It is used to determine the ability of some organisms to produce a neutral end product, acetyl methyl carbinol (acetoin) from glucose fermentation. The production of acetoin, a neutral reacting end product produced by members such as Klebsiella, Enterobacter etc., is the chief end product of glucose metabolism and form less quantities of mixed acids. In the presence of atmospheric oxygen and 40% KOH, acetoin is converted to diacetyl and α-naphthol serves as catalyst to bring out red color complex.