Food and Bioprocess Technology

, Volume 4, Issue 7, pp 1253–1263 | Cite as

Ohmic Heating of Liquid Whole Egg: Rheological Behaviour and Fluid Dynamics

  • Filiz IcierEmail author
  • Hayriye Bozkurt
Original Paper


Although ohmic heating is used as an alternative heating method for liquid egg products commercially, there is a lack of information on the change of rheological properties and fluid dynamics characteristics of ohmically heated liquid whole egg in the literature. The change of rheological behaviour of the ohmically heated liquid whole egg, across a temperature range of 4–60 °C, was determined by using a concentric rotational viscometer. The ohmic heating was conducted by applying the voltage gradient (20 V/cm) at 50 Hz. The temperature dependency of the electrical conductivity of liquid egg was linear (R 2 = 0.999). The rheological behaviour was found to be shear thinning since power law model had higher regression coefficient and lower χ 2 and root mean square error values than Newtonian model. Ohmically heated liquid whole egg exhibited higher degree of thixotropic index indicating the occurrence of the protein denaturation at 60 °C. The flow behaviour of liquid whole egg in the continuous ohmic heating system was predicted as laminar (GRe range of 87.59–538.87) for the mass flow rate range of 0.0056–0.0166 kg/s. The friction factors and pressure losses in the system in those mass flow rates were also assessed. The result of this study will give necessary information on flow characteristics of liquid whole egg for the modelling, designing and the scaling up of the continuous ohmic heating systems for pasteurisation of liquid egg products.


Ohmic heating Liquid whole egg Rheology Fluid dynamics Non-Newtonian fluid 



Pressure drop (Pa)


Area of cross-section of the electrodes (m2)


Diameter of pipe (m)


Activation energy (kJ/mol)


Friction factor (dimensionless)


Generalised Reynolds number (dimensionless)


Current (A)


Consistency coefficient, (Pa s n )


Consistency coefficient at reference temperature (Pa s n )


The distance between the electrodes (m)


Flow behaviour index (dimensionless), number of constants in Eq. (12)


Number of observations in Eqs. (12)–(13)

Ideal gas constant (8,314 J/mol K) in Eq. (3) (Table 1), radius (m) in Eq. (9), Eq. (10) in Table 1
Table 1

Some general relations used


Equation number


Newtonian model

\( \tau = \mu \dot \gamma \)

Eq. (1)

Rao et al. 1984

Power law model (Ostwald–de Waale model)

\( \tau = K{\dot \gamma^n} \)

Eq. (2)

Rao et al. 1984

Temperature dependency of consistency coefficient

\( K = {K_0}{e^{ - \frac{E_a}{R}\left( {\frac{1}{T_0} - \frac{1}{T}} \right)}} \)

Eq. (3)

Rao et al. 1984

Generalised Reynolds number

\( {\text{G}}{\rm Re} = \frac{{{D^n}{\upsilon^{\left( {2 - n} \right)}}\rho }}{{{8^{\left( {n - 1} \right)}}K{{\left( {\frac{3n + 1}{4n}} \right)}^n}}} \)

Eq. (4)

Geankoplis 2003

Friction factor for non-Newtonian fluid, laminar flow

\( f = \frac{16}{{{\text{G}}{\rm Re} }} \)

Eq. (5)

Geankoplis 2003

Pressure drop

\( \Delta P = 4f\frac{L}{D}\frac{{\rho \upsilon_{\text{ave}}^2}}{2} \)

Eq. (10)

Geankoplis 2003

Electrical conductivity

\( \sigma = \frac{I}{V}\frac{L}{{{A_{\text{e}}}}}\,\,\,\,\,({\text{S/m}}) \)

Eq. (11)

Sastry and Salengke 1998


Reynolds Number (dimensionless)


Temperature (°C), (K) in Eq. (3) (Table 1)


Time (s)


Reference temperature (K)


Voltage (V)



Raw material


Root mean square error


Revolutions per minute


Standard error


Shear stress


Shear rate

Greek Letters


Shear stress (Pa)


