Standards and Test Methods
The Preservative Efficacy Test is based on an artificial contamination created on samples under laboratory conditions and the numerical data obtained regarding this contamination.
The result of the test is determined by evaluating the logarithmic number of microorganisms in the artificially contaminated product at certain time intervals (such as the 2nd, 7th, 14th and 28th days).
ISO 11930: ISO 11930 provides standardized guidelines for evaluating the preservative effectiveness of cosmetic products. This method is crucial for testing preservation systems by inoculating products with 5 specific strains of microbes (Pseudomonas aeruginosa, Staphylococcus aureus, E. coli, Candida albicans, Aspergillus brasiliense) and monitoring their growth over time. It ensures that the products remain microbiologically safe throughout their shelf life.
The process is initiated by inoculating the product with the following microorganisms;
- Pseudomonas aeruginosa ATCC®9027
- Staphylococcus aureus ATCC®6538
- Escherichia coli ATCC®8739
- Candida albicans ATCC®10231
- Aspergillus brasiliensis (A. niger) ATCC®16404
in laboratory conditions and with a number of microorganisms appropriate to reference methods.
When is a challenge test needed?
The challenge test is used to evaluate the protection of a cosmetic formulation against microbial contamination. It applies to all cosmetic products unless they meet the exemption criteria. For exemption criteria, see our article “What Products Are Exempt from the Challenge Test?”
Need Challenge testing? Check out our Preservative Efficacy (Challenge) Test!
