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

•Enhanced liquid retention by capillary recesses in PET packaging through plasma treatment.•Localised oxygen plasma treatment of recess walls led to higher retention than untreated or full area treatment.•Proposed solution compatible with mono-material packaging: no absorbent materials required for liquid retention.•Longevity of plasma treatment effect is suitable for application on food plastic trays.