Cowpeas are grown for their leaves and grains both of which are used as relish or side dishes together with the staple food. Little information is available on the nutritional quality of local and improved cowpea varieties grown in Tanzania as well as the recipes in which they are ingredients. This study was done to investigate cowpea utilization in Iringa and Dodoma regions of Tanzania. A cross-sectional survey was carried out where a total of 517 farmers were interviewed using a pre-tested structured questionnaire. Proximate and mineral composition of different varieties of cowpea grains and leaves were determined using standard AOAC methods. More than half of the households interviewed consumed cowpeas in one or more forms. Most cowpea recipes included them as relish being eaten with rice or stiff porridge (ugali), a mixture of dehulled maize and cowpea grains (kande) and cowpea buns (bagia). Improved cowpea varieties had relatively higher fat content ranging from 8 to 11.2% compared to local varieties (5.4%). Local cowpea grains had higher levels of calcium varying between 958.1 and 992.4 mg/kg than dehulled cowpea (360 to 364 mg/kg) and cowpea flour (303 to 311 mg/kg). Zinc ranged from 32.6 to 31.5 mg/kg, while iron content ranged from 27.6 to 28.9 mg/kg. Fresh cowpea leaves had the highest levels of minerals, with calcium varying between 1800.6 and 1809.6 mg/kg, zinc between 36.1 and 36.0 mg/kg and iron between 497.0 and 499.5 mg/kg. The improved cowpea varieties, IT99K-7212-2-1 (23.8 mg/kg) and IT96D-733 (21.2 mg/kg) had the highest iron content. IT99K-7-21-2-2-1 (32.2 mg/kg) and IT97K499-38 (28.3 mg/kg) had the highest zinc concentration. The bagia (cowpea buns), prepared in Dodoma had higher mineral composition, calcium (893mg/kg), zinc (13.7 mg/kg) and iron (16.3 mg/kg) compared to those prepared in Iringa; calcium (32.6mg/kg), zinc (4.96 mg/kg) and iron (5.2 mg/kg). The cowpea daily per capita consumption for the majority of the households surveyed ranged from 41 to 200 gm. The contribution of micro and macro nutrients is significant for both developed lines and local varieties but with leaves having greater mineral content than the grains; hence, promotion of consumption of the leaves alongside the grains would be of nutritional advantage. Additionally, farmers should be encouraged to plant the higher yielding cowpea varieties and preferred local varieties.

Traditional indigenous vegetables are the most economically efficient source of micronutrients in terms of both land required and production costs per unit. Promotion of production and consumption of such micronutrient-rich foods will improve intakes, the overall diet, and health status. This study aimed to determine nutrient (iron, calcium, vitamin A and ascorbic acid) and anti-nutrient (oxalates and polyphenols) contents in raw, cooked and dried sweet potato leaves Two varieties of sweet potatoes, which were identified as commonly grown for leaves consumption were analyzed at Department of Food Technology, Sokoine University of Agriculture and at the Government Chief Chemist Laboratory Tanzania. The analysis included proximate, nutrient (ascorbic acid, carotenoids, iron and calcium) and anti-nutrient (oxalate and polyphenols) composition. The purple midrib sweet potato leaves were further analyzed for nutrient and anti-nutrient retention after cooking (with and without lemon) and open sun-drying (with and without salting). There was no significant difference (P>0.05) between the two varieties in crude protein, crude lipid and moisture content. The purple midrib sweet potato leaves had significantly (P<0.05) higher ash, crude fibre, carotenoids, calcium and iron contents while the green midrib sweet potato leaves had significantly (P<0.05) higher ascorbic acid content. The polyphenols were about 4 times higher in the purple midrib sweet potato leaves (22.16%) as compared to that of the green ones (5.28%), which had significantly higher oxalate levels (3730 mg/100g). Drying with salt and cooking with lemon reduced polyphenols significantly (p<0.05), with retention of 42% and 56% respectively; while cooking with lemon lowered significantly the oxalate levels. The traditional methods of cooking SPL with addition of lemon is advantageous because it reduces polyphenols while retaining higher levels of minerals, β carotene and vitamin C. Drying with salt results in a nutritionally and organoleptically good product, hence, drying with salt and cooking with addition of lemon is encouraged. Since the sweet potato leaves are harvested more than once before the plant is uprooted, further studies are recommended to assess whether there is variation in nutrient and antinutrient contents in consecutive harvests.

