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


İÇİER F. , Bozkurt H.

FOOD AND BIOPROCESS TECHNOLOGY, cilt.4, ss.1253-1263, 2011 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 4 Konu: 7
  • Basım Tarihi: 2011
  • Doi Numarası: 10.1007/s11947-009-0229-4
  • Dergi Adı: FOOD AND BIOPROCESS TECHNOLOGY
  • Sayfa Sayıları: ss.1253-1263

Özet

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 A degrees 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 chi (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 A degrees 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.