The Voges-Proskauer test differentiates Enterobacteriaceae based on their ability to convert acetoin to 2,3-butanediol. The test principle involves the addition of alpha-naphthol and potassium hydroxide to a culture medium containing acetoin. A positive test produces a red color due to the formation of 2,3-butanediol, while a negative test remains yellow. The test aids in the differentiation of Enterobacteriaceae genera, such as Citrobacter, Enterobacter, and Klebsiella, which perform a mixed-acid fermentation, from species like Escherichia and Salmonella, which undergo butanediol fermentation.