Predicting the dielectric behavior of orange and other citrus fruit juices at 915 and 2450 MHz

Author(s)

Franco, Arlet Patricia ; Tadini, Carmen Cecilia ; Wilhelms Gut, Jorge Andrey

• Document type: Journal article
• Source: INTERNATIONAL JOURNAL OF FOOD PROPERTIES; v. 20, p. 21-pg., 2017-01-01.

Abstract

Dielectric properties (DP: relative permittivity and loss factor) and electrical conductivity are important parameters for evaluating the microwave penetration depth and designing applicators for pasteurization processes. In this context, generalized equations that can predict the DP of a group of food products as a function of their characteristics are useful. The dielectric behaviours of eight citrus fruit juices (Pera, Lima, and Navel oranges, Ponkan tangerine, Murcott tangor, Mediterranean mandarin, Sicilian lemon, and Persian lime) and three Pera/Lima blends (25, 50, 75%) for temperatures between 0 and 90 degrees C and frequency between 500 and 3000 MHz were studied. The results were correlated with temperature at frequencies of 915 and 2450 MHz. It was possible to quantify the ionic and dipolar contributions. DPs were modelled based on the behaviour of pure water in a semiempirical approach using correction factors, which were correlated with temperature and juice physicochemical characteristics (pH, Brix, conductivity). Polynomial regressions can successfully predict relative permittivity with mean absolute errors of 0.49 +/- 0.35% and 0.58 +/- 0.48% and the loss factor with errors of 4.1 +/- 3.9% and 2.8 +/- 2.3% at 915 and 2450 MHz, respectively, for juices with Brix/acid ratio between 1.26 and 29.9. (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