Absorbent pads are widely used in fresh meat packaging due to their role in minimising food waste. Their primary function is to manage the liquid released by the meat during storage, helping to maintain product quality and shelf life. Future developments in absorbent pads must therefore ensure that this functionality is preserved, as performance remains directly linked to reducing food waste.
Performance requirements shaping absorbent pad design
The design of absorbent pads is driven by several key functional requirements, which directly influence material selection and design choices.
First of all, the pad should only absorb the natural drip loss released by the meat. For this reason, it is important to avoid direct contact between the absorbing material and the meat. A protective layer is therefore typically placed between the meat and the absorbent core. In practice, this is usually a plastic film, which helps prevent the formation of capillary forces that could otherwise lead to unwanted liquid extraction.
In addition, the absorption capacity of the core should be higher than the maximum possible drip loss from the meat. Any free liquid remaining in the tray can result in a lower shelf life. At the same time, the liquid released by meat is a mixture of fat, blood and water, meaning that the absorbent core must be capable of handling all these components. Cellulose can handle blood and fat, while superabsorbent polymers are effective for water absorption. These polymers may be replaced by very high amounts of cellulose, although this reduces the efficiency of the pad.
Finally, the absorbent core material and the films should be thin, preferably not much more than 1 mm thick together, in order to minimise production, storage and transportation costs. In line with industrial requirements, both the core material and the films should also be available as roll stock.
Addressing material performance and system integration challenges
These functional requirements define the main challenges when replacing conventional absorbent pad materials with wood-derived fibre solutions.
One of the key challenges is achieving sufficient absorbency using only wood-derived solutions, while still keeping the structure thin enough. In parallel, the surface of the pad should preferably exhibit properties comparable to those of plastic films, particularly in terms of liquid management.
At the same time, when integrating a bio-based absorbent pad into a recyclable-by-design fibre-based packaging system, maintaining performance remains essential. The pad should not compromise its functionality compared to traditional solutions and should still be capable of securing a low food waste ratio.
Another important aspect concerns end-of-life. Currently, there are no recycling processes available that can clean absorbent pads from meat juice contamination. For this reason, a key focus within REDYSIGN is the development of recycling processes capable of cleaning the pad materials from meat juices, which will be further explored in the coming months.
Towards fully bio-based absorbent pads
In this context, efforts are focused on replacing conventional plastic components with fibre-based alternatives. In order to develop 100% wood-based pads efforts were focused on the development of films based on pulp fibres that could replace the polyethylene (PE) films conventionally used in absorbing pads. Therefore, RISE-PFI focused on the development of pulp fibres-based films for the absorbing pads, including a bio-based impregnation to reduce water absorption of the films and a bio-based glue to seal the films.
The replacement of the PE films with biobased films is in line with efforts to develop fully biobased absorbing pads and with the current bio- and circular economy initiatives.
Another breakthrough in the project dealt with optimizing the internal architecture of the absorbent materials to enhance their efficiency. TECNALIA researchers have demonstrated a significant advancement in water retention capacity by reimagining how the material is structured. Specifically, by arranging cellulose fibers into an original, binder-free 3D form, the team found that the same quantity of fibers can absorb 25% more water. This result, measured on a g/g basis and under testing conditions specifically designed for absorbing pads (absorption under load), shows that the physical organization of the fibers plays a critical role in performance.
By eliminating binders and utilizing this 3D structure, the project moves closer to developing more sustainable packaging solutions that maintain high functionality while reducing material waste, with further improvements in end-of-life performance to be addressed in the next phases of the project.
Article prepared in collaboration with Álvaro Tejado from TECNALIA (project coordinator), Gary Chinga Carrasco and Eva Pasquier from RISE PFI, and Erik Andersin from McAirlaid’s.
