Soy protein isolate films: a biodegradable solution for UV protection alternatives

Abstract

The uncompromising need to protect against harmful UVA and UVB radiation and to alleviate plastic pollution has catalyzed the development of innovative, eco-friendly materials. This study presents a solution by developing a transparent coating derived from Soy Protein Isolate (SPI), offering UV protection as well as sustainable bioplastic alternatives to synthetic polymers. The structural and chemical properties of SPI coatings, highlighting their UV protective capabilities, were analyzed using UV absorption spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Differential Scanning Calorimetry (DSC), Nuclear Magnetic Resonance (NMR), and High-Resolution Liquid Chromatography-Mass Spectrometry (HR-LCMS). X-ray photoelectron spectroscopy (XPS) analysis showed decrease in carbon composition between SPI powder and film, suggesting a different surface composition for the film from powder, whereas denaturation was further confirmed by DSC. Contact angle measurement gives insights about the surface properties of the film and HR-LCMS gives the amino acids present in SPI. The biodegradability of SPI, coupled with its durability and transparency, underscores its potential as a versatile host material for various coatings. highlighting its additional advantage. From the FE-SEM study, the coating shows uniformity, which presents an innovative approach to transparent coatings. Notably, alongside transparency, the inherent UV absorption properties of SPI remained consistent before and after denaturation, showing potential applications in UV protective biodegradable coatings for various industrial applications, promoting eco-friendly alternatives to synthetic polymers. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2025.