The effect of sodium bicarbonate and glycerol monostearate addition on the extrusion behaviour of maize grits

Studies were conducted to investigate the effect of sodium bicarbonate (NaHCO3) and Glycerol monostearate (GMS) addition with changing extrusion temperature on the extrusion behaviour and product characteristics of maize grits. The dependent variables recorded were die pressure, specific energy consumption (SEC) while the product characteristics analysed were expansion, water absorption index (WAI), water solubility index (WSI) and viscosity. Second-order polynomials were computed to describe the influence of temperature within the extruder and also NaHCO3 and GMS addition level on the dependent variables in the extrusion process. The effect of NaHCO3 on expansion, WAI, WSI and viscosity of extrudates was observed to be temperature-dependent. NaHCO3 at lower extrusion temperature (125 degrees C) increased expansion, WAI and WSI while at higher extrusion temperature (175 degrees C), a reverse effect of NaHCO3 on these characteristics was observed. (C) 2000 Elsevier Science Ltd. All rights reserved.