Sanitizing Sprouts - Brief Article

Nutrition Research Newsletter, Jan, 2001

Although they are considered health foods, seed sprouts can be dangerous. Because they are grown in high moisture environments and are often times eaten raw, they are prone to carry Salmonella and other foodborne pathogens. In recent years, there have been multiple reports of human illness associated with seed sprouts in the United States. Because treatment of seeds with sanitizers has proven to be ineffective at times, the use of 20,000 ppm calcium hypochlorite is recommended for sanitizing seeds intended for sprout production. However, use of calcium hypochlorite may not eliminate Escherichia coli O157:H7 and use of such high concentrations of this chemical may cause other harm. Therefore, identification of other, more effective and less toxic sanitizers is warranted. Although a large number of aqueous chemical treatments have been evaluated for their efficacy in destroying pathogens on alfalfa seeds, a single or combination treatment that is capable of sterilizing seeds without reducing germination percentage has not been found.

Recently, researchers evaluated chemical sanitizers for their efficacy in killing Salmonella on alfalfa seeds and sparing the germination process. Six Salmonella serotypes isolated from outbreaks of salmonellosis associated with raw vegetables or unpasteurized fruit juice were utilized in this study. Inoculated seeds were submersed in 20,000 ppm free chlorine, 5% [Na.sub.3][PO.sub.4], 8% [H.sub.2][O.sub.2], 1% Ca[(OH).sub.2], 1% cacinated calcium 5% lactic acid, 5% citric acid, 1,060 ppm Tsunami or Vortex, 1,200 ppm acidified Na[ClO.sub.2], or 5% acetic acid for 10 minutes.

Twenty thousand ppm free chlorine, 5% [Na.sub.3][PO.sub.4], 8% [H.sub.2][O.sub.2], 1% Ca[(OH).sub.2], 1% cacinated calcium 5% lactic acid, 5 % citric acid resulted in reductions of 2.0 to 3.2 [log.sub.10] CFU/g. Treatments with the remaining chemicals were less effective in reducing Salmonella populations. With the exceptions of 8% [H.sub.2][O.sub.2], 1% Ca[(OH).sub.2], 1% cacinated calcium, none of the treatments reduced the number of Salmonella by more than 2.2 [log.sub.10] CFU/g without significantly reducing the seed germination percentage. Treatment with 5% acetic, lactic, or citric acids significantly reduced the ability of the seeds to germinate.

Although a few treatments decreased the amount of Salmonella, none of the treatments analyzed in this work eliminated the pathogen completely. Further research is needed to determine the appropriate sanitizing treatment to ensure safety of alfalfa seeds from Salmonella.

W. Weissinger, L. Beuchat. Comparison of aqueous chemical treatments to eliminate Salmonella on alfalfa seeds. Journal of Food Protection;63:1475-1482 (November, 2000) [Correspondence: L. R. Beuchat. Phone: 770-4124740. Fax: 770-229-3216. E-mail: lbeucha@cfsque.griffin.peachnet.edu].

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