Caramelization Of Liquid Submersible Biological Indicators Due To Extended Thermal Insult

By Kurt McCauley

Steam sterilization of liquid products, especially large volumes, can take significantly longer than sterilizing dry or porous materials. This additional thermal insult, much of which occurs during the come-down phase, can chemically alter the product. Many companies have moved away from these excessive cycles due to this. However, many liquid products, including water, are not compromised by longer sterilization cycles, and as such, longer cycles are still in use. The liquid submersible biological indicators (LSBI) used to monitor these longer cycles can be affected; at times, the thermal insult is great enough to caramelize the culture media in the LSBI, resulting in colors other than those expected both after recovery from the load and after incubation.

Learn more about LSBIs, including the three basic formats of LSBIs and how caramelization affects the media's ability to promote spore growth.