Effect of concentration and consistency on ohmic heating

摘要

Ohmic heating (OH) is an emerging technology that has shown great potential in the food industry. Product consistency, concentration, and electrical conductivity are critical factors in OH. These variables are interrelated; how they affect each other, however, is not well described in the literature. This study aimed to verify the impact of concentration and consistency on OH, by evaluating the electrical conductivity of several carboxymethyl cellulose (CMC) solutions. CMC solutions of different concentration (0.5-3%) were processed by high-pressure homogenization (HPH) at 100 and 200MPa (unprocessed as control), to obtain solutions with different consistencies and same concentration. Electrical conductivity at 25 degrees C increased as solution concentration increased (ranging from 0.118 Sm-1 at 0.5% to 0.493 Sm-1 at 3%), and HPH treatment increase the electrical conductivity (ranging, at 3%, from 0.493 Sm-1 at 0 MPa to 0.575 Sm-1 at 200MPa), however no significant difference between 100 and 200MPa samples. Several correlations were possible to between concentration, consistency, and electrical conductivity. These correlations may be used as an indirect tool to determine consistency from electrical conductivity and may be applied in process and equipment design. The results corroborate the potential of OH in fluids with high consistency.Practical applicationsFood consistency is a critical factor in many processes, and ohmic heating shows a great potential for the treatment of highly viscous fluids. How rheological parameters impact ohmic processing without altering product composition has never been investigated. Moreover, the models developed in this study can be used as an indirect tool to estimate rheological parameters from electrical conductivity readings.