From the HBD Archive
From: Enders <enders@plains.NoDak.edu>
Subject: Re-pitching vs. Re-culturing
Date: 1990-04-17 16:01:29 GMT

While re-pitching the yeast does have the advantage of introducing a
large number of active yeast cells into the wort, the objection I have to
this method of yeast re-use is that you _MUST_ pitch the reclaimed yeast
within a short period of time after collection (certainly less than a week,
even under refrigeration). This is fine (and probably the prefered way to
go), IF you are going to brew another batch soon.

So, what does one do if one doesn't brew quite so frequently, but still
wants to re-use his/her yeast? Well, frozen samples and maintaining cultures
on agar slants/petri dishes are a couple of possibilities. Re-culturing from
a bottle fremented with the desired strain is also a viable option IMHO, IF
certain precautions are followed:

1. The bottle should be reasonably fresh, certainly not more than 2 mo.
old.

2. Use STERILE wort for reculturing. At the minimum, this involves
canning the starter wort. The more suspicious might want to pressure
can (autoclave) it.

3. If the beer shows _ANY_ sign of infection, DO NOT culture from that
batch!

4. sterilize the mouth of the bottle in a flame before collecting the
dregs in a sterile container. Try to transfer as little of the
leftover beer as possible from the bottle to the sample, or let the
sample settle out, and decant most of the excess liquid.

5. clean and sterilize EVERYTHING as well as possible.

Granted, this is quite a bit more involved than simply repitching, but
it is somewhat less involved than maintaining a culture on agar, and on a par
with frozen samples. However, it is cartainly less sterile than culturing
from the liquid yeast packet (either by freezing or on agar), but, if one is
careful, you can culture from a bottle fairly safely.

Also, it really isn't a good idea to stretch repitching/reculturing very
far, certainly no more than one batch for reculturing from a bottle, or
repitching, and probably no more than 2 batches from one of the more sterile
reculturing techinques (i.e. starting with the sample, make a starter, pitch
and then possilby repitch ONCE).
Well, enough of that for now. It looks like I'm going to be bottling my
I. not so P. A. tonight. I just have to wait another week or two to sample it
(if my patience holds out that long


Todd Enders arpa: enders@plains.nodak.edu
Computer Center uucp: ...!uunet!plains!enders
Minot State University bitnet: enders@plains
Minot, ND 58701


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