| 摘要 |
A foodstuff is located in a container open at its top end in which ambient gas (air) occupies the space inside the container above the product. The container is immersed into a liquid having a low dielectric loss factor, such as water, to such an extent that the liquid level is somewhat below the upper side of the product in the container. Using electrodes located to either side of the container, there is passed through the container from one side thereof to the other a first high-frequency electromagnetic alternating field having a respective first frequency such that the penetration depth of said first field is at least as great as the width of the container. From the open end of the container at which the air filled portion thereof is located, there is passed into the container through the air and into the adjoining portion of the product a second high-frequency electromagnetic alternating field having a respective second frequency such that the penetration depth of the second field is small compared to the penetration depth of the first field.
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