Abstract:
The study was designed to formulate sorghum-soybean composite supplementary foods
and investigate the effect of extrusion on nutritional value and tannin content. The products
were extruded and analysed for nutritional value, tannin content, urease activity, sensory
and anti-oxidant activity. Results showed that, the extruded composite products had good
nutritional value and conformed to the requirements for supplementary foods for older
infants and young children. Nutritional composition of the composite supplementary foods
were: protein 17.36 – 21.60 g/100 g DM, carbohydrates 67.35 – 77.46 g/100 g DM, fat
1.85 – 8.27 g/100 g DM, energy values 400.91 – 424.06 Kcal/100g and had appreciable
quantities of Ca (77.57 – 272.37 mg/100 g DM), Zn (1.61 – 3.15 mg/100 g DM), Fe (2.72
– 11.21 mg/100 g DM), Mg (53.46 – 132.78 mg/100 g DM), Cu (0.51 – 0.83 mg/100 g
DM) and K (74.14 – 255.61 mg/100 g DM). Extruded composite products had good
physical and sensory attributes. A test of antioxidant activity using DPPH (1,1- Diphenyl-
2-picryhydrazyl) demonstrated considerable radical scavenging activity for all the products
(71.79 – 97.91 μg/ml). The highest radical scavenging effect was observed in plain red
sorghum (RS-C) with EC 50 value of 68.32 μg/ml. Extrusion resulted in loss of antioxidant
activity by 1 – 20%. Extruded products had significantly lower concentrations of tannin
and urease activity compared to the non-extruded products. The extruded products had
higher WAI, WSI and were more acceptable than products that were not extruded. Based
on the results, it may be concluded that, various blends of sorghum with sardines and
soybeans can be used to produce high quality supplementary foods. Extrusion adds value
to the products in that it transforms the products into instant, convenient products with
better organoleptic properties. Therefore, extrusion technology should be adopted by small
and medium scale food processors.
