ELECTRICAL CONDUCTIVITY of APPLE and SOURCHERRY JUICE CONCENTRATES DURING OHMIC HEATING

Journal of Food Process Engineering - Tập 27 Số 3 - Trang 159-180 - 2004
Fılız İçıer1, Coşkan Ilıcalı1,2
1Food Engineering Department Engineering Faculty Ege University 35100, Bornova-Izmir, Turkey
2Present address: Department of Process and Food Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia.

Tóm tắt

ABSTRACTOhmic heating is based on the passage of electrical current through a food product that serves as an electrical resistance. In this study, apple and sourcherry concentrates having 20–60% soluble solids were ohmically heated by applying five different voltage gradients (20–60 V/cm). the electrical conductivity relations depending on temperature, voltage gradient and concentration were obtained. It was observed that the electrical conductivities of apple and sourcherry juices were significantly affected by temperature and concentration (P < 0.05). the ohmic heating system performance coefficients (SPCs) were defined by using the energies given to the system and taken up by the juice samples. the SPCs were in the range of 0.47–0.92. the unsteady‐state heat conduction equation for negligible internal resistance was solved with an ohmic heating generation term by the finite difference technique. the mathematical model results considering system performance coefficients were compared with experimental ones. the predictions of the mathematical model using obtained electrical conductivity equations were found to be very accurate.

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Journal of Food Process Engineering

Tập 27 Số 3

159-180

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