Did you know that the warm, dark, moist environment inside a compressed air system is the perfect place for microbes to grow and flourish? Drying the air to a lower dew point is an effective way to inhibit this microbial growth, but will not completely stop it. For growth to occur, microbes need food, water and the right temperature. If one or two of these nutrients is removed, the growth stops temporarily. When nutrients in the surrounding environment are depleted, the microbial pathogens that are categorized as hazards to food safety form spores and/or protect themselves by moving into a dormant stage. These dormant spores resume propagation as soon as the missing nutrients become available again through contact with the food. McLandsborough (2012 Reference) notes:
"Bacterial spores survive very dry conditions without any problem. Vegetative bacterial cells can survive dried states for a period of time. In fact, lyophilization (freeze drying) is a common way to preserve bacteria. Once conditions are again favorable for growth, the bacteria can grow. The food borne pathogen Salmonella is notorious for surviving under water-limited conditions."
Best practice for ensuring food safety
A best practice for ensuring food safety is to first dry the air to lower the dew point, then utilize point of use filtration to capture the microbes and spores, thus preventing them from coming into contact with the food.
This is Part 4 of a 6 Part series on Compressed Air Contamination in Food Plants.
Below are the rest of the links to the series.
This series was written by Lee Scott, market development manager, Parker Hannifin
Reference: McLandsborough, Dr. Lynne, A., PhD. Associate Professor and Director of Undergraduate Food Science Program, Department of Food Science, University of Massachusetts, Amherst, (24th, October 2012). Email communication to: Scott, L. (firstname.lastname@example.org).