Reduction in microbial survival on food contact surfaces by a spray coated polymerized quaternary ammonium compound

Abstract

Using polymerization and immobilization techniques, the loss of antimicrobial efficacy of a quaternary ammonium compound (QAC) was minimized by decreasing its solubility and crosslinking it to metal substrates. The survivability of Listeria innocua and Escherichia coli K12 inoculated to silane QAC coated metal surfaces was compared with uncoated metal surfaces at different treatment conditions for up to 6 months storage. Resilience of the coating material to repeated cleaning, up to 20 washing and rinsing cycles, was also investigated. No evidence of bacteria viability (>5 log reduction of colony-forming unit) was observed for L. innocua when they were inoculated onto coated surfaces stored for 3 months, whereas E. coli was reduced by 3 to 4-logs. For the viable L. innocua cells on the coated surfaces, >5 log reductions were achieved even after the coated surfaces were cleaned by 20 washing and rinsing cycles prior to the cells' inoculation. For the E. coli cells, ~ 2 log reductions were achieved after 5 cleaning cycles and <1 log reduction after 10 or more cleaning procedures. Overall, the results showed that the coating had antimicrobial activity against Gram-positive bacteria while it showed moderate activity to Gram-negative bacteria. K E Y W O R D Santimicrobial activity, Escherichia coli, food contact surface, Listeria, surface sanitization

Effectiveness and Durability of a Quaternary Ammonium Compounds-Based Surface Coating to Reduce Surface Contamination

“…QAC-based coatings are known to have good antibacterial activity towards Gram-positive bacteria and enveloped viruses [14,24]. From the view of disinfection, they are bactericidal for a wide range of pathogens such as E. coli, Staphylococcus aureus, Streptococcus mutans, Bacillus subtilis, Pseudomonas aeruginosa and the fungal pathogen Candida albicans [25][26][27][28].…”

Advances in Nonfouling and Antimicrobial Coatings: Perspectives for the Food Industry

“…Interestingly, as Gharibi et al demonstrated, quaternary ammonium compounds can be derived from soybean oil to create biobased, nonleaching antimicrobial coatings, offering a greener synthesis approach to traditional petroleum-based antimicrobial coatings . Compared to other chemicals, quaternary ammonium compounds can be easily dissolved and do not readily evaporate and, if used within guidelines established by the Environmental Protection Agency (EPA), are considered safe . Although their antimicrobial efficacy may be reduced by the presence of organic matter (e.g., addition of 3 g/L BSA resulted in a 10-fold increase of the minimum bactericidal concentration against P. fluorescens ), their performance across a wide range of pH values still makes them desirable for food manufacturing environments, which regularly are exposed to pH extremes. , In one report, Lee and Pascall coated stainless steel with a quaternary ammonium compound derivatized silane and tested against Listeria innocua and Escherichia coli.…”

“…Although their antimicrobial efficacy may be reduced by the presence of organic matter (e.g., addition of 3 g/L BSA resulted in a 10-fold increase of the minimum bactericidal concentration against P. fluorescens ), their performance across a wide range of pH values still makes them desirable for food manufacturing environments, which regularly are exposed to pH extremes. , In one report, Lee and Pascall coated stainless steel with a quaternary ammonium compound derivatized silane and tested against Listeria innocua and Escherichia coli. Here, the coating (compared to bare stainless steel) demonstrated superior antimicrobial efficacy (>5-log reduction for Listeria innocua , and 3–4-log reduction for Escherichia coli), but more importantly, the antimicrobial efficacy remained intact following a 20-cycle washing process . Additionally, the ability for quaternary ammonium compounds to be immobilized, via polymerization, for example, minimizes environmental release and subsequent resistance development in environmental microorganisms .…”

“…Below, we offer a critical review and survey of the state-of-the-art technology in major classes of antimicrobial compounds (summarized in Table 1) with an emphasis on their suitability to food manufacturing. 48−51,75−80 interaction between (−) cell membrane and (+) peptide residues cause disruption of membrane and eventually cell death stability in extreme pH conditions, antimicrobial efficacy without human toxicity, production cost, and solubility N-halamines 52,62,[85][86][87]93 oxidation of cell wall by direct transfer of halogen leading to cell leakage and death performance in high organic load environments quaternary ammonium compounds (QAC) 103 electrostatic interaction between (−) cell wall and (+) QAC; QAC hydrophobic tail integrates into te cell membrane, causing cell lysis performance in high organic load environment benzoic acid 112,113,116−119 interaction with the cell surface and membrane causes disruption of ion gradient, leading to cell lysis and death; additionally, the reduction in pH can prevent growth or even lead to cell death demonstration of efficacy in expanded conditions of use organometallic compounds 120,122,123,132,133 Interaction of the metallic compound with bacteria causes protein inhibition, oxidation of cellular structures, and ligand dissociation leading to cell death demonstration of efficacy in expanded conditions of use and when incorporated into a coating metal nanoparticles 121,124,126,128−130 Peptides and Peptidomimetic Compounds (PMCs). Peptides and peptidomimetic compounds (PMCs) or synthetic peptide-like molecules, including peptoids, 48 have been reported to present both antimicrobial and nonfouling functionality.…”

“…Here, the coating (compared to bare stainless steel) demonstrated superior antimicrobial efficacy (>5-log reduction for Listeria innocua, and 3−4-log reduction for Escherichia coli), but more importantly, the antimicrobial efficacy remained intact following a 20-cycle washing process. 103 Additionally, the ability for quaternary ammonium compounds to be immobilized, via polymerization, for example, minimizes environmental release and subsequent resistance development in environmental microorganisms. 105 While the overall log reduction varies among different Grampositive and Gram-negative species, the ability of quaternary ammonium compounds to preserve their antimicrobial behavior without the need for an external "recharge" provides an exceptional starting point for future research on how to commercially incorporate the compounds for the near future.…”