Indirect conductivity measurement of liquids in flexible containers

This paper presents an indirect method for measuring the conductivity of liquid foods, packed in flexible TEA (Tetra Brik Aseptic) food-containers. The method is intended for intensive (100%) non-invasive sterility-testing of aseptically packed liquid food-products. It can also be applied for other containers, which have similar construction. An electric model is developed for the measured impedance, which consists of a few components. Some of them are dependent on the conductivity /spl sigma/ of the liquid. Relation is derived between the active component R of the measured impedance and the conductivity of the food. The sensitivity and the robustness of the method is investigated with respect to its application under industrial conditions and experimental results are presented.