Process indicators are placed on the surface of sterilization packages in order to logistically distinguish sterilized goods from non-sterilized ones. Process indicators are not able to provide information about the quality of a sterilization process because possible problems of a sterilization process never occur on the outside but always exclusively in the inner areas of the ackaging. Therefore the indicators placed outside of the packaging can give no information about the inner areas of a sterilization packaging.

Depending on temperature and sterilization time the indicators changes colour from blue via brown-beige into dark brown. Every discrepancy from the deep blue colour indicates, that the indicator respectively the package concerned has passed a sterilization process. Because of the requirements of new European standards the colour change behaviour was modified i.e. the indicator has to pass a longer sterilization process to reach its final brown colour. From the colour shades of beigebrown or brown no conclusions can be made on the quality of the sterilization process.

In order to check the quality of the sterilization process we recommend the use of time temperature integrating indicators or even better of indicator systems that are sterilized together with every batch. They can be evaluated at the end of the sterilization process and provide information for the release of the batch to the user.