Development of a time–temperature indicator based on Maillard reaction for visually monitoring the freshness of mackerel

Due to the highly cost-effective and maneuverable property, Maillard reaction-based time–temperature indicators (TTIs) are considered ideal devices for temperature track and quality indication. The objective of this study was to develop a cold-sensitive TTI based on the Maillard reaction reflecting the freshness of chilled seafood. Firstly, the color evolution trends of a series of Maillard reaction-based TTIs were investigated and the xylose-lysine group represented obvious color change. Fourier transform infrared (FTIR) spectroscopy revealed the color change was associated with the formation of C N bond in melanoidin. Simultaneously, the relationships of the color change of TTI with time and temperature were established. The activation energy value ( Ea ) of TTI was close to that of mackerel. There existed a good relevance (R 2  = 0.98) between the color change of TTI and the total volatile basic nitrogen content of mackerel, suggesting this novel TTI might have the potential to monitor the freshness of mackerel.