Paper and cardboard packaging presents challenges relating to its permeability to mineral oils and gases, as well as its sensitivity to water and fats. To overcome these limitations, such packaging is laminated with synthetic polymers, at the expense of recyclability and biodegradability.

Therefore, in a recent study conducted by a group of Italian researchers (Feroce et al., 2025), the application of a bio-based coating, consisting of an aqueous suspension of micro/nano cellulose fibrils, was evaluated to improve the barrier properties against mineral oil hydrocarbons (MOH) and resistance to fats. This suspension was developed from cellulose-rich biomass (51%) subjected to several cycles of high-pressure homogenisation to achieve defibrillation of the cellulose fibrils. The samples were characterised in terms of: pH, viscosity, dry matter content, the ratio of micro- to nano-fibrils, their dimensions, and any chemical changes resulting from the homogenisation treatment.

The coating application method was optimised using a factorial design with 3 levels and 2 factors for both selected coating methods (bar coating and spray coating). The coated cardboards were evaluated for coating weight, grease resistance and heptane transmission (HVTR) as a simulant for MOH. The surface properties of the cardboards selected as the best were evaluated using SEM and AFM microscopy.

The results show that even with a low coating weight (<10 g ^m⁻²) excellent grease resistance and a significant reduction in HVTR are achieved. Finally, the spray coating method ensures a more homogeneous coverage with less waste and at process speeds compatible with industrial production.

References: A. Feroce et al., National Conference on Food Science and Technology, Bologna, 9–10 June 2025, 78.