Challenges associated with cleaning plastic food packaging for reuse

Reuse of plastic packaging for food is a promising route to reduce the environmental burdens but presents particular challenges due to the need to avoid cross contamination of contents. This study investigates the challenges associated with cleaning and assessing existing recycled PET (rPET) food-to-go (FTG) pack forms and provides recommendations to enable a shift towards reusable food packaging systems. Pack forms were fouled under controlled conditions and washed in accordance published guidelines. Three fouling media were selected to represent food residue typically found in FTG packs. Investigated parameters included fouling type and quality, wash and rinse times, and detergent dosage. Cleanliness was assessed using adenosine triphosphate (ATP) swabbing and the effect on the material properties was studied via tensile testing, IR spectroscopy and differential scanning calorimetry. The results demonstrate that cleaning effectiveness is dependent on the quantity of fouling, the duration of the wash cycle and the dosing of detergent indicating the potential to optimise parameters for different fouling conditions. It is also concluded that ATP testing is an inappropriate cleanliness assessment method for food packaging due to many opportunities for it to produce false negative readings, its high cost and slow response. The rPET material properties remained largely unchanged apart from a slight increase in stiffness, however packaging suffered significant deformation.