African indigenous green leafy vegetables play important role in income generation and subsistence; they are the cheapest and most readily available sources of important minerals and vitamins. On the other hand, they contain anti-nutritional factors that reduce availability of vital nutrients. This study was conducted to determine oxalates, phytates and nitrates content in commonly consumed Amaranths cruentus, Spider plant (Cleome gynandra) and African night shade (Solanum villosum) at 21, 28 and 35 days age of the plant harvest. Vegetables were planted on plots and harvested at 21, 28 and 35 days. At each stage, about 600±2 g of the edible part was harvested and standard chemical analyses procedures were followed to determine oxalate, phytate and nitrate contents. Using Statistical Product and Service Solutions (SPSS 20) data were analysed and results presented as simple means, ranges and standard deviations. Analysis of variance (ANOVA) with 5% level of significance was done to determine differences in the levels of nutrients between the vegetable varieties and three maturity stages. African nightshade Nduruma BG 16 had lowest oxalate concentrations (28.7  0.1 mg/100 g) at maturity stage I while African nightshade Olevolosi SS 49 had the highest value (60.9  0.9 mg/100 g) at maturity stage III. There was no particular trend for phytates in all maturity stages and in all varieties but amaranths Madiira AM 38 had exceptionally the highest values (0.7  0.0 mg/100 g) at stage III of maturity. The highest nitrate content was 85.6  1.8 mg/100 g in Olevolosi SS 49 at maturity stage I, whereas the lowest value was 45.3  1.3 mg/100 g in amaranths Madiira AM 38 at stage III. There was a slight variation in antinutrients composition of the studied vegetables and the composition was generally very low.

The banana-based farming system of Kagera region of Tanzania has good edible food diversity. However, households still consume monotonous diets, which are mainly energy dense and have inadequate content of micronutrients. To enrich the preferred energy-rich diets, this study formulated dishes with improved content of vitamin A, iron and protein for children aged between 6 to 23 months. Mothers (n = 50) were randomly selected from Izimbya ward and participated in a recipe development exercise whereby five recipes modified from the traditional banana based 'katogo'/'matoke' and three types of porridges were developed using locally available foods such as bananas, beans, amaranths, red palm oil, pumpkin, groundnut, maize and orange-fleshed sweet potato (OFSP). Mothers were asked to give options of improving the porridge intended to be fed to children as well as to propose means of improving the local banana diets. Vitamin A was increased by red palm oil, OFSP, pumpkin fruit and leaves in the modified recipes. Red kidney beans formed a good source of iron, protein and energy when incorporated in complementary foods. The family dishes and children's local popular dishes were modified to improve the consistency by making a purée to increase food intake and, therefore, vitamin A, iron and protein. Based on the food composition table, the developed recipes contained more than 100% of vitamin A and protein and between 61% to 99% of the iron recommended dietary allowance (RDA) for children 6-23months. The conversion factor of 12:1 for beta-carotene was used. Vitamin A, iron, protein and energy content in modified recipes ranged from 108-2768 RAE, 6-17 mg, 28-56 g and 697-1635 kcal, in 500g consumption portion, respectively. The created recipes based on locally available and affordable ingredients have a potential to meet RDAs of vitamin A, iron and protein for children aged 6 to 23 months in the banana-based system and other communities in Africa with the same settings. The communities need to establish home gardens so as to use vegetables and foods which are cheap and good sources of micronutrients and protein.