The convergence of food wasted due to spoilage and disposal of single use, non-compostable plastic packaging represents a significant economic & environmental challenge. The current market trend of reducing additive use in foods is likely to result in an unintended decrease in product shelf life due to increased susceptibility to spoilage reactions such as oxidative degradation. Active packaging technologies which seek to extend ‘clean label’ product shelf life at the post-retail level using bioderived and biodegradable polymers thus represents a unique opportunity in reducing volumes of both wasted food and single-use plastic diverted to municipal solid waste. Real food systems have varying and complex matrices which can impact the performance of active packaging technologies, because the active moieties bound at the interface will perform differently depending on the food matrix itself. Therefore, an understanding of the interfacial behavior is necessary to tailor active materials to meet their end application. Here we present a characterization of the surface 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 that PLA-g-NTA would be useful as an antioxidant material in food systems with pH’s 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 extend shelf of foods 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.

Interfacial chemistry of a bioderived active packaging film dictates its performance in complex matrices

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.