Green Production of ZnO Via Wine Pomace Extract to Design Novel Agarose Aerogel Composites for UV-shielding Applications

Aerogels loaded with zinc oxide (ZnO) offer promising applications in secondary food packaging. In fact, zinc oxide shows antimicrobial and UV-blocking properties, and when incorporated into aerogels, it could enhance the shelf life of packaged food by preventing the growth of bacteria and the degradation related to sensible light compounds. The present work is focused on fabricating a novel composite ZnO-Agarose aerogel produced by supercritical drying using biogenic zinc oxide nanoparticles produced by using a wine processing waste extract as reducing agent. Such particles showed a mean size of 92 nm and an energy band gap of 2.98 eV, similar to that of commercial ZnO (3.22 eV). The effect of ZnO loading into agarose (AG) aerogels was investigated and compared to commercial ZnO. The presence of ZnO gets better the mechanical stability and the porosity by reducing the pores’ mean size from 0.068 μm for pristine agarose aerogel to 0.036 μm for 1% wt ZnO loaded one. Moreover, a higher hydrophobicity (CA = 75°) and lower swelling degree (153%) were observed for ZnO loading agarose aerogel. The composite agarose aerogel exhibited a generally higher reflectance from 41% (pristine AG) to 80% (AG + 1% ZnO) over the considered solar wavelength range. This effect is associated with the presence of ZnO, which determines a light scattering effect promoting the increase in UV Protection Factor (UPF) up to 15. The produced systems can be potentially employed in the secondary food packaging area.