Methylene Blue Staining

Brief Description:

Methylene blue was first identified in 1876 by Heinrich Caro, a German chemist. It has since been used in many applications, from an antidepressant, to a cure for cyanide poisoning, to a titration indicator in a laboratory.

This substance is an aromatic compound that comes as a dark green powder; it turns a deep blue when in aqueous solution. Its chemical formula is: C16H18N3SCl. This compound is used for a variety of processes in scientific experiments. In chemistry, it is an effective redox indicator, as it turns clear when it comes in contact with reducing agents. It is added to solutions as a titration aid. It is also used as a pigment used in microbiological settings to examine nucleic acid chains. It can be added to a solution to dye RNA and DNA so that it may be visually analyzed.

Application in Wine Microbiology:

Methylene blue staining is useful in determining cell mortality. If methylene blue stain is applied to a sample, a healthy cell with turn the stain colorless. This is due to the cell’s enzymes, which reduce the methylene blue, causing it to lose its color. If the cell is dead, there will be no reaction, as the cell’s enzymes have been inactivated. This test could be useful in determining cell viability of a yeast culture in wine inoculations. By using a method like this, a winemaker can eliminate the risk of adding too little inoculant to a juice or must, which could result in a stuck fermentation.


  • Brooks, M.M. 1936. Methylene Blue as an Antidote for Cyanide and Carbon Monoxide Poisoning. The Scientific Monthly. 43(6).
  • Glick, B. R., and J.J. Pasternak. 1998. Molecular biotechnology: principles and applications of recombinant DNA. American Society of Microbiology Press.
  • Gillman P.K. 2008. Methylene blue is a potent monoamine oxidase inhibitor. Can J Anaesth. 55(5).