Effects of Organic and Conventional Growth Systems on the Content of Flavonoids in Onions and Phenolic Acids in Carrots and Potatoes

Department of Food Chemistry, National Food Institute, Technical University of Denmark, Mørkhøj Bygade 19, DK-2860 Søborg, Denmark.
Journal of Agricultural and Food Chemistry (Impact Factor: 2.91). 10/2010; 58(19):10323-9. DOI: 10.1021/jf101091c
Source: PubMed


The demand for organic food products is steadily increasing partly due to the expected health benefits of organic food consumption. Polyphenols, such as flavonoids and phenolic acids, are a group of secondary plant metabolites with presumably beneficial health effects, and contents in plants are affected by, for example, plant nutrient availability, climate, pathogen infection, and pest attack. In the current study, onions, carrots, and potatoes were cultivated in two-year field trials in three different geographical locations, comprising one conventional and two organic agricultural systems. The contents of flavonoids and phenolic acids in plants were analyzed by pressurized liquid extraction and high-performance liquid chromatography-ultraviolet quantification. In onions and carrots, no statistically significant differences between growth systems were found for any of the analyzed polyphenols. On the basis of the present study carried out under well-controlled conditions, it cannot be concluded that organically grown onions, carrots, and potatoes generally have higher contents of health-promoting secondary metabolites in comparison with the conventionally cultivated ones.

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    • "Higher amounts of both anthocyanins and total phenolics were also observed at locations with longer days and cooler temperatures (Reyes et al. 2004). Studies on the effects of the production system on the nutrient composition of potato tubers showed that potatoes produced in organic cultivation when compared with conventional cultivation contained higher or similar levels of phenolic compounds (Rosenthal and Jansky 2008; Søltoft et al. 2010). Literature data are, however, not consistent enough to conclude that potato tubers grown under organic farming contain higher amounts of phytochemicals. "
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    ABSTRACT: Beyond providing energy through its high starch content, the potato tuber can make a significant contribution to the dietary intake of certain minerals including potassium, phosphorous, magnesium and iron, as well as of vitamin C, dietary fibres and phenolic compounds. While some animal and human studies have shown beneficial associations between the consumption of potato, or some of its components, and health, some other studies could not confirm these positive effects. Numerous factors may indeed influence (i) the composition of the potato tuber itself, i.e. genotype, environmental conditions during growth, post-harvest storage conditions, cooking and processing, and (ii) the bioaccessibility and bioavailability of its components, affecting the final bioactivity. The purpose of this paper is to provide a brief overview of potato composition variability followed by an analysis of potential health-promoting effects and bioavailability of specific components including iron and phenolic compounds. It appeared that the various components of the potato matrix might interact with each other at the intestinal level, leading to favourable or detrimental effects on their bioavailability. The consumption of a potato cultivar with a high level of phenolic compounds may improve the health status of an individual regarding its risk of developing chronic diseases on the one hand, but may reduce iron absorption on the other hand, putting an individual at risk of micronutrient deficiency. Tailoring potato varieties or products to match the population nutritional needs appears therefore of major importance.
    Potato Research 12/2015; 57(3-4). DOI:10.1007/s11540-015-9287-3 · 0.91 Impact Factor
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    • "It might be one of the reasons that the possible health benefits of organic food consumption are still controversial. Søltoft et al. (2010) observed that there were no significant differences in the content of any of the flavonoids between organic and conventional onions. Similar result was shown in quercetin content in a study by Mogren et al. (2009) and polyphenols in a study by Faller and Fialho (2009). "
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    ABSTRACT: This study aimed to compare bulb and leaf characteristics, leaf diseases, physiological disorder, bulb nutritional quality, and storage loss of onion from both organic and conventional farms in southeastern Korea during the 2011/2012 growing season. Soil and plant samples were collected from 8 certified organic fields managed organically for more than 5 years and 8 conventional fields adjacent to the organic fields. Onion bulb fresh weight and marketable bulb yield were significantly higher in the conventional field than in the organic field. At harvest, tops-down and leaf yellowing were 15.0 and 16.9%, respectively, lower in organic onions compared to conventional onions. Total phenolic compounds were significantly higher in conventional than organic onions, while there were no significant differences in pyruvic acid, soluble solid and flavonoids content between conventional onions and organic onions. In principal component analysis, highly weighted variables under PC1 included the number of scales, leaf yellowing, soluble solids, pyruvic acid, flavonoids, phenolics and storage loss in organic onions, but bulb weight and leaf weight in conventional onions. In organic onions, leaf yellowing correlated positively with flavonoids (p = 0.015), but negatively with soluble solids (p = 0.040); soluble solids were negatively correlated with flavonoids (p = 0.049). By contrast, conventional onions showed a positive correlation between bulb weight and leaf weight (p = 0.038), and between soluble solids and phenolics (p = 0.019), but a negative correlation between leaf weight and leaf yellowing (p = 0.016).
    Horticulture, Environment and Biotechnology 08/2015; 56(4):427-436. DOI:10.1007/s13580-015-1036-7 · 0.73 Impact Factor
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    • "Indeed, secondary plant metabolites such as lycopene and phenolic compounds may function as defence mechanisms against plant pathogens and pests (Gravel et al., 2010). Therefore, it has been proposed that organic vegetables may contain more of these molecules than conventional ones as the former may be more exposed to both biotic and abiotic stressors (Lundegårdh and Mårtensson, 2003; Søltoft et al., 2010). However, a functional link between production of functional molecules and farming system has so far not been established and a cause–effect relationship cannot be unequivocally claimed (Brandt and Mølgaard, 2001; Poiroux-Gonord et al., 2010). "
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    ABSTRACT: Consumers demand for healthier food and governments' policies for environmental sustainability of agricultural processes are increasingly promoting a rapid expansion of organic farming. Nevertheless, the link between organic products and their enhanced nutritional/environmental values is far from being fully understood. In this context, we have begun to assess the effect of cultivation variables that may interact with farming systems and ultimately affect the final product quality. By comparing the response to conventional vs. organic farming of cauliflower, endive and zucchini here we demonstrate that the overall quality of organic products depends on many interacting variables. In cauliflower, the cultivar effect overwhelms other quality determinants with respect to antioxidant activity and nitrate accumulation. In endive, the liposoluble antioxidant activity increases under organic cultivation only in the absence of mulching. Finally, organic farming promotes the accumulation of K in zucchini grown on clay but not on sandy soil. Therefore, understanding the functional links between cultivation variables and physiological responses is essential to improve and standardize the quality of organic products.
    Scientia Horticulturae 12/2013; 164:532–539. DOI:10.1016/j.scienta.2013.10.005 · 1.37 Impact Factor
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