The purpose of this study is to maximize the nutritional status of predigested soymilk to prevent weaning deficiency and maximize growth among weaning infants. Nutritional value of fortified soymilk extracted from 12 h steeped and 72 h sprouted TGX 923-2E soybean variety was optimized using central composite design (CCD), a design for response surface methodology (RSM). Box-Wilson (1951) experimental design matrix was used for the fortification with three variable factors (K=3) namely ferric ammonium citrate (Fe), calcium carbonate (Ca) and vitamin C (vC). Each of the three process variables were examined at 5 equally spaced levels coded -1.682, -1, 0, +1 and +1.682. Data on each run were statistically regressed with Minitab (version 11.21) computer software. Matlab (version R2007b) computer software was used to generate the response surface plots. Regression analyses showed that all the fortificant variables were positively linearly related to their respective responses. Maximum concentration of 5.517 mg/100 ml recorded for dietary iron came from fortificant combination 5, 150 and 24 mg/100 ml; 253.675 mg/100 ml for calcium came from fortificant combinations of 3, 250 and 24 mg/100 ml) while 40.60 mg/100 ml for vitamin C came from fortificant combination of 3, 150 and 40 mg/100 ml). All the fortificants had cross product effects on growth performance with maximum growth performance from fortificant combinations 5, 150 and 24 for iron, calcium carbonate and vitamin C, respectively. Ferric ammonium citrate had positive linear significant (P ≤ 0.05) effect on soymilk VCT and colour. Each fortificant is responsible for their respective concentration increase. Effective growth performance only comes from interactions of two fortificants with that from calcium and vitamin C being the most effective. Ferric ammonium citrate increases colour and decreases general acceptability of soymilk.

Keywords: Complementary feeding, nutritional value, predigested soymilk, fortified soymilk, response surface methodology.