If a factor has been identified as non-critical, there is probably no need to validate it. The second part, how do you determine which factors need to be validated. If you’re developing a process in the modern era, it’s probably fairly straightforward to look at standard fermentation variables and see which ones affect product quality and which ones don’t. The ones that do affect product quality are the ones that ought to be validated. For a process that’s already been running for 30 or 40 years some types of retrospective analysis under the right conditions is probably appropriate?
