Electrical impedance spectroscopy (EIS) is a relatively new method applied to food quality assessment. It has been demonstrated that impedance measurement is capable of reflecting rapid changes when the food has any physical damage, such as chilling and bruising. Numerous studies have been made to devise accurate food quality measuring techniques. However, some of the new techniques, such as infra-red spectroscopy, or gas chromatography have expensive equipment and strict experimental environment requirements. In contrast, EIS allows relatively (1 order of magnitude) inexpensive assessment, is fast, easy to operate and non-invasive. It has been adopted for investigation of fundamental electrical properties of fruits. However, the sensors applied are laboratory equipment without viability in an industrial context or in the field. The applications of EIS for fruit analysis have been reported previously, the analytically relationships between electrical impedance properties and metabolic properties of the fruit have not yet been fully developed and more importantly the ability to classify fruits during the ripping process was not yet fully explored.This dissertation aims to investigate the electrical impedance properties of fruits and vegetables, and explore the relationship between impedance and quality criteria. It gives a description of a prototype impedance system based on the integrate system AD5933, which operates from a PC, with a software from “Analog Devices”.In particular, the present dissertation outlines experimental research conducted the impedance changes observed during ripening process. With the correct system calibration measurements on different fruits have been performed with results which clearly demonstrate the high potential of the technique for future applications on the field. The research was also devoted on the sensor calibration as well as system reliability. Statistical processing of the results using both, analise of variance (ANOVA) and signal processing techniques using multivariate data analysis, enable the differentiating types of fruits and stages of maturation. The results demonstrate that this system is a very promising technique, with exciting viability for further development to mobile devices suited to at line monitor the fruit quality has a great potential in assessing fruit ripening.
Date of Award | 29 May 2017 |
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Original language | English |
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Awarding Institution | - Universidade Católica Portuguesa
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Supervisor | António Silva Ferreira (Supervisor) & Miguel Velhote Correia (Co-Supervisor) |
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- Mestrado em Engenharia Alimentar
Portable sensor for impedance analysis in fruit
Magalhães, S. M. (Student). 29 May 2017
Student thesis: Master's Thesis