UV-Curable Silicone-Modified Polyurethane Acrylates for Food Freshness Monitoring

Abstract

Intelligent materials for monitoring the condition of the packaged food or its surroundings are highly desired to ensure food safety. In this paper, UV-curable silicone-modified materials for monitoring the freshness of high-protein food such as shrimp and pork were prepared from polyurethane acrylates with covalent-grafted neutral red groups and thiol silicone resin. The UV-curable materials exhibited visible pH-sensitive performance and long-term color stability because their color did not change when they were immersed in aqueous solutions with different pH values for 20 min, and the color remained even when they were immersed for over 5 h. The distinctive color variation in the UV coatings makes them suitable as potential pH-sensitive sensors. These pH-sensitive intelligent materials can be applied to monitor the freshness of high-protein food such as shrimp and pork. Additionally, the thermal stability and adhesive properties of the UV-curable materials were also studied. A conclusion can be drawn that the covalent bonding of neutral red groups onto a silicone-modified polymer matrix is an ideal strategy for developing pH-sensitive intelligent materials with good pH stability for monitoring the freshness of high-protein food.