The antimicrobial activity of copper-coated paper for use as bags for secondary food packaging was evaluated. In particular, the survival of food-borne microorganisms intentionally inoculated on copper-coated paper (+Cu) and on traditional copper-free paper (-Cu) was evaluated. Both the papers were inoculated, stored at a 20±2°C and analysed at time 0 and 24 h. The reduction of the inoculated microbial load was maximum (100%), when the inoculum consisted of a suspension in peptoned water of the tested microorganisms. It has been demonstrated that the presence of the water of the bacterial suspension favoring the leaching of copper increased its effect against the tested microorganisms. Conversely, when the inoculum was dry the reduction was between 60 and 100%. The reduction observed on copper-free paper was limited and between 2 and 33%. In all the tested cases the reduction was strictly dependent on the microorganism considered and on the lot of copper-coated paper. Given the antimicrobial effect of copper, it is suggested to pack the food in secondary packaging consisting of coated-copper paper.
