IS THE MOUTHWATERING SENSATION A TRUE SALIVARY REFLEX?

Although widely perceived, there is no clear physiological mechanism for the sensation known as “mouthwatering.” Previous studies conflict as to whether humans have a conditioned reflex to the sight or thought of food despite being well established in other animals. Parotid and submandibular/sublingual secretions to a set of standardized (taste, chewing, smell) stimuli were compared to mouthwatering samples elicited by handling (but not consuming) food. Handling food elicited a small, but measurable, increase in submandibular/sublingual and parotid salivas. Analyses revealed these salivas had a similar protein profile as a resting salivary sample. It is concluded that no true reflex secretion occurs in response to the thought or handling of food but that small amounts of saliva ejected into the mouth, possibly by muscle activity, is likely to be the cause of the mouthwatering sensation. PRACTICAL APPLICATIONS The concept of mouthwatering is often used to promote or sell a food product and yet the physiological basis of this response is unclear. Unlike animals, and in particular Pavlov's dogs, humans are not able to salivate at the thought of food. Instead small volumes of saliva have been secreted/detected while handling real foods that may relate to the mouthwatering phenomenon.