Staphylococcal food poisoning results from the con- sumption of a food in which enterotoxigenic staphylococci have grown and produced toxins. Within 1–6 h after inges- tion of staphylococcal enterotoxin (SEs)-contaminated foods, victims experience nausea, abdominal cramps, vom-
iting, and diarrhea (Archer & Young, 1988; Garthright, Archer, & Kvenberg, 1988). Although EO water has been proved to be effective against Staphylococcus aureus, trace amounts of enterotoxin produced by the bacteria may remain active after disinfection. Suzuki, Itakura, Watana- be, and Ohta (2002a) reported that exposure of 70 ng, or 2.6 pmol, of staphylococcal enterotoxin A (SEA) in 25 lL of phosphate buffer saline (PBS) to a 10-fold volume of EO water, or 64.6 · 103-fold molar excess of HOCl in EO water, caused a loss of immuno-reactivity between SEA and a specific anti-SEA antibody. Native PAGE indicated that EO water caused fragmentation of SEA, and amino acid analysis indicated a loss in amino acid content, in par- ticular Met, Tyr, Ile, Asn, and Asp. EO water denatures SEA through an oxidative reaction caused by OH radicals and reactive chlorine. Thus, EO water might be useful as a preventive measure against food-borne disease caused by SEA.
Suzuki et al. (2002b) also reported that EO water could sterilize Aspergillus parasiticus and eliminate the mutage- nicity of aflatoxin AFB1 by the OH radical originating from HOCl. Exposing A. parasiticus at an initial density of 103 spores in 10 lL to a 50-fold volume (500 lL) of EO water containing 390 lmol HOCl for 15 min at room temperature resulted in a complete inhibition of fungal growth. Three nanomoles of AFB1 showed a high mutage- nicity for both Salmonella Typhimurium TA98 and TA100 strains, but this mutagenicity was reduced markedly after exposure to 20-fold molar amount of HOCl in the EO water in both TA98 and TA100. However, foods contain compounds such as proteins, lipids, vitamins, minerals, color, etc., and concerning food soundness, it may not nec- essarily be appropriate to apply EO water to wash food materials.