But Qiaoxuan Zhou and Keith Cadwallader think that inverse gas
chromatography can solve that problem -- and so does the USDA, which
will contribute over $280,000 from its National Research Initiative
Grants Program so their research can continue.
"Most people are
convinced of soy's health benefits, but they think soy has a beany
or bitter flavor," said Zhou, a researcher in Cadwallader's
University of Illinois lab.
That perception is soy's first problem. The second problem is
that flavors added to processed soy foods can either change or fade
-- a lot -- because soy protein has the ability to bind flavors.
"For example, vanilla soy milk is very popular, but it's driving the
industry crazy," said Cadwallader, a U of I associate professor of
food chemistry. "Over time, the vanilla flavor binds to the soy
protein, causing flavor fade."
He added that flavoring designed for other uses usually doesn't
work in soy: "When a flavor binds to soy protein, it can turn out
completely different from what you'd expect. You can add a nice
strawberry flavor, and it can end up tasting like cough medicine."
But Zhou has found a way to evaluate a flavor compound's ultimate
performance and staying power. A food flavoring can contain more
than 20 different compounds, and the soy protein may bind with three
of them or 10 of them, with some but not with others. Zhou uses
inverse gas chromatography to figure out "in a sensitive, precise,
accurate and rapid way" which of those compounds will bind to soy
protein. The technology also tells her how weak or strong those
binding affinities are.
That's important to food manufacturers who want to get enough soy
into their products to qualify for the health labels. "The idea is
to get enough soy protein in a product to allow these health claims
so consumers can reap the benefits of soy," Cadwallader said. "And
sometimes that's a lot of soy -- enough to affect flavor."
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To complicate matters further, the chemist said that a flavoring
that works in a liquid soy product won't work in a dry soy product,
such as cereal bars or bakery products. "We found that water
molecules compete with flavor molecules to bind to the protein, so
just a trace of moisture in a dry soy food can have a big effect on
Until Zhou started her current research, little work
had been done in flavor binding in low-moisture soy foods,
Cadwallader said. And food manufacturers are eager to know how these
compounds will interact because they want to be able to store dry
soy products without losing flavor.
Using inverse gas chromatography, Zhou is evaluating how soy
affects flavor in soy-enhanced products. Using soda crackers as a
model, she successfully demonstrated that soy-enhanced crackers
interact or bind with specific butter-flavor compounds much
differently than butter flavor in plain wheat crackers. These
results will help processors design suitable flavorings for soy
foods in which flavor binding has hindered product development.
Cadwallader said inverse gas chromatography is less expensive,
less time-consuming, and more sensitive and reliable than human
panelists who use their olfactory systems to distinguish the
So both scientists are optimistic about the use of this
technology by food manufacturers. They also believe the work they're
doing will make soy foods more appealing to the American consumer.
"And that's important because soy has proven health benefits," he
said. "We'd like to see everyone eating more of it."
The initial part of this research was published in the Journal of
Agricultural and Food Chemistry. Funding was provided by the
Illinois Center for Soy Foods at the University of Illinois.
[News release from the
University of Illinois College
of Agricultural, Consumer and Environmental Sciences]