Ohmic Heating of Basil-based Sauces: Influence of the Electric Field Strength on the Electrical Conductivity
Casaburi, Oriana
Brondi, Cosimo
Romano, Aldo
Marra, Francesco

How to Cite

Casaburi O., Brondi C., Romano A., Marra F., 2021, Ohmic Heating of Basil-based Sauces: Influence of the Electric Field Strength on the Electrical Conductivity, Chemical Engineering Transactions, 87, 343-348.


The Moderate Electric Field (MEF) processing of foods consists in the application of an electric potential gradient (????/??) ranging from 1 to 1000 V/cm on a food item (homogeneous or heterogeneous) placed between two electrodes, its main effect being the food heating due to the dissipation of a part of the electric energy into heat within the food item. The heating performances of such a system depend on several process and system parameters, including the applied ????/??, the food electrical conductivity, and its thermo-physical properties. In this study, the effects due to the salt composition and to the applied ????/?? to a heterogeneous food (constituted by a basil-based sauce, mainly fibers dispersed in a slightly salted water-oil emulsion) treated in a custom MEF system on the food heating rate are investigated. The samples were prepared at different salinities (3.25, 1.63, 0.86 and 0.43% w/w respectively). In the explored range of compositions, the heating rate increased linearly with the square power of applied ????/??. A slight linearity deviation above 55°C was observed for the basil-based sauce at 1.63% and 5.20 V/cm, associated with bubble formation within the ohmic system and the electrolytic reactions occurring at the electrode-solution interface during the MEF heating process.
The salt content as well as the ratio between water and oil in the sample formulation played a crucial role in determining the thermo-electrical behavior of the basil-based sauce samples. Samples with salinity of 1.63%, compared to samples at 3.25%, exhibited a higher electrical conductivity, being due to a minor concentration of the non-conductive phase (namely the oil phase as well as the dispersed vegetable fibers into the solution) that exerts a major degree of electrical insulation. As the salinity decreases from 1.63% to 0.43%, samples were characterized by lower electrical conductivities, being due to a reduced ionic mobility when the salt contained into the sample is drastically reduced.