Enhanced chitosan–microfibrillated cellulose hydrogen bonding for edible packaging and food shelf-life extension

Abstract

This study explores new pathways for extending the shelf life of fresh produce by developing edible composite coatings utilizing chitosan (CH) and microfibrillated cellulose (MFC), with enhanced functional properties. Edible films were initially prepared by dissolving CH in acetic acid and incorporating glycerol as a plasticizer to improve flexibility. MFC, derived from bleached hardwood kraft pulp, was added at varying concentrations to reinforce the composite films. The incorporation of MFC improved the films’ thermal stability, crystallinity, mechanical strength, and water and oxygen barrier properties, while reducing solids content, pH, and contact angle. The CH/MFC-5 films, containing 5 % MFC, showed 49.7 % reduction in water vapor permeability, 80.1 % decrease in oxygen transmission rate, and 415 % increase in tensile strength, compared to CH films. Colloidal stability analysis over 40 days revealed that the dispersion and suspension of MFC particles are influenced by surface charge. FTIR and XPS analyses confirmed enhanced hydrogen bonding between CH and MFC, contributing to improved stability, particularly at 5 % MFC loading. When applied to strawberries and stored for 5 days, uncoated fruit exhibited 33.55 % weight loss and 1.83 kgf firmness, CH-coated fruit had 24.50 % weight loss and 4.08 kgf firmness, while CH/MFC-5-coated fruit showed only 17.43 % weight loss and maintained firmness at 6.46 kgf. SEM and EDX confirmed uniform coating coverage over the strawberry's surface. Overall, the study demonstrates the benefits of incorporating optimized MFC into the CH matrix for extending the shelf life of fresh produce, such as strawberries, by preserving key quality parameters.