Tropical root and tuber crops (cassava, sweet potato, yam and cocoyam) are both important household food security and income generating crops in many developing countries. Over coming the perishability of the crops, improving marketing, enhancing nutritional value and adding economic value through processing are the main areas of the research at the Natural Resources Institute.

NRI collaborates with national programmes in many countries. In such collaborations, a multi-disciplinary, participative approach is taken to solving the problems and exploiting the opportunities that these crops provide for improving the incomes of poor people. In-country work is supported by laboratory-based strategic studies.

Key Research Areas

• Understanding the mechanisms of cyanogen reduction during cassava processing
• Commercialisation of traditional root crop products.
• Improving small scale root crop processing
• Development of new market opportunities for root crop farmers and processors
• Development of improved storage systems for cassava and sweet potato
• Understanding and improving the marketing and handling systems of tropical root crops.
• Improving varietal selection of sweet potato for extended shelf life
• Reducing the pollution associated with root crop processing
• Improving root crop fermentation systems

Other supporting activities

NRI play a major role in the development of the "Global Cassava Development Strategy", an initiative to develop a common understanding of the best approaches to maximising the contribution of cassava to the livelihoods of poor people. The group is a founder member of the European Group for the Root and Tuber Crops and plays a major role in the International Society for Tropical Root and Tuber Crops.

Staff

Prof. Andrew Westby
Debbie Rees
Andrew Graffham
Ulrich Kleih
Andy Hall
Keith Tomlins
Tanya Stathers

Projects

A0911--Sweet Potato Cultivars with Improved Keeping Qualities for East Africa

A0851--Development of new marketing opportunities, to increase the contribution that cassava makes to sustainable rural livlihoods

A0528--Improved cassava utilisation practices in Tanzania

A0497--Post-harvest constraints and opportunities for marketing of yam

A0898--Commercialisation of Cassava Fufu Processing in West Africa that maximises benefits to livelihoods

Publications

Agona, J.A., Nahdy, S.M., Giga, D.P. and Rees, D. (1999) A visual scale of loss assessment for dried sweet potato chips due to Araecerus fasciculatus Degeer (Coleoptera: Anthribidae) infestation on-farm. Uganda Journal of Agricultural Sciences 4: 1-5

Agona, J.A., Silim Nahdy, M., Gigia, D.P. and Rees, D. (1998) The effect of salting sweetpotato chips prior to drying on infestation by Araecerus fasciculatus Degeer (Coleoptera: Anthribidae) Trop. Agric. (Trinidad) 75, 84-88.

Bainbridge Z , A Westby & K Tomlins, four-part book on methods for assessing the quality characteristics of non-grain starch staples, ISBN 0-85954-400-1, April 1996

Bainbridge, Z., Harding, S., French, L., Kapinga, R., and Westby, A. (1998) A study of the role of tissue disruption in the removal of cyanogens during cassava root processing. Food Chemistry 62, 291-297.

Bainbridge, Z., Tomlins, K., Wellings, K. and Westby, A. (1996) Methods for assessing the quality characteristics of non-grain starch staples. Natural Resources Institute: Chatham. ISBN: 0-85954-400-1.

Bainbridge, Z., Wellings, K and Westby, A. (1997) Introduction to village level cassava processing. A distance learning package. Natural Resources Institute: Chatham. ISBN 0-85954-456-7.

Bancroft, R. D. Crentsil, A. Gray, S. Gallat and S. Gogoe (1998). The Marketing System for Fresh Yams in Techiman, Ghana and Associated Post-Harvest Losses. Paper presented at the 11th Symposium of the International Society for Tropical Root Crops (ISTRC), Trinidad and Tobago. Tropical Agriculture (Trinidad) 75, 115-119.

Bancroft, R., Crentsil. D. and Westby, A. (1998) Preliminary assessment of the marketing systems for Yam in Ghana. In L'igname, plante seculaire et culture d'avenir. Actes du seminaire international CIRAD/INRA/ORSTOM/CORAF. Pp. 343-345. Ed. Berthaud, J., Bricas, N. and Merchand, J.-L. , 3-6 June 1997, Montpellier, France.

Bockett, G. (1996) Improved sweet potato storage: an extension guide. Publication funded from ASSC funds, Overseas Development Administration, London: UK. .

Bockett, G. (1998) Safe methods of using bitter cassava varieties: an extension guide. Publication funded through the Crop Post-Harvest Programme of the United Kingdom's Department for International Development, London: UK. (Extension guide).

Gallat S, D. Crentsil, D. and R. D. Bancroft (1998) 'Development of a Low Cost Cassava Fresh Root Storage Technology for the Ghanaian Market'. Pp. 77-84. In Postharvest technology and commodity marketing R.S.B. Ferris (ed.) 300 pp. 1998 ISBN 978-131-111-8

George, M., Westby, A. and Adams, M.R. (1998) A note on the microbial safety of cassava flour. Journal of Root Crops 23(1) 57-60. Graffham, A. J. 1997. Market potential for cassava flour and starch in Ghana. GASGA Newsletter.

