E. coli O157:H7 and norovirus have each been responsible for outbreaks of foodborne illness involving fresh leafy green vegetables.... Show moreE. coli O157:H7 and norovirus have each been responsible for outbreaks of foodborne illness involving fresh leafy green vegetables. Peroxyacetic acid (POAA) has the potential to be an effective sanitizer during commercial fresh-cut produce washing. The addition of high power ultrasound (HPU) to the washing system may enhance the POAA efficacy. The purpose of this study was to reduce E. coli O157:H7 and norovirus contamination during commercial fresh-cut lettuce washing using POAA and HPU. Fresh-cut romaine lettuce leaves were inoculated with E. coli O157:H7 or murine norovirus (MNV, a surrogate for the human norovirus) and washed by POAA and HPU. Cross-contamination was tested by washing clean leaves in contaminated processing water where pre-inoculated leaves were washed previously. A high level of cross-contamination (4.5-log CFU/g E. coli) occurred after uninoculated leaves were rinsed in contaminated wash water for 2 min. A subsequent 2 min wash in POAA alone or in combination with HPU reduced counts by approximately 1.2-log and 2.3-log, respectively. More than 2-log norovirus was removed from washing 2 min in either DI water or POAA. However infectious MNV washed from leaves was not detected in wash water containing POAA. Those results implied a high possibility of cross-contamination during freshproduce washing, and indicate that adding POAA and HPU in addition to washing water in wash water can reduce cross-contamination rate. M.S. in Food Safety and Technology, December 2011 Show less
