Dielectric properties of green coconut water relevant to microwave processing: Effect of temperature and field frequency

Author(s)

Franco, Arlet P. ^[1] ; Yamamoto, Leticia Y. ^[1] ; Tadini, Carmen C. ^{[1, 2]} ; Gut, Jorge A. W. ^{[1, 2]}

Affiliation

^[1] Univ Sao Paulo, Dept Chem Engn, Escola Politecn, BR-05508010 Sao Paulo, SP - Brazil

^[2] Univ Sao Paulo, FoRC Food Res Ctr, BR-05508010 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: Journal of Food Engineering; v. 155, p. 69-78, JUN 2015.
• Web of Science Citations: 32

Abstract

Dielectric properties (relative permittivity epsilon' and loss factor epsilon `') are key parameters for microwave heating of food products. In view of continuous microwave processing of green coconut water (GCW), dielectric properties and electric conductivity were determined by open-ended coaxial probe technique at temperatures between 0 and 90 degrees C and frequencies between 500 and 3000 MHz. Simulated solutions of salts and sugars from GCW were also tested to evaluate component contributions and interactions. At 915 MHz, ionic conduction plays an important role in microwave heating, while a balance between ionic and dipolar mechanisms was observed at 2450 MHz, depending on temperature. Sugars had a weak effect on polarization or loss. Component interaction reduced epsilon `' (approximately 12% at 915 MHz and 8% at 2450 MHz). It was possible to follow the change of the dielectric properties and the power penetration depth as the temperature raised and correlations were adjusted to model temperature dependence. (C) 2015 Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 13/07914-8 - FoRC - Food Research Center
• Grantee: Bernadette Dora Gombossy de Melo Franco
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 12/04073-0 - Experimental determination of the dielectric properties of liquid and pasty foods considering the continuous heat treatment using microwave technology
• Grantee: Carmen Cecilia Tadini
• Support Opportunities: Regular Research Grants