Author
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FETT, WILLIAM |
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Submitted to: Food Microbiology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 8/1/2002 Publication Date: 8/1/2002 Citation: N/A Interpretive Summary: Illnesses due to consumption of alfalfa and other types of sprouts contaminated with bacterial human pathogens continue to occur both in the US and in other countries. As the original source of the pathogen is almost always the seed used for sprouting, improved methods for sanitizing sprouting seed are needed. In this study we wished to determine the efficacy of combining water rinses of alfalfa seed along with treatment with high levels of chlorine (18,000 ppm). Such treatments resulted in 99.99% reductions of two pathogens, Salmonella and Escherichia coli O157:H7, from alfalfa seed that had been inoculated in the laboratory. Similar treatment of alfalfa seed naturally contaminated with Salmonella led to the complete elimination of the pathogen. Most of the 29 types of sprouting seed tested could withstand such a treatment without a drastic reduction in seed germination rate or percentage. Treatment of sprouting seed with high levels of chlorine along with water rinses should significantly reduce or eliminate outbreaks of foodborne illness due to contaminated sprouts. Technical Abstract: Treatment of laboratory-inoculated and naturally contaminated alfalfa seed with free chlorine provided by Ca(OCl)2 along with rinsing both before and after treatment was evaluated for the elimination of Escherichia coli O157:H7 and Salmonella. Treatment (10 min) of laboratory-inoculated seed with buffered (to pH 6.8) or unbuffered 3.0% (w/v) Ca(OCl)2 (16,000 and 18,000 ppm free chlorine, respectively) along with the rinses led to significant reductions of the pathogens (3.9 to 4.5 log cfu g-1) but not their elimination. Lower concentrations of Ca(OCl)2 (2.0 to 2.5% w/v) were less effective. Altering the treatment times to 5 or 20 min did not lead to large changes in efficacy. Treatment (10 min) of alfalfa seed naturally contaminated with Salmonella with buffered or unbuffered 3.0% (w/v) Ca(OCl)2 eliminated the pathogen from the seed. A similar treatment with buffered 0.3% (w/v) Ca(OCl)2 was ineffective. Of 29 types of sprouting seed treated for 10 min with buffered 3.0% Ca(OCl)2, only the germination of spelt and hard, soft and Kamut wheats was drastically reduced. Treatment of sprouting seed with high levels of chlorine should help to reduce the number of sprout-related outbreaks of foodborne illness. |
