16th IFOAM Organic World Congress, Modena, Italy, June 16-20, 2008 Archived at http://orgprints.org/12324 The antioxidant compounds in rat experimental diets based on plant materials from organic, low-input and conventional agricultural systems Wiśniewska, K.1, Rembiałkowska, E.1, Hallmann, E.1, Rusaczonek, A.2, Lueck, L.3, Leifert, C.3 Key words: rat feed, organic, conventional, low input, polyphenols Abstract Results presented in this paper are part of a study that investigates the effect of four production systems on health effects in rats. This study was aimed to evaluate differences in the levels of flavonols, total polyphenols, beta-carotene and lutein which are well known antioxidants in four rat feeds. Raw plant materials were produced according to four different agricultural systems: organic farming (without synthetic pesticides and mineral fertilizers), low-input 1 (organic plant protection was used in combination with mineral fertilizers), low input 2 (conventional pest management and organic fertilizers were used) and conventional farming (synthetic pesticides and mineral fertilizers were used). The results indicate that rat feed prepared from the organically produced plants contained more antioxidant compounds, especially total polyphenols, flavonols and lutein. Rat feed produced for feeding experiments varied significantly in a series of key phytochemicals and therefore have the potential to produce different health effects in the subsequent feeding trials. Introduction In opinion of many consumers organic farming may supply safer and healthier food products than conventional farming. There is quite a lot of evidence that organic plant products contain more vitamin C, polyphenols, iron, magnesium, phosphorus as well as less nitrates, nitrites and pesticides residues than conventional ones (Leclerc 1991, Rembiałkowska 2003). However, there are almost no papers about the composition of the processed organic foods and the presented experiment is the only one comparing the exact composition of the rat feed based on organic, low input and conventional crops. The analysed feeds are used in the experiment comparing the health parameters of rats; the results are published separately. In 2006 a rat feeding trial was established at to assess the impact of four production systems and their two management components -fertility management and crop protection- on the general health and immune status in rats (Baranska et al 2007). Prerequisite for this trial is that food is supplied that varies in its properties depending on the management factors and that this variability is high enough to produce differences in the feeding experiment as well. Several groups of plant metabolites are thought to contribute to the potential health effects of organic food. For instance polyphenols and especially flavonoids have a role in prevention of cardiovascular disease and carcinogenesis (Czeczot, 2000). Because organic production systems do not use synthetic pesticides plants have to rely on their own defense strategies against insects and pests. A common strategy is to produce more phytochemicals. Consequently, the use of organic agriculture may be a way to increase the phytochemical content of plant foods (National Organic Program 2004). 16th IFOAM Organic World Congress, Modena, Italy, June 16-20, 2008 Archived at http://orgprints.org/12324 The aim of this study is to assess whether rat feed produced from grain and vegetables from four different management systems varied in key phytochemical that potentially affect health in the subsequent rat study. Materials and methods Barley, potatoes, carrots and onions were produced in the Nafferton factorial systems comparison (NFSC) at the University of Newcastle’s Nafferton Experimental Farm, Northumberland, UK in 2006. Conventional crop protection was applied according to the British Farm Assured standards, and organic crop protection according to Soil Association organic farming standards. Under conventional fertility management mineral fertilizers are applied, and composted manure is used under organic fertility management. The combination of the two factors results in four factor combinations: organic fertility and crop protection management (OF-OP), organic fertility management and conventional crop protection (OF-CP), conventional fertility management and organic crop protection (CF-OP) and conventional fertility management and crop protection (CF-CP). Samples from these factors combinations (four replicates, n=16) were dried at moderate temperature in order to keep their nutritive value. Rat feed based on these materials was produced according to the nutritional recommendations for rat feeding trials. Compositional analysis of four above mentioned rat feeds were done in 2007 in the Division of Organic Foodstuff, Warsaw