Valorizing brewery industry waste in nanocellulose cryogel-PEG composites for cold chain packaging

Global concerns about food and energy waste call for new sustainable solutions. Phase changing materials (PCM) are promising thermal storage and management materials which have potential to mitigate food waste, yet they often suffer from leakage and non-shape stability. Here, a green shape-stabilized polyethylene glycol 300 (PEG) nanocellulose-based composite was developed using readily available and cost-effective side streams from the brewery industry. Two different routes were examined for the incorporation of PEG into the cellulose nanofiber (CNF) cryogel including adding different dry mass ratios of PEG in the sol stage, with or without physical crosslinking, or adding the PEG after CNF gelation. FTIR and TGA analysis revealed the improved thermal stability of PEG after incorporation into the CNF cryogel. The PEG/CNF composite produced by adding PEG in the gel stage outperformed the other material formulations by demonstrating the highest enthalpy value (93.2 J/g) and the best mechanical properties (Young's modulus of 140 kPa). The package containing the PEG/CNF composite could maintain the meat temperature below 0 °C around 4 times longer than the control package when the cold system was interrupted. Furthermore, the PEG/CNF composite showed a positive effect on the color and drip loss values of frozen meat.