Abstract
The structure of extruded pea flour can affect chewing performances. Our objective was to relate the bolus properties (fragmentation, moisture content and viscosity) of chewed extruded pea snacks to their structure. In order to have control over oral physiological parameters, we opted for an in vitro approach using a chewing simulator, the variables of which were the flow rate of artificial salivary fluid and chewing time. The structure of the extruded pea snacks was characterized by its density and protein solubility in dithioerythritol (DTE), which reflected the amount of protein aggregates cross-linked by disulphide bonds. The particle size distribution and median width (D-50) of the bolus fragments were determined by imaging technique. Bolus viscosity and saliva uptake (Delta WC) were respectively determined by capillary rheometry and gravimetric method. Extruded snacks were persistently reduced to small particles (similar to 2 mm) during chewing process following a unique curve of D-50 = f (chewing time) fitted by a power function. Delta WC evolution during chewing process was expressed as a function of the structure index, defined as the product of the snacks' relative density by protein solubility in DTE. The boluses' viscosity exhibited a shear thinning behaviour the consistency index of which was negatively correlated to the saliva uptake (Delta WC) through a plasticization coefficient (alpha). alpha values (< 2) were much smaller than those reported for cereal products (15-30) and depended on protein solubility in DTE.