Saliva in Food … How does it drive sensory perception?

Saliva is a highly complex body fluid composed of many proteins, peptides, small organic molecules and ions. Saliva is produced and secreted by major and minor salivary glands to protect the mouth and to participate to the digestion. Generally distinction is made between resting saliva that is a result of autonomic stimulation, and stimulated saliva that is produced during chewing and taste stimulation. The link between saliva and sensory perception can be thus regarded through two main angles: the role of resting saliva as a background taste and the mechanistic role of saliva during eating. Indeed resting saliva (and its components) is continuously bathing our oral cavity and as such stimulates our taste receptors playing thus a role in taste sensitivity against some active taste substances. Beside, during eating, foods are chewed and a significant level of stimulated saliva is rapidly incorporated in the bolus. In this oral process flavor compounds and nutrients are progressively released from the food matrix into saliva. This in-mouth phenomena impact on flavor perception (aroma and taste) but also on mouthfeel attributes (astringency, creaminess, fattiness, ...) through saliva-food physical interactions but also through the action of biological compounds (enzymes mainly) against the food matrix. Therefore it is the products of the food-saliva interaction that are perceived rather than the food itself. Based on the literature and recent scientific results, the role of saliva in food sensory perception will be discussed according to these two angles. The question of the high between-subject variability in view of saliva properties and its consequence on perception will be emphasized