Magnetic Induction Spectroscopy-Based Non-Contact Assessment of Avocado Fruit Condition
This study demonstrates that the ripeness of avocado fruits can be analyzed using frequency-dependent electrical conductivity and permittivity through a non-invasive Magnetic Induction Spectroscopy (MIS) method. Utilizing an MIS system for conductivity and permittivity measurements of a large sample...
Saved in:
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-07-01
|
| Series: | Sensors |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1424-8220/25/13/4195 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1839631534657634304 |
|---|---|
| author | Tianyang Lu Adam D. Fletcher Richard John Colgan Michael D. O’Toole |
| author_facet | Tianyang Lu Adam D. Fletcher Richard John Colgan Michael D. O’Toole |
| author_sort | Tianyang Lu |
| collection | DOAJ |
| description | This study demonstrates that the ripeness of avocado fruits can be analyzed using frequency-dependent electrical conductivity and permittivity through a non-invasive Magnetic Induction Spectroscopy (MIS) method. Utilizing an MIS system for conductivity and permittivity measurements of a large sample set (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>N</mi><mo>=</mo><mn>60</mn></mrow></semantics></math></inline-formula>) of avocado fruits across multiple frequencies from 100 kHz to 3 MHz enables clear observation of their dispersion behavior and the evolution of their spectra over ripening time in a completely non-contact manner. For the entire sample batch, the conductivity spectrum exhibits a general upward shift and spectral flattening over ripening time. To further quantify these features, normalized gradient analysis and equivalent circuit modeling were employed, and statistical analysis confirmed the correlations between electrical parameters and ripening stages. The trend characteristics of the normalized gradient parameter <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>P</mi><mi>y</mi></msub></semantics></math></inline-formula> provide a basis for defining the three ripening stages within the 22-day period: early pre-ripe stage (0–5 days), ripe stage (5–15 days), and overripe stage (after 15 days). The equivalent circuit model, which is both physically interpretable and fitted to experimental data, revealed that the ripening process of avocado fruits is characterized by a weakening of capacitive structures and an increase in extracellular solution conductivity, suggesting changes in cellular integrity and extracellular composition, respectively. The results also highlight significant inter-sample variability, which is inherent to biological samples. To further investigate individual conductivity variation trends, Gaussian Mixture Model (GMM) clustering and Principal Component Analysis (PCA) was conducted for exploratory sample classification and visualization. Through this approach, the sample set was classified into three categories, each corresponding to distinct conductivity variation patterns. |
| format | Article |
| id | doaj-art-c2816b78b10b4b3c81fcdeb4142d6df5 |
| institution | Matheson Library |
| issn | 1424-8220 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Sensors |
| spelling | doaj-art-c2816b78b10b4b3c81fcdeb4142d6df52025-07-11T14:43:41ZengMDPI AGSensors1424-82202025-07-012513419510.3390/s25134195Magnetic Induction Spectroscopy-Based Non-Contact Assessment of Avocado Fruit ConditionTianyang Lu0Adam D. Fletcher1Richard John Colgan2Michael D. O’Toole3Department of Electronic and Electrical Engineering, University of Manchester, Manchester M13 9PL, UKDepartment of Electronic and Electrical Engineering, University of Manchester, Manchester M13 9PL, UKNatural Resources Institute, University of Greenwich, Medway Campus, Central Avenue Chatham Maritime, Kent ME4 4TB, UKDepartment of Electronic and Electrical Engineering, University of Manchester, Manchester M13 9PL, UKThis study demonstrates that the ripeness of avocado fruits can be analyzed using frequency-dependent electrical conductivity and permittivity through a non-invasive Magnetic Induction Spectroscopy (MIS) method. Utilizing an MIS system for conductivity and permittivity measurements of a large sample set (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>N</mi><mo>=</mo><mn>60</mn></mrow></semantics></math></inline-formula>) of avocado fruits across multiple frequencies from 100 kHz to 3 MHz enables clear observation of their dispersion behavior and the evolution of their spectra over ripening time in a completely non-contact manner. For the entire sample batch, the conductivity spectrum exhibits a general upward shift and spectral flattening over ripening time. To further quantify these features, normalized gradient analysis and equivalent circuit modeling were employed, and statistical analysis confirmed the correlations between electrical parameters and ripening stages. The trend characteristics of the normalized gradient parameter <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>P</mi><mi>y</mi></msub></semantics></math></inline-formula> provide a basis for defining the three ripening stages within the 22-day period: early pre-ripe stage (0–5 days), ripe stage (5–15 days), and overripe stage (after 15 days). The equivalent circuit model, which is both physically interpretable and fitted to experimental data, revealed that the ripening process of avocado fruits is characterized by a weakening of capacitive structures and an increase in extracellular solution conductivity, suggesting changes in cellular integrity and extracellular composition, respectively. The results also highlight significant inter-sample variability, which is inherent to biological samples. To further investigate individual conductivity variation trends, Gaussian Mixture Model (GMM) clustering and Principal Component Analysis (PCA) was conducted for exploratory sample classification and visualization. Through this approach, the sample set was classified into three categories, each corresponding to distinct conductivity variation patterns.https://www.mdpi.com/1424-8220/25/13/4195magnetic induction spectroscopy (MIS)bioimpedance (BIS)non-contact testingeddy-currentpermittivity membrane behaviordispersion |
| spellingShingle | Tianyang Lu Adam D. Fletcher Richard John Colgan Michael D. O’Toole Magnetic Induction Spectroscopy-Based Non-Contact Assessment of Avocado Fruit Condition Sensors magnetic induction spectroscopy (MIS) bioimpedance (BIS) non-contact testing eddy-current permittivity membrane behavior dispersion |
| title | Magnetic Induction Spectroscopy-Based Non-Contact Assessment of Avocado Fruit Condition |
| title_full | Magnetic Induction Spectroscopy-Based Non-Contact Assessment of Avocado Fruit Condition |
| title_fullStr | Magnetic Induction Spectroscopy-Based Non-Contact Assessment of Avocado Fruit Condition |
| title_full_unstemmed | Magnetic Induction Spectroscopy-Based Non-Contact Assessment of Avocado Fruit Condition |
| title_short | Magnetic Induction Spectroscopy-Based Non-Contact Assessment of Avocado Fruit Condition |
| title_sort | magnetic induction spectroscopy based non contact assessment of avocado fruit condition |
| topic | magnetic induction spectroscopy (MIS) bioimpedance (BIS) non-contact testing eddy-current permittivity membrane behavior dispersion |
| url | https://www.mdpi.com/1424-8220/25/13/4195 |
| work_keys_str_mv | AT tianyanglu magneticinductionspectroscopybasednoncontactassessmentofavocadofruitcondition AT adamdfletcher magneticinductionspectroscopybasednoncontactassessmentofavocadofruitcondition AT richardjohncolgan magneticinductionspectroscopybasednoncontactassessmentofavocadofruitcondition AT michaeldotoole magneticinductionspectroscopybasednoncontactassessmentofavocadofruitcondition |