It is a rapid and simple test used for the determination of microbiological quality of milk. It is commonly employed in dairy laboratories to estimate the bacterial load present in milk samples. The test is based on the principle that actively growing bacteria utilize dissolved oxygen during their metabolic activities. Due to this oxygen consumption the oxidation–reduction potential of milk decreases which results in colour change of the indicator.
In this test a definite quantity of methylene blue dye is added to milk and the mixture is incubated at 37°C. Methylene blue acts as a redox indicator which is blue in oxidized form and…
