Effect of fat content and temperature on dielectric properties of ground beef

Microwave heating depends on dielectric properties, microwave frequencies, food composition, physical state of water in the food, and product temperature and density. Proper microwave cooking and thawing procedures for ground beef products are needed to ensure food safety. Recent studies showed that the fat content significantly affected the survival of pathogens. The objective of this study was to determine the effect of fat content and temperatures on dielectric properties of ground beef. The dielectric properties were determined using an open-ended, coaxial line with copper conductors, connected to a network analyzer. The relationship among dielectric properties, fat level, and temperature was obtained for 915 MHz and 2450 MHz. Results of the experiment showed that dielectric loss factor and dielectric constant increased with increase in temperature at both frequencies at temperatures below the freezing point. Above the freezing point, dielectric constant decreased with increase in temperature. Dielectric loss factor increased with temperature at 915 MHz. At 2450 MHz, it remained almost constant with varying temperature. Dielectric constant and dielectric loss factor of low-fat ground beef were higher than that of high-fat ground beef. Regression equations were developed for predicting dielectric properties at different temperatures and fat levels.