Efficacy of Various Sanitizers against Salmonella during Simulated Commercial Packing of Tomatoes

Abstract

Chemical sanitizers are usually added to dump tank water to minimize cross-contamination during tomato packing. However, the efficacy of sanitizers continues to be questioned. This study assessed the ability of six commonly used sanitizers (40 ppm of peroxyacetic acid, 40 ppm of mixed peracid, 40 ppm of available chlorine alone or acidified to pH 6.0 with citric acid or T-128, and electrolyzed water containing 40 ppm of available chlorine at pH 6.7) to reduce Salmonella on tomatoes, in wash water, and on equipment surfaces using a pilot-scale processing line. Red round tomatoes (11.3 kg) were dip inoculated to contain Salmonella at ∼6 log CFU/g, air dried for 2 h, treated for 2 min in a 3.3-m-long dump tank and then dried on a roller conveyor, with sanitizer-free water serving as the control. Tomato and water samples were collected at 15-s intervals during washing with additional dump tank, water tank, and roller conveyor surface samples collected after washing. All samples were appropriately neutralized, diluted, and surface plated on Trypticase soy agar containing 0.6% yeast extract, 0.05% ferric ammonium citrate, and 0.03% sodium thiosulfate with or without membrane filtration to enumerate Salmonella. All six sanitizer treatments were more efficacious than the water control (P ≤ 0.05), with chlorine plus citric acid yielding the greatest Salmonella reduction on tomatoes (3.1 log CFU/g). After processing, all sanitizer wash solutions contained significantly lower (P ≤ 0.05) levels of Salmonella than the water control (3.0 log CFU/ml). The four chlorine-based sanitizer treatments yielded significantly lower Salmonella populations (P ≤ 0.05) in the wash solution compared with peroxyacetic acid and mixed peracid. After processing with sanitizers, Salmonella populations decreased to nondetectable levels (<0.2 log CFU/100 cm(2) ) on the equipment surfaces.

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

“…The WWW control showed reductions of 0.5-1.2 log CFU/fruit across all tested pathogens on cucumbers and tomatoes in this study. These results are similar to those of Wang and Ryser (2014), who 8 | A comparison of the reduction of Salmonella and surrogate E. faecium on tomatoes (log CFU/tomato) by triple-wash procedure WAW or WWA in water, SH (100 ppm, pH 8.2), ASH (SH, 100 ppm, pH 6.8 adjusted by citric acid), LCA (Veggiexide ® , 2.5%), and a PAA and hydrogen peroxide mix (SD, 0.0064, 0.25, and 0.50%). reported a 1.0 log CFU/g reduction of Salmonella from plain water wash for 15 s in a pilot-scale processing line.…”

“…The results of this study suggest that the antimicrobial efficacy of chlorinated water in the concentration of 100 ppm was significant against Salmonella, and the reductions were improved when the pH of SH was adjusted to 6.8 in most cases, except for E. faecium on tomatoes. A previous study by Wang and Ryser (2014) also reported that chlorine plus citric acid (pH 6.0) yielded a greater reduction (3.1 log CFU/g) of Salmonella on tomatoes than chlorine at alkaline status (2.1 log CFU/g). This is because hypochlorous acid, the most effective antimicrobial component, predominates in chlorine water at near-neutral pH, whereas the hypochlorite would be in the ionic form rather than the antimicrobial protonated state in an alkaline-pH solution (White, 2010).…”

Postharvest Supply Chain with Microbial Travelers: a Farm-to-Retail Microbial Simulation and Visualization Framework

“…Particularly, removal was the most influential model parameter for APC but was less influential for TC levels. Removal during washing via dump tanks or spray and brush systems has been studied for several produce commodities, and the importance of chlorine efficacy is well reported (29)(30)(31); however, it is also well established that removal of microorganisms from produce by chlorinated washing is unpredictable and prone to the cross-contamination of other products (32,33). Furthermore, growth rates at the packinghouse, distribution center, and retail storage were highly influential parameters, most likely due to long holding times and variable conditions suitable for survival and growth.…”

Effect of relative humidity on inactivation of foodborne pathogens using chlorine dioxide gas and its residues on tomatoes

“…Recently, several sanitizers have been evaluated to inactivate foodborne pathogens on tomatoes, including electrolysed water (Wang and Ryser ), alkaline water (Islam et al . ), ozone (Mukhopadhyay et al .…”