Quantitative Determination of Ethyl Alcohol in Kombucha Using an Inexpensive Sensing Device

Abstract

Kombucha, a popular probiotic beverage, contains detectable concentrations of ethyl alcohol. To be sold as a nonalcoholic product, alcohol concentrations in kombucha must be shown to be less than 0.5% by volume. This paper describes the use of an inexpensive, commercially available sensor to reliably and accurately measure alcohol concentrations in kombucha across a variety of undergraduate chemistry laboratory courses. Procedures and assessment data are also provided for two courses: an introductory course for nonchemistry majors and upper-division analytical chemistry. In the case of the analytical chemistry course, results from the alcohol sensor were compared to headspace gas chromatography as a capstone assessment. In all cases, the alcohol content of multiple commercial kombucha samples were determined, and students submitted final reports using appropriate scientific writing aligned with precise learning objectives.