Consumers have become more aware of healthy and safe food produced with low environmental impact. Organic agriculture is of particular interest in this respect, as manifested by 5.768 million hectares managed pursuant to Council Regulation (EEC) 2092/91 in Europe. However, there can be a considerable risk that the avoidance of chemical inputs in organic farming will result in poor food quality. Here the results of a study on the quality of wheat (Triticum aestivum L.) grown in a 21 year agrosystem comparison between organic and conventional farming in central Europe are reported. Wheat was grown in a ley (grass/clover) rotation. The 71% lower addition of plant-available nitrogen and the reduced input of other means of production to the organic field plots led to 14% lower wheat yields. However, nutritional value (protein content, amino acid composition and mineral and trace element contents) and baking quality were not affected by the farming systems. Despite exclusion of fungicides from the organic production systems, the quantities of mycotoxins detected in wheat grains were low in all systems and did not differ. In food preference tests, as an integrative method, rats significantly preferred organically over conventionally produced wheat. The findings indicate that high wheat quality in organic farming is achievable by lower inputs, thereby safeguarding natural resources.

Consumers buy organic food because they believe in the high quality of the product. Furthermore, the EU legal regulatory framework for organic food and farming defines high quality of the products as an important goal of production. A major challenge is the need to define food quality concepts and methods for determination. A background is described which allows embedding of the quality definitions as well as evaluation methods into a conceptual framework connected to the vision and mission of organic agriculture and food production. Organic food quality is defined through specific aspects and criteria. For evaluation each criterion has to be described by indicators. The determination of indicators should be through parameters, where parameters are described by methods. Conversely, the conceptual framework is described according to underlying principles and starting definitions are given, but further work has do be done on the detailed scientific description of the indicators. Furthermore, parameters have to be defined for the evaluation of suitability of these indicators for organic food production.

Feeding experiments comparing organically and conventionally produced food are performed to assess the overall impact on the animals' health as a model for the effects experienced by the human consumers. These experiments are based on systems research and characterized by their focus on production methods, whole food testing and procedures in accordance with the terms of organic farming. A short review of such experiments shows that the majority of these tests revealed effects of the organically produced feed on health parameters such as reproductive performance and immune responses. Systems research is not just about simple cause-effect chains, but rather about the pluralism of interactions in biological networks; therefore, the interpretation of the outcome of whole food experiments is difficult. Furthermore, the test diets of organic and conventional origin can be constituted in different ways, compensating for or maintaining existing differences in nutrient and energy contents. The science-based results suggest positive influences from organic feeds, but there is still a need for confirmation in animals and, finally, in humans. For this purpose animal feeding trials with feed from different production systems should be conducted, with the aims to define health indicators and to establish biomarkers as a basis for future dietary intervention studies in humans.

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a b s t r a c tThere is extensive evidence that rats are able to sense toxicants and essential nutrients in their food and avoid foods that contain these substances. This ability was employed to assess whether the two major management factors soil fertility management and crop protection affected the food preferences of laboratory rats. Samples of wheat grown in 2005 and 2007 under four combinations of these management factors in the Nafferton Factorial Systems Comparison at Northumberland UK were used as experimental diets in food preference tests. In both years, the rats preferred organically fertilized wheat. The influence of organic and conventional crop protection was inconsistent. But a statistically significant interaction of soil fertility management and crop protection was observed: under organic soil fertility management there was generally no difference between the two crop protection methods but under conventional soil fertility management either the combination with organic crop protection (2005) or the fully conventional combination (2007) resulted in the most disliked food. In conclusion, the findings emphasize the role of soil fertility management for producing food of not only a quality that was preferred by rats but also for a high quality of the organic production system in general.