How to unboil an egg

UC Irvine scientists have found a way to unboil an egg (Photo: Steve Zylius/UC Irvine)

A team of scientists led by UC Irvine has shown that you can unboil an egg, or at least egg whites ... but it isn't easy. Far more than a breakfast table trick, the feat is designed to demonstrate a new technique for recovering valuable molecular proteins quickly and cheaply that could have important biochemical applications.

Boiling an egg may seem like the simplest part of breakfast, but it involves some interesting chemistry. An egg is 90 percent water and ten percent protein, which is what gives egg whites their gloppy appearance. These proteins are in the form of long chains of amino acids tangled and folded in upon themselves like microscopic piles of yarn held together by weak atomic bonds. When the egg is dropped into boiling water, the heat breaks these bonds and the chains start to unravel and break. The chains then bond with other amino acids and capture water inside the new folds, causing the whites to turn white and gelatinous. Cook them too long, and the chains curl in on themselves; forcing the water out and turning the whites hard and rubbery.

This is what the UC Irvine team did when they boiled their eggs. In fact, they boiled the heck out them for 20 minutes at 90 degrees C (194 degrees F), so they were very hard indeed. They then set out to reverse the process and turn the hard whites into a clear protein called lysozyme by adding urea, which breaks down the chemical bonds that cause the coagulated chains to misfold on one another. The rather unpalatable liquid mass was then run through a vortex fluid device designed by Professor Colin Raston at South Australia’s Flinders University. This set up shear stresses that caused the chains to untangle into their previous uncooked form.

Thankfully, unboiled eggs won't be added to breakfast menus anytime soon. The purpose behind all this is to demonstrate a new technique for recovering molecular proteins. Where conventional techniques take up to four days to recover the proteins, the UC Irvine process takes only minutes.

"It’s not so much that we’re interested in processing the eggs; that’s just demonstrating how powerful this process is," says Gregory Weiss, UCI professor of chemistry and molecular biology and biochemistry. "The real problem is there are lots of cases of gummy proteins that you spend way too much time scraping off your test tubes, and you want some means of recovering that material."

The team says that the process has valuable applications in producing proteins for science and industry, such as a cheaper, faster way of making antibodies for cancer treatments or using recombinant proteins for cheesemakers.

The team's results were published in ChemBioChem.

Source: UC Irvine

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