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ARS Home » Research » Publications at this Location » Publication #135326
Title: RF DIELECTRIC HEATING FOR REDUCTION OF HUMAN PATHOGENS ON SPROUTING SEED

Author
item Nelson, Stuart
item LU, C.Y. - UGA-ATHENS, GA
item BEUCHAT, L.R. - UGA-GRIFFIN, GA
item HARRISON, M.A. - UGA-ATHENS, GA

Submitted to: Microwave Power Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/22/2002
Publication Date: 7/22/2002
Citation: NELSON, S.O., LU, C., BEUCHAT, L., HARRISON, M. RF DIELECTRIC HEATING FOR REDUCTION OF HUMAN PATHOGENS ON SPROUTING SEED. MICROWAVE POWER SYMPOSIUM PROCEEDINGS. 2002. PP. 46-49.

Interpretive Summary: There have been some outbreaks of human illness associated with eating vegetable sprouts that were contaminated with Salmonella and E. coli. The likely source of the bacterial contamination has been identified as the sprouting seed used for sprout production. Several chemical treatments and produce washes have been tested, but none has so far been found completely effective in eliminating the bacterial contamination from the seed. Radio?frequency and microwave dielectric heating treatments were earlier found effective for increasing the germination of alfalfa seed lots that contain percentages of hard seed, i.e., seed with naturally impermeable seed coats that protect the seed, but also prevent the entrance of moisture needed for germination. Such seed lots in the commercial seed trade are scarified, i.e., subjected to an abrasive process that scratches the seed coat to permit the entry of moisture so they can germinate. Therefore, research was conducted to determine whether such dielectric heating treatments might be useful in reducing bacterial populations on alflafa seed. Treatments of a few seconds that raised the temperature of alfalfa seeds, artificially contaminated with Salmonella, E. coli, and Listeria, were found to provide significant reductions in the bacterial populations without significantly lowering the seed germination. However, treatments that reduced bacterial populations to desirable levels also reduced the seed germination. Those treatments that lowered bacterial populations also increased the seed germination percentages, thus improving sprout yield. Thus, dielectric heating treatments that produce moderate reductions in bacterial populations and improve sprout yield might be considered for application, but are not likely to provide the desired control of bacteria that may contaminate alfalfa seed stocks intended for sprout production.

Technical Abstract: 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 that was artificially contaminated with three pathogens. 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.