Introduction
During feeding, mastication is the first transformation
process for a food en route to the gut. Basically, it consists
of a rhythmic activity of the jaw-opening and -closing
muscles, controlled by a central pattern generator (Lund,
1991). This rhythmic activity is modulated by sensory
inputs throughout the chewing sequence, allowing adjustment
in the masticatory process in response to the bolus
texture at any moment. It follows that chewing is a highly
complex sensory–motor activity which integrates the various
components of the masticatory system, such as teeth
and their investing structures, jaw muscles, temporomandibular
joints, tongue, lips, cheeks, palate and salivary
secretions (Orchardson & Cadden, 1998). During chewing,
the food sample is fragmented by compressive and shear
bite forces as saliva is incorporated. The resulting small
particles form a cohesive mass, the bolus. The point of
maximum cohesion may provide the trigger to swallow,
thereby minimising the risk of dysphagia (Prinz & Lucas,