Exploration and application prospect of the advanced technology of time–temperature indicators

The time–temperature indicator (TTI) is a kind of indicator that can monitor the safety of food, drugs and other products. It produces the cumulative effect of time–temperature through physical and mechanical deformation, chemical or biological reaction, and makes an irreversible and obvious color change, so as to record the temperature change course experienced by products. This review details the selection and characteristics of TTI materials in the last 15 years. The classification of TTIs, such as enzyme type, chemical type, microbial type, diffusion type, nanomaterial type and Maillard type, self-healing type and electronic type, are described in detail. Finally, the application of TTIs in various kinds of food packaging, such as meat products, aquatic products, fruits and vegetables and dairy products, is emphatically studied. This review provides ideas for the further improvement and research of TTIs, and provides a reference for the performance of TTIs in other commercial fields.