Posted By Allan Petrie Hi, not sure if should be posting this here, but since it is noted at work that I have an interest in H&S, I have been asked to determine what risks arise from freeze drying bacterial cultures in a biological research environment. Basically, we are trying to determine if, during the freeze drying process, there is the potential for bacteria to be dispersed into the airborne environment. I have gone through the manual for the system and there is no mention of it. The freeze drier operatres on a vacuum pump which has a exhaust filter for the capture of oil droplets from the pumps exhaust, but it makes no mention of filtering any possible bacterial contamination. So, is it possible that there is a potential bacterial risk from freeze drying cultures? Thanks in advance Allan

Posted By Merv Newman The first stage of the freeze-drying process (when the vacuum is applied) will generate a contaminated aerosol. Same if centrifugal or static chamber. So, if you are dealing with pathogens, appropriate filtration should be required. Interesting name Mr Petrie. Are you related to the inventor of the famous dish ? (and for regular readers of this column that has nothing to do with food) Merv