Biologisch geteelde tomaten veel gezonder.*
Biologisch geteelde tomaten blijken veel meer
bioactieve stoffen te bevatten dan “normaal” geteelde. Door het ontbreken van de stikstof uit kunstmest gaan biologisch geteelde tomaten als verdedigingsmechanisme meer bioactieve stoffen produceren. De stikstof uit kunstmest belemmert dit proces. Na een
studie van 10 jaar blijkt inderdaad dat biologisch geteelde tomaten o.a. 79% meer
quercetine en 97 % meer kaempferol hebben.
Bioactieve stoffen staan bekend in de strijd tegen hart- en vaatziektes, kanker
en dementie.
Organic Tomatoes Better For Heart And Blood Pressure
Organic tomatoes have significantly higher levels of flavonoids, compared to non-organic tomatoes, according to the results of a ten-year study carried out by researchers at the University of California.
You can read about this study in a report coming out soon in the Journal of Agricultural Food Chemistry.
Flavanoids are a class of water-soluble pigments that are present in many plants. Scientists have identified a few thousand different flavonoids. Flavonoids are known to lower hypertension (high blood pressure), thus lowering heart disease and stroke risk. Studies have also indicated that flavonoids may protect us to some extent from cancer and dementia.
The researchers believe that it is the quality of the soil that gives the organic tomatoes their higher flavonoid levels, specifically, the absence of
fertilizers.
In this study, the researchers measured the amounts of quercetin and kaempferol, two flavonoids, in dried tomato samples. They found that levels of quercetin were 79% higher, and kaempferol 97% higher in the organic tomatoes, compared to the non-organic ones.
When nitrogen levels are not high enough in the soil, plants produce flavanoids as a defence mechanism. If inorganic nitrogen, which is present in everyday fertilizers, are applied to the soil, this over-fertilization may hinder flavonoid production.
"Organic tomatoes have more antioxidants"
Duncan Graham-Rowe
Healthful Compounds in Tomatoes Increase Over Time in Organic Fields. Levels of flavonoids increase over time in crops grown in organically farmed fields, according to a rare long-term study
J. Agric. Food Chem., 55 (15), 6154 -6159, 2007. 10.1021/jf070344+ S0021-8561(07)00344-5
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 55108
Abstract:
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.
(Juli 2007) (Opm. Dit zal natuurlijk
niet alleen gelden voor tomaten doch voor veel biologisch, zonder kunstmest,
geteelde groenten en fruit.)
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