Estimation of Electrical Conductivity of Aonla (Amla) Juice with Varied TSS Levels Using Ohmic Heating.
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Date
2018
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Punjab Agricultural University, Ludhiana
Abstract
New technologies for thermal processing of liquid foods are of great industrial and scientific interest. Ohmic heating is one of these new technologies. Ohmic heating is also known as resistive heating or Joule heating. In this process, when electrical current is passed through a food substance, the food acts a resistor and heat is generated internally. The present study aimed to design, build and test ohmic heating system. Ohmic heating behavior was studied in amla juice for five different voltage gradients (16, 14, 12, 10 and 8 V/cm) and concentrations (100, 90, 80, 70, 60 %) in the temperature range 30 to 70˚C. Ohmic heating process is influenced by a number of factors such as electrical conductivity, concentration, viscosity, pH, solid content and electric field strength. Results indicated that there was a significant effect of voltage gradients and concentrations on the heating rate and heating rate showed a linear behavior. Also, plots between temperature and electrical conductivity depicted a linear trend. Other parameters- viscosity, pH and total soluble solids (TSS) were measured before and after ohmic heating. Statistical analysis was done on all of these parameters and it was concluded that ohmic heating had no effect on pH and TSS of sample. There was a non- significant effect of this treatment on viscosity at 12 V/cm and significant effect on rest of the voltage gradients. System performance coefficient (SPC) was calculated for all voltage gradients and all concentrations. It was observed that SPC was higher for 16V/cm for all concentrations and its value decreased as the voltage gradient was decreased.
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