System parameters in a high moisture extrusion process for microparticulation of whey proteins

Whey proteins can be texturized by thermo-mechanical treatment during high moisture extrusion. Thereby, protein aggregates with specific functional properties can be obtained. In this study, a heated co-rotating twin screw extruder was used to particulate whey protein concentrate. For data evaluation, process, product and system parameters affecting the extrusion process were distinguished. To characterize the process by system parameters is an important step towards an improved process understanding. The maximum product temperature (T_P,max) correlated linearly with the extruder barrel temperature and the mass flow. The specific mechanical energy input (SME) was found to be mainly affected by screw speed and mass flow. Independent of the respective adjusted process parameters, aggregate size was only affected by the resulting SME value. Equally, the degree of denaturation was only affected by the T_P,max. Thus, manipulation of system parameters (SME and T_P,max) can be applied for an indirect control of micro-particle properties.