Waste-derived carbon dots from Syzygium cumini seeds reinforced Gond Katira films as multifunctional biodegradable packaging for banana preservation

This study developed multifunctional biodegradable Gond Katira (GK) films reinforced with Syzygium cumini seed-derived carbon dots (SCSCD) for preserving bananas during ambient storage. SCSCD were produced hydrothermally and incorporated into GK at 0.5, 1.0, and 1.5% (w/w relative to dry GK), corresponding to 5, 10, and 15 mg SCSCD per 100 mL of film-forming solution. The resulting carbon dots were quasi-spherical, with an average size of 3.5 ± 0.9 nm, a zeta potential of −28.3 ± 1.7 mV, and excitation-dependent blue photoluminescence. SCSCD incorporation significantly modified the structural, optical, mechanical, thermal, barrier, antioxidant, and biodegradation properties of GK films. GK–SCSCD2 showed the best mechanical performance, with tensile strength, elongation at break, and Young's modulus of 29.78 MPa, 69.63%, and 456.7 MPa, respectively. GK–SCSCD3 exhibited the highest antioxidant activity, reaching about 66% DPPH and 70% ABTS radical-scavenging activity, while soil-burial weight loss increased from 46% for neat GK to 78% after 20 days. When applied to mature-green bananas stored at 27 ± 3 °C for 6 days, SCSCD-containing films delayed ripening. At day 6, GK–SCSCD3 reduced CO 2 production to 33.08 mL kg −1 h −1 versus 79.81 and 88.31 mL kg −1 h −1 for commercial PE and GK, respectively, retained firmness at about 308 g, and limited reducing sugars to 13.8%. Ethylene production was also suppressed. These findings confirm the potential of SCSCD reinforcement to improve film functionality and slow climacteric banana metabolism during storage.