Abstract
Growing concern over the environmental burden of petrochemical food packaging has directed attention toward agricultural and aquatic residues as secondary raw materials. This review examines polypropylene (PP) composites containing lignocellulosic fillers and biogenic calcium carbonate derived from eggshells and mollusc shells, together with chitosan- and nanocellulose-based coatings. Bulk modification, waterborne coatings and primers, barrier performance, active packaging, and migration safety are analysed in turn. As an organising framework, we propose a functional-separation strategy in which the bulk matrix carries mechanical load, a continuous coating governs mass transfer, and an active layer preserves the packaged food. Fillers are compared in terms of modulus gain and the retention of strength and impact resistance, with explicit acknowledgement of the limits inherent in comparing heterogeneous datasets. Replacing part of the PP with waste-derived material does not, in itself, confer biodegradability, a lower carbon footprint, or suitability for food contact. The principal knowledge gap is the scarcity of studies in which mechanical, barrier, and migration properties are measured on one and the same packaging system. Moderate filler loadings combined with a thin functional coating are identified as a direction warranting further verification, including assessment of recyclability and life-cycle performance.