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Big beer efficiency and fermentation question

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imperialstout:
Having problems hitting efficiency and SG targets consistently with big beers. AG brew 5 gal batches with 8 gal pot, 10 gal MT and batch sparge. Know efficiency will drop with big beers. Wondering if as a general rule increasing the mash from 60 to 90 min and increasing the sparge from 30 to 45 min will increase efficiency without adding off flavors. Know SG can be increased with DME but would like to try longer mash / sparge times first.

Typically ferment in primary for 14 days and in secondary for 7 days, both at 68 F. Just started making a yeast starter. Thinking of increasing primary to 21 days, especially for big beers but wondering if the longer primary time is needed with a yeast starter.

a10t2:

--- Quote from: imperialstout on January 22, 2013, 10:29:10 am ---Wondering if as a general rule increasing the mash from 60 to 90 min and increasing the sparge from 30 to 45 min will increase efficiency without adding off flavors.
--- End quote ---

There's no way to say without knowing what your typical conversion efficiency would be for a 60 min mash.


--- Quote from: imperialstout on January 22, 2013, 10:29:10 am ---Thinking of increasing primary to 21 days, especially for big beers but wondering if the longer primary time is needed with a yeast starter.
--- End quote ---

With normal pitching rates, a good rule of thumb is ~2°P (eight points) of attenuation per day. So even a really big beer should reach FG in about 10 days. I'd still leave it on the yeast for at least a few days though, depending on how it tastes at that point.

dmtaylor:
Extending the mash time won't help at all.  The thing you really need to consider for big beers is whether to sparge more, and thusly boil more.  For a big beer I will often boil for 2 to 2.5 hours, and sparge enough to account for the longer boil time.  Then you can still get your efficiency in the 70s or maybe even 80s.

As for fermentation time, don't rush it.  The yeast will tell you when they are done.  As a general rule, I'd give it a good 3 to 4 weeks before even thinking about secondary or bottling/kegging, and even then, check your gravity every few days to see if it is still changing.  Warming the beer up near the final gravity is also a great idea.  Even for lagers, you can safely take the beer up into the upper 60s at the end of the fermentation without ill effect to help the yeast finish up their job.

snowtiger87:
So many things affect efficiency it is hard to say. A 60 minute sach rest is plenty. Increasing sparge time may help. Also look at your grain crush, mash pH, and filter. Step mashing may help. Water to grain ratio makes a difference too.

denny:
You don't say whether you fly sparge or or batch sparge, but if you batch sparge a longer sparge won't make any difference.

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