Abstract: The method includes the steps of: preheating a selected volume of product to a temperature proximate to the maximum temperature of the treatment; irradiating the product with an alternating electromagnetic field in order to heat the product to approximately 50.degree. C.; maintaining the product at a substantially constant temperature for a set time; cooling the product to a temperature close to the packaging temperature. An apparatus for performing the above method includes a pair of facing emitting surfaces connected to the terminals of an oscillator operating below 1 GHz and set to heat the product to a maximum temperature of approximately 50.degree. C. The apparatus also includes a thermally insulated region to maintain the product at the maximum temperature of the treatment for a selected time adapted to ensure the complete destruction of the bacterial and sporal loads.