Agricultural University. They include: dry matter analysis by scale method (PN-91/R-87019), flavonols analysis by Christ – Müller methods described by Strzelecka et. al (1978), total polyphenols analysis by Folin – Ciocalteau colorimetric methods described by Singleton and Rossi (1965), beta-carotene and lutein analysis by liquid column chromatography described by Saniawski and Czapski (1983), antioxidant activity analysis by colorimetric method described by Re et al. (1999). The results of these qualitative characteristics of each of the different rat feeds were statistically evaluated using Statgraphics 5.1 program ANOVA. Results and discussion As shown in tab. 1, all examined rat feeds contained similar levels of dry matter and differences were not statistically significant. Organic vegetables often contained more dry matter then conventional ones (Rembialkowska 2003, Rembialkowska 2004). Obviously the preparation procedure of the feeds (drying, mixing, cooling, pelleting) reduced differences that might have been present previously. Total polyphenols content of the rat feed varied considerably between the experimental treatments (Tab. 1). The highest level was observed in organic rat feed (OF-OP), and the lowest in conventional (CF-CP) rat feed. Feeds from low-input systems CF-OP and OF-CP have levels lower than the organic but higher than the conventional feed. Both the fertility management and crop protection as well as their interaction had an significant effect on the polyphenols status of the experimental diets. The low-input version with pesticides and without fertilizers contains slightly more polyphenols than that one with fertilizers. The lack of synthetic pesticides and mineral fertilizers seems to have stimulated the polyphenol production. The total content of flavonol was the highest in the organic feed and the lowest in the CF-CP feed. Similar levels were observed in feeds from two low-input system (OF– CP, CP-OF). Both, fertility management and crop protection had an significant effect on the flavonol content of the feed. The results confirm a generally found tendency to 16th IFOAM Organic World Congress, Modena, Italy, June 16-20, 2008 Archived at http://orgprints.org/12324 higher flavonoids content in the organically produced plant materials (Rembialkowska 2004). Table 1: The levels of: dry matter, polyphenols, flavonols, beta-carotene, lutein and antioxidant activity in rat feeds from four management systems ANOVA Mean P-value Parameter Main Effects OF-OP OF-CP CF-OP CF-CP Fertilizer Health Interactions Dry matter g/100g d.m. 90.02 89.85 89.66 89.95 0.76 0.56 0.29 Polyphenols mg/100g d.m. 2166.9 1575.6 1530.3 1137.8 < 0.0001 <0.0001 0.05 Flavonls mg/100g d.m. 3.39 3.00 2.97 2.31 0.03 0.02 0.55 Beta-carotene mg/100g d.m. 0.82 0.82 0.80 0.72 0.68 0.58 0.73 0.41 0.33 0.38 0.24 0.04 0.25 0.54 28.59 28.06 28.16 27.71 0.07 0.13 0.91 Lutein mg/100g d.m. Antioxidant activity uM Trolox/1g. There were no significant differences in beta-carotene concentration between the treatments. Lutein was identified as an important carotenoid in the feeds. The highest level of lutein was found in organic rat feed (OF-OP) and the lowest level in the conventional one(CF-CP). The two other rat feeds were less abundant in this compound and similar in this respect (Tab. 1). Statistical analysis showed that the lutein content was only affected by the fertility management. There were no significant differences in the antioxidant activities of rat feeds from the organic, conventional, and low-input cultivations. The composite rat feed that contained barley, potatoes, carrots and onions produced in the four management systems contained significantly different levels of polyphenols, flavonols and lutein. Both, fertility management and crop protection caused these differences but fertility management seems to have a stronger impact. The results shown represent the second batch of rat feed used in the feeding trial and confirm trends observed in the first batch analysed (Rembialkowska et al 2007). 16th IFOAM Organic World Congress, Modena, Italy, June 16-20, 2008 Archived at http://orgprints.org/12324 Conclusions 1) Rat feed produced for feeding experiments varied significantly in a series of key phytochemicals and therefore have the potential to produce different health effects in the subsequent feeding trials. 2) Rat feeds prepared from the organically produced plants contained more antioxidant compounds, especially flavonoids total polyphenols and lutein. Acknowledgments This study was supported by the EU project QualityLowInputFood FOOD-CT-2003506358 and by the Polish Ministry of Science and Higher Education. References Barańska A., Skwarło-Sońta K., E. Rembiałkowska E., Brandt K., Lueck L., Leifert C. 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