Highly Sensitive Colorimetric Ammonia Sensors Based on Polydiacetylene/Zinc Oxide Nanopellet-Embedded PDMS Films for Meat Spoilage Detection

Simple-to-use colorimetric sensors that can detect the release of gases from food spoilage are of great interest in food safety, as a shelf-life indicator and for food waste management. Herein, we demonstrate polydiacetylene/zinc oxide nanopellet (PDA/ZnO)-embedded polydimethylsiloxane (PDMS) films for colorimetric sensing of meat spoilage based on ammonia gas detection. In particular, by optimizing the weight ratio of ZnO nanopellets in the composite film (15 wt %), a high colorimetric response of ∼51.5% can be achieved for 200 ppm ammonia gas exposure and observed by the naked eye. The PDA/ZnO-embedded PDMS film sensors exhibited a high thermal stability up to 100 °C and a long-term storage stability up to 180 days. In addition, the sensors showed excellent selectivity for ammonia gas when compared with other volatile organic compounds. Using the PDA/ZnO-embedded PDMS sensors, we investigated the degree of food spoilage of chicken and pork meat under various storage conditions. The color transition can be observed with the food storage period, indicating that the PDA/ZnO-embedded PDMS sensors can be potentially applied as colorimetric sensors for meat freshness indicators in smart food packaging.