Electrical conductivity (S/m)


Density (kg/m3)

\( \dot \gamma \)

Shear rate (s−1)


Velocity (m/s)

\( \dot \upsilon \)

Volumetric flow rate (m3/s)


Viscosity (Pa s)


Yield stress (Pa)


Chi square







Predicted by using Newtonian model


Predicted by using non-Newtonian model




In the ohmic heating test cell




In the pipe


In the overall system


At the tube wall



Authors are grateful to the editor and reviewers for their valuable comments, which have been utilised to improve the quality of the paper.


  1. Allali, H., Marchal, L., & Vorobiev, E. (2008). Blanching of strawberries by ohmic heating: effects on the kinetics of mass transfer during osmotic dehydration. Food and Bioprocess Technology, doi: 10.1007/s11947-008-0115-5, in press.
  2. Anonymous. (2005). More solutions to sticky problems, user manual (pp. 3–8). Middleboro: Brookfield Engineering Labs.Google Scholar
  3. Atilgan, M., & Unluturk, S. (2008). Rheological properties of liquid egg products (LEPS). International Journal of Food Properties, 11(2), 296–309.CrossRefGoogle Scholar
  4. Ayadi, M.-A., Benezech, T., Chopard, F., & Berthou, M. (2007). Thermal performance of a flat ohmic cell under non-fouling and whey protein fouling conditions. LWT—Food Science and Technology, 41, 1073–1081.Google Scholar
  5. Bozkurt, H., & Icier, F. (2009). Rheological characteristics of quince nectar during ohmic heating. International Journal of Food Properties, doi: 10.1080/10942910802102962, in press.
  6. Darby, R. (1996). Chemical engineering fluid mechanics. New York: Marcel Dekker.Google Scholar
  7. Doymaz, I. (2006). Thin-layer drying behaviour of mint leaves. Journal of Food Engineering, 74(3), 370–375.CrossRefGoogle Scholar
  8. Geankoplis, C.-J. (2003). Transport processes and separation process principles (4th ed.). Upper Saddle River: Prentice Hall.Google Scholar
  9. Geveke, D.-J. (2008). UV inactivation of E. coli in liquid egg white. Food and Bioprocess Technology, 1(2), 201–206.CrossRefGoogle Scholar
  10. Góngora-Nieto, M.-M., Pedro, P.-D., Swanson, B., & Barbosa-Canovas, G.-V. (2003). Energy analysis of liquid whole egg pasteurized by pulsed electric fields. Journal of Food Engineering, 57, 209–216.CrossRefGoogle Scholar
  11. Hamid-Samimi, M.-H., & Swartzel, K.-R. (1985). Maximum change in physical and quality parameters of fluid foods during continuous flow heating: application to liquid whole egg. Journal of Food Processing and Preservation, 8, 225–239.CrossRefGoogle Scholar
  12. Hamid-Samimi, M.-H., Swartzel, K.-R., & Ball, J. R.-H.-R. (1984). Flow behavior of liquid whole egg during thermal treatments. Journal of Food Science, 49, 132–136.CrossRefGoogle Scholar
  13. Hermawan, N., Evrendilek, G.-A., Dantzer, W.-R., Zhang, Q.-H., & Richter, E.-R. (2004). Pulsed electric field treatment of liquid whole egg inoculated with Salmonella enteritidis. Journal of Food Safety, 24, 71–85.CrossRefGoogle Scholar
  14. Ibarz, A. (1993). Rheology of salted egg yolk. Journal of Texture Studies, 24, 63–71.CrossRefGoogle Scholar
  15. Ibarz, A., & Sintes, J. (1989). Rheology of egg yolk. Journal of Texture Studies, 20, 161–167.CrossRefGoogle Scholar
  16. Icier, F. (2003). The experimental investigation and mathematical modeling of ohmic heating of foods. PhD Thesis, Ege University Institute of Natural and Applied Sciences, Food Engineering Section, 245, electronic press in (No:134687), in Turkish.
