Development of a Maillard reaction-based time-temperature integrator/indicator (TTI) for visual monitoring of chilled beef during long-term storage and distribution

Time-temperature integrator/indicator (TTI) is a temperature monitoring tool that visually presents the temperature history of foods to easily and cost-effectively manage the temperature of food products in cold chain system. However, few TTIs exhibit suitable performance under chilled conditions over a long period, such as beyond 100 days, as in the storage and distribution of chilled beef across the world. This study aimed to visualize the temperature history of chilled vacuum-packed beef, during international distribution, using Maillard reaction–based TTIs to record the accumulated temperature under chilled conditions, for more than 100 days. The developed Maillard reaction–based TTI comprised of double-sealed large and small plastic pouches. While the small pouch contained 500 μL D-xylose solution, the large pouch contained 1000 μL glycine solution with disodium hydrogen phosphate solution. Both the solutions were mixed by breaking the small pouch into the large pouch, following which the Maillard reaction started, depending on the ambient temperature. We examined two different combinations of the solution concentrations of TTI that turned brown and yellow at -0.5 °C after approximately 77 days and 100 days, respectively. The developed TTIs, along with Tasmanian chilled beef, were transported from Australia to Japan through commercial supply chains and stored at a constant temperature of -0.5 °C. One of the TTIs (TTI-brown) turned pale brown after 77 days which is the current shelf life of Australian chilled beef in Japan. The color of TTI-yellow changed to clear yellow after 150 days, when the chilled beef developed an off-odor, as judged by sensory evaluation. The TTI-brown was functional until day 77 which is the current shelf life of Australian beef in Japan, while the TTI-yellow was functional until day 150 to indicate remaining shelf life of beef. The results collectively indicated the Maillard reaction–based TTIs to realize visualization of temperature history during long-term storage and distribution of chilled beef.