Why perform a Product D-value Study?

Part 1

By Laurent BERLIET and Silvia RIZZI from Mesa Labs France

When sterilizing an aqueous liquid product with steam, we generally validate its sterilization by using a liquid submersible commercial Biological Indicator (BI) compliant with ISO 111138-3 suspended in the coldest position of the liquid mass (Spore-News-Vol-7-No-5.pdf), showing whether specified sterilization conditions have been correctly achieved. Biological Indicators such as MagnaAmp or SterilAmp consist of a sealed glass ampoule, with spores of Geobacillus stearothermophilus or Bacillus subtilis 5230 inoculated in a culture medium with a pH color indicator which will change color if spores survive. These BIs have a known resistance as described in the standards, measured in a resistometer (ISO 18472) and expressed by the D-value and a population that characterize each manufactured batch.

Depending on heat-sensitivity of the liquid product to be treated, there are...

To continue reading this issue, please fill out the form.