Reusing lees
from Heather
Thanks,
Heather
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olbol
On 21 дек, 19:47, from Heather <for_heat...@hotmail.com> wrote:
> Can someone remind me why it is a bad idea to start a new batch of cider using lees from a previous batch? I remember there was talk, especially about when the fermentation was from wild yeasts, but I can't seem to find the discussions.
>
> Thanks,
> Heather
>
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from Heather
> Date: Mon, 21 Dec 2009 12:20:41 -0800
> Subject: [Cider Workshop] Re: Reusing lees
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Andrew Lea
why not.
One is the risk of infection from non-yeast organisms, bacteria etc,
which may have multiplied with the yeast and carried over. In breweries,
where re-use is common, yeast is often acid-washed to mitigate this. Two
is that in a wild yeast fermentation, which is a succession, you will be
starting from the climax part of the succession i.e. the Saccharomyces
not the Kloeckera. So you won't duplicate the original fermentation.
Three is that the yeast at the end of fermentation has weak cell walls
due to lack of oxygen and hence needs a period of oxidative (not
fermentative) growth to renew its ability to ferment and not to stick.
Four is that the hexose transporters will be of the wrong type by the
end of the fermentation and adapted for the situation where sugar levels
are low rather than the high concentration you are suddenly about to
pitch them into. So you may need time for new cells to grow which are
adapted for the new environment.
It is often done, but if your second fermentation is sluggish or even
tainted then those are some of the possible reasons why.
Andrew
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James Fidell
> It is often done, but there are several (largely theoretical) reasons
> why not.
I see to recall reading somewhere that one of the good quality real ale
brewers adds a significant proportion of the lees from a previous batch
at the start of fermentation. Unfortunately my children have very
generously shared their stomach infection with me though and today my
brain is incapable of functioning well enough to recall who wrote it
where about which brewery or beer.
In fact, it's entirely possible I made the whole thing up. As you were.
James
Andrew Lea
> Andrew Lea wrote:
>> It is often done, but there are several (largely theoretical) reasons
>> why not.
>
>
> I see to recall reading somewhere that one of the good quality real ale
> brewers adds a significant proportion of the lees from a previous batch
> at the start of fermentation.
No I'm sure you didn't and your children are not to blame! I am no
brewer but according to Prof Dennis Briggs' classic tome "Brewing -
science and practice" ... "typically yeast is serially repitched between
5 and 20 times" (and then goes into detailed reasons including genetic
drift). One reason that serial repitching is uncommon in wine and cider
is because (traditionally) they are seasonal products so the yeast would
be very old and sad if it were kept a whole year before re-use. Whereas
beer is made on a much shorter cycle throughout the year so the spent
yeast is always fresh and a new batch of beer is always coming along. I
suspect serial repitching is quite common in 'through the year'
cidermaking from concentrate and sugar syrups.
Andrew
--
Wittenham Hill Cider Page
http://www.cider.org.uk
Andrew Lea
>
>>> It is often done,
And also...
> serial repitching is uncommon in wine and cider
Sorry this looks like I'm contradicting myself. Just to clarify, what i
mean is that yeast from an ongoing and active early fermentation started
in September may well be used to start a new one in the same season say
in November. That is in some ways equivalent to what a brewer might do.
What is uncommon is to keep yeast over from one season say autumn 2009
to the next year autumn 2010.