Limits...
Fruit and Vegetable Quality Assessment via Dielectric Sensing.

El Khaled D, Novas N, Gazquez JA, Garcia RM, Manzano-Agugliaro F - Sensors (Basel) (2015)

Bottom Line: The demand for improved food quality has been accompanied by a technological boost.A better electrical characterization of the dielectric properties of fruits and vegetables is required for this purpose.It comprehensively and chronologically covers the dielectric experiments explored for fruits and vegetables, along with their appropriate sensing instrumentation, analytical modelling methods and conclusions.

View Article: PubMed Central - PubMed

Affiliation: Departmentof Engineering, University of Almería, 04120 Almería, Spain. dalia.elkhaled@gmail.com.

ABSTRACT
The demand for improved food quality has been accompanied by a technological boost. This fact enhances the possibility of improving the quality of horticultural products, leading towards healthier consumption of fruits and vegetables. A better electrical characterization of the dielectric properties of fruits and vegetables is required for this purpose. Moreover, a focused study of dielectric spectroscopy and advanced dielectric sensing is a highly interesting topic. This review explains the dielectric property basics and classifies the dielectric spectroscopy measurement techniques. It comprehensively and chronologically covers the dielectric experiments explored for fruits and vegetables, along with their appropriate sensing instrumentation, analytical modelling methods and conclusions. An in-depth definition of dielectric spectroscopy and its usefulness in the electric characterization of food materials is presented, along with the various sensor techniques used for dielectric measurements. The collective data are tabulated in a summary of the dielectric findings in horticultural field investigations, which will facilitate more advanced and focused explorations in the future.

No MeSH data available.


(a) Loss factor behaviour versus frequency for carrots and peaches on a logarithmic scale; (b) Dielectric Constant behaviour versus frequency for carrots and peaches on a logarithmic scale.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4541835&req=5

sensors-15-15363-f005: (a) Loss factor behaviour versus frequency for carrots and peaches on a logarithmic scale; (b) Dielectric Constant behaviour versus frequency for carrots and peaches on a logarithmic scale.

Mentions: In regard to frequency, most lossy materials, i.e., materials that absorb and loose energy from RF or MW heating, have dielectric properties that vary considerably with the frequency variation. The imposed electric field and its orientation influence the polarization of molecules, resulting in the dependence of dielectric properties and frequency [48]. At MW frequencies, both σ and d (of free water) play a major role, whereas only σ is dominant at lower frequencies (<200 MHz). This phenomenon was observed for the avocado fruit, for which Nelson attributed the energy loss at high frequency to the dipole relaxation and the ionic conduction at low frequencies [37]. Figure 5 shows the loss factor and dielectric constant behaviour of carrots [66] and peaches [110]. The same pattern is concluded after the navel orange measurement conduction as well. While the dielectric constant is always decreasing with the frequency increase, the loss factor patterns prove to have either a declining curve (carrots) or a V-type curve with a point of inflection (peaches). This critical frequency point identifies each product and characterizes its behaviour. Thus, fruits and vegetables cannot be distinguished according to the dielectric constant that has similar behaviour, but the loss factor can be characterizing because it differs from one product to another.


Fruit and Vegetable Quality Assessment via Dielectric Sensing.

El Khaled D, Novas N, Gazquez JA, Garcia RM, Manzano-Agugliaro F - Sensors (Basel) (2015)

(a) Loss factor behaviour versus frequency for carrots and peaches on a logarithmic scale; (b) Dielectric Constant behaviour versus frequency for carrots and peaches on a logarithmic scale.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541835&req=5

sensors-15-15363-f005: (a) Loss factor behaviour versus frequency for carrots and peaches on a logarithmic scale; (b) Dielectric Constant behaviour versus frequency for carrots and peaches on a logarithmic scale.
Mentions: In regard to frequency, most lossy materials, i.e., materials that absorb and loose energy from RF or MW heating, have dielectric properties that vary considerably with the frequency variation. The imposed electric field and its orientation influence the polarization of molecules, resulting in the dependence of dielectric properties and frequency [48]. At MW frequencies, both σ and d (of free water) play a major role, whereas only σ is dominant at lower frequencies (<200 MHz). This phenomenon was observed for the avocado fruit, for which Nelson attributed the energy loss at high frequency to the dipole relaxation and the ionic conduction at low frequencies [37]. Figure 5 shows the loss factor and dielectric constant behaviour of carrots [66] and peaches [110]. The same pattern is concluded after the navel orange measurement conduction as well. While the dielectric constant is always decreasing with the frequency increase, the loss factor patterns prove to have either a declining curve (carrots) or a V-type curve with a point of inflection (peaches). This critical frequency point identifies each product and characterizes its behaviour. Thus, fruits and vegetables cannot be distinguished according to the dielectric constant that has similar behaviour, but the loss factor can be characterizing because it differs from one product to another.

Bottom Line: The demand for improved food quality has been accompanied by a technological boost.A better electrical characterization of the dielectric properties of fruits and vegetables is required for this purpose.It comprehensively and chronologically covers the dielectric experiments explored for fruits and vegetables, along with their appropriate sensing instrumentation, analytical modelling methods and conclusions.

View Article: PubMed Central - PubMed

Affiliation: Departmentof Engineering, University of Almería, 04120 Almería, Spain. dalia.elkhaled@gmail.com.

ABSTRACT
The demand for improved food quality has been accompanied by a technological boost. This fact enhances the possibility of improving the quality of horticultural products, leading towards healthier consumption of fruits and vegetables. A better electrical characterization of the dielectric properties of fruits and vegetables is required for this purpose. Moreover, a focused study of dielectric spectroscopy and advanced dielectric sensing is a highly interesting topic. This review explains the dielectric property basics and classifies the dielectric spectroscopy measurement techniques. It comprehensively and chronologically covers the dielectric experiments explored for fruits and vegetables, along with their appropriate sensing instrumentation, analytical modelling methods and conclusions. An in-depth definition of dielectric spectroscopy and its usefulness in the electric characterization of food materials is presented, along with the various sensor techniques used for dielectric measurements. The collective data are tabulated in a summary of the dielectric findings in horticultural field investigations, which will facilitate more advanced and focused explorations in the future.

No MeSH data available.