Dissertation
THE DEVELOPMENT OF TIME-TEMPERATURE INDICATORS FOR MICROWAVE ASSISTED PASTEURIZATION PROCESSES
Doctor of Philosophy (PhD), Washington State University
01/2014
Handle:
https://hdl.handle.net/2376/116953
Abstract
A pilot plant scale 915 MHz single-mode microwave assisted pasteurization (MAP) system was developed at Washington State University for prepackaged food products. Methods to determine the heating patterns inside the food products in this system are needed to develop appropriate thermal processes. Such methods are also necessary to validate computer simulation methods for prediction of interactions between the electromagnetic field within the microwave cavities and the food packages. The main goal of my dissertation is to develop two complementary time-temperature indicating methods to directly map the heating patterns and help visualizing the cold and hot spots in MAP systems for in-package pasteurization applications.
A time temperature indicating system normally consists of a model food serving as a chemical marker carrier and chemical marker precursors. Two models, the egg white and whole egg gel models and the gellan gel models, were selected for this study, based on their relevant physical properties including dielectric properties, gelation temperature, gel strength, and water holding capacities. Both models could be formulated into homogeneous gel models with different solid and salt contents to provide a wide range of dielectric properties to model various food products. Depending on their gelation temperatures, the egg white, whole egg, and gellan gel models could be used for heating pattern determination in microwave processes at temperatures higher than 70, 80, and 65 °C, respectively.
D-ribose and L-lysine were added to the model foods as chemical marker precursors. The formation of the possible chemical marker, and the color change of the model foods were studied using oil/water baths at pasteurization temperatures. Chemical marker M2 (4-hydroxy-5-methyl-3(2H)-furanone) and an unidentified substance(s) with the maximum UV absorbance peak at 268 nm were suitable in the egg white and gellan gel model food, respectively. The heating patterns determined by both systems were accurate based on the temperature monitored at the predetermined cold and hot spots. With the development of both time-temperature indicators, the temperatures at cold and hot spots during food processing could be monitored for proper process development, and for the improvement of the uniformity of the MAP system.
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Details
- Title
- THE DEVELOPMENT OF TIME-TEMPERATURE INDICATORS FOR MICROWAVE ASSISTED PASTEURIZATION PROCESSES
- Creators
- WENJIA ZHANG
- Contributors
- Juming Tang (Advisor)Shyam Sablani (Committee Member)Barbara Rasco (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Biological Systems Engineering, Department of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 161
- Identifiers
- 99900581844601842
- Language
- English
- Resource Type
- Dissertation