Optimization of process variables to develop honey based extruded product

Abstract

In the present work, the processing variables were optimized to study their effect on functional properties of honey based ready-to-eat expanded snack food. The blends of rice flour, wheat flour and honey were extruded in a twin-screw extruder. Experimental design with temperature (115 to 135°C), screw speed (270 to 350 rpm) and feed proportion (5 to 15%) as independent variables which produced 20 different combinations, were studied using response surface methodology to investigate the effect of these variables on product responses (lateral expansion, bulk density, color, Water absorption and solubility index characteristics). Multiple regression equations were obtained to describe the effects of each variable on product responses. Results showed that increasing the barrel temperature resulted in extrudate with higher expansion, water absorption index, a* value and lower bulk density and L* and b* values. Increasing screw speed resulted in higher expansion, water solubility index, L value and lower bulk density whereas, increasing honey proportion of feed composition resulted in higher a* value, bulk density, water solubility index and lower expansion, water absorption index and L*value. The graphical optimization studies resulted in temperature (119 to 122°C), screw speed (301 to 321 rpm) and feed composition (9.68 to 10.35%) as optimum variables to produce acceptable honey based extrudates. Key words: Twin screw extrusion, honey, response surface methodology, rice flour, wheat flour.