  17. Icier, F., & Ilicali, C. (2005a). Temperature dependent electrical conductivities of fruit purees during ohmic heating. Food Research International, 38(10), 1135–1142.CrossRefGoogle Scholar
  18. Icier, F., & Ilicali, C. (2005b). The use of tylose as a food analog in ohmic heating studies. Journal of Food Engineering, 69, 67–77.CrossRefGoogle Scholar
  19. Icier, F., & Tavman, S. (2006). Ohmic heating behaviour and rheological properties of ice cream mixes. International Journal of Food Properties, 9, 679–689.CrossRefGoogle Scholar
  20. Mizrahi, S. (1996). Leaching of soluble solids during blanching of vegetables by ohmic heating. Journal of Food Engineering, 29, 153–166.CrossRefGoogle Scholar
  21. Nolsoe, H., & Undeland, I. (2009). The acid and alkaline solubilisation process for the isolation of muscle proteins: state of the art. Food and Bioprocess Technology, 2, 1–27.CrossRefGoogle Scholar
  22. Peker, M.-S., & Helvaci, S.-S. (2007). Solid liquid two phase flow. London: Elsevier.Google Scholar
  23. Punidadas, P., & Mckellar, R.-C. (1999). Selected physical properties of liquid egg products at pasteurization temperatures. Journal of Food Processing and Preservation, 23, 153–168.CrossRefGoogle Scholar
  24. Rao, M.-A. (1999). Rheology of fluid and semisolid foods. Gaithersburg: Aspen.Google Scholar
  25. Rao, M.-A., Cooley, H.-J., & Vitali, A.-A. (1984). Flow properties of concentrated juices at low temperatures. Food Technology, 38, 113–119.Google Scholar
  26. Reznick, D. (1996). Ohmic heating of fluid foods. Food Technology, 250–251, MayGoogle Scholar
  27. Sastry, S.-K., & Salengke, S. (1998). Ohmic heating of solid–liquid mixtures: a comparison of mathematical models under worst-case heating conditions. Journal of Food Process Engineering, 21, 441–458.CrossRefGoogle Scholar
  28. Scalzo, A.-M., R-W, D. J. R.-, Peeler, J.-T., & Read, J. R.-B. (1970). The viscosity of egg and egg products. Food Technology, 24, 1301–1307.Google Scholar
  29. SPSS (2001) Statistical Package Version 11.0.1., Chicago, USA.Google Scholar
  30. Telis-Romero, J., Thomaz, C.-E.-P., Bernardi, M., Telis, V.-N., & Gabas, A.-L. (2006). Rheological properties and fluid dynamics of egg yolk. Journal of Food Engineering, 74, 191–197.CrossRefGoogle Scholar
  31. Tung, M. A., Watson, E.-L., & Richards, J.-F. (1971). Rheology of egg albumen. Transactions of the ASAE, 17–19.Google Scholar
  32. Vikram, V. B., Ramesh, M. N., & Prapulla, S. G. (2005). Thermal degradation kinetics of nutrients in orange juice heated by electromagnetic and conventional methods. Journal of Food Engineering, 69, 31–40.CrossRefGoogle Scholar
  33. Yildiz, H., Bozkurt, H., & Icier, F. (2009). Ohmic and conventional heating of pomegranate juice: effects on rheology, colour and total phenolics. Food Science and Technology International, in press.Google Scholar
  34. Zell, M., Lyng, J. G., Cronin, D. A., & Morgan, D. J. (2009). Ohmic cooking of whole beef muscle-optimization of meat preparation. Meat Science, 81(4), 693–698.CrossRefGoogle Scholar

Copyright information

© Springer Science + Business Media, LLC 2009

Authors and Affiliations

  1. 1.Food Engineering Department, Engineering FacultyEge UniversityIzmirTurkey
  2. 2.Food Engineering Section, Institute of Natural and Applied SciencesEge UniversityIzmirTurkey

Personalised recommendations