Non-invasive identification of food fluids from the outside of opaque containers by low-power ultrasound

Cleaning in place (CIP) is widely utilized in the beverage industry to clean and lower bacteria levels in pipelines, tanks, and other processing equipment without the need for disassembly or manual cleaning. In this process, it is crucial to distinguish between fluids to determine its duration and to minimize product and water losses. The feasibility of low-power ultrasound (LPU) as a suitable technology to perform an in-line and non-invasive method to identify different food fluids (orange juice, banana puree, banana & apple puree and water) in a stainless steel (SS) opaque container was studied. Different ultrasonic key parameters (time of flight difference (DTOF), gain 80 %, full screen high (FSH) and amplitude difference) have been analysed by using both pulse-echo (PE) and through-transmission (TT) techniques and also, different frequencies (1, 2.25 and 5 MHz). Furthermore, the temperature fluctuation influence on the ultrasound response was studied, considering a typical overall temperature range in industrial juice production (14 °C–22 °C). DTOF together with the temperature and amplitude, was the combination of key parameters able to distinguish all the analysed products. Finally, a simple and easily scalable at an industrial level methodology for non-invasive identification of food fluids is proposed. This work highlights the potential of LPU technology to distinguish and control food fluids in-line, in a harmless way for the products and in a non-invasive way for the facility. This would make such monitoring feasible in many situations where it would otherwise be impractical, thereby improving the efficiency of the processes involved.