Mastication and its influence on human salivary flow and alpha-amylase secretion

Unilateral parotid saliva was collected from ten subjects following oral stimulation with water, chewing on parafilm, mastication of celery and bread, and holding of bread in the mouth. Salivary flow induction was independent of chewing rate. Mastication of bread and celery resulted in higher flow rates than did chewing on parafilm. Although limited to two foods at two weights, the results suggest a possible dependence of flow rate on both the type and weight/size of the stimulus. Mastication increased the secretion rate but not the concentration of protein and alpha-amylase. The rate of alpha-amylase secretion was influenced by mastication in accord with digestive function, in that more secretion was induced by food than by nonfood stimuli, more by bread than by celery, and more by larger than smaller pieces of bread. However, these increases might be related more to the physical characteristics than the composition of the stimuli, e.g., force of chewing, dryness, and surface area.