Effects of Iron Fortification and Fermentation on Processing, Functional, Microbiological and Storage Properties of Maize-Blend Weaning Foods

ABSTRACT

Iron deficiency anaemia (IDA) has been a significant public health problem in the developing world. Fortification has been identified as one o f the most cost-effective and sustainable approaches for controlling IDA. Addition of various bionutritional substances creates several technical challenges for the Food Technologists and therefore it is necessary to maintain the overall quality o f the product in terms o f the bioavailability o f the fortifying agent. The main objective of this work is therefore to investigate the effects o f iron fortification on the physical, functional and microbiological properties o f weaning foods. The iron compounds used were ferrous sulphate and ferrous fumarate.    Oven drying at 60°C was used to reduce the moisture content o f the fermented maize dough to produce dehydrated product. A 4x3x2x2 factorial experiment with, fermentation time, iron compound, iron concentration and the mode o f iron addition as variables were replicated. The indices measured were pH, titratable acidity, colour, fat acidity, water absorption, viscosity, total iron content, energy content and microbiological study. A roasted weaning food - maize/cowpea/groundnut blend was prepared and response surface methodology studies using a central composite rotatable design for factor, k=3 ( iron concentration, legume concentration and roasting temperature) conducted. Samples were packaged in polyethylene bags and stored for 4 months and analysed for pH, titratable acidity, colour, water absorption and fat acidity. Sensory evaluation/consumer acceptability test was performed on three iron-fortified cooked products namely, dehydrated fermented maize dough, maize/cowpea dough and roasted maize /cowpea/groundnut blend. Even though iron fortification brings about relative increase in pH, the values (3.51- 4.11) were optimal for cereal phytase in fermented maize dough system. Breakdown of triglycerides was high in both iron-fortified and non-fortified products. Fermentation and iron addition were found to increase the total iron content o f the products. Energy content o f at least 460 kcal/lOOg was recorded for all samples. This is higher than a recommended energy for a quality weaning food. The concentration o f iron added before fermentation did not interfere with the microbial growth o f the fermented maize signifying that the levels added were not toxic to the microorganisms. Even though storage had significant effect on the indexes measured, there was not much change in the characteristics when comparing the iron-fortified and the non-fortified products. Regression models developed to predict product characteristics o f roasted weaning food were influenced by the process variables. These were mainly legume concentration and roasting temperature. Iron addition however, affected the characteristics when legume concentration was high. Storage o f the roasted blend was highly affected by iron addition. Products were generally acceptable to mothers from the sensory evaluation and consumer acceptability test conducted in five communities in the Central region.