The transfer of microorganisms on packaging materials to a contact surface has only been investigated in the context of laboratory-produced spiked packaging products and agar surfaces in small quantities (0.03-0.10%) so far. Correspondingly, this study focused on the localization of microorganisms on/in industrially produced packaging materials and on the establishment of an experimental laboratory set-up to determine and quantify the parameters influencing the microbial transport from surfaces and different layers of packaging materials to contact agar media. We established a simple model to determine the transfer of microorganisms from packaging materials to microbiological agar plates. In order to clarify the transfer of microorganisms within the material, the samples were split horizontally in their z-dimension, and so produced layers (inner layers) were investigated for their microbial transfer. The parameters incubation time, applied weight and bacterial load for the samples were investigated in more detail in the outer layers (front/back) and the inner layers. No significant difference in the microbial transfer was observed between the outer and inner layers of all samples. We indicate a time-dependent transfer to the media and an independence of the transfer from the applied weight. Moreover, the number of transferred microorganisms is not dependent on the bacterial load of the samples.
Keywords: applied weights; bacteria; incubation time; transfer.