630 Landwirtschaft und verwandte Bereiche
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Vorwort Nach Leuven (2000) und Sydney (2004) findet 2008 das 3. Symposium „Postharvest Unlimited“ in Berlin statt. Seit der ersten Veranstaltung wurden einige Themenkreise ausgetauscht, der primäre inhaltliche Schwerpunkt bleibt aber ganz klar die „Haltbarkeit von Obst und Gemüse entlang der gesamten Nacherntekette“. Dies ist ein Themenkomplex, der weltweit zunehmend in den Fokus der Diskussionen kommt. Das Symposium ist mit dem Abschlusstreffen der COST Action 924 „Enhancement and preservation of quality and health promoting components in fresh fruits and vegetables“ verknüpft. Das wissenschaftliche Programm, 55 Vorträge und 90 Poster, ist in die fünf Unterthemen der COST Action 924 gegliedert: 1) Verbesserung der Nacherntekette in Bezug auf Qualität, Gesundheit und Sicherheit; 2) Nacherntephysiologie und Metabolomics: Verbindung von Nachernteszenarien mit biochemischen und physiologischen Aspekten und Prozessen; 3) Alternative Methoden zur Verbesserung von Haltbarkeit und Sicherheit; 4) Zerstörungsfreie Methoden der Qualitätsanalyse, und 5) Modellierung als ein Werkzeug der Integration und des Managements der gesamten Nacherntekette. Die Veranstaltung wird von der Europäischen Gemeinschaft mit gefördert, wofür wir uns hier ganz herzlich bedanken möchten. Organisiert wird das Symposium vom Leibniz-Institut für Agrartechnik Potsdam-Bornim e. V. in enger Kooperation mit der Landwirtschaftlich-Gärtnerischen Fakultät der Humboldt- Universität zu Berlin. Wir sind sehr stolz, die Veranstaltung hier in Berlin durchführen zu dürfen und wünschen Ihnen erfolgreiche Präsentationen, interessante Diskussionen und einen angenehmen Aufenthalt in Berlin.
The task of this workshop is to inform the participants in detail about innovative optical methods to non-destructively detect health promoting compounds in fruit and vegetables. The main questions which have to be solved are: which compounds are important for human nutrition and how can we detect these substances. The following session is dealing with physical basics of spectrometry and recent hardware developments. The next morning different optical applications are presented followed by a lecture to quality insurance of new analytical methods. In the early afternoon several manufacturers for non destructive measuring devices will present their products.
Bornimer Agrartechnische Berichte
Bornimer Agrartechnische Berichte
Microbial contamination of fruits and vegetables can lead to high economic losses as well as to foodborne diseases. Washing procedures, which are commonly applied, only reduce the microbial load by 0.5 to 2 log units. Conventional thermal inactivation processes cannot be applied to fresh fruit and vegetables because these products are physiologically active food systems and temperatures above 45 °C can result in unwanted deterioration. Since heat sensitivity of fruits and vegetables limits the application of thermal inactivation processes, new emerging inactivation technologies have to be established to fulfil the requirements of food safety without affecting the produce quality. On one hand an early detection of produce contamination is essential to enable a contamination-related process design and on the other hand the efficiency of inactivation treatments has to be ensured and monitored. Monitoring of inactivation effects is commonly performed using traditional cultivation methods which have the disadvantage of the length of time needed to obtain results. In this study, the potential of flow cytometry in short-time monitoring of inactivation effects (thermal treatment, treatment with peracetic acid, ozone, and atmospheric pressure plasma) was investigated. For this purpose morphological and physiological properties of bacteria (size, granularity, membrane integrity (thiazole orange & propidium iodide), esterase activity (carboxyfluorescein diacetate), pump activity (carboxyfluorescein efflux), and membrane potential (3,3'-diethyloxacarbocyanine iodide)) were determined by flow cytometry. In the initial step appropriate staining procedures had to be developed. Especially, Gram-negative bacteria restrict the dye uptake due to their cell membrane constitution. This limits the determination of esterase activity of Gram-negative bacteria. In this study, an adequate dye concentration (0.83 mmol l-1 carboxyfluorescein diacetate) and incubation time (45 min) at 37 °C were defined which enables a reliable determination of esterase activity of Gram-negative bacteria. This developed staining procedure was successfully applied to monitor inactivation treatments. It was shown that the test bacteria (E. coli, L. innocua, P. carotovorum) lose their culturability due to the applied inactivation treatments but physiological activities were still detectable using flow cytometry. The remaining physiological activities may still result in product spoilage and also may cause human diseases. For example, E. coli cells still showed esterase activity after 10 min of thermal treatment at 70 °C and also after 2 min treatment with 0.25 % PAA at 10 °C. Esterase activity of E. coli cells was also detected after 2 min plasma treatment with an operating power of 40 W. The degree of bacterial damage due to the inactivation processes is highly dependent on treatment parameters as well as on treated bacteria. This study clearly indicates the potential of flow cytometry to monitor the efficacy of inactivation processes within a short time. Additionally, important information regarding the inactivation mechanisms can be obtained by flow cytometric measurements and this enables the definition of critical process.
The objective of the workshop titled “The future of the quarter individual milking” is to discuss the results of such collaboration with the pioneering scientists and to light the future path in milking technology area. This objective is planned to be achieved by gathering international state of knowledge in quarter individual milking and discussing the fundamental papers. Individual quarter milking is now a feature of automatic and conventional milking systems. Hence, a special attention to use systems with quarter-individual milking should be given to reduce SCC and udder diseases in all dairy farms.