Contactless monitoring of food drying and freezing processes with millimeter waves

Gokarna Pandey, Werner Vandermeiren, Vladimir Matvejev, Johan Stiens

Research output: Contribution to journalArticle

7 Citations (Scopus)


Millimeter (mm) waves are of interests to monitor the properties of interest (POIs) of food products
which are opaque for optical and infrared frequencies as they not suffer from all the atomic and intermolecular
absorption processes situated in the latter bands of the Electromagnetic (EM) spectrum. They
also offer a higher penetration depth into water containing products than the IR domain. With respect to
the microwave domain, they are less perturbed by ionic contributions of food products, hydration shell
effects and finally they offer a higher spatial resolution compared to microwaves. In the considered mmwave
frequency range, the dipole moment of free water molecules plays a dominant role compared to the
other constituents, hence the electromagnetic interaction depends mainly on the amount and phase
state of free water present in food products. These features make mm-wave based sensors an appealing
alternative for monitoring and quality control of food processes. However, the effectiveness of mm-wave
sensing solutions has not yet been explored in the food industry. In this paper, we present a real time,
contactless and non-destructive sensor methodology based on mm-waves to monitor food processes. An
analytical model is developed to estimate the dielectric properties of food products with varying POIs
and to establish the relation between the mm-wave sensor's output and the POIs. A drying and freezing
process of potato slabs are monitored by measuring the transmission and reflection coefficients by
means of mm-wave sensors. The theoretical and experimental results are compared and validated. It will
be proven that mm-wave based sensors are a promising real time, contactless and non-destructive
monitoring tool for food quality control.
Original languageEnglish
Pages (from-to)1-8
Number of pages8
JournalJournal of Food Engineering
Publication statusPublished - 1 Jun 2018


  • Food
  • drying
  • freezing
  • millimeter wave
  • sensing


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