I can finally sleep better knowing this ...

And that's how the cookie crumbles
Thursday, October 2, 2003 Posted: 4:51 AM EDT (0851 GMT)

Scientists say their research will help bakers make the "perfect biscuit."

LONDON, England -- When cookie-lovers open packages of their favorite snacks, some of the biscuits are often in bits.

Now scientists say they know why -- and it has little to do with the way cookies are packaged and transported.

Instead, laser tests carried out by British physicists found that cookies -- or biscuits, as they are known in Britain -- often develop "fault lines" a few hours after baking.

According to researchers at the University of Loughborough in Leicestershire, central England, as biscuits cool down after coming out of the oven, they pick up moisture around the rim which causes them to expand.

At the same time, moisture at the center makes them contract. The difference results in a build-up of strain forces that can pull a cookie apart.

Cracks appear that weaken cookies so they easily break apart when handled, moved or packaged.

Manufacturers try to tackle the problem by removing problem cookies before they reach store shelves. But many crumbly cookies still end up in shoppers' hands.

"We now have a greater understanding of why biscuits develop cracks shortly after being baked," said doctoral student Qasim Saleem, who led the research.

"This will help biscuit manufacturers adjust the humidity or temperature of their factory production lines to change the cooling process in such a way that the biscuits won't break up due to normal handling, and hence producing the perfect biscuit."

The scientists used an optical technique called "digital speckle pattern interferometry" to study the surface of cookies cooling to room temperature.

A paper on the research, entitled "A novel application of speckle interferometry for the measurement of strain distributions in semi-sweet biscuits," appeared Thursday in the journal Measurement, Science and Technology.