Improvement in liquid absorption of open-cell polymeric foam by plasma treatment for food packaging applications

Free-moving meat exudate in plastic packaging is perceived as unhygienic and unattractive by consumers. It facilitates the deterioration of meat quality and safety, increasing meat waste and loss. This work discusses an innovative approach in scavenging meat exudate within commercial plastic packaging. This involves improving the liquid absorption capabilities of open-cell polystyrene (PS) foam through the application of oxygen plasma treatment rather than chemical wetting agents. The excited plasma species diffuse into the porous foam structure introducing polar oxygen groups onto the pore walls and improves their surface hydrophilicity. Hence, the foam pores, with enhanced wettability towards water-based liquids, are proposed to have a larger sucking capillary pressure thus increasing the absorption capacity of the porous PS foam. The specific liquid absorption capacity of PS foam sheets (thickness: 5 mm) increased from 1.09 g g(-1) (grams of exudate simulant liquid absorbed per gram of PS foam) to 8.78 g g(-1) as a result of plasma treatment; an eightfold increase in liquid capacity (g g(-1)) that persisted even 60 days post treatment. This study demonstrates the practicality of using plasma treatment as a non-chemical and efficient technology in scavenging meat and food exudates in plastic packaging.