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Featured researches published by Johannes Kahl.


Journal of the Science of Food and Agriculture | 2012

Organic food quality: a framework for concept, definition and evaluation from the European perspective.

Johannes Kahl; Ton Baars; Susanne Bügel; Nicolaas Busscher; Machteld Huber; Daniel Kusche; Ewa Rembiałkowska; Otto Schmid; Kathrin Seidel; Bruno Taupier-Letage; Alberta Velimirov; Aneta Załȩcka

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.


Biological Agriculture & Horticulture | 2010

Standardization of the Biocrystallization Method for Carrot Samples

Nicolaas Busscher; Johannes Kahl; Jens-Otto Andersen; Machteld Huber; Gaby Mergardt; Paul Doesburg; Marianne Paulsen; Angelika Ploeger

ABSTRACT The growing organic market demands methods which can describe food quality within the organic system (authentication). Several studies indicate that methods, such as the biocrystallization method, are suitable for this question. More or less reproducible crystallization patterns emerge when an aqueous dihydrate cupric chloride solution with plant extract is crystallized on a glass dish. The emerging patterns are characteristic of sample material. To be applied in routine analysis for example for authentication of organic products, the biocrystallization method has to be standardized. After the laboratory process was documented and a computerized pattern evaluation tool was further developed and applied, the method was standardized for selected carrot samples, which is described here. For standardization, several factors of influence were tested and the reproducibility between three different laboratories in the EU was investigated. The method is able to differentiate patterns from samples from different farming treatments and processing steps as statistically significant. This represents a significant step forward beyond the state of the art.


Journal of the Science of Food and Agriculture | 2013

Quality of carrots as affected by pre- and postharvest factors and processing

Randi Seljåsen; Hanne L. Kristensen; Charlotte Lauridsen; Gabriela Wyss; Ursula Kretzschmar; Inès Birlouez-Aragone; Johannes Kahl

The aim of this review is to provide an update on factors contributing to quality of carrots, with special focus on the role of pre- and postharvest factors and processing. The genetic factor shows the highest impact on quality variables in carrots, causing a 7-11-fold difference between varieties in content of terpenes, β-carotene, magnesium, iron and phenolics as well as a 1-4-fold difference in falcarindiol, bitter taste and sweet taste. Climate-related factors may cause a difference of up to 20-fold for terpenes, 82% for total sugars and 30-40% for β-carotene, sweet taste and bitter taste. Organic farming in comparison with conventional farming has shown 70% higher levels for magnesium and 10% for iron. Low nitrogen fertilisation level may cause up to 100% increase in terpene content, minor increase in dry matter (+4 to +6%) and magnesium (+8%) and reduction in β-carotene content (-8 to -11%). Retail storage at room temperature causes the highest reduction in β-carotene (-70%) and ascorbic acid (-70%). Heat processing by boiling reduces shear force (-300 to -1000%) and crispiness (-67%) as well as content of phenolics (-150%), terpenes (-85%) and total carotenes (-20%) and increases the risk of furan accumulation. Sensory and chemical quality parameters of carrots are determined mainly by genetic and climate-related factors and to a minor extent by cultivation method. Retail temperature and storage atmosphere as well as heating procedure in processing have the highest impact in quality reduction.


Biological Agriculture & Horticulture | 2010

Standardization and validation of the visual evaluation of biocrystallizations.

M. Huber; Jens-Otto Andersen; Johannes Kahl; Nicolaas Busscher; Paul Doesburg; Gaby Mergardt; Sebastian Kretschmer; Aneta Załęcka; Aumaporn Meelursarn; Angelika Ploeger; Dré Nierop; Lucy van de Vijver; Erik Baars

ABSTRACT The biocrystallization method has been used as a holistic method for evaluating food samples since the 1930s and has, as recent reviews have concluded, been successful in discriminating farming systems in several studies. However, it is noted that a standardization and validation for more objective means of evaluation of biocrystallization pictures and a clearly defined and communicable language, as well as possibilities for verification, are still lacking. During the years 2002–2006 a project for standardizing and validating the visual evaluation of these biocrystallizations took place, performed by a group consisting of three European research institutes. As no pre-set methodology nor norms for the visual evaluation existed, the choice was made to work according to existing norms on sensory analysis and to adapt these to the visual evaluation. The main norm, ISO-Norm 11035, for establishing sensory profiles was adapted towards these pictures. A panel was formed, mainly morphological descriptors were selected and defined, a scale with references was established, the panel trained and tested for pictures, produced on the basis of carrots of different qualities. Reliability and validity aspects of the panel, as well as the structure of the set of criteria were evaluated. According to standard rates for diverse statistical tests the panel has been validated for the evaluation of carrots with a defined set of descriptors. The set of descriptors contains sub-domains which can be used for further development of the evaluation method, towards a more integrated, holistic ‘Gestalt’-evaluation, and towards finally interpretation of these pictures. The followed process and results are unique in connection to this method.


