88C-17 |
Effect of fat content and temperature on dielectric properties of ground beef |
G. NISHKARAN1, P. Mallikarjunan1, and S. Riad2. (1) Dept. of Biological Systems Engineering, Virginia Polytechnic Institute & State Univ., 200 Seitz Hall, Blacksburg, VA 24061-0303, (2) Dept. of Electrical & Computer Engineering, Virginia Polytechnic Institute & State Univ., 340 Whittemore Hall, Blacksburg, VA 24061-0111 Dielectric properties of a food material play a major role in determining the interaction between food and electromagnetic energy. Microwave frequencies, food composition, product temperature, physical state of water in the food, and product density affect these properties. Microwave heating is the widely used for cooking or thawing frozen ground beef patties. Thus a proper cooking or thawing procedure for ground beef products should be used to ensure food safety. Recent studies showed that the fat content significantly affected the survival of pathogens. The objective of this study is to determine the dielectric properties of ground beef at three different fat levels (3%, 8% and 20%) in the frequency range of 0.3 to 3.0 GHz and at temperatures from -25°C to 75°C. Ethylene glycol bath was used to maintain the temperature. Readings were taken for every 10°C in the temperature range. Ground beef samples were obtained from local grocery store. The dielectric properties were determined by measurements on an open-ended, coaxial line with copper conductors, connected to a Network analyzer. Dielectric Probe Kit software was used to calculate the dielectric properties. Results of this experiment showed that the dielectric constant decreased at higher frequencies and it has lower value for the frozen product compared to that of unfrozen product. The dielectric loss factor was higher at high temperature and decreased with an increase in frequency. At lower temperatures, the loss factor was nearly unaffected by frequency. The dielectric constant and the dielectric loss factor of low fat product was higher than that of high fat level ground beef. Results of this research will be highly helpful in developing microwave-heating procedures that will increase microbial safety, and in developing proper thawing procedure.
Session 88C, Food Engineering: Physical and Chemical Properties
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