Temperature-dependent Dielectric Properties of Adulterated Honey – A Quality Assessment Measure for Fraud Detection

Honey has become a main target of adulteration due to its important nutrient commodity of high price and in short supply. It can include illegal adulteration as well as overheating by adding water and sugar syrups. For this purpose, the dielectric assessment kit (DAK) which offers measurements of high precision dielectric attributes such as dielectric permittivity, penetration depth, conductivity and loss tangent over a wide frequency range has been used. Dielectric parameters of pure yellow standard honey (A) and their adulterated samples with moisture levels from 17.5 % to 31.2 % were measured with coaxial-line probe from 600 to 6000 MHz at 25–55 ℃. Influence of water content and temperature on dielectric properties (dielectric constant, loss tangent, electrical conductivity and penetration depth) of various honey brands B, C and D were also investigated. Temperature and moisture content have a substantial impact on honey's dielectric properties over the complete frequency range. It was observed that the dielectric constant and dielectric conductivity of honey brand named C were related to that of the pure honey sample A, although the values for various parameters of C and D were drastically different from A. Results show that the 915 MHz frequency is more appropriate for microwave heating of honey than the 2450 MHz frequency due to its deeper penetration depth. Finally overheating and water content of honey directly affects its dielectric parameters and their measurements can be used in quality assessment for degraded honey detection.