The convergence of food wasted due to spoilage and disposal of single use, non-compostable plastic packaging presents a significant economic and environmental burden. The ongoing market trend of reducing additive use in foods generates an opportunity to extend shelf life through alternative means. Active packaging technologies which seek to extend ‘clean label’ product shelf life at the post-retail level using bioderived polymers thus represents a unique solution in reducing volumes of both food and plastic municipal solid waste. An understanding of the active packaging interfacial behavior is necessary to predict performance in complex food systems. Here we present a characterization of the carboxylate pKa for polylactic acid (PLA) films grafted with the antioxidant nitrilotriacetic acid (NTA), PLA-g-NTA. Attenuated total reflectance Fourier transform infrared spectroscopy was used to determine the pKa values of 3.97 and 8.99 for the carboxylic acid groups of NTA and a pH dependent ABTS radical scavenging assay was performed to determine the pKa value of 6.74 for the tertiary amine of NTA. These results indicate PLA-g-NTA would be useful as an antioxidant material at the food interface with pH values above 6.74, as an electron transfer from the deprotonated tertiary amine was shown to be the largest driver of radical scavenging capacity. Utilizing a biodegradable antioxidant packaging material such as PLA-g-NTA thus gives way to protect food from oxidation while meeting consumer demands for reduced additive use towards the goal of reducing food waste and the environmental impact of petroleum based single-use plastics.