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31.08.2018 - Cosmetics

Preservative Efficacy Test according to DIN EN ISO 11930

A summary of burden tests according to DIN EN ISO 11930:

• Inoculation of a product with various microorganisms (each germ individually) and determination of the germ count
• Storage of the inoculated product under defined conditions
• Determination of germ counts at specified time points and evaluation of germ count development

Checking whether the germ counts are reduced according to the specifications. This provides an indication of the microbial stability of the cosmetic product.

Test strains according to ISO 11930

• Pseudomonas aeruginosa ATCC 9027
• Staphylococcus aureus ATCC 6538
• Escherichia coli ATCC 8739
• Candida albicans ATCC 10231
• Aspergillus brasiliensis ATCC 16404

The ISO 11930 points out that, depending on the operation and case, the addition of other strains may be useful. These are often germs that have already caused problems within the company.

In non-standardized burden test methods, there are procedures for practical reasons or to reduce the testing effort, where two or even more test strains are mixed together in a microorganism suspension. However, the problem with using mixed cultures is that mutual effects of the microorganisms during the burden test cannot be ruled out. Furthermore, it is disadvantageous that there are no standardized procedures and criteria for evaluating the results of burden tests with mixed cultures or multiple inoculations.

Test time points according to ISO 11930

• 7 days (exception: A. brasiliensis)
• 14 days
• 28 days

Depending on the results, it may be useful to continue the burden test after 28 days to obtain further information about the long-term development of germ counts in the product. This is particularly true in cases where germ counts are only slowly reduced and/or there is a risk that germ counts could rise again.

Acceptance criteria

If criterion A is met, the standard assumes that the product is protected against microbial growth.

If only criterion B is achieved, further safety measures, such as protective packaging, must be taken to appropriately reduce the microbial risk during use and to meet the standard requirements.

The BAV Institute is one of the largest and most modern microbiological contract laboratories in Germany. Due to the high routine in cosmetic investigations, there are also no waiting times for preservative burden tests.

We deliver fast and reliable results for you. Our customer advisors are very happy to assist you with any questions.