New York Times Oct 3, 2007

The Curious Cook

Organic, and Tastier: The Rat's Nose Knows 


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

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

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

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

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


517-282-3557 (cell)

517-353-3834 (fax)

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