Antimicrobial powders and bio-based films

Food safety can be improved by various antimicrobial applications through the effective inhibition of microorganisms for certain periods by controlled release. Antimicrobials in powders and films were studied to investigate their activities and properties.;Nisin (NisaplinRTM) (200, 400, 600, 800, and 1000 IU/ml) was adsorbed to silica and different corn starches and their antimicrobial activities against Listeria monocytogenes were evaluated by agar diffusion assay. Nisin-adsorbed silica (Celpure P-65) powder had the highest antimicrobial activity at 600 IU/ml and also confirmed that the highest amount of nisin was adsorbed onto silica at the same concentration by thermogravimetric analysis. Efficacy of corn starches for adsorption of nisin was less than that of silica due to low retained activity onto powder and much loss activity in supernatant during nisin-adsorbed powder processing.;NisaplinRTM and GuardianRTM incorporated gelatin films were evaluated for their film properties, and antimicrobial activities against Listeria monocytogenes in liquid media, solid media and ready-to-eat turkey bologna. As antimicrobial concentrations increased in films, intensity of yellowness increased and lightness decreased. Also, film tensile strength was reduced and elongation increased. Both oxygen permeability (OP) and water vapor permeability (WVP) of gelatin-based NisaplinRTM films increased as antimicrobial concentration increased. OP of gelatin-based GuardianRTM films increased as level of incorporated antimicrobial increased while WVP decreased. Gelatin-based NisaplinRTM films (0.025 ∼ 0.5%) completely inhibited Listeria monocytogenes within 6 hours. Gelatin-based GuardianRTM films (0.5 ~ 3%) inhibited Listeria monocytogenes in liquid media and two lower concentrations (0.5% and 1%) were more effective at inhibiting Listeria monocytogenes than two higher concentration (2% and 3%). Antimicrobial activity of both films against Listeria monocytogenes on solid media were evaluated for 16 weeks and gelatin-based GuardianRTM films were more stable than gelatin-based NisaplinRTM films. Both antimicrobial films effectively inhibited Listeria monocytogenes on bologna at 4°C for 56 days.;Gelatin films containing trans-2-dodecenal were developed and their antimicrobial activities against Listeria monocytogenes and Escherichia coli O157:H7 were evaluated in model system using peptone solution and turkey bologna. Also, film properties were evaluated. Trans-2-dodecenal gelatin films completely inhibited Listeria monocytogenes in 0.1% peptone solution within 8 hours. Also, this film reduced Escherichia coli O157:H7 populations for 48 hours compared to control. Total color difference (DeltaE) of all treatments inoculated with Listeria monocytogenes increased during storage at 4°C for 56 days. Films inoculated with Escherichia coli O157:H7 also showed increased DeltaE as storage time increased while there was no change in bologna from day 1 to 56 and DeltaE was higher in order as follow 2% TD > 1% TD > Control > Bologna. Trans-2-dodecenal impregnated gelatin film suppressed Listeria monocytogenes and Escherichia coli O157:H7 on bologna pieces during storage at 4°C for 56 days. Antimicrobial activity of films against Listeria monocytogenes was more effective than activity against Escherichia coli O157:H7.