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Publications (6)3.1 Total impact

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    ABSTRACT: In the course of the production of red wine, electroporation of mash enables a fast extraction of the red pigments from the skin without remarkable heating of the mash. For white wine, the formation of pores in the cells fosters, among others, the extraction of flavoring substances. During the harvest in 2008, the electroporation device KEA-WEIN has been operated successfully in two wineries. All together, more than 5 m<sup>3</sup> of mash has been treated. During this year's experiments, some experience in the operation of the electroporation device on-site in a winery has been gained. To facilitate the evaluation of the experimental results, the electroporation device has been equipped with different sensors and measurement systems, e.g., for the power drawn from the grid and the temperature of the mash before and after the electroporation. The data logged during one exemplary run are presented in this paper. Based on the measurements, an estimation about the energy consumption and efficiency of the device has been made. Must and wine made from the grape varieties Pinot Noir and Riesling have been chemically analyzed. Selected data are presented in this paper.
    IEEE Transactions on Plasma Science 09/2010; · 0.87 Impact Factor
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    ABSTRACT: The degree of cell opening after electroporation can be derived from an electric impedance measurement in a frequency range between 500 Hz and 10 MHz. For a simple detection in a continuously flowing medium a measurement at a discrete frequency evaluating the phase shift between a measurement voltage across an electrode system and a current flowing through the sample volume has been investigated. The paper describes impedance measurements of the mash of wine grapes. For different grape varieties the frequency dependency of the phase shift has been measured. The data showed that the frequency of maximum phase shift differs with the grape variety. For the mash of wine grapes the measurement results based on the measurement of the complex impedance have been compared to the degree of extraction of color from the peel tissue of red wine grapes as a conventional method to determine the degree of denaturation. The measurements showed a correspondence between the color intensity of the must and the electric measurements.
    IEEE Transactions on Dielectrics and Electrical Insulation 11/2009; · 1.36 Impact Factor
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    ABSTRACT: In the course of the production of red wine the electroporation of mash enables a fast extraction of the red pigments from the skin without remarkable heating of the mash. For white wine the formation of pores in the cells fosters among others the extraction of flavouring substances. To demonstrate and further investigate these advantages the mobile electroporation device KEA-WEIN has been built. During the harvest in 2008 the electroporation device KEA-WEIN has been operated successfully in two wineries. All together more than 5 m<sup>3</sup> of mash has been treated. The electroporation device KEA-WEIN is equipped with a 6-stage Marx-generator operating at a repetition rate of up to 20 Hz. For the pulse application the mash is pumped through an electroporation reactor with a homogeneous field distribution. It was the aim of this year's experiments to gain some experience in the operation of the electroporation device on-site in a winery. To facilitate the evaluation of the experimental results, the electroporation device has been equipped with different sensors and measurement systems, e.g. for the power drawn from the grid, the temperature of the mash before and after the electroporation, and the throughput. A computer interface enables a continuous data logging. The paper presents and discusses the measurement results and experience gained during operation.
    Pulsed Power Conference, 2009. PPC '09. IEEE; 08/2009
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    ABSTRACT: During the last few years, electroporation has been introduced to the food-processing industry as an effective method to open cell membranes for the extraction of substances. Currently, it has been investigated whether electroporation is also useful as a part of an energy-efficient drying process for plant material for the production of biofuel. To omit the use of additional water, the material has been placed in contact with the electrodes by means of its own juice after a first pressing step. This paper describes a laboratory-scale parameter study on the electroporation-assisted drying of whole maize plants, grass, and lucerne. The influence of the applied electric-field strength and the number of applied pulses on the drying curves is presented. For the electroporated material, an increased yield of juice during a pressing step after the electroporation and a faster drying have been observed.
    IEEE Transactions on Plasma Science 11/2008; · 0.87 Impact Factor
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    ABSTRACT: Summary form only given. In the course of the production of red wine, fermentation or heating are traditional methods for the disruption of the cells in the grape skin in order to extract the red pigments. Although fermentation is considered to guarantee the best quality of the wine, the extraction takes several days. A faster way is the thermal treatment, but extensive heat may have a bad influence on the flavor. An alternative method to foster the extraction of substances from biological cells is electroporation. It allows a fast processing without a remarkable temperature increase of the material. In recent years the electroporation of mash has been investigated. The experiments had been performed with the electroporation device KEA-WEIN manufactured by KEA-TEC based on the know-how by Forschungszentrum Karlsruhe. Although an extraction of the pigments within 24 h could be observed, the color of the electroporated must was less intense than the color of the thermally treated one. To analyze the electroporation assisted extraction process, laboratory-scale experiments have been performed. For the electroporation the numbers of applied pulses and the field strength have been varied. The electroporation effect has been verified by means of an impedance measurement. These results have been compared to a thermal denaturation with a subsequent extraction process. For the extraction the temperature has been varied. With an extraction at room temperature, both methods show nearly the same yield of tannin and color intensity. The original electroporation reactor of the electroporation device KEA-WEIN has an inhomogeneous field distribution. While high-field regions foster a flash-over inside the reactor, an incomplete opening of the membrane may occur in the low-field regions. To guarantee a good electroporation effect now a new electroporation reactor with a more homogeneous field distribution has been implemented. In autumn 2007 approximately 1 m3 of must hav- - e been treated with the new reactor successfully. After finishing the vinification process a comparison based on chemical analysis and additional sensoric tasting will be made to evaluate the quality.
    IEEE International Conference on Plasma Science 01/2008;
  • M. Sack, R. Stangle
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    ABSTRACT: Since 2000 a mobile electroporation device has been operated for scientific and testing purposes. Now a breakdown of the insulation at one Marx generator output to ground has occurred due to an electric overstressing. This failure makes a redesign of the Marx generator necessary. For the redesign a bipolar Marx generator with a transient insulation to ground has been compared to one with a fixed center ground connection. The paper describes why the solution with the fixed ground connection is considered to be more suitable for the application in the mobile electroporation device.
    Pulsed Power Conference, 2007 16th IEEE International; 07/2007