EFFECT OF SOY FORTIFICATION ON PROXIMATE, FUNCTIONAL AND SENSORY CHARACTERISTICS OF CASSAVA BASED FLOURS AND PRODUCTS

Abstract

Diets in most households in developing countries are based on starchy staples which do not provide sufficient proteins for children below age five, predisposing them to Protein Energy Malnutrition. Cassava is one such staple consumed in Western Kenya in form of ugali and porridge either singly or mixed with millet, maize or sorghum. Fortification of cassava with a legume is a sustainable approach to improve the protein quality, and content and nutrient density of staple food products. The aim of this study was to investigate the effect of soy fortification on the proximate, functional and sensory characteristics of cassava cereal composite flours and products. To establish the nutrient composition, proximate analyses included the determination of moisture, crude protein, crude fat, ash and carbohydrates using the AOAC Internationally approved methods. For the functional tests, bulk density, water and oil absorption capacities and viscosity were determined. Sensory evaluation of porridge was conducted using a trained descriptive panel consisting of 10 members, who generated descriptors, while a consumer panel was used to test acceptability of the cassava cereal soy fortified porridges using a 9-point hedonic scale. The proximate results showed a significant increase in the protein, mineral and lipids content of the cassava and its composites by 89%, 71% and 69%, respectively at 30% fortification and at 50% fortification, 95% 89% and 79%, respectively. All millet based ugali variations including the plain, composited and fortified had higher proximate values for ash, fat and protein compared to maize and sorghum variations. The protein content of porridge was higher than ugali by 55%. Soy fortified flours had better functional characteristics. Bulk densities ranged from 1.4 g/cm3 for millet flour to 1.69 g/ cm3 for cassava: millet: soy 50%, water absorption capacity from 84.7 ml/100 g for cassava maize to 141.7 ml/ 100 g for cassava millet soy 50%, viscosity from 2.68 for maize meal porridge to 4.83 for cassava soy 50% and fat absorption capacity from 72.67 ml/ 100 g for cassava maize to 95.67 ml/100 g for cassava millet soy 50%. The sensory panelists were able to generate 23 sensory descriptors which they used to evaluate eight porridge variations. The first two Principal Component Analyses (PCA1 and 2) explained 64% of the variation in sensory attributes based on fortification at 41.55% for PCA1 and colour intensity at 22.26% for PCA 2. PCA3 explained the source of variation by 14.2% based on texture. Consumer panelists preferred the soy fortified porridges which were darker in colour especially cassava millet soy 30%, 50% and cassava soy 50%. In conclusion, porridges and ugali fortified at 30% were found to provide 50% of the daily protein requirements per 100 g for children aged 1-3 years. The soy fortified porridges scored better per sensory descriptors and were found acceptable by the consumer panelists therefore can be used for supplementary feeding in schools to alleviate PEM as well as household consumption in Western Kenya or any other population.