The usage of Ohmic heating in milk evaporation and evaluation of electrical conductivity and performance analysis

Ohmic heating is based on the principle of heating by passing an alternating current through the product between two electrodes and is an increasingly current electrical heating technique in food applications. The main purpose of the present study is to evaporate milk (cow's milk) from 7.85 kg-water/kg-dry matter (DM) content to approximately 3 kg-water/kg-DM content under atmospheric conditions in different voltage gradients and to examine the electrical conductivity (EC) value during the evaporation process. Also, performance evaluation was determined and compared with the traditional method. It was determined that the total process time in the Ohmic heating assisted evaporation (OHAE) process was 31–92.5 min, while in the traditional evaporation process, the total process time was 41.10 ± 2.1 min. The EC value was 0.43–1.89, 0.44–1.89, and 0.44–1.92 S/m for 7, 9, and 11 V/cm, respectively. In the OHAE process, it was determined that as the voltage gradient increased, the energy and exergy efficiency increased. The lowest energy and exergy efficiency values were obtained in the traditional method. In general, OHAE can be applied to milk, and it was a highly efficient process. Practical applications: Ohmic heating is one of the current electrical heating techniques studied in many areas by researchers. In this study, the change in electrical conductivity and performance values during the milk evaporation process was examined and compared with the traditional method. The OHAE process was more efficient than the traditional method in terms of both energy and exergy efficiency. It is thought that this evaluation will contribute as a data source for both industry and pilot-scale designs. Besides, it will contribute data to the literature with the exergy analysis that is limited in the Ohmic heating process. As a result, a concentrated milk sample with high yield and approximately 3 kg water/kg DM content was obtained.