Development of model food systems for quality evaluation of thermally pasteurized foods

Ellen Rose Bornhorst

Model foods with time temperature integrators (TTIs) are a critical part of microwave thermal process development, simulation validation, and optimization. Model food systems with Maillard reaction product TTIs have been an effective tool to assess process lethality for microwave-assisted thermal sterilization. However, model food systems used for sterilization applications (110-130°C) are not optimal for pasteurization (70-100°C). The goal of this research was to develop model food systems as tools to evaluate the quality of pasteurized foods, especially those pasteurized using a Microwave Assisted Pasteurization System (MAPS). Five model food systems, egg white, mashed potato, gellan, green pea, and garlic, were developed for use in thermal pasteurization process evaluation. Egg white, mashed potato, and gellan model foods utilized Maillard reaction product TTIs, while green pea and garlic models had alternative color formation mechanisms. Reaction kinetics for all model foods were first order and temperature dependence followed an Arrhenius relationship. At a constant heating temperature of 90°C, the Maillard reaction product TTIs were significantly correlated to the accumulated thermal lethality and cook value, which suggested that these TTIs could be used to evaluate the thermal processing severity for both safety and quality applications. However, when the heating temperature was expanded to 80-100°C, correlation analysis indicated the TTIs were more relevant for pasteurization process quality evaluation than safety. Model foods with Maillard reaction products TTIs were more temperature sensitive, with z-values from 10-29°C, compared to garlic (37°C) and green pea (40°C). Among the model food systems, mashed potato and green pea were the optimal model foods for evaluating food quality in processes targeting a 90°C for 10 min treatment. Pasteurization validation results showed that there was a quantifiable color difference between model foods with different time-temperature histories, including the unheated control, MAPS, and hot water pasteurization. Median color values obtained from image analysis were useful in assessing overall color change and interquartile range was an indicator of burnt areas on the top surface. These new quality evaluation tools could be utilized to visualize the potential food quality volumetrically, validate computer simulations, and aid in the optimization of MAPS and traditional pasteurization processes.

Development of model food systems for quality evaluation of thermally pasteurized foods

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