Ohmic Heating Characteristics of Jambolana (Syzygium cumini) Juice as Affected by Voltage Gradient Gemala Hardinasina (a,b,*), Diyah Yumeina(a), Olly S. Hutabarat (a,b), Muhammad Tahir Sapsal (a), Hartono A.(a)
(a) Agricultural Engineering Study Program, Hasanuddin University, Makassar, Indonesia
(b) Science-technology Center of Excellence in Food Diversification Product, Hasanuddin University, Makassar, Indonesia
(*) gemalahardinasinta[at]unhas.ac.id
Abstract
Ohmic heating as an emerging technology for processing of liquid product is distinguished by it^s rapid and uniform heating generated by electrical energy. The heating process is mainly affected by the product^s electrical conductivity and the applied voltage gradient. This study aims to evaluate the ohmic heating characteristics of jambolana juice, an exotic fruit wildly grown in Indonesia, at different voltage gradient levels of 5, 12.5, and 20 V/cm. The result found a linear correlation between the electrical conductivity with voltage gradient and temperature. The electrical conductivity of jambolana juice was ranging from 0.04 to 0.41 S/m at 30 - 110 celcius. The highest electrical conductivity and heating rate were achieved at 20 V/cm. The correlation between electrical conductivity, temperature, and voltage gradient were determined using the multiple regression model with R-squared > 0.98. Due to the rapid heating, ohmic heating resulted in a high system performance coefficient (SPC), ranging from 0.58 to 0.79 with the highest SPC observed at 20 V/cm.
Keywords: electrical conductivity- heating rate- degradation rate- first-order kinetic model
Topic: Food processing, safety and diversification
