| 摘要 |
<p>Heat treatment process for food preservation, e.g. sterilization of milk products, employing high frequency electromagnetic irradiation. The product in its container is immersed in a bath of liquid to a depth at which the level of the top surface of the product remains slightly above the level of liquid in the bath, i.e. the gas space above the product is completely above the level of bath liquid. In this position the product is irradiated between electrodes emitting electromagnetic energy at a frequency low enough to ensure penetration right through the container, i.e. wavelength of the order of metres to decametres; simultaneously, a much higher frequency electromagnetic field, with a very limited penetrating power, is set up at right angles to the transverse field between the electrodes, e.g. from a parabolic antenna above the container, and irradiates the gas space above the product, the wavelength in this case being of the order of centimetres to decimetres. Heat treatment such as sterilization for the preservation of food products in non-metallic containers such as plastic pots, glass jars and bottles, in partic. milk products such as yoghourt and cream dessert, meat and meat pastes.</p> |
