The applicability of dielectric properties of starch in the range of low frequencies (316 Hz-10 kHz) and of electromagnetic wave attenuation in the range of very high frequencies (9.3 GHz) to measurements of starch humidity was studied. The effect of the starch's humidity on its permittivity and tangent of dielectric loss angle was analysed for various degrees of sample pressing and different frequencies of measurement voltage in constant temperature. The possibility of suitable modification and application to measurements of starch humidity of a serially produced microwave hygrometer WILMER type 63 was demostrated.
Changes of rheological properties of semi-sweet chocolate coverture were studied during 24-h dry conching in an industrial conche. Measurements were carried out with a Rheotest 2 rotational rheometer with coaxial cylinders at various shear rates and at temperatures ranging from 30 to 80°C. The obtained rcsults show thai simple and fast methods of studying rheological properties can be employed to control conching of chocolate masses.
The influence of various concentrations of water suspensions of starch on the coefficient of reflection of the beam of infrared radiation was examined. A 20 W lamp, was used as the source of infrared radiation. For the detection of the reflected beam of infrared radiation, a photoresistor made PbS, was applied.