New York Times Oct 3, 2007
The Curious Cook
http://www.nytimes.com/2007/10/03/dining/03curi.html?_r=2&oref=slogin&ref=dining&pagewanted=print
IN any controversy it
can be helpful to consider the views of disinterested parties. So, on the
subject of agricultural policy and practice, it’s worth noting that an
unimpeachably neutral group has joined the ranks of those who prefer organic
foods over foods produced with the help of synthetic chemicals. That group is
40 Swiss rats.
A team of Swiss and
Austrian scientists recently concluded a 21-year study of organic wheat
production. As an “integrative method” for assessing quality, they gave
lab animals a choice of biscuits made from organic or conventional wheat. The
rats ate significantly more of the former. The authors call this result
remarkable, because they found the two wheats to be very similar in chemical
composition and baking performance.
In fact, the rats were
better at telling the difference between organic and conventional foods than
many humans have been. In the handful of carefully designed taste-offs reported
in the last few years, people were often unable to identify the organic foods,
and often didn’t prefer them.
This is puzzling,
since organic produce generally does pack more antioxidants and other
potentially healthful — and potentially flavorful — phytochemicals
than conventional produce. Just last July, Professor Alyson Mitchell and
colleagues at the University of California, Davis summarized 10 years of data
from tomatoes grown in carefully controlled organic and conventional systems.
The antioxidant contents varied from year to year, but were consistently higher
in the organic tomatoes.
What do phytochemicals
have to do with flavor? Phytochemicals are chemicals created by plants, and
especially those that have effects on other creatures. Plants make many of them
to defend themselves against microbes and insects: to make themselves
unpalatable, counterattack the invaders and limit the damage they cause. Most
of the aromas of vegetables, herbs and spices come from defensive chemicals.
They may smell pleasant to us, but the plants make them to repel their mortal
enemies.
Why should organic
produce have higher phytochemical levels? The current theory is that because
plants in organic production are unprotected by pesticides and fungicides, they
are more stressed by insects and disease microbes than conventional crops, and
have to work harder to protect themselves. So it makes sense that organic
produce would have more intense flavors. For some reason, taste tests
haven’t consistently found this to be the case.
This puzzle remains
unsolved. But a few pieces have come together to reveal a simple way of getting
more flavor into some kinds of produce no matter how or where it’s grown.
And that includes backyards and windowsills.
Plants sense and
respond to any kind of attack by means of chemical signals. Cells in the
attacked area first detect telltale molecules from the invader. Then they respond
by releasing warning molecules that trigger the rest of the plant — and
even neighboring plants — to start producing chemical defenses.
Biologists discovered many years ago that they could induce the plant’s
defensive response without any live insect or fungus. All they had to do was
supply the initial chemical signals — the invader molecules or the
plant’s warning chemicals.
At Clemson University,
Dr. Hyun-Jin Kim and Professor Feng Chen recently exploited this fact to
intensify the flavor of basil plants. They induced a defensive response in the
plants by exposing them to a material derived from chitin, a long chainlike
molecule that funguses use to reinforce their cell walls. Insects and
crustaceans also build their hard exoskeletons out of chitin. The chitin from
crab and shrimp waste is processed industrially to make a shortened form called
chitosan, and this is what the Clemson food scientists used.
They soaked basil
seeds for 30 minutes in a chitosan solution, then soaked the roots again when
they transferred the seedlings to larger pots. After 45 days, they compared the
chemical composition of leaves from treated and untreated plants. They found
that at the optimum chitosan concentration, the antioxidant activity in treated
plants was greater by more than three times. The overall production of aroma
compounds was up by nearly 50 percent, and the levels of clove-like and flowery
components doubled.
Chitosan is readily
available as a dietary supplement that supposedly encourages weight loss. When
I asked Professor Chen by e-mail if chitosan capsules from the health food
store dissolved in water would work as well as his lab-grade chemical, he
replied, “I would guess they will have the same or similar effect.”
He added, “I would like to encourage master gardeners to try them for
fresh aromas.”
A few years ago I gave
up my big garden for a few pots of dwarf citrus and herbs. I’m currently
pseudostressing a pot of basil and cilantro seedlings, hoping for freshly
intensified flavors that won’t require a rodent’s nose to
appreciate.
Vicki Morrone
Organic Vegetable and Crop Outreach Specialist
Michigan State University
C.S. Mott Sustainable Food Systems
303 Natural Resources Bldg.
East Lansing, MI 48824
517-353-3542
517-282-3557 (cell)
517-353-3834 (fax)
For information on organic
agriculture production please visit:
http://www.MichiganOrganic.msu.edu/
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