EN Lebendzellzahl auf Produkten

This standard describes a microbiological method for determining the hygiene quality of a product or the effectiveness of sterilization methods.

For this purpose, the test objects are transferred to sterile reaction vessels, poured with eluent and shaken on a mechanical shaker for a defined period of time to flush out the microorganisms. After centrifugation of the test material, the number of microorganisms in the shaking liquid obtained is determined using the plate counting method or by membrane filtration.

The plate counting method describes a method in which sample extracts are diluted in stages and spread on nutrient agar. After an appropriate incubation period (1-7 days), the number of viable bacteria or yeasts can be determined in the form of colony-forming units (CFU) per ml of sample. In membrane filtration, an appropriate amount of sample is sucked through a sterile filter under vacuum, which is then placed on agar plates and incubated at 30 °C to 35 °C for at least 5-7 days.

For evaluation, all visible colony-forming units per plate are counted and the microorganism growth visually assessed.