Improved performance of less purified cellulosic films obtained from agar waste biomass

The residues generated after the extraction of agar from Gelidium sesquipedale by means of a hot-water treatment, with (NaOH+HW residue) and without (HW residue) an alkali pre-treatment have been valorized to produce high performance cellulosic films. Both residues were mainly composed of structural carbohydrates (in particular, agar), ashes and lipids. The residual agar could only be completely removed by applying a two-step process based on bleaching and alkaline treatments. The application of the alkaline pre-treatment for the extraction of agar did not significantly affect the properties of the films produced from the extracted fractions, hence making the HW residue more sustainable and economically viable. The agar remaining in the less purified fractions had a positive effect on the performance of the films, improving their transparency, mechanical properties and water vapour barrier, outperforming benchmark biopolymers; in addition, these materials presented antioxidant capacity inhibiting the degradation of β-carotene.Synchrotron experiments were performed at NCD beamline at ALBA Synchrotron with the collaboration of ALBA staff (2018022638 project). This work was financially supported by the “Agencia Estatal de Investigación” (PCI2018-092886 Grant) and co-funded by the European Union’s Horizon 2020 research and innovation programme (ERA-Net SUSFOOD2).Peer reviewe