Measurement of Moisture Content in Powdered Food Using Microwave Free-Space Transmission Technique

Abstract

In this study, microwave free-space transmission technique was applied to measure the moisture content of powdered food (wheat flour, milk powder, and coffee powder). In frequency range from 1 to 15 GHz, the microwave attenuation and phase shift due to moisture content of food samples were measured and analyzed using vector network analyzer, double rigid horn antennas, and sample holder filled with moist food samples. To estimate the relationship between moisture density of powdered food and the attenuation and phase shift, correlation analysis was performed. The correlation coefficients at each food sample were greater than 0.91. The calibration equation for moisture content measurement having attenuation and phase shift as independent variables at 15 GHz was developed and evaluated. The coefficient of determination and root mean square for all food samples were 0.974 and 0.328 % respectively.

Measurement Methods and Extraction Techniques to Obtain the Dielectric Properties of Materials

“…In this framework, researches have been carried out on the analysis of many kinds of materials, and the results are shared. Some researches attempted to determine the effects of ambient conditions, which are created for the preservation of foods and preservation of freshness for a long time in food industry, on the material by the change in the permittivity [14,15]. Successful studies have been conducted to examine the effect of changes in humidity on the freshness of the food [16,17].…”

“…Obtained signal should be at least 25 times of the noise. But the magnitude of obtained THz pulse by MLD is one hundredth or millionth of the magnitude of the pulsed system [15]. Therefore, the diameters of the parabolic mirrors should be large and positioned as close to the antenna as possible.…”