AUTHOR=Li KaWang , Chiu Yu-Chun , Jiang Wentao , Jones Lisa , Etienne Xiaoli , Shen Cangliang 

TITLE=Comparing the Efficacy of Two Triple-Wash Procedures With Sodium Hypochlorite, a Lactic–Citric Acid Blend, and a Mix of Peroxyacetic Acid and Hydrogen Peroxide to Inactivate Salmonella, Listeria monocytogenes, and Surrogate Enterococcus faecium on Cucumbers and Tomatoes

JOURNAL=Frontiers in Sustainable Food Systems

VOLUME=4

YEAR=2020

URL=https://www.frontiersin.org/journals/sustainable-food-systems/articles/10.3389/fsufs.2020.00019

DOI=10.3389/fsufs.2020.00019

ISSN=2571-581X

ABSTRACT=<p>This study was designed to evaluate two triple-wash procedures with commercial antimicrobials to inactivate foodborne pathogens and surrogate bacteria on cucumbers and tomatoes. Fresh, West Virginia locally grown cucumbers and tomatoes were dip-inoculated with <italic>Salmonella</italic> Typhimurium and Tennessee, <italic>Listeria monocytogenes</italic> (3-strain), and <italic>Enterococcus faecium</italic>. Produce was washed through two triple-wash steps (10 s each) including water dip, antimicrobial dip, and water dip (WAW), or water dip, water dip, and antimicrobial dip (WWA), followed by draining (2 min) on aluminum foil. A triple-water (WWW) process was also included as a water-only control. Tested treatments were (1) water; (2) sodium hypochlorite (SH, 100 ppm, pH 8.2); (3) acidified sodium hypochlorite (ASH, 100 ppm, pH 6.8 adjusted by citric acid); (4) lactic and citric acid blend (LCA, 2.5%); and (5) a H<sub>2</sub>O<sub>2</sub>-peroxyacetic acid mix [SaniDate-5.0 (SD) 0.0064, 0.25, and 0.50%]. Surviving bacteria were recovered on xylose lysine tergitol-4 (XLT-4, <italic>Salmonella</italic>), Modified Oxford (MOX, <italic>L. monocytogenes</italic>), and bile esculin agar (<italic>E. faecium</italic>). Data (two replicates, four samples/replicate) were analyzed using the mixed model procedure of SAS (<italic>P</italic> = 0.05). Counts of <italic>Salmonella, L. monocytogenes</italic>, and <italic>E. faecium</italic> on unwashed cucumbers and tomatoes were 5.42–6.23, 6.31–6.92, and 6.05 log colony-forming units (CFU)/produce, respectively. Triple-wash with water only reduced all three tested bacteria by 0.45–1.36 log CFU/fruit. Triple-wash by WWA with antimicrobials achieved additional reductions [least squares means (LsMeans)] of 0.38 log CFU/cucumber (<italic>Salmonella</italic>), 0.56 log CFU/cucumber (<italic>E. faecium</italic>), 1.48 log CFU/tomato (<italic>Salmonella</italic>), 1.09 log CFU/tomato (<italic>L. monocytogenes</italic>), and 0.71 log CFU/tomato more than the WAW procedure. Applying SD-0.25 and SD-0.50% solutions in triple-washing cucumbers and tomatoes resulted in reductions (<italic>P</italic> &gt; 0.05) similar to ASH and greater reductions (<italic>P</italic> &lt; 0.05) than SH and LCA. <italic>E. faecium</italic> was less susceptible (<italic>P</italic> &lt; 0.05) or there was no difference (<italic>P</italic> &gt; 0.05) in comparison with <italic>Salmonella</italic> in most cases, except for tomatoes treated with WWA. The results of this study indicate that SD could be used as an alternative antimicrobial agent for chlorine water in triple-wash processing at local small produce plants. Future pilot plant validation studies and cost-effectiveness analyses are needed for applying SD solutions in triple-wash by WV local small produce growers.</p>