Development and characterization of a new nonenzymatic colored time–temperature indicator

Time–temperature indicators (TTIs) are effective tool for monitoring food quality during processing and distribution. In this study, a new colored nonenzymatic browning (fructose and glycine)-based TTI was developed. Twelve TTIs were made at four different substrate concentrations and three pH ranges 8.0–10.0. The mathematical models of each TTI were drawn up, which showed the relationships between the color change in terms of absorbance (420 nm), time and temperature. The activation energies (Ea), calculated from Arrhenius relationship ranged between 58.09 and 95.54 kJ mol⁻¹ of all TTIs. Activation energies could be changed to match the Ea of food product, by modifying pH and the proportion of the fructose and glycine. A visual color change of TTI and a wide range of activation energy illustrated that this new chemical-based TTI could be applied to show the time–temperature history of foodstuffs, and to indicate the food quality, which is associated with the undergoing of the time–temperature exposure.

Practical applications

This work provides the development of a new smart temperature indicator based on nonenzymatic browning. The indicators are more useful for food quality monitoring from manufacturing till consumer consumption. However, the application of the TTI's can be extended to food processing, that is, sterilization, pasteurization, and drying process. Thus, the use of the TTIs can encourage food producers to scrutinize food processing and distribution to deliver good quality to consumers with guaranteed security.