Kaiser
Well-Known Member
While browsing the "Weihenstephan brewing school" server (again) I came accross a dissertaion that investigated the affect of lauter clarity and hot break removal on the beer quality. Here is the conclusion:
Looks like not much, if any, is gained by recirculating until the lauter runs fully clear. And if you get some hot break into the fermenter, no problem, it's even good for the yeast.
Most of this is new to me as well and I can now be less obsessed with these things.
Kai
Finally, the investigations presented in this paper
showed that a variation of lauter parameters, particularly
permanent raking in the deep position, caused an increase
of average lauter turbidity, in this case from around 40
EBC to 80 EBC units, which is far above most of todays
lauter performance specifications. The conclusion was
that not only the raw material quality, but also the applied
lauter techniques and procedures, have an important impact
on the quantity of lauter turbidity. Here, the upper
value of 80 EBC units represents a "worst case" scenario.
This covers all cases that may occur in large-scale production,
even under extreme conditions. Despite the great
increase in lauter turbidity, it may be concluded that the
wort qualities were quite similar, except for a slight but
significant increase of linoleic acid concentration in the
turbid worts. Considering the variation in turbidity, the
differences in wort quality would be expected to be much
greater than what was actually detected by the analytical
methods applied. It appears that particularly the boiling
step, followed by an extensive wort clarification, has an
attemperating effect on differences in wort quality caused
by lauter variations. Neither insufficient spent grain extraction
nor higher iodine values were observed due to
turbid lautering. The fermentation performance, expressed
as extract degradation, pH decrease and ethanol formation,
was increased by turbid lautering as applied, and
yeast vitality appeared to be improved by applying turbid
lautering, even in the 6th fermentation cycle, probably due
to better yeast nutrition. Despite a high lauter turbidity,
the resulting beers did not show filtration problems. In
terms of staling, only a small and insignificant increase of
staling compounds was detected, which is in agreement
with the small increase of linoleic acid in wort due to turbid
lautering. The beers were evaluated as being quite
similar in taste, and for both fresh and forced aged beers,
neither a professional nor a non-professional panel was
able to significantly distinguish "turbid" from standard
beers. The improvement of foam stability for most of the
beers indicates better yeast nutrition due to turbid worts.
In conclusion, not only may fermentation performance
be improved by more turbid lautering but, additionally,
the negative consequences of such a production practice
may be exaggerated, since none of the quality parameters
of the final beers were significantly compromised in this
study. If and when fermentation problems occur in a brewery,
particularly when yeast has already been repitched
several times, a moderate increase in lautering turbidity
should be preferred, since excessively bright worts may
be detrimental to yeast nutrition. When higher lauter turbidities
are occasionally observed due to changes in the
lauter procedure, the risk of decreased beer quality appears
to be minimal.
Looks like not much, if any, is gained by recirculating until the lauter runs fully clear. And if you get some hot break into the fermenter, no problem, it's even good for the yeast.
Most of this is new to me as well and I can now be less obsessed with these things.
Kai