Detection of Mesophilic Aerobic Bacteria, Yeasts and Moulds

Numerous detergents, cosmetic and personal care products are vulnerable to microbial contamination because of their ingredients. In all the most varied product groups – from shower gels to hair colors to facial creams – risks occur because of possible contamination of the product. Thus, for manufacturers of cosmetics, there is good reason not to lose track of guaranteeing microbiological quality.

In accordance with Regulation (EU) 1223/2009 with mandatory implementation beginning in July 2013, cosmetics must be safe for all foreseeable applications. This well includes microbiological safety. The EN ISO 17516 standard establishes microbiological limits for cosmetics. In addition to the basic prerequisites of hygienic production, such manufactured cosmetics must not exceed the defined quantities of microorganisms.

By taking appropriate hygienic measures in production and/or by the addition of preservatives, many products fall well below the permitted upper boundary limits for the total viable aerobic mesophilic plate count as well as for those for yeasts and moulds. At the same time for the big majority of products, no microbial contamination is detected when examining 0,1 gram of product.

By using Sy-Lab’s impedance technology, a simple, cost effective and very quick screening system is available for investigating cosmetic and personal care products and detergents for the presence of mesophilic aerobic bacteria as well as for yeasts and moulds. This now can be achieved for the first time by using only one test vial. With the BacTrac 4300 impedance system, all microorganisms capable of replication are safely detected. The measurement signals remain unaffected by the different complex matrices of cosmetic products.

Robust Technology

Neither the product consistency, the coloration of the sample nor the addition of particular components produce an effect on the measurement. Preservative additions are inactivated by the neutralizers present in the enrichment media.

The samples can thereby be processed in parallel or sequentially. Products with negative results from the impedance screening may be instantaneously released since depending on the initial dilution these specimens will have a bioburden load < 10/g or < 100/g respectively and are therefore well below the allowed limits. If a precise quantification of (the typically low amount of) specimen showing a positive impedance screening result is required, they can be repeated using the standard counting procedure before a final release decision is made. Alternatively they can be repeated with a higher dilution in the BacTrac 4300 to obtain a significant semi-quantitative impedance result. This automated cultural procedure profits from simplification in execution and evaluation. A fast and sure determination of microbial contamination below the requested limits becomes possible, also without comprehensive microbiological expertise.

Investigation using BacTrac 4300 with automated documentation of results.

31/1/2025