A university professor has revealed the best way of getting ketchup out of a glass bottle isn’t by banging on the end.
Dr Alan Mackie, a professor of Colloid Chemistry at the University of Leeds, said that banging on the end of a glass bottle will make the ketchup inside too runny which is why it will inevitably spurt out all over your meal.
Instead, he says tapping on the neck of the bottle will give you much better control over the flow of ketchup.
He will reveal the method to presenter Matt Tebbutt on Friday night’s episode of Channel 4’s Food Unwrapped.
Ketchup is made up of tomato particles that are suspended in water which are thin and runny but it also contains long chains called polymers which when they entangle get thicker
Dr Mackie explained to Matt that ketchup is made up of thin tomato and water particles, and thicker long chains called polymers.
When you turn a bottle of ketchup upside down, these polymers become entangled and the sauce becomes thicker, which is why it doesn’t flow out of the bottle.
When you bang on the end of a bottle however, these polymers untangle and the ketchup thins – resulting in a very quick and uncontrolled flow.
Dr Mackie explained: ‘What’s happening in the bottle is that there’s a polymer in there, a thickener.
Letting the sauce pour naturally can take a long time as the polymers will be entangled but to make it flower quicker you can tap on the neck which will still allow you control
‘When you turn it upside down, the polymers entangle and it doesn’t flow.
‘When you hit it on the bottom, you tend to make the entire jar liquid if you hit it hard which is not what you want and that’s why it comes out in a big splurt.’
It’s why ketchup tends to spurt everywhere when you use this method.
However Dr Mackie said that if you tap on the neck of the bottle, only the ketchup at the top will become more liquid and you can control the flow more easily.
The professor and Matt put the theory to the test on the show by using the two methods to fill pots of ketchup.
The professor managed to fill the pots neatly and quickly by just tapping on the neck, while Matt’s ketchup went everywhere when he banged on the end.
Dr Mackie said: ‘What I would do is tap the neck region and that liquefies the neck region and has a controlled flow over your chips.’