Characterisation and analysis of alcohol in baijiu with a microwave cavity resonator

Li, Z, Haigh, A, Wang, P, Soutis, C and Gibson, A ORCID: https://orcid.org/0000-0003-2874-5816 (2021) Characterisation and analysis of alcohol in baijiu with a microwave cavity resonator. LWT: Food Science and Technology, 141. p. 110849. ISSN 0023-6438

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Abstract

The world's most consumed liquor-baijiu is characterised by measuring the perturbation in the resonance condition of a cylindrical microwave cavity as a function of alcohol content. Compared with other methods, the microwave sensor described here is compact, portable, low-cost and need of a small sample size (<0.1 mL) of liquid. The dielectric properties are obtained from the shift of the resonance frequency and changes in the quality factor. The measurement accuracy is validated by comparison with standard liquid samples, where high estimation accuracy (better than 6%) is achieved. The resonant responses and permittivity of baijiu samples are evaluated, where the alcohol content has a significant effect. Six other types of alcoholic drinks and ethanol-water mixtures were also measured for comparison purposes. From all the experimental results, it is demonstrated that the alcohol by volume can be readily deduced from the regressed functions obtained. In addition, the principal component analysis is successfully applied to the classification of liquids with varied alcohol contents.