Résumé
Detailed field surveys in Botswana and Tanzania on food habits and on consumer preferences were conducted by various project partners including CIRAD. The recipes for the preparation of traditional porridges made with sorghum and millets, the cooking procedures and the characteristics of commercial and traditional flours were collected by the CIRAD Cereal Technology Laboratory in order to develop specific laboratory tests to characterize the cooking quality of the thick porridge « bogobe » in Botswana and « ugali » in Tanzania. The texture defined as the consistency of the cooked product was identified as the main quality criteria for the african consumers and was measured using extrusion tests on the Instron Universal Texturometer. The relationships with some physicochemical characteristics of sorghum grains and flours were established showing the importance of the amylose content of the flour and to a lesser extent of the ash content of the grain. The differentiation among the sorghum varieties and their ranking according to the extrusion test were confirmed by another field survey in Botswana where cooking tests and texture evaluation by villagers were conducted. This laboratory test was applied on 31 sorghum varieties from Botswana and ICRISAT, Zimbabwe. Sorghum cultivars with high amylose content and good dehulling properties should be selected. The tests should also be useful in evaluating and therefore improving the quality of the sorghum flours obtained on mechanical dehulling and grinding equipment. It will help promoting commercially the milled products in towns and the industry. It was shown also that the ranking of the sorghum varieties according to their quality for bogobe and ugali was similar to the ranking obtained using a compression test already developed on « tô » quality, a west african soft porridge. It was concluded that the SADC variettes good for bogobe and ugali could also be good for thick « tô ». (Résumé d'auteur)