Controlling Attenuation Through Mash Times

My first all-grain is having some attenuation issues. Getting stuck around 1.025. Honestly though I'm not stressing, still tastes great. Basically it's just about a bit over 4% ABV versus 6% like I was shooting for. The hops make up for it though and the average person wouldn't even notice the alcohol difference. Going to try to get a bit lower next time and try the longer mash, just because now I know how to fix it.

Bobcatbrewing42 said:

I've been using Beer Smith and hitting the target strike water (about 164 degrees depending on grain temp) and the mash temp of about 150 deg for 75 minutes. My ferments with Safale 04, safale 05 or Nottingham seem to go well but the FG is often in the 1018 range (starting from 1046 to about 1056). My current session IPA fermented at 68F for a couple of days and is flocculated. The gravity is 1020. It tastes great but WTF? I just roused the carboy and am raising the temp in the fermentation closet. Any other ideas? Longer mash? Cooler mash?

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You might also want to check the thermometer you are using and verify you are measuring down in the mash and not just the surface water temp. We came across one dial thermometer we had that was fairly new but reading almost 8 degrees higher than three other devices used to measure temperature

Your mash targets seem adequate although i've read the strike water should be closer to 170. How long are you fermenting? Fermentation continues for days even after the bubbling stops. Ferment for @8 days in a primary then rack to a secondary for another 4 days. Also, I've found better attenuation with liquid yeast in viles although that could just mean i really suck at dry yeast prep. California ale yeast is known for high atten. and works well in temps as low as 64F. Make sure you aerate the wort for 10 minutes before pitching.

I just peeled off 2 separate batches that significantly over attenuated. They were supposed to finish at 1.013 but actually finished at 1.009. Both got mashed for 60 minutes. 45@145 and 15@168. Guess this time Ill try flip flopping those mash times and see whats up

My understanding is that you're not mashing at 168. All the enzymes are denatured at that temperature. Mashing at 145 for 45 minutes is going to give you a very dry beer, so you got exactly what should be expected. Try doing the primary mash closer to 150 or 154, that'll give you more body.

Mash temps for a single infusion mash should generally be between 148 (light body) and 156 (full body). Much below 148 and you start to get thin, dry and over attenuated. Much over 156 and you start to shut down conversion and get under attenuation. The 168 is for mash out to stop conversion and "lock in" the mash profile before an extended fly sparge. If you batch sparge, you don't really need it.

Once you get into multi-step mashes, you can play around with different temperature ranges to accomplish different profiles. Part of the reason many Belgians have FGs close to 1.000 is that they spend a lot of mash time in the 130s and 140s (that and a lot of candi sugar). I just did an Oktoberfest with three different temperature steps. I'm not sure my pallette is sophisticated enough to tell the difference between that and a single infusion or decoction mash but I take the word of people witb a lot more knowledge than I that it does make a difference. More importantly, I like the results. It's also a fun challenge to manage the whole process.

BlueHouseBrewhaus said:

Mash temps for a single infusion mash should generally be between 148 (light body) and 156 (full body). Much below 148 and you start to get thin, dry and over attenuated. Much over 156 and you start to shut down conversion and get under attenuation. The 168 is for mash out to stop conversion and "lock in" the mash profile before an extended fly sparge. If you batch sparge, you don't really need it.

Once you get into multi-step mashes, you can play around with different temperature ranges to accomplish different profiles. Part of the reason many Belgians have FGs close to 1.000 is that they spend a lot of mash time in the 130s and 140s (that and a lot of candi sugar). I just did an Oktoberfest with three different temperature steps. I'm not sure my pallette is sophisticated enough to tell the difference between that and a single infusion or decoction mash but I take the word of people witb a lot more knowledge than I that it does make a difference. More importantly, I like the results. It's also a fun challenge to manage the whole process.

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Decoction is a whole different ball game, it adds in the melanoidin flavor for German beers.

billbill said:

Your mash targets seem adequate although i've read the strike water should be closer to 170. How long are you fermenting? Fermentation continues for days even after the bubbling stops. Ferment for @8 days in a primary then rack to a secondary for another 4 days. Also, I've found better attenuation with liquid yeast in viles although that could just mean i really suck at dry yeast prep. California ale yeast is known for high atten. and works well in temps as low as 64F. Make sure you aerate the wort for 10 minutes before pitching.

