This article is from the Food Preserving FAQ, by Eric Decker firstname.lastname@example.org with numerous contributions by others.
From: Bruce Carpenter
My day gig is as a chemist and I looked very closely at the study that
everyone is quoting. You must read all of it very closely. They found no
detectable bateria after 3 months in a quick bread in a jar. The only time
they did find bateria was when they put it in there to start with. The only
logical conclusion from this is that the processing does not kill all of the
harmfull bateria if it is present to start with. This is only one study and
the conclusion the researchers reached is that more study was needed.
So - it is dangerous ? - probably not very if you start with clean high quality
ingredients. Is it smart ?? probably not - the parameters seem to be quite
tight and the risk possibly high for such a small return.
Since I save so much freezer space by canning everything else in sight all of
which have excellent track records and safety guidelines ) I choose to put all
of my breads up in the freezer and thus eliminate any risk.