Rheological properties of artificial boluses of cereal foods enriched with legume proteins

Abstract

[EN] The properties of artificial food bolus are studied by dynamic oscillatory and capillary rheometry as functions of bolus water content (WC), in the usual range of saliva hydration, for four cereal products: sponge cake, extruded flat bread and their counterpart enriched in legume proteins. All boluses followed the same rheological behavior characterized by (1) solid -like in the linear viscoelastic domain and (2) Herschel-Bulkley model for large shear strain. Hence, four characteristic rheological properties are determined: modulus at viscoelastic plateau, characteristic stress at transition to flow, yield stress and consistency in the flow regime. The decrease of these properties with WC was fitted by an exponential decay function, from which was extracted a coefficient alpha (5 = alpha < 30), defined as a coefficient of interaction of the food with water. The values of alpha are of the same order of magnitude as the plasticization coefficient of starch by water. They were larger for the extruded pea based (EFP, alpha >= 15), and were lower for the sponge cake (SC, alpha < 15). The variations for the different rheological properties are discussed in terms of matter state, envisioning bolus as a suspension of soft swellable particles. The comparison of these values with those encountered for real boluses from similar foods suggests that these results contribute to define a coefficient of interaction of food with saliva.