Microwave and Radio Frequency Heating

Microwave and radio frequency heating refers to the use of electromagnetic waves of certain frequencies to generate heat in a material (Metaxas (1996); Metaxas and Meredith (1988); Roussy and Pearce 1995). The frequencies allocated by the Federal Communications Commission (FCC) for the purposes of heating are listed in Table 1.З.2.1. Typically, microwave food processing uses the two frequencies of 2450 and 915 MHz. Of these, the 2450 MHz frequency is used for home ovens, and both are used in industrial heating. It is worthwhile to note that outside of the United States, frequencies of 433.92, 896, and 2375 MHz are also used.

Radio frequency heating in the United States can be performed at any of the three frequencies listed in Table 1.3.2.1. As mentioned earlier, there is not much commercial use of these frequencies for food pasteurization or sterilization, although they are used in baking and other processes in the food industry (US FDA, 2015).

Table 1.3.2.1 Frequencies Assigned by the FCC for Industrial, Scientific, and Medical Use (US FDA, 2015).

Frequency

Radio

13.56 MHz ± 6.68 kHz

27.12 MHz ± 160.00 kHz

40.68 MHz ± 20.00 kHz

Microwaves

915 MHz ± 13 MHz

2450 MHz ± 50 MHz

5800 MHz ± 75 MHz

24125 MHz ± 125 MHz

 
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