Inactivation of Escherichia coli O157:H7, Salmonella enteritidis, and Listeria monocytogenes on apples, oranges, and tomatoes by lactic acid with hydrogen peroxide

The objective of this study was to develop a practical and effective method for inactivating or substantially reducing Escherichia coli O157:H7, Salmonella Enteritidis, and Listeria monocytogenes on apples, oranges. and tomatoes. Apples, oranges, and tomatoes were spot-inoculated with five-strain mixtures of E. coli O157:H7, Salmonella Enteritidis. and L. monocytogenes near the stem end and were submerged in sterile deionised water containing 1.5% lactic acid plus 1.5% hydrogen peroxide for 15 min at 40degreesC. Inoculated samples treated with sterile deionized water at the same temperature and for the same duration served as controls. The bacterial pathogens on fruits subjected to the chemical treatment ere reduced by >5.0 log(10) CFU per fruit, whereas washing in deionized water decreased the pathogens by only 1.5 to 2,0 log(10) CFU per fruit. Furthermore, substantial Populations of the pathogens survived in the control wash water. whereas no E. coli O157:H7, Salmonella Enteritidis, or L. monocytogenes Cells were detected in the chemical treatment solution. The sensory and qualitative characteristics of apples treated with the chemical wash solution ere not adversely affected by the treatment, It as found that die treatment developed in this study could effectively be used to kill E. coli O157:H7. Salmonella Enteritidis. and L monocytogenes on apples, oranges, and tomatoes at the processing or packaging level.