Graffham, A. J. and Westby, A. (1998) Contributions for Africa.. In: Global cassava market study, business opportunities for the use of cassava. Guelph, dTp Studies.

Graffham, A. J. And Westby, A. 1998. Opportunities for cassava use in Africa. In: Global cassava market study, business opportunities for the use of cassava. Guelph: dTp Studies

Graffham, A. J., Ababio, J. T., Dziedzoave, N., Day, G., Andah, A., Budu, A., Ayernor, G. S., Gallat, S. And Westby, A. 1998. Market potential for cassava flours and starches in Ghana. Journal of Tropical Agriculture (Trinidad). 75, 267-270.

Graffham, A.J., Shegaonkar, V., Saxena, S., Thangaraj, G.S., Raghu-Raman, S.V. and Westby, A. (1998) Chemically acidified wet storage of cassava starch in India. In Tropical Tuber Crops in Food Security and Nutrition, pp. 27-36.ed. C. Balagopalan, Nayar, T.V.R., Sundaresan, S., Premkumar, T and Lakshmi, K.R. Oxford and IBH Publishing Co.Pvt.Ltd, Calcutta.

Hall, A.J. and Devereau, A.D. (2000) Low-cost storage of fresh sweet potatoes in Uganda: lessons from participatory and on-station approaches to technology choice and adaptive testing. Outlook on Agriculture 29, 275-282.

Hall, A.J., G.N. Bockett, S, Nahdy 1998 Sweet Potato Postharvest Systems In Uganda: Strategies Constraints and Potentials. International Potato Centre (CIP) Social Science Department Working Paper Series No. 1998-7 CIP, Lima, Peru. ISSN 0256-87 48

Hall, A.J., and S. Nahdy. 1999. New methods and old institutions: systems problems of farmer participatory research. ODI, Agricultural Research and Extension Network Paper No 93, January 1999

Henry, G. and Westby, A. (2000) Global Cassava starch markets: current situation and outlook. In Cassava, Starch and Starch Derivatives, Proceedings of the International Symposium held in Nanning, Guangxi, China, November 11-15, 1996. Pp 79-100. Edited by R.H. Howeler, G.C. Oates and G.M. O'Brien. Colombia, Centro Internacional de Agricultura Tropical.

Henry, G., Westby, A. and Collinson, C. (1998) Global Cassava End-Uses and Markets: Current Situation and Recommendations for Further Study. FAO, Rome.

Kajimbwa, M. G. A., Bockett G. N. A., Goodland A.D., and Mlingi N., (1998) Improving Traditional Cassava Processing Methods- A Case Study to Introduce a Village-based Monitoring System in Mtwara, Tanzania. A paper presented at the Global Symposium on Farming Systems Approaches in Rural Livelihood Empowerment and Environment: Going Beyond Farm Boundary. 30 November to 4 December 1998, Pretoria, South Africa. (Conference proceedings).

Kapinga, R., Westby, A., Rwiza, E. Bainbridge, Z. and Nsanzugwanko, A. (1998) Diversification of cassava utilisation in the Lake Zone of Tanzania: a case study. Tropical Agriculture (Trinidad) 75, 125-128.

Kapinga, R., Westby, A., Rwiza, E., Bainbridge, Z.A., and Amour, R. (1999) Stakeholder participation in technology testing and dissemination of cassava diversification in the Lake Zone of Tanzania. In Food Security and crop diversification in SADC countries the role of cassava and sweetpotato. Pp 90-99. Edited by M.O. Akoroda and J,J, Terri, SARRNET, Malawi.

Klieh, U., Digges, P. and Westby, A.. (1997) Assessment of the needs and opportunities in post-harvest systems of non-grain starch staples. Natural Resources Institute: Chatham. ISBN 0 85954 471 0.

Mcneill, M. and Westby, A. (1999) Ergonomics evaluation of a manually operated cassava chipping machine. Applied Ergonomics 30(6), 565-575.

Mlingi, N. and Bainbridge, Z. (1999) The efficiency of cyanogen removal in rapid processing methods at village level in Tanzania. Food Security and crop diversification in SADC countries the role of cassava and sweetpotato. Pp 415-422 Edited by M.O. Akoroda and J,J, Terri, SARRNET, Malawi.

Ndunguru, G., Thomson, M., Waida, R., Rwiza, E. and Westby, A.. (1998) Methods for examining the relationship between quality characteristics and economic value of marketed fresh sweet potato. Tropical Agriculture (Trinidad) 75, 129-133.

Ndunguru, G.T., Modaha, F., Bancroft, R.D., Digges, P.D., Kleih, U., Westby, A. and Mashamba, F. (1998) The use of needs assessment methodologies to focus technical interventions in root and tuber crop systems: A case study to improve the marketing and post-harvest handling of cassava entering Dar es Salaam, Tanzania. Proceedings of the 6th symposium of the International Society for Tropical Root Crops - Africa Branch. Edited by A.O. Akoroda and I.J. Ekanayake. Pp 76-82. International Society of Tropical Root and Tuber Crops-Africa Branch, c/o International Institute of Tropical Agriculture, Nigeria. ISBN 978-33604-O-X.

