Quality evaluation of porridges prepared from maize-groundnut composite flours

Abstract

Abstract: Cereals are a major staple in many African homes contributing significant amounts of energy and protein, but limiting in essential amino acid, lysine. Legumes on the other hand, are protein and amino acid rich foods, but lacking in amino acids which contain sulphur, such as methionine. It therefore, follows that a combination of cereals and legumes would improve on the nutritional density of the subsequent food products, which can be used in alleviating protein-energy malnutrition (PEM), a problem in Africa and other developing nations of the world, where high levels of poverty are experienced. In this study, the quality and nutritional aspect of maize-groundnut composite flours and porridges were investigated. To do that, full fat and defatted groundnut flours were composited with maize flour at various levels, i.e., 45:55, 30:70, 15:85 and 0:100, respectively. Analyses of the nutritional content of composites revealed that compositing maize flour with groundnut flour significantly (p ≤ 0.05) increased protein and fat contents in flours and porridges. Accordingly, protein increased from 10% in maize flour to about 21% in composite porridge that consisted of 45% groundnut defatted flour (acronym DFC1), whereas fat content in maize fortified with groundnut flour ranged from 1 to 10.6%. The energy values for composite porridges were also determined and found to vary between 395 and 434 Kcal/100 g when compared to 398 Kcal/100 g reported for maize porridge alone. Lysine content was at least 3 times higher in composite flours (0.98%) than for maize flour (0.35%), meanwhile in composite porridges, it was 4 times (0.96%) higher than in maize porridge that had a level of 0.20%. Oleic acid increased close to 35% when maize flour was composited with groundnut flour. Despite this increased nutritional quality, groundnuts and maize flours are prone to deterioration during storage and therefore, their composites may not be ideal choices as they may be highly susceptible to microbial contamination accompanied by toxin production known to induce taints, unpleasant odours or off-flavours in these foods. Moreover, these toxins or taints may be harmful to humans after ingestion. It was therefore important to determine the storage stability and shelf-life of the developed composites to ascertain their safety levels. Full fat and defatted flours and composite flours were thus, analyzed for safety quality over a storage period of 3 months at room temperature (25ºC). The findings revealed a significant (p ≤ 0.05) increase in water activity in all flours tested. Peroxide value (PV) in...M.Tech. (Food Technology