It's a Cracker!

You will need:

A packet of crackers - dry and fairly big!
A jug of water
Some volunteers
A watch with a second hand

What to do:

Challenge your volunteers to eat three crackers in under a minute, with no water, butter or other lubricant.
Give them a drink of water when the minute is up!
If you volunteers go separately they can try different techniques like shoving the crackers all in at once or breaking them into small pieces first.

What’s going on?

It is almost impossible to eat three crackers in under a minute because our bodies do not manufacture enough saliva to get the crackers to go down. Saliva is a very clever substance; not only does it provide enzymes to start breaking down food in your mouth it is absolutely essential for lubricating the mouth and throat to assist with swallowing. It also helps us taste, and keeps down infections in the mouth.

Our bodies manufacture between 1 and 2 litres of saliva each day, most of which ends up in our stomachs and is digested again. Unfortunately the crackers are very dry, great for storage, but not so great if you are trying to eat loads at once.

If you want to delve a little deeper you can get one of your volunteers to keep a cracker in their mouth for a while, while the enzyme amylase in their saliva gets to work and turns the starch in their cracker to sugar. It should start to taste sweet.

Warning - don't try this alone and do have a drink of water ready as it can cause choking if you aren't careful!