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 (d = 0.12 – 1.2 um) 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: caffeic acid > hymecromone > curcumin > quercetin. Regardless of the type of bioactive compound used, no significant changes were observed in clarity and haze of OPP. Additionally, a greater coating thickness resulted in 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.