Purpose: The objective of this study was to identify and synthesize carbohydrate complexes that could be used as antimicrobial coatings on plastic packaging materials.
Methods: Carbohydrates were explored for antimicrobial properties. A carbohydrate complex on magnetic nanoparticle support (MNP-F#2) was synthesized, suspended in water, applied as droplets on plastic strips (F#2-strip), and heated for attachment. Three types of plastic packaging materials were employed for the antimicrobial experiments in 25 ml of milk samples (Vitamin D, 2%, and fat free). Phosphate buffer solution (PBS) was used as control matrix. Antimicrobial effects were monitored by bacterial growth and transmission electron microscopy (TEM).
Results: By itself, the carbohydrate complex did not attach to the plastic packaging. Successful attachment was achieved when it was immobilized on magnetic nanoparticles. The MNP-F#2 stayed attached on plastic strips even when exposed to water, milk or phosphate buffer solution over a longer period of time. The carbohydrate complex acted as both ligand and antimicrobial agent against Salmonella Enteritidis (Se), E. coli O157:H7 (Ec), Bacillus cereus (Bc), and Listeria monocytogenes (Lm). Ligand action was observed to be on the flagella for Se and on surface molecules for the other bacteria as evidenced through TEM images. Antimicrobial effects were observed to damage bacterial cell walls leading to cell lysis and growth inhibition.
Significance: We have successfully synthesized a very inexpensive antimicrobial carbohydrate complex that could be used to coat plastic packaging materials. The carbohydrate complex may be useful for other antimicrobial applications.