Journal of Colloid and Interface Science | 2010

Evaporation influences on the crystallization of an aqueous dihydrate cupric chloride solution with additives

Nicolaas Busscher; Johannes Kahl; Paul Doesburg; Gaby Mergardt; Angelika Ploeger

The overall structure of the crystallization results of dihydrate cupric chloride with additives in a petri dish is affected by the duration between the beginning of the evaporation and the start of the crystallization. Experiments done with polyvinylpyrrolidone and freeze-dried carrot as additive are compared with those of the additive free case. The dependency of dewetting on the dihydrate cupric chloride amount is discussed in terms of depletion of the solution and the surface tension properties of the system. The possible influence of the depletion is depending on the moment the crystallization starts. This is defined by the size of the evaporated area on the dish.


Organic agriculture | 2017

Organic Agriculture 3.0 is innovation with research

Gerold Rahmann; M. Reza Ardakani; P. Barberi; Herwart Boehm; Stefano Canali; Mahesh Chander; Wahyudi David; Lucas Dengel; Jan Willem Erisman; Ana C. Galvis-Martinez; Ulrich Hamm; Johannes Kahl; Ulrich Köpke; Stefan Kühne; Sang-Beom Lee; Anne-Kristin Løes; Jann Hendrik Moos; Daniel Neuhof; Jaakko Nuutila; Victor Olowe; Rainer Oppermann; Ewa Rembiałkowska; Jim Riddle; Ilse A. Rasmussen; Jessica Shade; Sang Mok Sohn; Mekuria Tadesse; Sonam Tashi; Alan Thatcher; Nazim Uddin

Organic agriculture can and should play an important role in solving future challenges in producing food. The low level of external inputs combined with knowledge on sustainablity minimizes environmental contamination and can help to produce more food for more people without negatively impacting our environment. Organic agriculture not only includes farming as a production practice but it also includes processing, trade and consumption. Nevertheless, Organic agriculture must always evolve to overcome emerging challenges. Science-based knowledge attained through dedicated research is required to strengthen organic food and farming as a means to solve future challenges. In 2010, a global discussion about Organic 3.0 was initiated to address current problems our agri-food systems are facing. Many scientifically and practically proven results are already available to make organic agriculture a strong tool to solve some of these challenges. However, the organic agri-food system has to be developed further to fulfill its potential. The contribution of organic agriculture to help solve current problems linked to food security and environmental quality was discussed during the International Society of Organic Agricultural Research (ISOFAR) Symposium “Organic 3.0 is Innovation with Research”, held September 20–22, 2015, in conjunction with the first ISOFAR International Organic Expo, in Goesan County, Republic of Korea. Some of the world’s most active scientists in organic agriculture attended the symposium. This paper is a result of their discussions and aims to give an overview of research conducted and required to strengthen organic agriculture in its ambitions to overcome agronomic challenges, contribute to food security and protect our common environment.


Journal of Food Science and Technology-mysore | 2015

Quality assessment of baby food made of different pre-processed organic raw materials under industrial processing conditions

Kathrin Seidel; Johannes Kahl; Flavio Paoletti; Ines Birlouez; Nicolaas Busscher; Ursula Kretzschmar; Marjo Särkkä-Tirkkonen; Randi Seljåsen; Fiorella Sinesio; Torfinn Torp; Irene Baiamonte

The market for processed food is rapidly growing. The industry needs methods for “processing with care” leading to high quality products in order to meet consumers’ expectations. Processing influences the quality of the finished product through various factors. In carrot baby food, these are the raw material, the pre-processing and storage treatments as well as the processing conditions. In this study, a quality assessment was performed on baby food made from different pre-processed raw materials. The experiments were carried out under industrial conditions using fresh, frozen and stored organic carrots as raw material. Statistically significant differences were found for sensory attributes among the three autoclaved puree samples (e.g. overall odour F = 90.72, p < 0.001). Samples processed from frozen carrots show increased moisture content and decrease of several chemical constituents. Biocrystallization identified changes between replications of the cooking. Pre-treatment of raw material has a significant influence on the final quality of the baby food.


