Physical and chemical modifications of cellulose fibers for food packaging applications

Cellulose fibers have gained considerable interest for use as gas barriers and reinforcing fillers in food packaging materials because of their interesting properties, including biodegradability, low density, nontoxicity, and low cost. Although modifications of cellulose nanomaterials for reinforcing applications have been reviewed in the literature, they suffer from a lack of comparative results, and the modifications related to food packaging applications have not been covered yet. This study reviews physical and chemical methods used to improve oxygen and water barrier properties, water uptake, mechanical strength, and transparency of different food packaging films of cellulose nanomaterials, and provides comparative results. Heat treatment, esterification, and TEMPO-mediated and periodate oxidation are the most common methods used to improve the barrier properties of free-standing, bilayer, and composite films prepared from cellulose nanomaterials. Modification using silane compounds is a well-established method for improving the mechanical properties of cellulose fibers and polymer composite films.