ABSTRACT: Aseptic processing of a low-acid multiphase food product using a continuous flow microwave heating system can combine the advantages of an aseptic process along with those of microwave heating. Dielectric properties of 2 different brands of 1 such product (salsa con queso) were measured under continuous flow conditions at a temperature range of 20 to 130 °C. At 915 MHz, the dielectric constant ranged from 58.7 at 20 °C to 41.3 at 130 °C with dielectric loss factor ranging from 41.0 at 20°C to 145.5 at 130 °C. The loss tangent at 915 MHz ranged from 0.61 at 20 °C to 3.52 at 130 °C. The temperature profiles at the outlet during processing of salsa con queso in a 5-kW microwave unit showed a narrow temperature distribution between the center and the wall of the tube. The study showed the feasibility of aseptic processing of salsa con queso using a continuous flow microwave system.