Cosmetics testing - Microbiology of cosmetics. Yeasts and molds counting (EN ISO 16212: 2017)
Test accredited by ENAC (Spanish National Accreditation Entitity).
The test allows to know the total number of yeasts and molds per voluyme unit (mL) or weight (grams) of the cosmetic and the results are expressed in CFU (colony forming units). To perform the test, the product is diluted 1:10 directly into a diluent-validated neutralizing solution when products are miscible in water. When products are non-miscible in water they are premixed with a solubilizing agent (polysorbate 80) and subsequently diluted 1:10 in a diluent-validated neutralizing solution. From this dilution, other dilutions are made. Aliquots of each dilution are seeded by inclusion in agar or by surface seeding in a medium suitable for the growth of yeasts and/or molds. The seeded culture plates are incubated at 22ºC for 5 to 7 days, and then the colonies developed are counted. It must also be performed neutralizing validation for the presence of inhibitors of microorganisms in the cosmetic that may mask the presence of yeast and/or molds, for which the cosmetic is treated with a neutralizer and it is inoculated with yeast and mold strains whose growth corroborates that have been correctly neutralized the inhibitors.