Optical Colorimetric Sensing Label for Monitoring Food Freshness †

Abstract

The development of optical sensors to monitor food freshness during storage and transportation helps to increase food security and customer satisfaction by preventing the misinterpretation of food date labeling. In this study, a simple, rapid, and low-cost paper-based optical sensing label was fabricated for the visual detection of food spoilage by the naked eye. The filter paper was coated with electrically conductive polyaniline ink. The pH-responsiveness of the coated polyaniline nanofibers allowed for the colorimetric detection of shrimp spoilage through the transition from the doped green emeraldine acid state to the dedoped blue emeraldine base state. The combination of the flexible filter paper as a substrate and the polyaniline ink as an indicator represents a facile approach for the fabrication of a colorimetric optical sensing label for food freshness monitoring applications.