Biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate)/curcumin composite film as a smart indicator of food spoilage

Due to the global issue of food wastage, smart packaging technologies have been garnering growing attention in the food industry. These technologies provide comprehensive information throughout the food distribution process, including maintaining freshness, regulating temperature and humidity of food products. In this study, we developed an intelligent indicator film composed of microbial aliphatic polyester poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (PHB), and curcumin, a natural pH-sensitive dye with antioxidant and antibacterial properties. The PHBC displayed various beneficial properties including UV protection and curcumin release, as well as antioxidant and antibacterial activities. In addition, the PHBC exhibited excellent colorimetric sensitivity to volatile nitrogen compounds generated during the spoilage of protein-rich foods like meat and seafood. The PHBC intelligent indicator film could detect the food freshness through colorimetric changes caused by volatile alkaline nitrogen compounds generated during food storage, confirming that it can be applied as an intelligent indicator for detecting food spoilage.