Effect of plasma treatment on improving liquid retention capacity of capillary recesses for food packaging applications

Liquid residue is a major issue in fresh food packaging, especially for meat products. This work investigates capillary recesses directly integrated into PET packaging film, with targeted plasma treatment of the recesses to enhance their liquid retention capacity. Localised oxygen plasma treatment (oxygen flow rate: 80 cm(3)/min, pressure: 0.14 mbar, power: 240 W) of PET recesses introduced polar oxygen groups onto their surface and increased their wettability. It is proposed that the difference in wetting characteristics of the recesses and rest of the packaging surface enhanced the capillary valve effect, which dramatically increased the liquid retention capacity. Untreated recess samples (diameter: 9 mm) had retention capacity of around 0.70 g, which increased to 1.50 g after localised O-2 plasma treatment. Even after aging of over 60 days, the plasma-treated recesses maintained the enhanced retention capabilities. The estimated resulting retention capacity of recesses of diameter 9 mm was 2972 +/- 62 mL/m(2), which is comparable with conventional absorbent pads (3000 mL/m(2)). This demonstrated the viability of applying plasma treatment in food packaging to effectively isolate any excessive exudate using only the packaging film.

Automated summary

This study demonstrates that introducing capillary recesses directly into PET packaging film, with targeted plasma treatment, can significantly enhance their liquid retention capacity, effectively isolating any excessive exudate.