Traditional microbiological counting methods and the visual assessment of deficiencies in the growth of antifungals such as natamycin have proven to be imprecise methods due to their limits in terms of opacity.
Colorimetric methods founded on tetrazolium salts are therefore another choice to traditional methods, as they are able to create endpoints founded on colour changes.
With this objective in mind, a study has been carried out in which a colorimetric test using two separate tetrazolium salts and an electron mediator was performed, instead of the traditional method involving counting viable germs and absorbance of the microorganisms that grow in not transparent spread out systems.
This test was applied to a culture sample. By using these tetrazolium salts and the electron, as well as the microdilution of the culture, it was possible to determine, evaluate and count the growth of natamycin and lemongrass essential oil.
The colorimetric method has consequently been shown to be more responsive than the ‘absorbance’ method for detecting yeast growth. The use of a reagent like INT/MNQ is also effective for determining the least possible restraining densities present in not transparent clearly defined systems.
The results show that this method works effectively, is simple and the total time required to carry it out is shorter than other methods used to obtain the same objectives.