the constraints and possibilities in the utilisation of African green leafy vegetables: Traditional and new preservation techniques in Morogoro, Tanzania
University of Goettingen, Dept. of Crop Science, Division of Quality of Plant Products, Germany
African green leafy vegetables (AGLVs) found in sub-Saharan Africa (SSA) are reported to be highly nutritious. About 73kg of vegetables per person per year are recommended to meet nutritional requirements and prevent chronic diseases. However, there is limited utilisation of vegetables in general in SSA. Ruel et al. (2005) reported lower consumption of vegetables in SSA (27kg - 114kg) per person per year. Therefore, the mixed-method study was conducted to gather data from literature and fields to document the constraints and possibilities in utilising AGLVs in SSA, including Tanzania. As a result, traditional vegetable preservation techniques and the nutritive value of various fresh and processed vegetables were documented. We found that limited consumption of vegetables was due to seasonality and high postharvest losses, accounting for more than 50% due to limited processing and preservation at farms to industrial levels. For example, 4 out of 30 farmers received formal training in the processing and preserving the vegetables in the Morogoro region, Tanzania. Moreover, only 24 out of 106 households traditionally sundry at least one type of AGLVs. Surprisingly, we found that wilted vegetables in households and markets are mostly discarded. Therefore, the wilted vegetables were traditionally dried, and we found that the wilted vegetables are suitable for sun-drying to minimise postharvest losses. However, the traditional drying methods have several setbacks, such as nutrient loss from direct sunlight, taste impairment, and contamination from foreign matters such as dust, moulds, and insects. Again, the local recipes for making the tomato and carrot sauces were studied and used to develop sauces by substituting the levels of tomato (6% and 12%) and carrot (0%, 6%, and 12%) with the leaves of African nightshade (Solanum americanum) and cowpea leaves (Vigna unguiculata). Furthermore, baobab fruit powder (BFP) (0% and 6%) and peanut paste and seasonings were added for functional and nutritional purposes. The findings show that the sauces with BFP had high nutritional quality, extended shelf life (beyond 28 weeks) and consumer acceptability. Therefore, it is possible to produce sauces from surplus AGLVs to overcome the challenges of high postharvest loss and traditional preservation methods in Tanzania.
Keywords: African leafy vegetables, postharvest loss, sauces, sun drying, wilting
Contact Address: Amina Ahmed, University of Goettingen, Dept. of Crop Science, Division of Quality of Plant Products, Carl-Sprengel Weg 1, 37075 Goettingen, Germany, e-mail: aahmed1gwdg.de