When we smell food, our mouth responds by producing saliva, and as we eat, the saliva lubricates our food and begins the process of digestion.

The average amount of saliva we can produce in one go is 300ml, and once this saliva has been used up, food becomes dry and difficult to chew and swallow.

Once Paul Newman has eaten a number of eggs, thus using up all of his available saliva, he would have to wait (so he can produce more) or drink something to help the eggs go down. Once chewed and swallowed, food passes down the oesophagus and into the stomach.