Antimicrobial activities and release phenomena in packaging materials containing propyl paraben or triclosan

Matrix system antimicrobial releasing packaging materials (M-ARPs) were studied to provide food with longer shelf life and better microbial safety. To prepare M-ARPs, a packaging paper was coated with mixtures of antimicrobial agent and coating polymer emulsion. Propyl paraben and triclosan were selected as the antimicrobial agents. Permax-801 and Carboset were selected as the polymer emulsions. The antimicrobial activities of the antimicrobial coated papers (M-ARPs) were evaluated by examining the microbial inhibition in agar diffusion and microbial culture tests. The release phenomena of the antimicrobial agents from Carboset coating into water and food simulating solvents were understood. The effects of propyl paraben release on the inhibition of Saccharomyces cerevisiae were examined.; The agar diffusion test showed that all the antimicrobial coated papers formed microbial inhibition zones due to the release of antimicrobial agents. The microbial culture test showed that all the coated papers reduced the specific growth rates and the final cell concentrations of target microorganisms. For water, the release of propyl paraben from Carboset coating was controlled by Fickian diffusion with constant diffusion coefficient (7 ∼ 11 x 10-11 cm2/s at 30°C), and independent of the initial propyl paraben concentration in the coating. The activation energy for propyl paraben diffusion estimated from Arrhenius relationship was approximately 88 kJ/mole. For an aqueous/acidic food simulation solvent, the propyl paraben release followed again the Fickian model with constant diffusion coefficient (30 ∼ 40 x 10-11 cm 2/s at 30°C). For high alcoholic and fatty food simulating solvents, the propyl paraben release was instantaneous and not controlled by Fickian diffusion. Triclosan was not released from Carboset coating into water. For the food simulating solvents, the triclosan release was instantaneous and not controlled by Fickian diffusion. The occurrence of propyl parabenresistant S. cerevisiae was observed only when propyl paraben was added at the beginning of incubation, and not under the condition of slow release of the antimicrobial agent. The release of propyl paraben from Carboset coating into the S. cerevisiae culture also followed the Fickian model with constant diffusion coefficient (16 ∼ 20 x 10-11 cm2 at 30°C).