International Journal of Agriculture, Environment and Biotechnology
Citation: IJAEB: 8(1): 21-27 March 2015
DOI Number: 10.5958/2230-732X.2015.00003.0
©2015 New Delhi Publishers. All rights reserved
Temperature dependent electrical conductivities of ginger
paste during ohmic heating
Sheshrao Kautkar*, Ram Krishna Pandey, Rishi Richa and Anjineyulu Kothakota
Department of Post Harvest Process and Food Engineering, G. B. Pant University of Agriculture and Technology, Pantnagar-263145
Distt. Udham Singh Nagar, Uttarakhand, India.
*Corresponding author: firstname.lastname@example.org
Paper No. 287
Received: 15 November 2014
Accepted: 11 January 2015
Published:24 March 2015
Ohmic heating is now regarded as highly attractive advanced technique for food processing wherein
electric current is passed through the liquid particulates foods with primary purpose of heating them.
The success of ohmic heating depends on the rate of heat generation in the system, the electrical
conductivity of the food, method by which the food flows through the system and composition of the
food. In this study, the ginger paste at different salt treatment (0-2% w/w) was heated in a laboratory
scale ohmic heater by applying voltage gradients (5–13 V/cm). The temperature dependent electrical
conductivity was obtained at different time interval of 0, 5 and 10 minute at different temperatures
(30-60˚C). Bubbling was observed above 70˚C especially at high voltage gradients. The electrical
conductivity measured in terms of point and bulk electrical conductivity. Point electrical conductivity
was greater than bulk electrical conductivity. The point and bulk electrical conductivity values were in
the range of 4.41 to 6.63 and 3.75 to 5.87 mS/cm respectively.
The electrical conductivity measured in terms of point and bulk electrical conductivity
Point electrical conductivity was greater than bulk electrical conductivity
The electrical conductivity of the ginger paste linearly increased with temperature and ionic
The determination of electrical conductivity changes and system performance coefficients during
ohmic heating are important in the design of ohmic heaters.
Keywords: Joule heating, point and bulk electrical conductivity, ginger, temperature, voltage gradient
Ohmic heating also called as electric heating or joule
of heating is directly proportional to the square of the
heating is a process wherein alternating electric
electric field strength, and the electrical conductivity
current (AC) is passed through liquid-particulates
of material (Palaniappan and Sastry, 1991). However,
foods with primary purpose of heating them.
the most important factor is electrical conductivity
The heating occurs in the form of internal energy
and its temperature dependence (Legrand et al. ,
generation within the product (Asgar et al. , 2012).
2007). The electrical conductivity increases with
AC voltage is applied directly to the electrodes at
increasing temperature, suggesting that ohmic
both ends of the product body which cause internal
heating becomes more effective as temperature
energy generation within the food material. The rate
increases. Since electrical conductivity is influenced