Nutritional quality of low-cost supplementary foods for supporting growth and rehabilitation of undernourished populations in Tanzania

Thesis

Severe undemutrition during childhood remains a common health problem in many parts of the world and contributes immensely to childhood morbidity and mortality. According to WHO/UNICEF, producing low-cost, ready-to-feed, nutritious foods from locally produced ingredients by using low-to-medium level technologies in local settings can considerably help mitigate child undemutriton through increased access to food. The aim of this study was to formulate, process, and evaluate the quality of processed, ready-to- feed bean-based composite supplementary foods for pre-school age children in low- income populations in Tanzania. Supplementary foods based on cereal-bean-sardine mixtures were formulated from ingredients produced locally in Tanzania. The products were formulated to maximize the amino acid score as recommended by the FAO/WHO/UNU for pre-school age children and to provide the desired amount of energy and fat as stated by the FAO/WHO Codex Alimentarius guidelines (CAC/GL 08-1991) for supplementary foods for older infants and young children. Red beans {Phaseolus vulgaris), com/maize {Zea mays), rice {Oryza sativa), sardines {Sardinops melanosticta) and red palm oil {Elaeis guineensis) were formulated into single/multi-mix diets and processed into ready-to-feed powders by extrusion, drum-processing and conventional cooking. The processed products were evaluated for true protein digestibility, net protein retention ratio, protein digestibility-corrected amino acid scores (PDCAAS), amino acid profile, residual phytohemagglutinins, trypsin, chymotrypsin, and a-amylase inhibitors. Foods were also evaluated for potential to support normal growth and for rehabilitation of undernourished children using a weanling rat model. Furthermore, the products were evaluated for storage stability at 38°C. The studies showed that com-bean-sardine, sorghum-bean-sardine and rice-bean sardine products had superior nutritional value compared to individual cereals or cereal + bean blends. The composite products had high true protein digestibility, ranging from 82 - 93%, high ratio of net protein retention ranging from 0.86 - 0.92 and PDCAAS ranging from 77 - 89%. The composite products also showed a good potential to support growth and rehabilitation of undernourished animals. Extrusion and drum-processing thoroughly cooked the foods as characterized by high gelatinization rate (95 - 100%) and low residual urease activity levels (< 0.05 units per 100 g food). They were also effective in inactivating the phytohemagglutinins (91 - 97%) and the anti-nutritional factors - trypsin, chymotrypsin and a-amylase inhibitors. Extrusion and drum-processing also resulted in products that had high protein digestibility and PDCAAS. During storage at 38°C, the food pH and total acids did not change significantly (p > 0.05). The products were shelf­ stable for at least 16 weeks.

United States Agency for International Development through the Bean/Cowpea Collaborative Research Support Program (CRSP)