The efficacy of combined (NaClO and organic acids) washing treatments in controlling Escherichia coli O157:H7, Listeria monocytogenes and spoilage bacteria on shredded cabbage and bean sprout

Abstract

The present study evaluated the efficacy of using 100 mg/L sodium hypochlorite (NaClO) followed by a second wash with various organic acids in reducing natural bacterial contaminants or intentionally contaminated Escherichia coli O157:H7 or Listeria monocytogenes in shredded cabbage or bean sprouts. NaClO wash followed by a second wash with any of the organic acids used could suppress the mesophilic and coliform bacterial growth continuously for up to 3 days of storage at 10 °C for shredded cabbage and 1 day for bean sprouts. For laboratory-inoculated (E. coli O157:H7 or L. monocytogenes) vegetable samples, the NaClO wash reduced both pathogens by approximately 3.0 log CFU/g, and a secondary wash with any of the organic acids used in this study reduced an additional 1.0 log CFU/g of these pathogens. Phytic acid exhibited similar or higher bacteriostatic effectiveness than the tested organic acids. Moreover, phytic acid washes effectively retained the color of bean sprouts and shredded cabbage throughout the 4 days of storage at 10 °C. Therefore, our results suggest that a NaClO wash followed by a second wash with phytic acid or any organic acid mentioned above could enhance the sanitation of raw vegetables.