[Editors] MIT student makes dough--in the lab

[Elizabeth Thomson]

MIT News Office
Massachusetts Institute of Technology
Room 11-400
77 Massachusetts Avenue
Cambridge, MA  02139-4307
Phone: 617-253-2700
http://web.mit.edu/newsoffice/www

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MIT student makes dough--in the lab
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For Immediate Release
TUESDAY, OCT. 10, 2006
Contact: Elizabeth A. Thomson, MIT News Office
Phone: 617-258-5402
Email: thomson at mit.edu

PHOTOS AVAILABLE

CAMBRIDGE, Mass.--Trevor Shen Kuan Ng rolls dough. He also stretches 
it like Silly Putty, twirls it like taffy and flattens it into 
rectangles like wide fettuccine.

Ng, an MIT mechanical engineering graduate student, is getting an 
education in dough. His Ph.D. thesis concerns the mechanical 
properties of matter--in this case, dough--and how it behaves when 
subjected to forces. In engineering-speak, this is called rheology, 
and it provides valuable information for commercial bakeries that 
need accurate, repeatable techniques for measuring the properties of 
dough to ensure the tastiest product.

Ng's work is part of the non-Newtonian fluid dynamics research group 
headed by Gareth H. McKinley, professor of mechanical engineering.

Non-Newtonian fluids are unusual materials. Their viscosity, or 
slipperiness, changes with the amount of strain applied to them. Many 
non-Newtonian fluids have microscopic structures that affect how they 
react when poked or prodded, and how fast they move when they flow. 
Picture peanut butter or mayonnaise dripping from a tap--they would 
not behave like water. Some non-Newtonian fluids such as polymers 
bounce like a ball if dropped but flow smoothly if placed on a 
surface.

McKinley's research group looks at DNA, saliva, tree sap and okra, a 
natural polymer used as a food thickener for thousands of years. 
Snail slime and such oddities as magnetic fluids also are 
investigated.

Ng's work area in a corner of the Hatsopoulos Microfluids Laboratory 
contains a variety of dough-manipulating devices. To measure torque, 
or turning properties, the mixograph twists the dough around metal 
pins the way saltwater taffy is spun in a candy shop; the filament 
stretcher pulls the dough until it snaps.

To conduct experiments, Ng works with small samples of flour ground 
from grains newly developed by farmers and food engineers. He 
painstakingly records how the resulting dough is treated and how it 
reacts to manipulation, because different blends of flour, water and 
additives can result in drastically different dough. Atmospheric 
conditions and time of day also can affect the product's elasticity 
and rise.

Getting the dough to stay put can be a chore. "It sticks to pretty 
much everything other than the things you want it to stick to," Ng 
said.

Ng wasn't always cut out for dough. He completed a master's degree in 
aeronautical engineering from Cambridge University in England and 
arrived at the Gas Turbine Laboratory at MIT with the goal of 
designing airplane engines. Airplane engines are designed with air 
flow in mind, and Ng made the switch to "fluid mechanics of a 
different sort," he said, when he heard McKinley needed a dough man. 
Working with dough, he said, sounded like something "different and 
fun."

The research also has a serious side. For millennia, bakers have 
developed a feel for dough as they kneaded it. But this homespun 
approach isn't good enough for large commercial operations, which 
need "numbers" representing a material's properties during the 
manufacturing process, Ng said.

Ng helps define those properties while seeking a deeper understanding 
of the micro-structure of dough.

Gluten gives dough its distinctive elastic behavior. To engineers, 
gluten is a nanoscale bio-macromolecule, one of the largest protein 
compounds on earth. These proteins form an entangled matrix whose 
quality, shape and distribution within the dough are intrinsically 
linked to its bread-making qualities.

"The texture of bread--the chewiness and mouth feel--is dependent on 
the dough you start with," Ng said. "The airiness of the bread, or, 
from a commercial point of view, the amount of air they sell you, is 
directly related to the ability of the dough to resist rupture during 
the deformation process as it rises. When bread is in the oven, air 
bubbles within the dough expand. At some point they break, and the 
bread stops expanding."

Wonder Bread, Ng said, is "a very airy product."

Ng doesn't usually eat his experiments because the laboratory dough 
is covered with silicone oil to keep it from drying out. But since 
starting this line of research in 2003, Ng has become a home baker. 
When he bakes bread, he brings a bit of the dough in for testing. 
White bread, he said, is his favorite.

Ng's work is funded by Kraft Foods.

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Written by Deborah Halber, News Office Correspondent