Development of a dielectric spectroscopy technique for the determination of apple (Granny Smith) maturity

Dielectric measurements of apple were done during its maturity in order to find relations with apple physiological compounds (sugar content, malic acid). An Agilent 85070E open-ended coaxial probe connected to an Agilent E8362B vector network analyzer were used in these experiments. All determinations were made at 30 C from 500 MHz to 20 GHz. These assays were performed in order to consider the potential use of dielectric spectroscopy for determining the state of fruit maturity. Good correlations among apples Thiault Index with a new defined Dielectric Maturity Index were found. The Dielectric Maturity Index was related to loss factor at two punctual frequencies (0.5 GHz and dipolar relaxation frequency). This work is presenting a non-destructive control method for the prediction of climacteric fruits maturity. Industrial relevance: The results of this research article are demonstrated to be useful for determining apple maturity. Thus, the industrial relevance is clear because the determination of fruit maturity is important to decide the best uses and storage time of the fruit. In the paper, a Maturity Index based on dielectric properties was developed. The results are obtained for the concrete application of apple fruit but they can be extended to other climacteric fruits although more studies are necessary. Dielectric spectroscopy, which can be considered an emerging technology, has the advantage of being an objective and a non destructive technique. For all these reasons we are sending to this journal "Innovative Food Science and Emerging Technologies" our results. (C) 2010 Elsevier Ltd. All rights reserved.