EFFECT OF OHMIC HEATING ON THE ELECTRICAL CONDUCTIVITY OF GUAVA JUICE
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Date
2013
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Punjab Agricultural University, Ludhiana
Abstract
Ohmic heating takes its name from Ohm’s law. The food material sandwiched between
electrodes has a role of resistance in the circuit. In the present study, an ohmic heater was
designed, fabricated and then used for performing the ohmic heating of different guava juice
samples. The different samples of guava juice were prepared with five different
concentrations of 50%, 60%, 70%, 80% and 90% by volume of the juice. The ohmic heating
was performed at five different voltage gradients viz. 5.5 V/cm, 7.5 V/cm, 9.5 V/cm, 11.5
V/cm and 13.5 V/cm across the two ends of the designed ohmic cell. Different instruments
and devices were used to measure the different properties of guava juice as a function of
temperature at a regular interval of time during the ohmic heating. An Ostwald’s viscometer
for viscosity, pH meter for pH and a hand refractometer for total soluble solid (TSS) were
used. The electrical conductivity obtained as a result of ohmic heating was in the range 0.037
S/m to 0.326 S/m. The mathematical model using the linear regression analysis and one-way
ANOVA using completely randomized design (CRD) led to the prediction of an equation of
electrical conductivity. The linear equation was found to be highly accurate with R2 value in
the range 0.173 to 0.999 showing the linear dependence of electrical conductivity upon the
temperature. The viscosity, pH and the TSS was found to vary from 1.66 cP to 14.83 cP, 1.83
to 5.29 and 5.2°B to 12.2°B respectively. The voltage gradient was statistically significant (p
< 0.05) on the heating times.
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