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[SANET-MG] organic tomatoes richer in nutrients
J. Agric. Food Chem., ASAP Article 10.1021/jf070344+ S0021-8561(07)00344-5
Web Release Date: June 23, 2007
Copyright © 2007 American Chemical Society
Ten-Year Comparison of the Influence of Organic and Conventional Crop
Management Practices on the Content of Flavonoids in Tomatoes
Alyson E. Mitchell,* Yun-Jeong Hong, Eunmi Koh, Diane M. Barrett, D. E.
Bryant, R. Ford Denison,# and Stephen Kaffka
Department of Food Science and Technology and Department of Plant
Sciences, One Shields Avenue, University of California-Davis, Davis,
California 95616, and Department of Ecology, Evolution and Behavior,
University of Minnesota, St. Paul, Minnesota 5510
Understanding how environment, crop management, and other factors,
particularly soil fertility, influence the composition and quality of
food crops is necessary for the production of high-quality nutritious
foods. The flavonoid aglycones quercetin and kaempferol were measured in
dried tomato samples (Lycopersicon esculentum L. cv. Halley 3155) that
had been archived over the period from 1994 to 2004 from the Long-Term
Research on Agricultural Systems project (LTRAS) at the University of
California-Davis, which began in 1993. Conventional and organic
processing tomato production systems are part of the set of systems
compared at LTRAS. Comparisons of analyses of archived samples from
conventional and organic production systems demonstrated statistically
higher levels (P < 0.05) of quercetin and kaempferol aglycones in
organic tomatoes. Ten-year mean levels of quercetin and kaempferol in
organic tomatoes [115.5 and 63.3 mg g-1 of dry matter (DM)] were 79 and
97% higher than those in conventional tomatoes (64.6 and 32.06 mg g-1 of
DM), respectively. The levels of flavonoids increased over time in
samples from organic treatments, whereas the levels of flavonoids did
not vary significantly in conventional treatments. This increase
corresponds not only with increasing amounts of soil organic matter
accumulating in organic plots but also with reduced manure application
rates once soils in the organic systems had reached equilibrium levels
of organic matter. Well-quantified changes in tomato nutrients over
years in organic farming systems have not been reported previously.
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