How to make the perfect pancake: Researchers reveal the ratios needed - and how they could help treat glaucoma

Cooking pancakes mimics the interaction of fluid build-up in human eyes
Varying batter ratios trap water vapour in different ways while cooking
Understanding the process could help improve treatments for glaucoma

With Shrove Tuesday upon us, many will be breaking out their secret recipes to kick off the pancake festivities – but making the perfect pancake all comes down to physics.

A team of researchers at University College London compared recipes for pancakes from around the world, to determine how different ratios effect the texture and pattern.

These processes mimic those which occur in the human eyes, the researchers say, and can help scientists to improve surgical methods for the treatment of glaucoma.

Depending on how thick the pancake batter is, a certain amount of water will escape during the cooking process.

This determines the final appearance of the pancake.

And, the physics behind this isn't just important for improving your pancakes skills.

According to researchers from UCL, the science of the perfect pancake can give insight on the actions between flexible sheets, like those found in human eyes, and flowing vapour and liquid.

This knowledge could be applied to improved methods of treatment for glaucoma patients, as glaucoma is a build-up of pressure in the eyes, caused by fluids.

Surgeons typically treat this by creating an 'escape route,' cutting the flexible sheets so the fluid can be released.

'Pancakes come in many shapes and sizes and everyone has their favourites – some prefer a small, thick pancake with a smooth surface whereas others enjoy a large, thin crêpe with 'craters' and crispy edges,' said professor Ian Eames, co-author of the study and Professor of Fluid Mechanics at UCL Engineering.

'We've discovered that the variations in texture and patterns result from differences in how water escapes the batter during cooking and that this is largely dependent on the thickness and spread of the batter.'

The team compared 14 international recipes, including the Canadian ploye and Malaysian lempeng kelapa.

Using these recipes, they then analysed the 'aspect ratio,' and the baker's percentage for each one.

The researchers identify these ratios as that of the pancake diameter to the power of three in relation to batter volume, and the ratio of liquid to flower to determine batter thickness, respectively.

A thick, round pancake would have as low an aspect ratio as three, while a thin crêpes could be as high as 300.

Baker's percentage ranged from 100 for thick batter, to 175 for thin.

The researchers put these different ratios to the test, using a fixed amount of flour and egg for each batter type, but varying the amounts of milk.

Then, the pancakes were cooked in the same pan, at a constant heat, and without fat.

'We found that the physics of pancake cooking is complex but generally follows one of two trends,' said Dr Yann Bouremel, co-author of the study and UCL Institute of Ophthalmology.

'If the batter spreads easily in the pan, the pancakes ends up with a smooth surface pattern and less burning as the vapour flow buffers the heat of the pan.

'We found a thin pancake can only be created by physically spreading the batter across the pan and in this case, the vapour tends to escape through channels or diffusion.'

The study revealed that thick batters with a baker's percentage of 100-120 will trap water vapour during cooking, lifting the pancake unevenly to form islands on the surface.

Thinner batters with a baker's percentage of 175 and small pancakes have a uniform colour on the bottom, and vapour is released smoothly.

The thinnest, with a baker's percentage of 200-225, have an evenly coloured bottom, but it is dotted with dark spots. Channels on the surface indicate escaping water vapour.

'We work on better surgical methods for treating glaucoma, which is a build-up of pressure in eyes caused by fluid,' said Professor Sir Peng Khaw, co-author of the study and Director of the NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology.

'To treat this, surgeons create an escape route for the fluid by carefully cutting the flexible sheets of the sclera.

'We are improving this technique by working with engineers and mathematicians. It's a wonderful example of how the science of everyday activities can help us with the medical treatments of the future.'

The activity of water vapour in some way mirrors the activities of the fluid build-up seen in glaucoma patients.

By the ways different ratios trap and release vapour, and the process by which this happens, researchers can apply the findings to improved techniques in surgical treatment.