Them's the breaks

Editorial Notebook

October 04, 2003

WHY DOES that cookie crumble? Maybe not why you'd think.

Pondering the physics of these hand-held treats is a perennial diversion for parents and other sofa- and car-seat cleaners. Most just put up with it, but a fed-up few have gone so far as to ban certain brands from their domiciles and vehicles, among them those frosting-painted industrial-sized shortbread cookies favored by a certain giant coffee chain.

But for those who manufacture cookies and sweet biscuits for sale nationwide, the issue is more serious - crumbly products lead to lost profits. "Breakage in the bag" or box irks customers, who may not ever buy another bag or box. And "breakage on the line" - during production - can add up to tons of rejected morsels and wasted ingredients and time.

Of course, giant U.S. treat-makers such as Kraft's Nabisco brand and Kellogg's Keebler brand don't say how much they lose to breakage or what cutting-edge techniques they use to fight it. The latter is what's called proprietary information in this $10 billion-per-year industry.

Big Industry can't always stop the inquisitive, though. Current common wisdom, based on years of communal supermarket and kitchen experience, places the blame for poor cookie integrity on bad packaging or ingredients that prevent the gluten in flour from forming strong bonds. But at Loughborough University in central England, researchers say they have found a new answer: humidity.

Using laser beams to measure tiny changes in the surface of rich tea biscuits right out of the oven, investigators described a new style of stress fracture. As the shortbread-style cookie cools, its rim expands as it picks up moisture from the air while its middle contracts as it loses moisture through steam.

Such tension may explain why these cookies sometimes develop hairline fractures hours after baking, fractures that could turn to bona fide cracks and crumbs with just a little jostle. Or a single, quick tea-dunk.

Their answer is for factories to alter the humidity on the line or cook their treats for longer at a lower temperature. The researchers offer a model "hygroscopic expansion coefficient" to start off the calibrations.

Should it work, hundreds of companies and millions of picky munchers would be saved from scores of tectonic-fault shortbread cookies. Not to mention the joy of the Dust Buster-wielders of the world.

It's not as clear what it would mean to those who toil to create sweet treats in home kitchens. Will cookbooks be rewritten to reflect the new science? Should cookies be left to cool way out on the edge of the counter, as kids claim, or kept closer to a still-warm oven?

All this means little, though, to those who like their treats on the gooey, sugary side. The not-too-sweet cookies in the study, similar to Kellogg's Carr's brands or the Scottish Walker's Shortbread, aren't the most popular munchies this side of the Atlantic, though there are plenty enough cookie ascetics who enjoy them here to leave a trail through the house.

But don't think those in the United Kingdom have some moral culinary high ground here - they like gooey-sweet cookies, too. In fact, the best-selling cookie in Britain is Burton's Maryland Cookies brand, which the firm claims comes from a recipe taken from our shores in 1956. Similar to a Famous Amos-style cookie, only bigger, Maryland Cookies come in chocolate chip with extras - hazelnut, coconut or more chocolate.

And while one could fold a Maryland Cookie in half before it broke, it still poses a danger to the furniture. Perhaps next time the great minds of food science will find the optimal level of goo.

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