Beyond Labeling: Hybrid Planar Photonic Crystals for Anti-tampering Detection of Amines

Abstract

Smart packaging promises to protect consumer health and safety, reduce food waste, and decrease energy and resource consumption. In other words, less food waste leads to better living conditions, decreasing plastic waste and greenhouse gas emissions. This work aims to create a colorimetric label for assessing food freshness by monitoring biogenic amines, which are the typical degradation byproducts of protein-based food such as meat, fish, and seafood. We focus on planar photonic crystals consisting of alternating thin films of a titanium dioxide-poly(acrylic acid) hybrid as a high-refractive-index medium and a blend of polystyrene and polylactic acid as a low-index and sensitive material. The colorimetric response of these sensors can be detected by visible reflectance spectroscopy and is visible to the naked eye, allowing a straightforward interpretation by any user. The response is tested for a prototype amine and for chicken meat, and it is caused by the loss of the structural color of the dielectric lattice resulting from the aminolysis of the polylactic acid that induces the collapsing of the rigid hybrid layers, thus providing effective nonreversible antitampering systems for smart labeling.