Comparative Biodegradation Behaviour of Musa acuminata Peel Waste-Based Bioplastics Using Soil Burial, Dip-Hanging and Modified ASTM G21-70 Methods

Abstract

Banana (Musa acuminata) peel waste is a renewable feedstock for bioplastic production, but the deterioration of the resulting materials depends on their composition and exposure conditions. This study compared the short-term degradation behaviour of bioplastic films containing different proportions of banana peel waste (BPW) powder and soluble starch. Films were prepared using a modified solvent casting method and characterised before exposure using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Material deterioration was assessed using three methods: a six-day soil burial test (SBT), a six-day dip-hanging test involving immersion in a Bacillus subtilis suspension followed by incubation at 30 °C, and a modified ASTM G21-70 test involving ten days of exposure to Aspergillus niger on potato dextrose agar at 30 °C. Percentage mass loss was measured for all methods, while optical microscopy was used to examine surface changes following bacterial and fungal exposure. ATR-FTIR analysis identified a broad absorption band at 3278–3265 cm⁻¹, consistent with O–H stretching vibrations in the film constituents. The highest mass losses were 68.08% under soil burial for the formulation without BPW and 26.68% and 14.45% under dip-hanging and fungal exposure, respectively, for the formulation containing 100 wt.% BPW in the BPW–soluble starch fraction. The results indicate that composition-associated mass-loss patterns differed among exposure conditions. However, the absence of independent replication limits statistical interpretation, and mass loss and surface changes alone do not establish complete biodegradation. These findings provide preliminary evidence to guide further replicated assessments of BPW-based bioplastics.