Effects of Chlorine-Based Antimicrobial Treatments on the Microbiological Qualities of Selected Leafy Vegetables and Wash Water

Pan, Xiaojun; Nakano, Hiroyuki

doi:10.3136/fstr.20.765

Cited by 12 publications

(17 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Zhang and Farber [48] reported the maximum log 10 reduction of L. monocytogenes at 4 and 22° C to be 1.3 and 1.7 log 10 CFU/g for lettuce and 0.9 and 1.2 log 10 CFU/g for cabbage, respectively. In the current study, chlorine (200 ppm) produced greater reductions for inoculated pathogens versus naturally occurring Enterobacteriaceae (Table 1 and Table 2; Figure 1), similar to results reported by other researchers testing 100–200 ppm HOCl on spinach [49,50], potentially resulting from differences in differing attachment strengths from naturally occurring versus inoculated pathogen cells, as well as potential for naturally occurring cells to locate effectively into protected niches on the leaf surface [51]. Erkman [52] reported that 10 ppm HOCl (pH 7.0) applied via immersion with agitation for 5 min reduced E. coli on lettuce, parsley, and pepper by 1.2, 1.6, and 2.6 log 10 CFU/mL, respectively.…”

Section: Discussionsupporting

confidence: 89%

Inhibition of Escherichia coli O157:H7 and Salmonella enterica Isolates on Spinach Leaf Surfaces Using Eugenol-Loaded Surfactant Micelles

Ruengvisesh

Kerth

Taylor

2019

Foods

View full text Add to dashboard Cite

Spinach and other leafy green vegetables have been linked to foodborne disease outbreaks of Escherichia coli O157:H7 and Salmonella enterica around the globe. In this study, the antimicrobial activities of surfactant micelles formed from the anionic surfactant sodium dodecyl sulfate (SDS), SDS micelle-loaded eugenol (1.0% eugenol), 1.0% free eugenol, 200 ppm free chlorine, and sterile water were tested against the human pathogens E. coli O157:H7 and Salmonella Saintpaul, and naturally occurring microorganisms, on spinach leaf surfaces during storage at 5 °C over 10 days. Spinach samples were immersed in antimicrobial treatment solution for 2.0 min at 25 °C, after which treatment solutions were drained off and samples were either subjected to analysis or prepared for refrigerated storage. Whereas empty SDS micelles produced moderate reductions in counts of both pathogens (2.1–3.2 log10 CFU/cm2), free and micelle-entrapped eugenol treatments reduced pathogens by >5.0 log10 CFU/cm2 to below the limit of detection (<0.5 log10 CFU/cm2). Micelle-loaded eugenol produced the greatest numerical reductions in naturally contaminating aerobic bacteria, Enterobacteriaceae, and fungi, though these reductions did not differ statistically from reductions achieved by un-encapsulated eugenol and 200 ppm chlorine. Micelles-loaded eugenol could be used as a novel antimicrobial technology to decontaminate fresh spinach from microbial pathogens.

show abstract

Section: Discussionsupporting

confidence: 89%

Inhibition of Escherichia coli O157:H7 and Salmonella enterica Isolates on Spinach Leaf Surfaces Using Eugenol-Loaded Surfactant Micelles

Ruengvisesh

Kerth

Taylor

2019

Foods

View full text Add to dashboard Cite

show abstract

“…A reduction of <1 log CFU•g −1 after a 5 min dip in 100 mg•L −1 free chlorine compared to a plain water dip when inoculated lettuce leaves with E. coli was obtained by Behrsing et al [34]. Pan and Nakano [35] also observed a reduction of approximately 2 log CFU/g in E. coli O157:H7 levels on leafy vegetables, as lettuce was washed with NaClO at 0, 50, 100, 200, and 500 ppm for 5 min compared with the unwashed lettuce. Seo and Frank [36] showed that while E. coli O157:H7 cells on the surface of iceberg lettuce leaves were killed by a 20 mg•L −1 chlorine decontamination treatment, the cells inside the stomata or those which had penetrated the cut edge of a leaf survived.…”

