Using whey protein gel as a model food to study dielectric heating properties of salmon (Oncorhynchus gorbuscha) fillets

It is desirable to develop rapid commercial microwave and radio frequency sterilization processes to produce high quality shelf stable muscle foods, particularly aquatic foods. Whey protein gels containing d-ribose and salt were studied as a model food to determine heating patterns in salmon fillets during high temperature microwave sterilization processes. Dielectric constant (ɛ′) and loss factor (ɛ″) of whey protein gels with d-ribose (0.5 g/100 g, 1 g/100 g, and 1.5 g/100 g) at different salt contents (0, 0.1 g/100 g, 0.2 g/100 g, 0.3 g/100 g, 0.4 g/100 g, and 0.5 g/100 g) and frozen and thawed pink salmon (Oncorhynchus gorbuscha) fillets were determined over the frequency range of 27–1800 MHz at temperatures ranging from 20 to 120 °C. The dielectric properties of whey protein gels containing 1 g/100 g d-ribose and 0.2 g/100 g or 0.3 g/100 g salt closely matched the dielectric behavior of salmon fillets in both radio frequency (RF, 27 MHz) and microwave (MW, 915–1800 MHz) ranges. Altering the salt content had a greater impact on dielectric constant and loss factors at lower frequencies. These results suggest that whey protein gel may be a good model food for microwave sterilization process development, particularly for determining the locations of cold and hot spots in complex muscle foods.