Optimisation of wheat-sprouted soybean flour bread using response surface methodology

The effect of sprouted soybean flour on wheat bread was studied. Sprouting significantly increased the vitamin C content of soybean flour from 2.0 mg kg-1 to 3.25 mg kg-1. The sprouted soybean flour resulted in increased loaf volume, a firmer, spongy and more elastic loaf. However, increasing the sprouted soybean flour beyond 10% adversely affected these qualities. The loaf with 4% yeast and 5% sprouted soybean was significantly rated better in taste and general acceptability than the control. Significant differences existed (p increase in protein, fibre and ash content of white bread. The quadratic polynomial regression model was adequate and acceptable at 0.05% for predicting the specific loaf volume and apparent yield stress. Response surface was saddle shaped for specific loaf volume where a maximum or minimum response is found at various combinations of the independent variables, corresponding to the optimal yeast (2.15%) and sprouted soybean flour (11.8%). Apparent yield stress value of 120 kN/m2 can be obtained from baking with yeast (2.4%) and sprouted soybean flour (10.6%).