Monitoring of Liquid Based Microbial Bioplastic Degradation by Differential Scanning Calorimetry (DSC)

To monitor the degradation of bioplastics by microbes and enzymes, conventional weight-based and chromatography-based methods have been commonly used. However, these approaches require time-consuming sample preparation and often suffer from low reproducibility from different recovery method. As an alternative, this study proposes a quantitative approach using differential scanning calorimetry (DSC), a technique traditionally used to analyze the thermal properties of polymers. This method directly applies lyophilization without washing and drying samples and uses DSC analysis to quantify the enthalpy change (Delta H) at the melting temperature of bioplastic residues. When PHB films were analyzed after optimizations, a strong linear correlation (R-2 > 0.99) between Delta H and film mass was observed across all cases. Compared to conventional, the DSC method showed less than 3.5% deviation from the gas chromatography (GC) method, contrary to the weight-based method showing more than 14% difference from the GC-based method. This method expands the ability to quantify different types of bioplastics such as poly(butylene succinate) (PBS) and polycaprolactone (PCL), simultaneously. This research highlights DSC as a simple, reproducible, and broadly applicable approach for monitoring bioplastic degradation quantitatively, offering a promising alternative to labor-intensive conventional methods.