Identification and nutrient composition of indigenous vegetables of Tanzania.

Thirty types of indigenous vegetables commonly utilized in rural areas of Tanzania were collected, identified and their nutrient compositions analyzed. High values up to 249.6, 266 and 7.7 mg/100 g of vitamin C, calcium and iron, respectively, were recorded. Protein content ranged from 0.6 to 5.0 and fat content 0.1 to 1.0 percent. Generally most of the vegetables were preferred by 50 to 90 percent of the persons surveyed.

Proteolytic activities in togwa, a Tanzanian fermented food.

Proteolytic activities were investigated in sorghum-based togwa prepared by natural fermentation and using starter cultures previously isolated from the native product, i.e., Lactobacillus brevis, Lactobacillus cellobiosus, Lactobacillus fermentum, Lactobacillus plantarum, Pediococcus pentosaceus, and Issatchenkia orientalis in coculture with either L. brevis or L. plantarum. Both proteinase and aminopeptidase activities were substantially higher in naturally fermented togwa than in those with starters (14-30%, 12-70%, respectively). A variable but substantial part of the proteinase activity followed the particulate fraction of togwa; aminopeptidase activity was mainly in that fraction. The breakdown of relatively high molecular mass protein (64 kDa) in togwa was detected by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE); the products were mainly in the 14-30 kDa range. Reversed-phase fast-protein liquid chromatography (RP-FPLC)-protein/peptide patterns changed during fermentation with some variation between togwa of different cultures. Supplementation of gruel with malt increased the concentration of total protein [from 9.5% to 11.0% (w/w) on dry weight basis)] and of most of the free amino acids. Fermentation had no effect on total protein content; however, the concentration of most of the amino acids was reduced, except for the proline content that increased. Natural fermentation also increased the concentration of glutamic acid and ornithine. Fermentation by P. pentosaceus increased aspartic acid, while L. cellobiosus, L. fermentum, and L. brevis in coculture with I. orientalis increased the concentration of citrulline.

Use of starter cultures of lactic acid bacteria and yeasts in the preparation of togwa, a Tanzanian fermented food.

Starter cultures of lactic acid bacteria (Lactobacillus brevis, Lactobacillus cellobiosus, Lactobacillus fermentum, Lactobacillus plantarum and Pediococcus pentosaceus) and yeasts (Candida pelliculosa, Candida tropicalis, Issatchenkia orientalis and Saccharomyes cerevisiae) isolated from native togwa were tested singly or in combination for their ability to ferment maize-sorghum gruel to produce togwa. All species of bacteria showed an ability to ferment the gruel as judged by lowering the pH from 5.87 to 3.24-3.49 and increasing the titratable acidity from 0.08% to 0.30-0.44% (w/w, lactic acid) in 24 h. Yeasts used singly showed little activity within 12 h, but lowered the pH to 3.57-4.81 and increased the acidity to 0.11-0.21% in 24 h. Yeasts in co-culture with lactic acid bacteria (LAB) had a modest effect on the final acidity (P<0.05). The number of lactic acid bacteria and yeasts increased while the Enterobacteriaceae decreased with fermentation time. The pH was lowered and lactic acid produced significantly (P<0.05) fastest in natural togwa fermentation and in samples fermented by L. plantarum or L. plantarum in co-culture with I. orientalis. The content of fermentable sugars was reduced during fermentation. Most volatile flavour compounds were produced in samples from fermentation by P. pentosaceus and I. orientalis in co-culture with either L. plantarum or L. brevis.

Microbiological and fermentation characteristics of togwa, a Tanzanian fermented food.

Selected microbiological and metabolic characteristics of sorghum, maize, millet and maize-sorghum togwa were investigated during natural fermentation for 24 h. The process was predominated by lactic acid bacteria (LAB) and yeasts. The mesophiles, lactic acid bacteria, and yeasts increased and the Enterobacteriaceae decreased to undetectable levels within 24 h. The isolated microorganisms were tentatively identified as Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus fermentum, Lactobacillus cellobiosus, Pediococcus pentosaceus, Weissella confusa, Issatchenkia orientalis, Saccharomyces cerevisiae, Candida pelliculosa and Candida tropicalis. The pH decreased from 5.24-5.52 to 3.10-3.34. Maltose increased initially and then decreased, fructose decreased and glucose levels increased during the first 12 h of fermentation. The organic acids detected during fermentation included DL-lactic, succinic, formic, pyruvic, citric, pyroglutamic and uric acid. Lactate was the predominant acid and increased significantly with time. The volatile organic compounds (VOC) detected included acetaldehyde, 2-methyl-propanal, 2-methyl-butanal, 3-methyl-butanal, ethanol, 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, diacetyl and acetoin. Ethanol was the predominant VOC and it increased significantly with time.

Evaluation of the nutritional quality and acceptability of sorghum-based tempe as potential weaning foods in Tanzania.

