Process conditions influencing wheat gluten polymerization during high moisture extrusion of meat analog products

The aim of this study was to investigate the influence of process conditions on changes in polymerization behavior of wheat gluten during high moisture extrusion processing. By considering the process as two hierarchical sections (i.e. screw and die section), wheat gluten extractability analyses under non-reducing conditions showed that polymerization reactions were determined by process conditions in screw section. Process conditions were characterized by material temperature at extruder exit as measure for thermal treatment, extruder pressure at extruder exit and specific mechanical energy input (SME) as measure for mechanical treatment. The effect of extruder pressure from 1.5 to 3.5 MPa and SME from 32 to 206 kJ⋅kg−1 was studied by varying die length and screw configuration. In the range investigated, extruder pressure and SME had no significant influence on polymerization reactions. Only extruder temperature from 90 to 160 °C induced significant changes in polymerization behavior which was moreover reflected by the visual appearance of the samples reflecting different anisotropic product structures.