Postharvest control of Escherichia coli O157:H7 on romaine lettuce using a novel pelargonic acid sanitizer

Abstract

A novel pelargonic acid (Pel) emulsion was evaluated for its ability to reduce Escherichia coli O157:H7 on romaine lettuce and cross-contamination The Pel emulsion was tested at concentrations of 7.50, 30, and 50 mM and compared to 80 ppm peroxyacetic acid (PAA), 200 ppm free chlorine (hypochlorous acid), sterile deionized water (SDW), and a no-rinse treatment. Efficacy of all sanitizer treatments was also examined in presence of organic matter (0.5% w/v romaine lettuce puree) in wash water. Sanitizer efficacy and impact on lettuce quality were examined after storing for 7 days at 4 °C. Overall, Pel emulsions at 30 and 50 mM significantly reduced E. coli O157:H7 by ≥ 0.6 log CFU/g immediately post-wash compared to all other treatments. Pel at 30 and 50 mM also performed significantly better than all wash treatments after 24 h and 7 d storage. Compared to the SDW treatment (4.9 log CFU/g at 0 h), All sanitizer treatments effectively limited cross-contamination by more than 3 log CFU/g, regardless of time interval or the presence of organic load. However, Pel exerted phytotoxic activity on lettuce leaves, so reformulation for produce washing or alternative applications such as non-food contact surface sanitation may be more appropriate.