The development of a curcumin-based sensor for the detection of volatile amines (specifically known as total volatile basic nitrogen, TVBN) is described. Curcumin [(1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-1,6-diene-3,5dione] is the major yellow pigment extracted from turmeric, a commonly used spice, derived from the rhizome of the plant Curcuma longa. Curcumin was immobilized onto bacterial cellulose membrane via the absorption method. Thus, the sensing materials are edible and suitable for food applications.
The curcumin/bacterial cellulose membrane as the TVBN sensor worked based on pH increase as the basic spoilage volatile amines produced gradually in the package headspace, and subsequently, the color of the sensor will change from yellow to orange, then to reddish orange for spoilage indication, which is easily visible to the naked eye. The curcumin membrane is a highly sensitive material toward acid–base reactions. Color changes, as a result of its interactions with increasing pH (as a result of increasing TVBN), were monitored directly with visual inspection and the color quantitatively measured with color analysis via Photoshop software. Furthermore, the membrane response was found to correlate with bacterial growth patterns in shrimp samples. Finally, the curcumin/bacterial cellulose membrane was successfully used as a sticker sensor for real-time monitoring of shrimp spoilage in ambient and chiller conditions.