Enzyme- and relative humidity-responsive antimicrobial fibers as active food packaging materials

Authors: AYTAC, ZEYNEP - Harvard University; XU, JIE - Harvard University; KUMAR, SURESH - Nanyang Technological University; EITZER, BRIAN - Nanyang Technological University; XU, TAO - Harvard University; VAZE, NACHIKET - Harvard University; NG, KEE - Nanyang Technological University; WHITE, JASON - Connecticut Agricultural Experiment Station; CHAN-PARKB, MARY - Nanyang Technological University; Luo, Yaguang - Sunny

Submitted to: ACS Applied Materials and Interfaces
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2021
Publication Date: 10/14/2021
Citation: Aytac, Z., Xu, J., Kumar, S., Eitzer, B., Xu, T., Vaze, N., Ng, K., White, J., Chan-Parkb, M., Luo, Y. 2021. Enzyme- and relative humidity-responsive antimicrobial fibers as active food packaging materials. ACS Applied Materials and Interfaces. 13(42):50298. https://doi.org/10.1021/acsami.1c12319.
DOI: https://doi.org/10.1021/acsami.1c12319

Interpretive Summary: Biodegradable packing materials that are capable of controlled release of antimicrobial agents have the potential to maintain food safety and quality in the supply chain. In this study, a novel enzyme- and relative humidity (RH)-responsive antimicrobial fiber was designed, synthesized, and tested. Biodegradable materials including cellulose, zein, and starch were electrospun to form fibers which were further incorporated with nature derived antimicrobials including thyme oil, citric acid, and nisin and their corresponding cyclodextrin-inclusion complexes. Results showed that these fibers can be triggered via high relative humidity (95% RH), and selective enzymes produced by microorganisms to release antimicrobial agents, which exert strong efficacy on pathogen inactivation. Such biodegradable, nontoxic, and multi-stimuli responsive antimicrobial fibers have great potential for broad applications for the food industry as active and smart packaging materials. This technology will reduce food waste, benefiting consumers, as well as the food industry.

Technical Abstract: Active food packaging materials that are sustainable, biodegradable, and capable of controlled release of antimicrobial ingredients (AIs) have great potential to enhance food safety and quality. Here, we report the design, synthesis, and characterization of novel enzyme- and relative humidity (RH)- responsive antimicrobial fibers. Cellulose nanocrystals (CNCs), zein (protein), and starch were electrospun to form fibers that incorporated a cocktail of nature derived antimicrobials including thyme oil, citric acid, and nisin and their corresponding cyclodextrin-inclusion complexes (CD-ICs). The chemical, structural, and biological properties of the fibers were tested via Scanning electron microscopy, X-ray diffraction analyzer, Fourier transform infrared spectrometry, and culture-based microbial procedure. Results showed that the fibers averaged 225±50 nm in diameter, and released AIs in response to high relative humidity (95% RH), and exposure to the enzymes protease, amylase and cellulase in a dose-dependent fashion. With 24 hours exposure, these trigger responsive fibers (at 10.9 m2/g) significantly reduced the populations of foodborne pathogenic bacterial surrogates Escherichia coli (by ~ 5 log unit) and Listeria innocua (by > 1 log unit), as well as pathogenic fungus Aspergillus fumigatus (by >1 log unit). Such biodegradable, nontoxic, and multi-stimuli responsive antimicrobial fibers have great potential for broad applications for the food industry as active and smart packaging materials.