Ohmic heating of fluid containing apple particulates
1999
Wang, C.S. | Wu, J.S.B.
Ohmic heating is a promising heating method for aseptic processing of fluids that contain particulates. The rate of ohmic heating is mainly determined by the electric conductance of both the liquid and the solid phases. The present study involved the investigation of the effect of vacuum infiltration and salt addition on electric conductance and heating rate in a model system which simulated the ohmic heating section in the aseptic canning of apple particulates in an acidified isotonic sucrose solution as the carrier fluid. Although particulates vacuum-infiltrated with isotonic sucrose solution exhibited lower electric conductance than the tested carrier fluids at ambient temperatures, the particulates' electric conductance increased at elevated temperatures and more rapidly reached pasteurization temperature. The addition of 0.05% sodium chloride or 0.31% potassium citrate to the sucrose carrier fluid containing 1.0% citric acid increased the heating rates of both the infiltrated particulates and the fluid in a 50V/cm electrical field, enabled these two phases to reach 85 degrees C simultaneously, and thus constituted a suitable ohmic heating procedure in the aseptic canning of apple particulates.
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