Study of ohmic heating behaviour of mango juice
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Date
2014
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Publisher
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. The present study aimed to design
and built ohmic heating system. The ohmic system so developed showed adequate
performance, and heating the product satisfactorily. Ohmic heating process is influenced by a
number of factors such as electrical conductivity, viscosity, pH, solid content and electric
field strength. The mango juice was heated on a laboratory scale static ohmic heater at
different voltage gradients 7-27 V/cm. The voltage gradient was statistically significant on the
ohmic heating rate for mango juice (P<0.05). Measurements were made from 14 to 70 °C and
showed a linear fashion with electrical conductivity. The electrical conductivity of mango
juice was in the range of 4-17 S/cm. The increase in the concentration of the juice from 50%
to 90% enhanced the ohmic heating rate of mango juice. Other parameters- viscosity, pH and
total soluble solids (TSS) were studied under ohmic heating. The viscosity of mango juice
varied from 6.78 to 31.61 cP. Change so observed in the viscosity and pH of juice came out to
be statistically significant for all the concentrations studied at different voltage gradients and
(P<0.01). The pH of juice varied from 2.06 to 3.57. The TSS values recorded were in the
range of 7.2 to 13.8 °Brix. The change in the TSS value of juice was statistically nonsignificant
(p<0.05). The predictions of mathematical model using obtained electrical
conductivity equation were found to be very accurate.
Description
Keywords
Mango juice-heating, Mangoes-processing, ohmic heating