Researcher Takes a Close Look at Potato Chips and Candy

Contact: Arlie Corday, WPI Media & Community Relations

Food researcher Franco Pedreschi, left, at Worcester Polytechnic Institute's Surface Metrology Laboratory, has been studying potato chips and candy using equipment originally used to examine NASA space flight runways. He's joined in the effort by WPI lab director Christopher Brown, right, associate professor of mechanical engineering, and lab manager Torbjorn Bergstrom, center.

WORCESTER, Mass. - What kind of knife (dull or sharp) would you use to slice potato chips if you wanted them to soak up the least amount of cooking oil?

The answer, surprisingly, is a dull one. That's because a dull blade separates the cells of the potato; a sharp one breaks the cell walls and allows more oil to be absorbed.

"More surface area is related to more oil absorption," reports food researcher Franco Pedreschi at Worcester Polytechnic Institute's Surface Metrology Laboratory (http://www.wpi.edu/~tral).

Oily potato chips may not seem like the most pressing scientific concern, but questions like this can be crucial to food manufacturers. That's why Nestle helped fund a study by Pedreschi, a visiting scholar at WPI, this spring.

Based on earlier research at WPI, Pedreschi wrote a paper, "Characterization of Food Surfaces Using Scale-Sensitive Fractal Analysis," that has landed in the top 10 entries in its category at the prestigious Institute of Food Technologists Conference, June 10-14 in Dallas, Texas. It also has been accepted for publication in the industry's Journal of Food Process Engineering.

Studying for a doctoral degree in food engineering at Pontificia Universidad Catolica de Chile in Santiago, Pedreschi researched (and, okay, nibbled) potato chips and candy with WPI lab director Christopher Brown, associate professor of mechanical engineering, and lab manager Torbjorn Bergstrom. Pedreschi hails from South America while Brown and Bergstrom grew up in neighboring Waterbury Center and Duxbury, Vt. Both attended Harwood Union High School.

Beyond potato chips, these researchers had the enviable job of finding out how various candies look, feel and taste, studying them with help from WPI's newly developed scanning laser microscope. To complete his doctoral thesis, Pedreschi needed a laboratory capable of surface studies. He found what he was looking for at WPI. Originally developed to study the surface of NASA flight runways, WPI's scanning laser microscope measures surface area or texture, creating a topographical map of any surface - including a potato chip or candy bar.

Topography, it seems, can prove more (or less) appealing to one's taste.

"Surface area can determine how much salt or other flavoring a potato chip absorbs, for example, and how uniformly the flavoring adheres to the food," said Brown. For candy, it can determine how fast the chocolate melts in your mouth, or how appealing it may be to your palate.

On July 31, Pedreschi will defend his findings in a thesis, hoping to earn the first doctorate of its kind from Pontificia Universidad Catolica de Chile in Santiago, Chile. Brown plans to be there, right beside him. You might say he'll be holding the bag - of peanut butter cups or potato chips - for the soon-to-be doctor of food engineering.

Founded in 1865, WPI enrolls 2,700 undergraduate and 1,000 full- and part-time graduate students in science, engineering, management, the humanities and arts and the social sciences.