Food processing facilities can harbor pathogenic bacteria in growth niches: areas within a facility that accumulate water and debris. Growth niches are often outside the regularly cleaned and sanitized areas and present a major issue for post-processing microbial contamination. Some pathogens are known to be resident contaminates in dry and wet facilities and can persist for years, even with proper cleaning and sanitation procedures in non-food contact areas. Here, we report synthesis and characterization of five antimicrobial quaternary ammonium compounds suitable for incorporation into polyurethane coatings. N,N-bis(2-hydroxyethyl)-N-methyl-N-R-1-ammonium bromides (R= -octan {C8QBR}, -decan {C10QBR}, -dodecan {C12QBR}, -hexadecan {C16QBR}, -octadecan {C18QBR}) were synthesized via the Menshutkin reaction with N-methyldiethanolamine (MDEA) and alkyl bromides of varying chain lengths. Quaternary ammonium compounds were characterized using Attenuated Total Reflection- Fourier-Transform Infrared Spectroscopy, Proton Nuclear Magnetic Resonance, and Differential Scanning Calorimetry. Minimum inhibitory concentrations were determined against Listeria monocytogenes and Salmonella enterica serovar Typhimirium. C16QBR and C18QBR displayed total inhibitory effects against Listeria monocytogenes at a concentration of 2.7ppm. C16QBR showed inhibitory effects against Salmonella enterica at a concentration of 21.3ppm. Quaternary ammonium compounds with hydroxyl end groups can be polymerized as antimicrobial polymer coatings to support routine cleaning and sanitization protocols in reducing cross-contamination of pathogenic microorganisms from persistent growth niches.

Synthesis and characterization of antimicrobial dihydroxy quaternary ammonium bromides

ACS Fall 2021

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