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FYI: You do realize you responded to a 4.5 month old thread. No worries...I've done it too.

This is a really good thread from 2008 that should be read from the beginning. I'm glad you found it and pointed me to it. Thanks!

P

PlexVector said:

FYI: You do realize you responded to a 4.5 month old thread. No worries...I've done it too.

This is a really good thread from 2008 that should be read from the beginning. I'm glad you found it and pointed me to it. Thanks!

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I like when old threads are reanimated. Then there is not so many to try to get through for answers on the same thing.

I concur, @madhook - I eschew thread proliferation - and welcome to HBT!

day_trippr said:

I concur, @madhook - I eschew thread proliferation - and welcome to HBT!

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Thanks, Im looking forward to learning a lot.

TheZymurgist said:

A lot of this is good to know in theory, but isn't necessary or essential for all-grain brewing. Many people (I would assume most) will do a 60 minute mash regardless of the temperature. I'll usually extend my mashes under 152 or so for 30 minutes, unless I'm pressed for time or just feeling lazy. Can't say I've ever really noticed a difference, or one that I can pinpoint to mash time.

I just brewed a porter on Saturday where a one hour mash turned into three hours because I couldn't get my burner working. This is one that regularly finishes at 1.018 to 1.020, with an OG of 1.055. I'll be curious to see if the extra time helps attenuation at all.

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I don't think it's about mash time as much is it's about conversion. I have been using iodine to check for conversion, and have seen different times to reach that point, doing the same recipe. Letting the mash temp drop, is not the end of the world, and you may find a better fermentation happens.

jerryh357 said:

I don't think it's about mash time as much is it's about conversion. I have been using iodine to check for conversion, and have seen different times to reach that point, doing the same recipe. Letting the mash temp drop, is not the end of the world, and you may find a better fermentation happens.

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Yes, getting complete conversion is more important than mashing for a particular length of time. The time for complete conversion is controlled primarily by the crush. Finer crushes convert faster (since gelatinization is the rate controlling step in conversion.) More reliable, and more quantitative than the iodine test is measuring the SG of the wort in the mash. Learn about measuring conversion efficiency/completeness in real time here.

Brew on

Thanks, great article and worth reading!

from the late 1970's I have brewed from the big book of brewing by Dave Line, the brew temperature dictates the amount of maltodextrines in the mash, the higher the temperature the more maltodextrines which are less fermentable than Maltose so will influence the final sweetness/dryness of the ale, and so the attenuation, a low mash temperature will give mostly maltose and a light dry fully attenuated ale, conversely a high mash temperature will give a sweeter fuller brew which will take longer to ferment and will not attenuate quite so fully. most important is getting the starch converted and I always use iodine to check for this.

I was just looking on homebrewtalk for something like this (original post). I have noticed that I get much better original gravity especially from grains like Maris Otter and American pilsner malt doing a 90-minute or even 120 minute mash. In addition they seem to finish drier as well.
I may have found this out by accidentally completely forgetting I was brewing when I was watching the kids one day. It has now become standard practice to do 90-minute mash for everything brew. I can get a lot of stuff done during that 90 minutes ie cleaning, cooking, running, etc.
I took some mash measurements today during brewing. It was 12 lb Maris, 1 pound C20, 8 oz of c-pils, 18 oz of instant oats. At dough in, I had a gravity of 1.023 which did not really change until 60 minutes when it was 1.043 and my Mash gravity at 90 minutes was 1.050. I also do no sparge so this was with 8 and 1/2 gallons of water that also had 2ml 85% lactic acid, 1g of gypsum and 1g of calcium chloride. This is roughly 70% mash efficiency with 7gals to bk. The math at 60 min is 60% mash effeciency.
The large jump as I approach 90 min has been consistent across at least 6 batches.
Last pils batch I made with 10# pils, 1# carapils and 1# vienna had boil G of 1.043 for again about 70% mash efficiency with 90 min. At 60 min was 1.035 (56% mash eff) . That ones fg prior to kegging was 1.004. Water treatment for that mash was 3ml lactic and 3g cacl2 in 8.5 gal water.