Characterisation of water in honey using a microwave cylindrical cavity resonator sensor

Li, Z, Meng, Z, Haigh, A, Wang, P and Gibson, A ORCID: https://orcid.org/0000-0003-2874-5816 (2021) Characterisation of water in honey using a microwave cylindrical cavity resonator sensor. Journal of Food Engineering, 292. p. 110373. ISSN 0260-8774

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Abstract

A low-cost microwave cavity resonator sensor is developed for the assessment of honey. When a liquid sample is placed in the cavity, the resonant responses are significantly changed caused by the material perturbation. From the measurement of standard liquid samples with known permittivity, it is well demonstrated that the electric permittivity can be accurately determined. For the honey-water mixtures with the added water content from 10% to 50% w/w, it is found that the resonance frequency decreases with increasing added water content, and its change conforms to the law of mixture. In addition, there is a linear relationship between the added water content and the real part of the permittivity, and a quadratic relationship is found between the real and imaginary parts of the permittivity. These findings agree well with the results of the mixtures with added water contents below 10%. Hence, both the resonant responses of the cavity and the permittivity obtained can be employed for the indication of adulteration and accurate evaluation of the water content. Further, it is shown that the full penetration of the liquid sample can be achieved. The microwave sensor presented here provides an alternative tool for rapid food evaluation.