There are times while waiting for food at a restaurant when a waiter walks past you with a steaming hot Italian pizza and your mouth starts to water. But why does it happen? What makes the phrase 'mouth-watering' so accurate? Science has the answer. In 2015, Hadi Fares won the ACS Chemistry Champions contest. He later released a video explaining the chemical mechanisms behind 'mouth-watering'. Here's the complete video that will help you understand everything in detail: Pretty fascinating!

Fares explained in the video that saliva not only helps in the digestion process but also helps us to eat by lubricating the food in our mouths, which further aids in chewing and tasting the food around. There are two types of saliva: mucous and serous. It is actually serous saliva which floods into our mouth at the smell, sight, or thought of food.

He further added,

The nerves that control saliva production are part of a reflex system. They fire without you consciously thinking about it when you are eating. The smells, tastes and even the movement of your jaw muscles can activate this reflex.