Synergistic reinforcement of starch matrices: Investing the combined effect of natural fiber (Banana Peel) and antioxidant (Polyphenol) on bioplastic performance

Abstract

The demand for sustainable materials has driven the use of agricultural residues to develop starch-based bioplastics as alternatives to conventional plastics. This study investigates the combined effect of polyphenol (PP) and banana peel (BP) on starch-based bioplastic properties. Four starch-based formulations were developed: P2B30 (2% PP, 30% BP), P2B60 (2% PP, 60% BP), P4B30 (4% PP, 30% BP), and P4B60 (4% PP, 60% BP), and characterized. Moisture content was highest for P4B60 (36.41±0.16%) and lowest for P2B30 (28.30±0.12%), whereas P2B60 and P4B30 showed intermediate values with significant difference (p<0.05). Thickness was highest for P4B60 (0.97±0.01 mm) and lowest for P2B30 (0.76±0.01 mm), whereas P2B60 (0.85±0.01 mm) and P4B30 (0.91±0.01 mm) were intermediate (p<0.05). Density was 1.12±0.02 (P2B30), 1.15±0.02 (P2B60), 1.17±0.02 (P4B30), and 1.19±0.02 g/cm³ (P4B60) with no significant difference between formulations (p>0.05). Tensile strength was highest for P4B30 (9.30±0.14 MPa) and lowest for P2B60 (5.32±0.13 MPa), whereas P2B30 (7.28±0.11 MPa) and P4B60 (8.45±0.12 MPa) (p<0.05). Elongation was highest for P2B60 (15.55±0.08%) and lowest for P4B30 (6.63±0.09%), whereas P2B30 (12.42±0.10%) and P4B60 (9.18±0.09%) (p<0.05). Total phenolic content (TPC) was highest for P4B60 (1.19 mg GAE/g) and lowest for P2B30 (0.94 mg GAE/g), whereas P2B60 (1.05 mg GAE/g) and P4B30 (1.12 mg GAE/g) (p<0.05). Antioxidant activity (AA) was highest for P4B60 (85.95±0.68%) and lowest for P2B30 (40.79±0.26%), whereas P2B60 (62.34±0.45%) and P4B30 (74.18±0.52%) (p<0.05). Biodegradability was highest for P4B60 (49.2%) and lowest for P2B30 (36.01%), whereas P2B60 (42.15%) and P4B30 (45.83%) (p<0.05). Results demonstrate synergy between natural fibres and antioxidants, supporting renewable bio-components as sustainable plastic alternatives.