In-line and non-destructive monitoring of core temperature in sausages during industrial heat treatment by NIR interaction spectroscopy

During industrial heat treatment of food products, the core temperature is a critical control parameter with respect to food quality and in particular food safety. This paper presents a novel prototype system based on near-infrared spectroscopy (NIRS) that enables continuous in-line and non-contact monitoring of core temperature in sausages during heat treatment in an industrial oven. NIRS interaction measurements in the 761–1081 nm region were used to probe the interior of the sausages. NIRS calibrations for the estimation of core temperature were developed for three different sausage types in the temperature range 60–90 °C. The best accuracy obtained for core temperature with NIRS was about ±1.0 °C. Results indicate that calibrations for core temperature can be transferred between different sausage types, which will ease implementation of such a method. The method was successfully tested in a modern sausage production plant.