New research with chlorine dioxide gas offers hope for fans of fresh sprouts who have food safety concerns about the pathogen-friendly growing process that makes them particularly susceptible to salmonella contamination.
Scientists have demonstrated that tumbling fresh bean sprouts in chlorine dioxide gas can reduce salmonella populations on bean sprouts 100,000-fold, compared to untreated sprouts. Traditional chlorine washes reduce salmonella populations 100-fold, according to a research report published in the "Journal of Food Protection."
In terms of percentages of pathogen reduction, the gas tumbling treatment achieved the so-called "four-nines" threshold, killing 99.9999% of the salmonella on the sprouts. Chlorine wash treatments only killed 99% of salmonella on sprouts.
The difference may seem miniscule, but in terms of foodborne pathogens, the numbers to the right of the decimal point are tremendous, according to researchers from Rutgers University and the Agricultural Research Service of the U.S. Department of Agriculture.
The researchers, lead by ARS microbiologist Bassam Annous, said in their report the gas treatment can reach salmonella within biofilm on the sprouts, something the industry standard of chlorine washes just doesn"t do.
"The difference in microbial reduction between chlorine dioxide gas versus aqueous chlorine wash points to the important role of surface topography, pore structure, bacterial attachment, and/or biofilm formation on sprouts," according to the research abstract.
"Scanning electron microscopy imaging indicated that chlorine dioxide gas treatment was capable of penetrating and inactivating cells attached to inaccessible sites and within biofilms on the sprout surface."
The researchers" report cited both the nutritional value of sprouts and the "major safety concern" that the lack of a kill step creates.
Those safety concerns include 39 foodborne salmonella outbreaks linked to sprouts in the U.S. and Canada since 1995, according to the Centers for Disease Control and the Canadian Food Inspection Agency.