Ndunguru, G.T., Thomson, M., Waida, T.D.R., Rwiza, E., Jeremiah, S. and Westby, A. (1999) Relationship between quality and economic value of dried cassava products in Mwanza, Tanzania. In Food Security and crop diversification in SADC countries the role of cassava and sweetpotato. Pp 408-414. Edited by M.O. Akoroda and J,J, Terri, SARRNET, Malawi.

Rees, D., Kapinga, R., Mtunda, K., Chilosa, D., Rwiza, E., Kilima, M., Kiozya, H. and Munisi, R. (2001). Damage reduces both market value and shelf-life of sweet potato: A case study of urban markets in Tanzania. Submitted to the Tropical Science

Rees, D., Kapinga, R., Rwiza, E., Mohammed, R., van Oirschot, Q., Carey, E. and Westby, A. (1997) The potential for extending shelf-life of sweet potato in East Africa through cultivar selection. Trop Agric. (Trinidad) 75, 208-11

Reilly, P.J.A. and Westby, A. (1997) Food fermentation - traditional low-cost food preservation systems. In Food Processing Technologies for Africa. Ed. H.A. Dirar pp. 69-78. Emerging technology series. UNIDO, Vienna.

Sanni, L. O., Akingbala, J. O., Oguntunde, A. O., Bainbridge, Z. A. Graffham, A. J. & Westby, A. 1997. Processing of fufu from cassava in Nigeria: Problems and prospects for development. Science Technology and Development. 16, 58-71.

Tomlins, K.I., Ndunguru, G.T., Rwiza, E. and Westby, A. (2000) Postharvest handling, transport and quality of sweet potato in Tanzania. Journal of Horticultural Science and Biotechnology 75, 586-590.

Van Oirschot, Q.E.A., O'Brien, G.M., Dufour, D., El Sharkawy, M. and Mesa, E. (2000) The effect of pre-harvest pruning of cassava upon root deterioration and quality characteristics. Journal of the Science of Food and Agriculture

Wareing, P.W., Westby, A., Gibbs, J.A., Halm, M. & Allotey, L.T. 2000 Mycotoxin contamination of dried cassava products from Ghana. International Journal of Food Science and Technology (In Press).

Westby, A. and Gallat, S. (1999) Cassava chip processing in Ghana: participatory postharvest research and technology transfer in response to new market opportunities. In Enhancing postharvest technology generation and dissemination in Africa. Pp. 59-65. Ed J. Kwarteng. Mexico City: Sasakawa Africa Association. ISBN 2-940200-10-16

Westby, A. and Graffham, A. (1998) Cassava biotechnology and post-harvest: the interface and issues for the future. Presented at the fourth meeting of the cassava biotechnology network. Abstract: Revisita Brasilira de Mandioca 17 (Suplemento), 71. Other

Westby, A. and Graffham, A.J. (2000) Improving cassava processing - approaches for achieving impact in a new millennium. Invited special paper at the International Symposium on Tropical Root and Tuber Crops: Root and tuber crops - concerns and development strategies for the new millennium. Thiruvananthapuram, India. 19-22 January 2000. In Press

Westby, A., A.J. Hall, G.N. Bockett, U.K. Kleih, A. Graffham. 1999 Needs Assessment As A Tool For Improving The Impact Of Post-Harvest Research And Development Work. Chapter in Grant, I.F. and Sear, C. (eds) (1999) Decision Tools in Natural Resources Development, NRI, Chatham, U.K. ISBN 0 85954 500-8

Westby, A., Henry, G., Best, R., Sourang, C., Bokanga, M. and Kapinga, R.,. (1998) Towards a Global Strategy for Cassava Development. Tropical Agriculture (Trinidad) 75, 111-114.

Westby, A., Kleih, U., Hall, A., Bockett, G., Crentsil, D., Ndunguru, G., Graffham, A. J., Gogoe, S., Hector, D., Nahdy, S. & Gallat, S. 1997. Improving the impact of interventions in the post-harvest sector of non-grain starch staples. The needs assessment approach. Journal of Tropical Agriculture (Trinidad). 75, 143-146.

Westby, A., Kleih, U., Hall, A., Bockett, G., Crentsil, D., Ndunguru, G., Graffham, A., Gogoe, S., Hector, D. Nahdy, S. And Gallat, S. (1998) Improving the impact of post-harvest research and development on root and tuber crops: the needs assessment approach. Tropical Agriculture (Trinidad) 75, 143-146.

Westby, A., Reilly, P.J.A. and Bainbridge, Z.A. (1997) Review of the effect of fermentation on naturally occurring toxins. Food Control. 8, 329-339.

Westby, A., U.K. Kleih, A.J. Hall, G.N. Bockett, A. Graffham, S. Gallat 1998. Improving The Impact Of Post-Harvest Research And Development On Root And Tuber Crops: The Needs Assessment Approach. Tropical Agriculture (Trinidad) Vol 75 No.1 January 1998 pp143-146.

Westby, A., Wareing, P.W. and Gibbs, J.A. (1994) Ability of cassava products to support mycotoxin formation. Paper and poster presented at the 10th triennial symposium of the International Society for Tropical Root Crops, Brazil, November 1994.