Cellulose nanofiber from sunflower heads and pomegranate peels as sustainable reinforcing agents in biopolymer-based films for active packaging of bread

Abstract Pomegranate peels and sunflower heads were used to prepare cellulose nanofibers (CNFs) via chemical and physical processes. The CNFs were characterized using FT-IR, TEM, and XRD, then incorporated into carboxymethyl cellulose (CMC) with clove, cumin, or cinnamon essential oils to form bioactive edible coating films. TEM revealed homogeneous nanofibers (diameters 6–15 nm), while XRD showed crystallinity of 69% (sunflower) and 72.5% (pomegranate). Essential oils were evaluated for chemical properties and antimicrobial activities. GC-MS identified eugenol (85.65%) and cinnamaldehyde (84.51%) as major constituents of clove and cinnamon oils, respectively. Clove oil showed the highest total phenolics and antioxidant activity, whereas cinnamon oil exhibited the strongest antimicrobial activity. Mechanical optimization was performed using CMC films reinforced with sunflower-derived CNFs, the maximum increases in tensile strength (from 10.4 to 28.5 MPa) and Young’s modulus (from 450 to 1603 MPa) at 10% CNFs loading, representing increases of 174% and 256%, respectively. Bread coated with films containing the cinnamon/cumin oil mixture had the lowest microbial counts after 72 h of open-air storage (bacteria: 9.4–9.5 × 10 4 CFU/g; mold/yeast: 7.0-7.5 × 10 3 CFU/g), which were lower than those of the uncoated control. Bread coated with pomegranate CNFs and clove oil showed the slowest weight loss and best freshness retention during the tested 72 h storage period. Organoleptic evaluation gave coated bread higher scores for crust color and aroma than uncoated controls. The CNF/essential oil containing coatings helped maintain bread quality and lowered microbial counts relative to the uncoated control during the tested 72 h open-air storage. This study demonstrates that agricultural wastes can be valorized through CNF extraction and that CNF-reinforced bionanocomposites with essential oils are promising candidates for short-term bioactive food-coating applications.