Effect of eucalyptus nanofibril as reinforcement in biodegradable thermoplastic films based on rice starch (Oryza sativa): Evaluation as primary packaging for crackers

This study investigated the incorporation of eucalyptus nanocellulose (CNF) into rice starch-based thermoplastic (TPS) films, evaluating the effects of four CNF concentrations (0 %, 2 %, 4 %, and 6 %, w/w) on the physicochemical properties of the films. The analyses included scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), solubility, mechanical properties, optical properties, biodegradability, and application for cookie preservation. Atomic force microscopy (AFM) confirmed good CNF dispersion at 4 %, while higher concentrations caused agglomeration. FTIR analysis revealed effective interactions between CNF and the starch matrix. The TPS + 4 % CNF film showed reductions in water solubility (44 %), solubility in acidic (34 %) and basic (32 %) conditions, water vapor permeability (51 %), and water retention capacity (27 %) compared to pure TPS. Tensile strength increased from 3 MPa (pure TPS) to 6.5 MPa (TPS with 4 % CNF), while elongation at break ranged from 38 % (pure TPS) to 65 % (TPS with 2 % CNF). At 6 % CNF, elongation decreased to 45 %, with increased rigidity. The TPS + 4 % CNF film demonstrated good performance in mechanical strength and water vapor barrier properties, while higher CNF concentrations resulted in stiffer, less flexible films due to restricted polymer chain mobility. Higher CNF concentrations also increased the film's opacity. With 90 % biodegradability after 15 days, the reinforced film showed environmental potential. In cookie preservation, TPS + 4 % CNF demonstrated promising performance, with moisture barrier and texture preservation capabilities comparable to oriented polypropylene (BOPP). The combination of biodegradable primary packaging with non-biodegradable secondary packaging offers an innovative solution for food protection with reduced environmental impact. [Display omitted] •Eucalyptus nanofibrils enhance the strength of rice starch-based films.•Film with 4 % nanofibrils reduces water solubility by 44 %.•Films with nanofibrils show up to 90 % biodegradability in 15 days.•Infrared spectroscopy reveals effective interactions between nanofibrils and starch.•Film with 4 % nanofibrils preserves cookie texture and moisture.