Genipin cross-linked antimicrobial nanocomposite films and gamma irradiation to prevent the surface growth of bacteria in fresh meats.

Abstract : A 125 μg/mL of nisin and 30 mM of disodium ethylenediaminetetraacetate (EDTA) were immobilized on the surface of the nanocrystal (CNC)/chitosan nanocomposite films by using genipin as a cross-linking agent. The effect of low-dose gamma irradiation on the antimicrobial activity of the films was tested in vitro against Escherichia coli and Listeria monocytogenes. The genipin cross-linked films prepared by irradiating at 1.5 kGy demonstrated the highest antimicrobial activity against both the bacteria at the end of 35 days of storage at 37 °C showing an inhibition zone of 27.1 mm for E. coli and 27.7 mm for L. monocytogenes as compared to 23.4 mm and 23.8 mm for the same respective bacteria at day 1. The films restricted the growth of psychrotrophs, mesophiles and Lactobacillus spp. (LAB) in fresh pork loin meats and increased the microbiological shelf-life of meat sample by more than 5 weeks. The films also reduced the count of E. coli and L. monocytogenes in meat samples by 4.4 and 5.7 log CFU/g, respectively, after 35 days of storage.