Application of a film method for microbial monitoring of cosmetic raw materials

The possibility of using a film plate-count method, instead of the too complex and lengthy traditional methods, has been evaluated in cosmetic products. Petrifilm® is a ready-to-use system for detecting any microbial contamination. It consists of a flexible polypropylene film supporting on suitable dehydrated medium, a second support containing guar (a cold-water soluble gel-former) and an indicator on the internal surface. Petrifilm® proved to have a good sensitivity and to be more convenient than the method recommended by the Italian National Pharmacopoeia. Results showed that it is possible to detect microbial and fungal contamination of raw materials of natural origin, which are frequently used in cosmetic preparations. Positive results were obtained on finished products (oil in water emulsions).