This article is from the Food Preserving FAQ, by Eric Decker firstname.lastname@example.org with numerous contributions by others.
>From Paul Hinrichs :
Someone asked here a while back what Fermento was and, collectively, we got
them sort of an answer, that it was a starter culture for fermented sausages.
These are of the general family of dry-cured sausages and the process making
these has been greatly accelerated and made more dependable by Fermento (or
Lactocel, a similar product).
Specifically, there are two stages in dry-curing. The first is called pan
curing. It takes about 3 days at 37 degrees and is used specifically to
allow time for some of the NaNO3 (saltpeter) to convert to NaNO2 (sodium
nitrite), which is the inhibiting agent for _C. botulinum_. The disadvantage
of this 3 day wait is that worked meats become harder to stuff into casings
since it "sets" some, becoming more viscous. Lactocel accelerates this es-
sential conversion process by using a _micrococcus aurantiacus_ culture which
converts NO3 to NO2 more rapidly. Products using Prague Powder #3 do not
require pan curing at all, since this already has nitrites (as well as nit-
rates for the longer run) in it.
Second process is called greening. It takes place after stuffing and is the
time that fermentation takes place, in which sugar is converted to lactic
acid for the characteristic "tangy" flavor. This would normally take 10 days
at 73 degrees F. However, with the _lactobacillus planarum_ starter present
in both Lactocel and Fermento, greening takes place in about 16 hours at 85
degrees F. The drying process used with these sausages (the period in which
the nitrates come into play for long term safety, converting to the _clo-
stridium_-inhibiting nitrites slowly) still takes 10-90 days, depending on
the type of product being made, but the use of starter cultures reduces the
13 days needed for pan curing and greening to a mere 16 hours.