A new chemical marker method for determining heating patterns in microwave pasteurization

Microwave pasteurization provides faster heating and better product quality than conventional thermal pasteurization of pre-packaged foods, but determining microwave heating patterns is a challenge. This study developed a new chemical marker method using a fructose-lysine gellan gel model food to visualize heating patterns in packages. Isothermal heating tests at 70, 80, and 90 °C showed that L∗ values of the model food followed first-order reaction kinetics. There was a strong correlation between the L∗ values and pasteurization lethality (F_90°C), suggesting that the changed L∗ values in the model food could indicate cumulative time-temperature effects of pasteurization. A color map of the model food was created based on L∗ values. The map clearly identified hot and cold spots in the heated model foods, which matched the results from both computer simulations and direct temperature measurements. This study presents a new, cost-effective chemical marker method suitable for rapidly mapping microwave heating patterns in industrial pasteurization processes.