnings.

Figure 1: The marketing system for fresh cassava roots in Dar es Salaam

A diagram of the marketing system for fresh cassava roots in Dar es Salaam is shown in Figure 1. After harvest, fresh cassava is sold directly at local markets to local consumers, village traders or inter-regional traders. Thereafter, inter-regional traders transport fresh cassava by truck to wholesale urban markets in Dar es Salaam. Wholesalers and commissioned agents sell consignments of fresh cassava on behalf of inter-regional traders or farmers to cooking and frying vendors or to retailers, who in turn sell to urban consumers.

The marketing system is similar in Tanzanian villages, with farmers selling fresh roots or dried chips to consumers or traders at local markets, who transport them to markets in big towns or cities for sale to retailers or market vendors.

Further resources on the cassava value chain in Tanzania

 
Resource organizations

Africare: processing and value addition of cassava products. Country Director for Tanzania: Sekai Chikowero, P.O. Box 63187, Dar es Salaam. Phone: +255 22 266 6690 or +255 22 266 7086. Email: schikowero@africacare.org

CARE: cassava processing, adding value and marketing. P.O. Box 10242, Dar es Salaam.

CAVA: A project which supports cassava production, processing, adding value, and linking farmers with markets. Contact: Grace Mahende, Country Manager (Tanzania), Tanzania Food and Nutrition Centre, 22 Ocean Road, P.O. Box 977, Dar es Salaam, Tanzania. Phone: +255 75 487 2892 & +255 22 211 6713. Email: gngwasi@yahoo.com

CRS (Catholic Relief Services): production, multiplication and supplying disease-free planting materials. Mr. Marandu. Phone + 255784531359. Email: eliawonimarandu@yahoo.co.uk

FAO (UN Food and Agriculture Organization): deals with multiplication and marketing of cassava. Mr. Lazier, P. O. Box 2, Dar es Salaam. Phone + 255 22 2664559. Fax + 255 22 2667286. Email: FAO-TZ@fao.org

Farm Concern International: cassava processing, adding value, and linking small-scale farmers with markets. Email: tanzania@farmconcern.org

IITA (International Institute of Tropical Agriculture): works on research, production, processing, marketing, and adding value, and has an office in Tanzania. Contact: Victor Manyong, Director for Eastern and Central Africa, Box 34441, Dar es Salaam. Phone +255 22 270092. Fax + 255 22 2775021.

Intermech Engineer: manfacturing cassava processing machines and equipment. Eng. Peter Chisawilo. Phone +255 756771182.

MUVI Tanzania. John Muta Karega. Phone (mobile): +255 782272057 and/or +255714272057. Email: jkarega@gmail.com

SIDO (MUVI): a government initiative linking production, processing, adding value and marketing.

SUA (Sokoine University of Agriculture), including:
Animal Science Dept.: research on feed formulations for chicken and goats. Prof. C. Chenyambuga, Box 30031, Morogoro. Phone + 255 23 260 3511. Fax + 255 023 2604651. Email sua@suanet.ac.tz or chenyas@yahoo.com Mr. Shayo. Phone +255 784 542 102. Email deogratiad@gmail.com or Professor Lekule at: lekulefp@yahoo.co.uk

Food Science Dept: food fortification with cassava, soybean, and cowpeas. Prof. H. Laswai. Phone + 255 23 260 4402. Fax + 255 23 260 3718. Email dfst@suanet.ac.tz

Engineering Dept: modification of cassava processing machines. Prof Silayo, Box 30031, Morogoro, Tanzania. Email sua@suanet.ac.tz

SUA Agri-business and Economic Dept: marketing. Dr. Jeremiah Makindara. Phone + 255 715272376. Email makindarajeremia@hotmail.com

Mikocheni Agriculture Research Institute: working on cassava brown streak disease and cassava mosaic disease diagnosis. Dr. J. Ndunguru. Email jndunguru2003@co.uk or mari@mar.or.tz

Naliendele, Kibaha, Ukiriguru and Maruku (Agricultural Institutes): cassava production, processing and post-harvest research. Dr. Geoffrey Mkamilo. Phone + 255 784 795389. Fax + 255 073 2934103. Email utafiti@iwayafrica.com or gmkamilo@hotmail.com Dr. Kiddo Mtunda Phone +255 754466201 Email kmtunda09@yahoo.com

TFNC (Tanzania Food and Nutrition Centre): a government agency that works on processing, utilization, adding value and cassava fortification. Dr. Towo, P O. Box 977, Dar es Salaam. Fax + 255 22 2117613. Email: eetowo@hotmail.com

Documents

ACP-EU Technical Centre for Agricultural and Rural Cooperation (CTA), 2007. Making High-Quality Cassava Flour. CTA Practical Guide Series, No. 5. https://publications.cta.int/media/publications/downloads/1380_PDF.pdf (831 KB).

Ben Bennett, Diego Naziri, Grace Mahende, and Elifatio Towo, 2012. CAVA (Cassava Adding value for Africa): Driving demand for cassava in Tanzania: The next steps. C:AVA. University of Greenwich and The Natural Resources Institute. https://cassava.nri.org/projects/40-cassava-adding-value-for-africa-c-ava (1.41 MB). FAO/IFAD, 2005: A review of cassava in Africa with country case studies on Nigeria, Ghana, the United Republic of Tanzania, Uganda and Benin http://www.fao.org/docrep/009/a0154e/A0154E00.HTM#TOC

Gaffney, A, Kpaka, C, Slakie, E & Anderson C.L. Cassava integrated value chain, EPAR Brief #223 (2012) https://epar.evans.uw.edu/sites/default/files/EPAR_UW_Request_223_Cassava_Integrated_Value_Chain_03.05.13_public.pdf (704 KB)

Neil Noble, 2006. Cassava processing. Practical Action. Download at: http://practicalaction.org/cassava-processing (346 KB). Neil Noble, 2006. Transformation du Manioc. Practical Action. Download at: http://practicalaction.org/cassava-processing-transformation-du-manioc (376 KB)

Ponsian T. Sewando, 2012. Urban Markets-Linked Cassava Value Chain in Morogoro Rural District, Tanzania. Journal of Sustainable Development in Africa, Volume 14, No. 3, 2012 hhttps://jsd-africa.com/Jsda/Vol14No3-Summer2012A/PDF/Urban%20Markets-Linked%20Cassava%20Value%20Chain.Ponsian%20Sewando.pdf (English only) (248 KB)