Extrusion of pea snack foods and control of biopolymer changes aided by rheology and simulation

International audiencePea flour and a blend of pea starch and protein isolate with a starch-to-protein ratio closeto 2/1 were processed using co-rotating twin-screw extruders. Different extruder scalesoperated at a moisture content of 18–35% and a screw speed of 120–700 rpm resulted inlarge intervals of melt temperature T (95–165 °C) and specific mechanical energy SME(150–2000 kJ/kg). With increasing T and SME, starch solubility in water increased due tostarch melting and depolymerisation, and protein solubility in SDS decreased due toformation of protein aggregates linked by disulphide bonds. Extruded foods’ morphologywas studied by CLSM. Protein cross-linking increased the median size of protein ag-gregates; starch destructuration increased the area of the starch phase to the detriment ofthe protein one. Melt shear viscosity was determined using a pre-shearing capillary rhe-ometer. The melts exhibited shear-thinning behaviour according to a power-law model,with values close to those of model parameters observed for pea flour and SP 2/1 blend.The rheological model was implemented in a 1D global extrusion model to simulate peaingredient extrusion. Satisfactory correlations between predicted extrusion variables (T,SME) and biopolymer transformation suggested that products with target structure can beobtained using simulation to tune extrusion conditions