Surface characterization of glass and poly(methyl methacrylate) soiled with a mixture of fat, oil, and starch

Micro-organisms on food contact surfaces provide a 'biotransfer potential', i.e. the ability to contaminate foods during processing or preparation. Su rfaces coated with organic materials can act as sites for microbial attachm ent. This investigation into the surface properties of glass and poly(methy l methacrylate) substrates soiled with a milk powder, oil, and starch compo site has found that fatty acid esters dominate the surface chemistry. A low er concentration of proteinaceous material was also detected, with the conc entration dependent on both the underlying substrate and the thickness of t he soiling material. The physical surface structure of the fouled surfaces showed a complicated surface topography with features of the order of tens of micrometres wide and up to 2 mu m high, which increased in size with inc reasing thickness of the soiling layer. The features reflect bulk incompati bilities between the components of the soiling material and demonstrate the heterogeneity of the surface as presented to micro-organisms.