Application of microwaves dielectric spectroscopy for controlling osmotic dehydration of kiwifruit (Actinidia deliciosa cv Hayward)

Abstract

Dielectric spectroscopy studies have been performed on fresh and osmotically dehydrated kiwifruits ( Actinidia deliciosa cv Hayward ). The osmotic treatment consisted on the immersion the samples into 65% (w/w) sucrose aqueous solution at 30 °C during different treatment times from 5 to 1440 min. Some physical–chemical parameters were measured in fresh, treated and reposed (24 h at 30 °C) samples. Dielectric spectra were measured in the frequency range from 500 MHz to 20 GHz by an Agilent 85070E Open-ended Coaxial Probe connected to an Agilent E8362B Vector Network Analyzer in the fresh, treated and reposed samples. It has been demonstrated that the dielectric technique is a good method to control the osmotic treatment in kiwifruit. Industrial relevance : The results of this research article are demonstrated to be useful for controlling candying of kiwifruits in bakery industries. Thus, the industrial relevance is clear in order to optimize the osmotic dehydration times and the final quantity of sugars added by using a non destructive technique that can be implemented in process line. Dielectric spectroscopy, which can be considered an emerging technology, has the advantage of being an objective and a rapid technique. For all these reasons we are sending to this journal “Innovative Food Science and Emerging Technologies” our results. ► The usefulness of using dielectric properties for controlling kiwifruits candying in a non-destructive way was demonstrated. ► Some physical–chemical parameters of samples were examined trying to find a relation with dielectric properties. ► A direct relation between the surface water activity with the loss factor at relaxation frequency was found. ► A new dielectric relation was defined for obtaining relations between dielectric measurements and structural changes.