Cosmetics testing - Microbiology of cosmetics. Detection and counting of aerobic mesophilic bacteria (EN ISO 21149: 2017).
Test accredited by ENAC (Spanish National Accreditation Entity).
The test allows to know the total number of aerobic mesophilic bacteria per unit of volume (mL) or weight (grams) of the cosmetic and the results are expressed in CFU (colony forming units). To perform the test, the cosmetic is diluted in a validated neutralizing solution. At the same time, the product is subjected to an enrichment culture to facilitate growth of some bacteria that may be present in low number. Dilutions of the product in the neutralizing solution and enrichment culture is plated on solid non-selective agar medium and incubated for 72 hours at 32.5ºC. The presence of inhibitors in the cosmetics must be excluded using a validated neutralizer as they may mask the presence of bacteria by culturing, for which the product is treated with a neutralizer and inoculated with bacterial strains whose growth corroborates that have been correctly neutralized the inhibitors.