Search

Liquid residues and moisture within the packaging is a big challenge to fresh food packaging, particularly for liquid-exuding food, such as meat, fish and poultry. The free-moving liquid (exudate) in the bottom of plastic food trays adversely affects the safety, quality and presentation of packaged meat products. However, the current food packaging solutions to isolate meat exudate including the addition of absorbent meat pads are not efficient, restricting the recycling process of plastic packaging and increasing plastic waste that ends up in landfill and oceans. This work reports the development of innovative plastic packaging solutions capable of effectively isolating the meat exudate within the packaging itself, ensuring more sustainable and recyclable plastic food packaging. The developed solutions include three innovative technologies:Geometry modification of liquid-holding recesses integrated into plastic food tray. The raised rims of the modified recesses act as capillary geometrical valves, enhancing the liquid pinning and pressure barrier. This results in an approximately 2.8 times increase in liquid retention capacity of the recesses, compared with a design without raised rims. Surface modification of liquid-holding recesses with oxygen plasma treatment. The localised plasma treatment of recess walls implants polar oxygen groups on the wall surfaces. This induces contrast in the surface wettability between plasma treated walls and untreated outer edges of the recesses, increasing their liquid pinning and pressure barrier, thus their liquid retention capacity. The functionality induced by plasma treatment was reserved long enough (> 60 days) for increasing the liquid retention capacity of ~2.2 times in comparison with untreated recesses. Surface modification of open-cell polymeric foam with oxygen plasma treatment. The plasma treatment results in improving the surface wettability of foam porous structure due to introducing polar oxygen groups on the pore walls. The improved wettability increases the sucking capillary pressure acting on the foam pores, allowing for higher liquid uptake and absorption of open-cell foam. The plasma treatment has sufficiently long effect on wettability improvement (> 60 days) to be used for the treatment of plastic foam packaging with an increase in the liquid absorption capacity of ~8 times. This work has led to developing innovative and sustainable plastic meat packaging for effective self-isolation of meat exudate. The plastic packaging trays incorporated with recesses are fully recyclable with liquid retention capacities comparable to the conventional absorbent meat pads. Therefore, plastic food packaging with liquid isolation capability can be manufactured with no need for additional absorbent components. The plasma treatment of open-cell polymeric foam can also replace the use of chemical wetting agents for facilitating liquid absorption, protecting human health and environment.