Nutritional and Microbiological Evaluation of Fermented Cereal Weaning Foods

Abstract: Protein energy malnutrition (PEM) is the most serious nutritional problem affecting pre-school children in developing countries. The low energy and nutrient density of the diet and the presence of anti-nutritional factors contribute to this condition, as do the low frequency of feeding and transmission of diarrhoea-causing pathogens via the food. The overall objective of this thesis was to evaluate the use of lactic acid fermentation in order to improve the nutritional quality and microbiological safety of cereal weaning foods. The study focused on Tanzanian cereal staple foods, and the nutritional factors specifically studied included dietary bulk properties, in vitro protein digestibility and in vitro estimation of iron availability. The microbiological study evaluated the survival of diarrhoea-causing pathogens in lactic acid-fermented gruels. A prospective epidemiological study was carried out to evaluate the effect of regular consumption of lactic acid-fermented gruels on the diarrhoea prevalence in pre-school children living in a rural setting of Tanzania. With a fermentation technique using a natural lactic acid starter culture and addition of flour of germinated seeds, it was possible to prepare liquid cereal gruels from maize, white sorghum, bulrush millet and finger millet with a 30 to 35% flour concentration. The energy density of such a lactic acid-fermented gruel was about 1.2 kcal/g, as compared with 0.4 kcal/g in a non-fermented gruel prepared to the same consistency. This represents a threefold increase in energy density. Fermentation of high-tannin sorghum gruels only resulted in a double increase of the energy density while maintaining a liquid consistency. The in vitro protein digestibility of high-tannin cereal varieties was significantly (p