Oral processing of hydrogels: Influence of food material properties versus individuals' eating capability

Food material properties play an important role in sensory perception and consumer acceptance of foods. However, the actual oral processing behavior may depend on both the material properties of the food that is being consumed and individuals' oral capabilities. This study aimed to examine the relationships between intrinsic (oral capabilities of healthy participants) and extrinsic (food material properties of a set of hydrogels) variables to the real oral processing behavior. Three κ-carrageenan hydrogels (κC), differing in fracture mechanics and oral tribology properties, were prepared: native κC, κC with added Na-alginate, and a κC matrix with added Ca-alginate beads of 300 μm. A composite score of eating capability (EC) was measured with non-invasive techniques (maximum bite force and tongue pressure) using a panel of 28 untrained consumers. The oral processing behaviors (number of chews, oral residence time, and chewing rate) were analyzed with the same participants using frame-by-frame video analysis. It was found that the EC scores did not correlate with any of the oral processing behaviors. The number of chews and oral residence time showed a strong correlation with the fracture force and friction force at orally relevant speeds (10-100 mm/s), whereas chewing rate did not vary with these properties. The results from this study indicate that oral processing in healthy adults seems mainly motivated by food material properties, and the chewing rate seems to relate more to individual differences and EC than to food properties. Insights from this study, using model hydrogels, have helped to promote knowledge on oral processing behavior in healthy individuals; could bridge the gap between consumer science, psychology, and food science; and may be of interest to product developers in designing foods with pleasant texture properties.