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CO2 Laser Surface Engineering of Polyethylene Terephthalate (PET) for Enhanced Meat Exudate Conditioning Film Formation and Bacterial Response
J. Lawrence and D.G. Waugh

The attachment of bacteria to a surface is initiated by the absorption of molecules to the surface of a substratum forming what is known as a conditioning film. The nature of conditioning films may be quite different depending on the type of environment the surface is exposed to. To date, limited studies on E. coli biofilms have been performed, which mimic the conditions encountered in the food processing and packaging environment, and so any research into this area is timely. The benefits of CO2 laser surface engineering on the physical properties of polyethylene terephthalate (PET) films, and the subsequent effects on conditioning film formation and bacterial response are presented. The influence of interfacial wetting on initial conditioning of the laser surface engineered PET film was analysed using contact angle measurements. Thereafter the equation of state approach was used to explain the relationship between laser engineered surface characteristics, wettability characteristics and conditioning film formation. Through this work it is clear that laser surface engineering significantly influenced the initial interfacial wettability characteristics of the PET, creating hydrophobic surfaces. Generally, the conditioning film was responsible for reducing the overall hydrophobic characteristics of the CO2 laser surface engineered samples. Bacterial adhesion analysis revealed a bacterial response to the CO2 laser engineered patterns (track and hatch) resulted in modulation of the distribution and morphology of the attached cells. This is significant as it presents the viability of laser surface engineering for creating anti-bacterial and bacteria-reactive surfaces at scale, highlighting the potential for deployment of laser surface engineering in the food manufacturing industry.

Keywords: CO2 laser, surface engineering, conditioning film, wettability, biofilm,
food packaging

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