Section: Resultsmentioning

confidence: 91%

Evaluation by Flow Cytometry of Escherichia coli Viability in Lettuce after Disinfection

et al. 2019

View full text Add to dashboard Cite

Foodborne outbreaks due to the consumption of ready-to-eat vegetables have increased worldwide, with Escherichia coli (E. coli) being one of the main sources responsible. Viable but nonculturable bacteria (VBNC) retain virulence even after some disinfection procedures and constitute a huge problem to public health due to their non-detectability through conventional microbiological techniques. Flow cytometry (FCM) is a promising tool in food microbiology as it enables the distinction of the different physiological states of bacteria after disinfection procedures within a short time. In this study, samples of lettuce inoculated with E. coli were subject to disinfection with sodium hypochlorite at free chlorine concentrations of 5, 10, 25, 50, and 100 mg·L−1 or with 35% peracetic acid at concentrations of 5, 10, 25, and 50 mg·L−1. The efficiency of these disinfectants on the viability of E. coli in lettuce was evaluated by flow cytometry with LIVE/DEAD stains. Results from this study suggest that FCM can effectively monitor cell viability. However, peracetic acid is more effective than sodium hypochlorite as, at half the concentration, it is enough to kill 100% of bacteria and always induces a lower percentage of VBNC. Finally, we can conclude that the recommended levels of chemical disinfectants for fresh fruit and vegetables are adequate when applied in lettuce. More importantly, it is possible to ensure that all cells of E. coli are dead and that there are no VBNC cells even with lower concentrations of those chemicals. These results can serve as guidance for lettuce disinfection, improving quality and the safety of consumption.

show abstract

“…However, chemical agents are often less efficient than physical methods (e.g., heat and pressure) in achieving microbial reduction. This limitation is, in part, due to regulatory limits on the allowable concentrations of these chemical agents in food and water systems and to the dependence of their biological activity on factors such as pH and temperature (10,11). Consequently, extended exposure times are often required to achieve an effective microbial load reduction using chemical agents.…”

mentioning

confidence: 99%

“…Consequently, extended exposure times are often required to achieve an effective microbial load reduction using chemical agents. To overcome these limitations, traditionally some chemical agents have been used following an initial physical treatment, mainly with the aims of extending the shelf life of food and preserving food and water systems (10,12).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Enhanced Antimicrobial Activity Based on a Synergistic Combination of Sublethal Levels of Stresses Induced by UV-A Light and Organic Acids

Oliveira

Cossu

Tikekar

et al. 2017

Appl Environ Microbiol

View full text Add to dashboard Cite

The reduction of microbial load in food and water systems is critical for their safety and shelf life. Conventionally, physical processes such as heat or light are used for the rapid inactivation of microbes, while natural compounds such as lactic acid may be used as preservatives after the initial physical process. This study demonstrates the enhanced and rapid inactivation of bacteria based on a synergistic combination of sublethal levels of stresses induced by UV-A light and two food-grade organic acids. A reduction of 4.7 ± 0.5 log CFU/ml in O157:H7 was observed using a synergistic combination of UV-A light, gallic acid (GA), and lactic acid (LA), while the individual treatments and the combination of individual organic acids with UV-A light resulted in a reduction of less than 1 log CFU/ml. Enhanced inactivation of bacteria on the surfaces of lettuce and spinach leaves was also observed based on the synergistic combination. Mechanistic investigations suggested that the treatment with a synergistic combination of GA plus LA plus UV-A (GA+LA+UV-A) resulted in significant increases in membrane permeability and intracellular thiol oxidation and affected the metabolic machinery of In addition, the antimicrobial activity of the synergistic combination of GA+LA+UV-A was effective only against metabolically active O157:H7. In summary, this study illustrates the potential of simultaneously using a combination of sublethal concentrations of natural antimicrobials and a low level of physical stress in the form of UV-A light to inactivate bacteria in water and food systems. There is a critical unmet need to improve the microbial safety of the food supply, while retaining optimal nutritional and sensory properties of food. Furthermore, there is a need to develop novel technologies that can reduce the impact of food processing operations on energy and water resources. Conventionally, physical processes such as heat and light are used for inactivating microbes in food products, but these processes often significantly reduce the sensory and nutritional properties of food and are highly energy intensive. This study demonstrates that the combination of two natural food-grade antimicrobial agents with a sublethal level of physical stress in the form of UV-A light can greatly increase microbial load inactivation. In addition, this report elucidates the potential mechanisms for this synergistic interaction among physical and chemical stresses. Overall, these results provide a novel approach to develop antimicrobial solutions for food and water systems.

show abstract

Effects of Chlorine-Based Antimicrobial Treatments on the Microbiological Qualities of Selected Leafy Vegetables and Wash Water

Cited by 12 publications

References 50 publications

Inhibition of Escherichia coli O157:H7 and Salmonella enterica Isolates on Spinach Leaf Surfaces Using Eugenol-Loaded Surfactant Micelles

Inhibition of Escherichia coli O157:H7 and Salmonella enterica Isolates on Spinach Leaf Surfaces Using Eugenol-Loaded Surfactant Micelles

Evaluation by Flow Cytometry of Escherichia coli Viability in Lettuce after Disinfection

Enhanced Antimicrobial Activity Based on a Synergistic Combination of Sublethal Levels of Stresses Induced by UV-A Light and Organic Acids

Contact Info

Product

Resources

About