Methods

The Institut für Produktqualität offers detection of microorganisms in food using conventional microbiological as well as modern, molecular biological methods.

Traditional microbiology

The classical microbiological method is to grow cultures, a procedure which is subject to various international ISO standards concerning sampling and the analytical procedure itself. Frequently these detection methods, also referred to as plate tests, serve as analytical reference methods. Here the colonies which have grown on the media under defined, constant conditions are counted after a certain period of time.

Molecular biology - polymerase chain reaction (real-time PCR)

Lengthy analyses and the conventional detection methods’ low sensitivity sparked interest in alternative detection methods and led to the polymerase chain reaction (PCR) becoming established in the quality assurance systems of the food industry. It is possible to detect bacterial contaminations in samples using a parameter-specific DNA sequence, since that DNA sequence is not found in other organisms. Short DNA sequences, so-called primers, help an extremely heat-resistant enzyme (DNA polymerase) to produce copies of the DNA section that is characteristic of the organism. Finally, these copies can be made visible with various processes such as DNA-binding dyes or, as in the case of real-time PCR, by means of fluorescence probes.