Time-domain reflectometry in carbohydrate solutions
1995
Loon, W.K.P van | Smulders, P.E.A. | Berg, C. van den | Haneghem, I.A. van
With time-domain reflectometry (TDR) the dielectric permittivity of foodstuffs can be measured with the use of a cheap cable tester, which has proved its value in soil science. The materials which are examined are solutions of mono-, di- and polysaccharides. The influence of the species, the composition and the temperature on the dielectric permittivity is considered. TDR is a suitable method for determining the water content of a sample, because the dielectric permittivity is mainly influenced by this property. Temperature has a complex influence on the measured dielectric permittivity: at high water contents the relation is negative, while at low water contents this relation is positive. This results in a cross-over point at water contents of about 55%. The dependency of the dielectric permittivity on water content is also modeled with a mixing model for non-interactive dispersed media From this model it can be concluded that, in the frequency range used, the interactive carbohydrate solutions behave more and more as non interactive media at lower temperature.
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