UV-Shielding Biopolymer Coatings Loaded with Bioactive Compounds for Food Packaging Applications

Four natural bioactive compounds with UV-absorbing properties—curcumin, quercetin, caffeic acid, and hymecromone—were incorporated into pectin-based coatings deposited on oriented polypropylene (OPP) to develop packaging films with UV-shielding capabilities. The effects of both bioactive compounds (used individually or in combination) and coating thickness (δ = 0.12–1.2 μm) on the optical properties (UV-Vis transmittance and haze) of the coated OPP samples were investigated. Coating deposition enhanced the UV-barrier properties in relation to the type of bioactive compound, following the order of caffeic acid > hymecromone > curcumin > quercetin. Regardless of the type of bioactive compound used, no significant changes were observed in clarity, haze, and tensile parameters of OPP, whereas the pectin coatings dramatically improved the oxygen barrier performance of the plastic substrate. Additionally, a greater coating thickness resulted in a lower UV-light transmittance of coated PP films. Although the combination of hymecromone and caffeic acid did not exhibit a synergistic effect, it demonstrated an additive benefit, effectively broadening the wavelength range of UV protection in the final packaging materials. While this study highlights that a performance gap remains compared to commercially available UV-shielding materials, it underscores the potential of replacing synthetic UV-absorbing additives with natural compounds through coating technologies rather than masterbatch incorporation.