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Radio-Frequency Dielectric Heating of Alfalfa Seed for Reduction of Human Pathogens

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  Paper number  026001,  2002 ASAE Annual Meeting . (doi: 10.13031/2013.9708) @2002
Authors:   S. O. Nelson, C.-Y. Lu
Keywords:   Alfalfa seed, Radio-frequency heating, Sprouts, Human pathogens

The problem of bacterial contamination of vegetable seed sprouts produced for human consumption is reviewed briefly. The potential for controlling human bacterial pathogens on alfalfa seed used in the production of sprouts by dielectric heating was studied by experimental exposure of alfalfa seed artificially contaminated with Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes to radio-frequency (RF) dielectric heating treatments at 39 MHz and different electric field intensities for varying times of exposure. Moisture content of alfalfa seed and final temperatures produced by the RF exposures were determined, and control and treated seed samples were analyzed in the laboratory for reduction of bacterial populations and effects on seed germination. Significant reductions in populations of all three pathogens were achieved without reductions in seed germination, but desired levels of pathogen reduction were not achieved without significant damage to seed germination. However, treatments effective in reducing bacterial pathogen populations also increase alfalfa seed germination through reductions in hard seed percentages, so the combined benefits should be considered in evaluating dielectric heating treatments for practical use.

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