Linking Polyelectrolyte Modification and Enzyme‐Catalyzed Phenolic Acid Functionalization of Cellulose Fiber for Functional Foams

A 2‐step modification system using polyelectrolyte and laccase‐catalyzed ferulic acid is used to make functionalized cellulose fibers. The functionalized fibers are converted into low‐density and highly porous cellulose‐based foams with bioactive and moisture‐resistant properties, showing high potential for food packaging applications. The functional fibers present high antioxidant (88%) and antibacterial (60%) activity, along with moderately reduced moisture adsorption rates (0.009 g min −1 ) compared to non‐functionalized fibers. The best laccase and ferulic acid formulations are selected for foam preparation, using a wet processing technique. The behavior of the wet foam is correlated with the extent of functionalization through measurements of foam capacity and stability. Functionalization affects the foam performance, especially when comparing anionic, cationic, and non‐ionic surfactants. Increasing the laccase and ferulic acid loads disrupt the foam stability when ionic surfactants are used over long times and results in foam collapse during the drying process, resulting in extremely large pores. Nevertheless, stable foams are achieved with a flexible compression modulus, 50% structural resilience, 99% porosity, and densities as low as 15 kg m −3 density along with the retained bioactive properties.