Cargando…
Dielectric Measurement of Agricultural Grain Moisture—Theory and Applications
Moisture content is a critical variable for the harvesting, processing, storing and marketing of cereal grains, oilseeds and legumes. Efficient and accurate determination of grain moisture content even with advanced nondestructive techniques, remains a challenge due to complex water-retaining biolog...
Autores principales: | , , |
---|---|
Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2022
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8954665/ https://www.ncbi.nlm.nih.gov/pubmed/35336259 http://dx.doi.org/10.3390/s22062083 |
_version_ | 1784676150460547072 |
---|---|
author | Jones, Scott B. Sheng, Wenyi Or, Dani |
author_facet | Jones, Scott B. Sheng, Wenyi Or, Dani |
author_sort | Jones, Scott B. |
collection | PubMed |
description | Moisture content is a critical variable for the harvesting, processing, storing and marketing of cereal grains, oilseeds and legumes. Efficient and accurate determination of grain moisture content even with advanced nondestructive techniques, remains a challenge due to complex water-retaining biological structures and hierarchical composition and geometry of grains that affect measurement interpretation and require specific grain-dependent calibration. We review (1) the primary factors affecting permittivity measurements used in practice for inferring moisture content in grains; (2) develop novel methods for estimating critical parameters for permittivity modeling including packing density, porosity, water binding surface area and water phase permittivity and (3) represent the permittivity of packs of grains using dielectric mixture theory as a function of moisture content applied to high moisture corn (as a model grain). Grain permittivity measurements are affected by their free and bound water contents, chemical composition, temperature, constituent shape, phase configuration and measurement frequency. A large fraction of grain water is bound exhibiting reduced permittivity compared to that of free water. The reduced mixture permittivity and attributed to hydrophilic surfaces in starches, proteins and other high surface area grain constituents. The hierarchal grain structure (i.e., kernel, starch grain, lamella, molecule) and the different constituents influence permittivity measurements due to their layering, geometry (i.e., kernel or starch grain), configuration and water-binding surface area. Dielectric mixture theory offers a physically-based approach for modeling permittivity of agricultural grains and similar granular media. |
format | Online Article Text |
id | pubmed-8954665 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-89546652022-03-26 Dielectric Measurement of Agricultural Grain Moisture—Theory and Applications Jones, Scott B. Sheng, Wenyi Or, Dani Sensors (Basel) Review Moisture content is a critical variable for the harvesting, processing, storing and marketing of cereal grains, oilseeds and legumes. Efficient and accurate determination of grain moisture content even with advanced nondestructive techniques, remains a challenge due to complex water-retaining biological structures and hierarchical composition and geometry of grains that affect measurement interpretation and require specific grain-dependent calibration. We review (1) the primary factors affecting permittivity measurements used in practice for inferring moisture content in grains; (2) develop novel methods for estimating critical parameters for permittivity modeling including packing density, porosity, water binding surface area and water phase permittivity and (3) represent the permittivity of packs of grains using dielectric mixture theory as a function of moisture content applied to high moisture corn (as a model grain). Grain permittivity measurements are affected by their free and bound water contents, chemical composition, temperature, constituent shape, phase configuration and measurement frequency. A large fraction of grain water is bound exhibiting reduced permittivity compared to that of free water. The reduced mixture permittivity and attributed to hydrophilic surfaces in starches, proteins and other high surface area grain constituents. The hierarchal grain structure (i.e., kernel, starch grain, lamella, molecule) and the different constituents influence permittivity measurements due to their layering, geometry (i.e., kernel or starch grain), configuration and water-binding surface area. Dielectric mixture theory offers a physically-based approach for modeling permittivity of agricultural grains and similar granular media. MDPI 2022-03-08 /pmc/articles/PMC8954665/ /pubmed/35336259 http://dx.doi.org/10.3390/s22062083 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Review Jones, Scott B. Sheng, Wenyi Or, Dani Dielectric Measurement of Agricultural Grain Moisture—Theory and Applications |
title | Dielectric Measurement of Agricultural Grain Moisture—Theory and Applications |
title_full | Dielectric Measurement of Agricultural Grain Moisture—Theory and Applications |
title_fullStr | Dielectric Measurement of Agricultural Grain Moisture—Theory and Applications |
title_full_unstemmed | Dielectric Measurement of Agricultural Grain Moisture—Theory and Applications |
title_short | Dielectric Measurement of Agricultural Grain Moisture—Theory and Applications |
title_sort | dielectric measurement of agricultural grain moisture—theory and applications |
topic | Review |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8954665/ https://www.ncbi.nlm.nih.gov/pubmed/35336259 http://dx.doi.org/10.3390/s22062083 |
work_keys_str_mv | AT jonesscottb dielectricmeasurementofagriculturalgrainmoisturetheoryandapplications AT shengwenyi dielectricmeasurementofagriculturalgrainmoisturetheoryandapplications AT ordani dielectricmeasurementofagriculturalgrainmoisturetheoryandapplications |