STUDIES ON THE OPTIMUM PROCESS CONDITIONS FOR THE PRODUCTION OF CUSTARD-SOY BEAN FLOUR BLENDS

ABSTRACT This study optimized the production of custard powder enriched with soy bean flour with a view to exploring the potential of soy bean flour to enrich corn starch in the production of custard powder for human consumption.Response Surface methodology was used to determined the protein content, reconstitution index and quantity of trypsin inhibitory activity to develop the optimized values for the flour blends. The proximate, functional and sensory properties of the optimized flour blends from custard-soy bean and ogi-soy bean flour were determined using standard laboratory procedures. The study had three independent variables; Level of inclusion of soy flour (A), mixing time (B) and volume of water (C) which were used as the factor for optimization with the three responses; protein content(%), reconstitution index(%) and the trypsin inhibitory level(mg/100). The analysis for the three responses were obtained in triplicates without much deviation. The result showed that the optimum conditions to enrich full-fatted soy bean flour with corn starch to produce custard powder ranged from 4.99 to 5.00g of soy flour for the level of inclusion, 45 secs approximate for the mixing time with 147.63mL to 150mL volume of water. The optimum conditions for the three responses were 17.3925%, 175.612% and 0.259459 respectively at 71.9% desirability obtained by the design expert software. The result of the proximate composition for the optimized flour blends ranged as follows; moisture (11.04% - 11.94%), fat content (3.93% - 9.25%), ash content (0.57% - 2.03%), crude fiber (0.70% - 0.73%), protein content (16.09% - 16.49%), carbohydrates content (61.73% - 66.89%) and energy value (367.37Kcal/100g – 396.20Kcal/100g). The functional properties of the optimized flour blends ranged as follows; Bulk density (0.33g/ml – 0.40g/ml), tapped density (0.50g/ml – 0.56g/ml) and swelling capacity (0.00% - 139.83%). However, the sensory mean scores for the optimized flour blends varied in appearance (7.26 – 7.60), aroma (7.40 – 7.53), taste (7.06 – 7.46), mouth-feel (7.06 – 7.33), texture (7.20 – 7.40), colour (7.46 – 8.33) and overall acceptability (7.53 – 8.00). The study concluded that soy flour can be used to enrich custard powder following the optimum conditions as predicted by the design expert software.