Six types of sorghum (Sorghum bicolor)-based tempe were developed by blending with various combinations and quantities of either bambara groundnut, sesame, cowpea, pigeonpea, common bean, mungbean, soybean, or groundnut (peanut) seeds. Their mixtures were then soaked and solid-state fermented by Rhizopus oligosporus to produce tempe. Soaking resulted in the loss of minerals. Mould fermentation did not change the proximate and mineral composition, but increased the in vitro protein digestibility by 10 to 14.1%. Tempe processing reduced the tannin content by 30.4 to 94.0%. The protein content of tempe ranged from 16.0 to 18.6%; the amino acid score, 63.0 to 69.0%; protein energy, 14.2 to 16.8%; net dietary protein energy, 7.3 to 8.4%; and total energy, 416.0 to 441.0 Kcal/100 g of tempe. The developed tempe had protein quality and energy recommended for weaning foods. The deep-fried snacks were mildly acceptable. More research work and promotion are proposed in order to improve the acceptability of sorghum-based tempe as potential weaning or supplementary foods in Tanzania.

Evaluation of the nutritional quality and acceptability of fingermillet-based tempe as potential weaning foods in Tanzania.

Six types of fingermillet (Eleusine coracana)-based tempe were developed by incorporating either commonbeans, groundnuts, cowpeas, mungbeans, chickpeas, sesame and/or their mixtures and fermented by Rhizopus oligosporus. The proximate and mineral composition was not changed significantly by fermentation. The protein content of tempe ranged from 13.3 to 15.7%; the total energy, 374.1 to 434.3 Kcal/100 g; the protein energy, 13.0 to 15.6%; the net dietary protein energy, 7.2 to 8.7%; and the chemical score, 61 to 71%. Tempe processing reduced the tannin and hydrogen cyanide content by 55.2 to 75.7, and 71.0 to 86.2%, respectively. It increased the content of reducing sugars, amino nitrogen, total acidity by 4 to 15, 3 to 6.9, and 4.3 to 12-fold, respectively. The in vitro protein digestibility was also improved. The developed tempe had protein quality and energy content recommended for weaning foods. The deep-fried tempe snacks were fairly organoleptically acceptable.

Production and storage stability of non-alcoholic pawpaw beverage powder.

Powder for instant non-alcoholic pawpaw beverage formulation was manufactured by traditional sundrying and controlled ovendrying. The reconstituted beverage was organoleptically acceptable. The effect of sundrying on mats and ovendrying on product quality was investigated. Sundrying resulted into losses of vitamins A and C, and total sugar by 97, 98 and 87 percent; while, oven drying losses were 92, 98 and 87 percent, respectively. Nutrient losses during storage in transparent polythene bags at ambient conditions reached 98, 98 and 82 percent in sundried samples and; 87, 99 and 67 percent in ovendried samples respectively. The moisture content of sundried and oven dried samples increased by 14 percent during storage. The increase in microbial load during storage was higher in sundried samples.

Production and storage stability of non alcoholic banana beverage powder.

Powder for an instant, non-alcoholic beverage formulation was manufactured by sundrying and ovendrying of a popular dessert ('silk') banana variety. The reconstituted beverage was organoleptically acceptable. The effect of traditional sundrying on mats and ovendrying methods on product quality was investigated. Sundrying resulted in losses of Vitamin A, C and total sugar contents by 74, 91 and 63%, while ovendrying losses were 73, 90 and 62%, respectively. Nutrient losses during storage for three months in transparent polythene bags reached 93, 93 and 70% in sundried samples and 84, 99 and 55% in ovendried samples, respectively. The moisture content of sundried and ovendried samples increased by 12 and 17%, respectively, during storage. The increase in microbial load in this period was higher in sundried samples.

The nutritive quality of sorghum-commonbean tempe.

The nutritive quality of sorghum-commonbean (40:60) tempe manufactured by Rhizopus oligosporus: Rhizopus oryzae (1:1) mixed culture fermentation was determined. The protein, crude fat and ash content increased slightly, while carbohydrates decreased. The dietary fibre of the tempe increased by 10%. Mould fermentation increased the content of reducing sugars, total acid and aminonitrogen 15.3, 6.7 and 4.6-fold, respectively. It decreased the phytate content by 44% and it increased the tannic acid content by 52%. In vitro iron absorption increased from 2.8 to 12.5%. The protein efficiency ratio of tempe was 1.61 +/- 0.33; the net protein ratio was 2.39 +/- 0.20; the in vitro and in vivo protein digestibility were 88.2 and 80.0 +/- 0.05% respectively, while the protein efficiency ratio, net protein ratio in vivo digestibility of skim milk was 2.96 +/- 0.17, 3.51 +/- 0.17 and 98.0 +/- 1.87, respectively. The sorghum-bean tempe could be used for supplementary feeding.

Bacteriological quality of potable water sources supplying Morogoro municipality and its outskirts: a case study in Tanzania.

Bacteriological quality of potable water supplying Morogoro municipality and its outskirts (population 135,000 people) was assessed by the determination of the most probable number (MPN) of faecal coliforms, Escherichia coli, faecal streptococci and Clostridium perfringens for a period of 6 months. River water and chlorinated pipeborne water were found contaminated with microorganisms in the order of 3.8 x 10(1) to 4.95 x 10(3); 3.2 x 10(1) to 4.5 x 10(3); 10(1) to 6.4 x 10(1) and 1.2 x 10(1) to 2.5 x 10(2)/100 ml of water respectively. Injured coliforms in treated water averaged 87%. Pollution of river water by organic matter was much above acceptable standard. These findings indicate that there is a need for further treatment of water before consumption in order to avoid potential health hazards.