Development and Quality Evaluation of Extruded Cereal Flours Fortified With Grain Amaranth, Baobab and Orange-fleshed Sweet Potato

Abstract

Micronutrient malnutrition continues to be a problem in developing countries. Food to food fortification which includes composite flour formulation is one of the methods used to reduce the problem. However, the effectiveness of the composite flours is questionable due to the presence of antinutrients in the raw materials used. Therefore, the current study aimed at developing a nutritious, shelf-stable porridge composite flour from maize, sorghum, grain amaranth, baobab and orange-fleshed sweet potatoes. Nutrient composition data of each ingredient was generated using standard analytical methods and used in the formulation of the composite flours using Nutrisurvey software. To produce various formulations of composite flours with maize and sorghum as the cereal base and grain amaranth, baobab and OFSP as the fortifiers, a completely randomized study design in factorial arrangement with ingredient ratio and extrusion as variables and seven levels was used. Half of each of the formulations were extruded at 160 °C. Nutritional and anti-nutritional profiling followed by sensory evaluation of the composite flours was done. A comparative analysis of acceptability was performed between the best formula and the commercial composites. Stored in kraft paper and plastic containers, the two best formulations, extruded and non-extruded were subjected to real-time shelf-life studies at 20 °C, 30 °C and 40 °C. The data were analyzed using the R Project for StatisticalComputing, R-3.6.3 and inferential statistics done by ANOVA and the means separated using Turkey’s HSD test. The protein content (8.99 ± 1.03 g/100 g), beta-carotene content (895.90 ± 346.85 μg/100 g), iron content (11.81 ± 9.73 mg/100 g) and zinc content (1.74 ± 0.18 mg/100 g) were improved by fortification of maize-sorghum blends on average. An increase in grain amaranth increased the phytate content. The protein content, beta-carotene content and antinutrients were decreased by xvii 4.7%,40.9% and 35% respectively by extrusion. Consumer acceptability studies showed that the colour, flavour and overall acceptability of the composites (mean 5.7-7.4 on a 9-point hedonic scale) were affected by formulation, with the most acceptable being those containing more sorghum. The comparative study showed that the new formulations had the potential of being accepted.Compared to plastic, the formulated composites stored in Kraft paper were found to degrade faster. The formulations can retain their quality and safety for six months in various ecological zones in both kraft and plastic. Therefore, locally available ingredients such as grain amaranth, Baobab and OFSP improves the nutrient composition of maize-sorghum composites while processes such as extrusion reduce antinutrients and have a detrimental effect on beta carotene. Extrusion should be used in baby food. Bioavailability studies on zinc and iron should be conducted to ascertain the effectiveness of extrusion on the reduction of antinutrients. Refortification of extruded flours with beta carotene is recommended.The Ministry of Agriculture, Livestock and Fisheries in collaboration with the Ministry Health can promote these local crops for consumption by the Kenyan population to reduce micronutrient malnutrition.