However, it is absorbed by the frozen pallets of bread only to a certain degree, restraining the tags at the far end of the container to be read.
This can be clarified by the amount of bound water present in bread, which is close to 25% (Swanson, 1943).
The term bound water refers to water in a product that does not freeze when the matrix temperature falls below 0 °C.
The behavior of the aqueous phase during freezing is significantly affected by the product formulation and the degree to which the water is bound within the product matrix.
Water is a dipole, thus when bound with flour it displays a significant elevation of dielectric loss, consequently increasing RF absorption.
The diluted salt in bread contains ions which are highly conductive and therefore RF absorptive.
In low moisture content foods, the effect of salt concentration on the dielectric behavior is closely related to the mobility of the water molecules inside the foods.
In addition, water condensation, not yet frozen on the product and its packaging, could have increased the RF energy absorption.
Note that in this test, the antenna was completely covered by the height of the load (2.4 m); therefore RF waves had only a small gap to travel through.