Frontiers in Nutrition | 2015

How the organic food system supports sustainable diets and translates these into practice

Carola Strassner; Ivana Cavoski; Raffaella Di Cagno; Johannes Kahl; Denis Lairon; Nicolas Lampkin; Anne-Kristin Løes; Darja Matt; Urs Niggli; Flavio Paoletti; Sirli Pehme; Ewa Rembiałkowska; Christian Schader; Matthias Stolze

Organic production and consumption provide a delineated food system that can be explored for its potential contribution to sustainable diets. While organic agriculture improves the sustainability performance on the production side, critical reflections are made on how organic consumption patterns, understood as the practice of people consuming significant amounts of organic produce, may also be taken as an example for sustainable food consumption. The consumption patterns of regular organic consumers seem to be close to the sustainable diet concept of FAO. Certain organic-related measures might therefore be useful in the sustainability assessment of diets, e.g., organic production and organic consumption. Since diets play a central role in shaping food systems and food systems shape diets, the role of organic consumption emerges as an essential topic to be addressed. This role may be based on four important organic achievements: organic agriculture and food production has a definition, well-established principles, public standards, and useful metrics. By 2015, data for organic production and consumption are recorded annually from more than 160 countries, and regulations are in force in more than 80 countries or regions. The organic food system puts the land (agri-cultura) back into the diet; it is the land from which the diet in toto is shaped. Therefore, the organic food system provides essential components of a sustainable diet.


Biological Agriculture & Horticulture | 2010

Questions on the Validation of Holistic Methods of Testing Organic Food Quality

Johannes Kahl; Nicolaas Busscher; Angelika Ploeger

ABSTRACT The regulation of organic production and processing focuses on process-related quality concepts rather than product oriented quality management. Therefore no standards exist that define the product oriented quality aspects of organic food. Methods such as the biocrystallization method seem to be able to classify organic products. Methods that are applied must reflect the history of the sample in growth and processing. These methods can be applied either for authentication or in relation to technical aspects (storage, processing steps) as well as human health. Each quality determination needs a question which will be answered from the laboratory method. The question needs to be specific enough and the method needs validation. Validation means testing if the method can answer the question or not. The process of validation is defined for analytical methods (single compound determination) in international norms such as the ISO 17025 for testing laboratories. The article describes how validation procedures can be applied to biocrystallization methods for quality tests of organic products.


Journal of the Science of Food and Agriculture | 2012

Multi-method comparison of carrot quality from a conventional and three organic cropping systems with increasing levels of nutrient recycling

Flavio Paoletti; Antonio Raffo; Hanne L. Kristensen; Kristian Thorup-Kristensen; Randi Seljåsen; Torfinn Torp; Nicolaas Busscher; Angelica Ploeger; Johannes Kahl

BACKGROUND There is a need to advance the study of the effects of organic and conventional systems on product quality. In particular, little is known about the importance of different farming practices concerning nutrient cycling and the use of external inputs within organic farming for the quality characteristics of the products. In this study the quality characteristics of carrot grown under different farming practices (conventional and three organic cropping systems) over a two-year period were analysed with the aim of discriminating between organic and conventional and investigating the effect of different organic farming practices concerning nutrient recycling and use of external nutrient input. RESULTS All quality characteristics measured did not give a clear differentiation between the carrots from the different growing systems, even when multivariate statistical evaluation (principal component analysis) was applied, because of the significance of the differences between the field replicates within each management system and of the seasonality. Only some tendencies were emphasised over the two years that could be related to the fertilisation practices and the external inputs used. CONCLUSION The results indicated that it was not possible to discriminate over the years between carrots from conventional and different organic cropping systems even though controlled conditions and a multi-method approach of analysis were adopted.

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Aneta Załęcka

Warsaw University of Life Sciences

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Ewa Rembiałkowska

Warsaw University of Life Sciences

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Flavio Paoletti

Consiglio per la ricerca e la sperimentazione in agricoltura

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Susanne Bügel

University of Copenhagen

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Ursula Kretzschmar

Research Institute of Organic Agriculture

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