Our Sun is at such a temperature on its surface that the predominant color of light it emits is a sort of greenish-yellow. Evolution has made the eye most sensitive to that color when objects are illuminated. Thus yellow fire trucks are more readily seen in daylight hours. When NASA sends space probes to bodies beyond earth, they routinely bathe the vehicles on the launch pad in ultraviolet radiation for several hours.
Ultraviolet photons are energetic enough to kill bacteria and other nasties.
Thus the body to which the probe is sent will not be contaminated with Earth life. Similarly the ozone in the atmosphere absorbs ultraviolet and protects the people below it from these damaging rays which can cause sunburn and cancer. The meat has much water in it. The microwaves have just the right energy to rotate water molecules causing friction which heats the meat. No water molecules in the plate means the plate doesn t get hot and burn.