Exploring composites of alternative flour sources and marine biomass residues for sustainable degradable food packaging films

abstract

This study proposes an innovative strategy to valorize agricultural and marine by-products by developing sustainable films based on different pigmented popcorn and sorghum flours, rich in bioactive polyphenols and starch, combined with holocellulosic residue from Gelidium corneum (marine biomass), a by-product of industrial agar extraction, as a possible alternative to conventional plastics. Films were produced by melt-compounding and compression-moulding with a 40:60 w/w ratio of popcorn or sorghum flour to algae residue and were compared to control films without marine biomass. The effect of incorporating and storing marine biomass was investigated. Results showed that the addition led to a more heterogeneous film morphology and modified the optical properties of the marine biomass films, decreasing luminosity, whiteness index, and internal transmittance, while enhancing yellow and green hues due to pigment interactions, with significant changes occurring during storage. In general, incorporating marine biomass increased tensile strength and stiffness, reduced elongation at break, and, upon storage, further enhanced rigidity through starch retrogradation. Additionally, the presence of biomass modulated water vapor permeability, water uptake, and hydrophobicity. These findings demonstrate the potential of combining pigmented popcorn and sorghum flours with Gelidium corneum residue as sustainable composite films, representing a promising strategy for environmentally friendly packaging. © 2026 Elsevier Ltd