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International Food Research Journal, Volume 24, Issue 2, 2017, pp. 741-746

Changes in pH and colour of watermelon juice during ohmic heating

Abstract :

Watermelon is a highly perishable fruit with a niche for majority of microrganisms. It comprises of 91% water and hence it is very difficult to preserve watermelon based products by application of conventional means. Ohmic heating, also known as Joule heating is an electrothermal technique of processing. In this study, the effect of ohmic heating on the electrical conductivity, pH and colour of the watermelon juice at various voltage gradients (10-23.33V/ cm) was investigated. The change in the pH and colour of the watermelon juice during storage was studied. The bubbling of juice was observed above 60°C at all voltage gradients. As the voltage gradient increased the time required to reach the desired temperature decreased. The electrical conductivity was observed to increase with increase in temperature. Linear model gave the best fit to the electrical conductivity of watermelon juice. The change in pH and colour has increased with increase in voltage gradient, ohmic heating time and storage period. Ohmic heated watermelon juice showed better retention of physicochemical properties when compared to conventional heating. © All Rights Reserved.

Keywords : Colour,Ohmic heating,PH,Watermelon
Subject Area : Food Science

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