Properties and characterization of carrot nanocellulose/starch biopolymer nanocomposites

Abstract In order to produce bio‐nanocomposites for potential food packaging applications, nanocellulose (NC) was extracted from carrot pulp and different weight fractions of NC (5, 7, and 10 wt%) were incorporated into corn starch, either with or without thyme extract, using the solvent casting process. The particle size of the extracted NC (200–300 nm) was determined using the dynamic light scattering test, and field emission scanning electron microscopy confirmed the spherical morphology of the NC, which was successfully extracted from carrot. Fourier transform infrared spectroscopy analysis demonstrated excellent chemical interactions between the starch and NC. According to SEM images of starch‐NC nanocomposites, uniform dispersion of NC into starch was observed for all formulations. Besides, increasing the proportion of NC up to 10 wt% enhanced the tensile strength of starch nanocomposites by 280%. Since the incorporation of NC into starch increased the crystallinity index of the samples, the water absorption capacity and oxygen transmittance rate tests showed that the presence of NC reduced water and oxygen gas diffusion into the starch matrix. Furthermore, thyme‐loaded nanocomposite had remarkable antimicrobial activity, particularly in the case of gram‐positive bacteria ( Staphylococcus aureus ), as it expanded the bacteria's inhibitory zone by about 10 mm compared with those without an antibacterial agent. Finally, the fabricated bio‐nanocomposites exhibited balanced mechanical characteristics, perfect gas and water barrier properties, as well as promising antibacterial activity for use in the food packaging industry.