OTP: Those smells

Odors From Foods May Be Nutritional Signals That
the Human Nose Has Learned to Recognize
By Science Writer RANDOLPH E. SCHMID

WASHINGTON -- That fresh grassy smell wafting up from the newly
sliced tomato may be its way of saying "I'm good for you."
Indeed, the odors from foods ranging from garlic and onions to
ginger and strawberries may be nutritional signals that the human
nose has learned to recognize.
"Studies of flavor preferences and aversions suggest that flavor
perception may be linked to the nutritional or health value" of
foods, researchers Stephen A. Goff and Harry J. Klee report in
Friday's issue of the journal Science.
However, they caution, domestication of many vegetables has not
been kind to them, tending to favor qualities like color, shape,
yield and disease resistance instead of flavor and nutrition.
Flavor is complex and uniquely challenging to plant breeders, they
note, and as a result has not been a high priority.
Take the tomato, for instance.
Klee and Goff analyzed two types of tomato, the wild cerasiforme
and the commercially grown Flora-Duke.
Except for one chemical that also affects color, the sugars, organic
acids and volatile compounds associated with tomato flavor were
reduced in the commercial product.
For example, one of the volatile compounds associated with the
"tomato" or "grassy" flavor is called cis-3-Hexenal, which is also
an indicator of fatty acids that are essential to the human diet.
They found that the wild tomato contained more than three times the
amount of that chemical than the cultivated version.
Two other contributors to tomato flavor _ 2- and 3-methylbutanal _ are
indicators of the presence of essential amino acids and are also three
times more common in the wild tomato.
In addition to tomatoes, those chemicals are also important constituents
of the flavors of apples, strawberries, bread, cheese, wine and beer,
they reported.
Goff and Klee also noted that the scent compounds produced in many
spices are associated with health properties.
For example, curcumin, which is present in tumeric, is reported to have
anti-inflammatory properties, compounds in ginger have antioxidants and
there are antimicrobial chemicals that contribute to the scent of
onions, garlic, rosemary, sage, clove, mustard, chili peppers and thyme.
"A preference for the flavors found in these spices is believed to have
developed due to the health benefit of less contaminated food," they
conclude.
The odors of the compounds are of particular interest because they are
a major factor in how taste of foods is perceived. The human tongue
senses just five flavors _ sweet, sour, salty, bitter and umami,
sometimes called savory _ and scent provides considerable added
information about a food.
Klee is at the Institute of Food and Agricultural Science, University
of Florida, and Goff works for Syngenta Biotechnology, an agribusiness
company. Their work was supported by the National Science Foundation
and Syngenta.
___
On the Net:
Science: http://www.sciencemag.org



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