Inactivation of non-toxigenic and toxigenic Escherichia coli O157:H7 inoculated on minimally processed tomatoes and cucumbers: Utilization of hydrosols of Lamiaceae spices as natural food sanitizers

Abstract

Hydrosols obtained from three Lamiaceae plants (thyme, summer savory and oregano) were evaluated for their antibacterial activity against two Escherichia coli O157:H7 strains inoculated to fresh-cut tomato and cucumbers. Complete inhibitions of both E. coli O157:H7 strains on fresh-cut tomato and cucumber were achieved by all hydrosol treatments in varying treatment periods for low inoculation level (10(4) cfu/mL) while water wash (control) was inefficient to eliminate the bacterial populations. In the case of high inoculation (10(6) cfu/mL), hydrosol treatments reduced the populations to undetectable levels on cucumber cuts. Moreover, reductions in E. coli O157:H7 populations of fresh-cut tomato were always higher than 2.50 log cfu/g at this inoculation. The results suggested that hydrosols from Lamiaceae plants have the potential to be used as natural food sanitizers for fresh-cut tomatoes and cucumbers to provide their microbial safety without causing any sensorial defect on treated products or health problems in human. (C) 2012 Elsevier Ltd. All rights reserved.