Attenuation - Too Good

[joe4444]

Attempted to brew a 4.4% APA with a FG of 1.013 (estimating 75% attenuation), and ended up at 1.009 for 5.3%

93% base malt, 7% specialty
WLP002 with starter
Mashed at 157 (have newish thermapen, so accurate)
60 minute mash @ 5.45 room temp pH, 1.5 qt/lb
1 min of oxygen at pitch
Internally controlled temperature of 65 for 1 week, 68 with dry hops for another week

This resulted in 82% attenuation from a yeast that is suppose to have a max of 70%. Additionally, almost all my beers seem to finish around 1.010. None have been infected.

I was hoping the selection of a highly flocculant english strain mashed at 157 would leave me with a few more residual sugars.

I guess I could increase the % of specialty malts, and possibly reduce the mash time?

Anybody have any other ideas?

Thanks!

 

[MachineShopBrewing]

I have noticed much higher attenuation also with the 002/1968 strain. I regularly get ~80%.

Which base malt did you use? Rahr? I have noticed that Rahr malt worts tend to ferment nice and dry.

You could try a British malt if you didn't already, or add in some carapils.

 

[FourSeasonAngler]

How accurate are your thermometers? Both mash temp and ferment temp swung 3% in the wrong direction could have an impact on your attenuation as well.

Otherwise, if your measurements are accurate I would blame the yeast & Rahr malt as the above poster mentioned.

 

[joe4444]

Like I mentioned, with the thermapen, I'm pretty confident in my mash temperature measurements. For fermentation temperature I use a Ranco with a thermowell inserted into the carboy. I guess I have no idea how accurate that is.

I'm not exactly sure on the maltster of the grains, but I know they were not Rahr. The 93% was composed of 1/2 domestic 2 row, 1/4 Vienna, and 1/4 Maris Otter, so a decent percentage of non domestic stuff. Carapils is a good idea for the future.

I have seen a few of the experiments of mash temperature and the relation to attenuation (http://woodlandbrew.blogspot.com/2013/01/measured-mash-temperature-effects.html has a good summary), and my recent thinking is that it does not make that much of a difference until you get over 160ish. If at 149 the mash is say 87% fermentable, and at 157 the mash is 83% fermentable, and you know your yeast can do up do up to 82%, it seems that both mashes would end up with 82% attenuation? It is not until you get up over 160 that fermentability really suffers enough to get it down to a range below what the yeast can actually handle.

I know everyone talks about mash temperature in relation to fermentability, I just feel like I'm missing something.

 

[Jayhem]

When I harvest yeast I find that each generation attenuates more and more so I start fresh after 3 generations.

 

[MachineShopBrewing]

I haven't noticed mash temperature making a huge difference in fermentability either. I have been working on some pilot batches lately for a start up brewery and I have been mashing 1.070 beers at 155 and using 1968 and getting them down to 1.010 easily. One was even a brown ale wort that IIRC was around 10% crystal.

You could always add some maltodextrin to the beer you already have. It won't change the ABV, but it might add in some more body and mouthfeel.

 

[IL1kebeer]

I haven't noticed mash temperature making a huge difference in fermentability either. I have been working on some pilot batches lately for a start up brewery and I have been mashing 1.070 beers at 155 and using 1968 and getting them down to 1.010 easily. One was even a brown ale wort that IIRC was around 10% crystal. You could always add some maltodextrin to the beer you already have. It won't change the ABV, but it might add in some more body and mouthfeel.

+1 on mash temps not making a huge difference (at least not as huge as people make it out to be)

 

[IL1kebeer]

Edit- deleted

 

[beerandloathinginaustin]

I had trouble with 002 stalling out on me before I had O2 capabilities etc, but I hear guys with better setups having trouble with it attenuating too well as well. I really like 006 for my session beers.

 

[uphillbrewer]

I've had the same problem with better than expected attenuation. I've yet to fix it, but I am going to try 2 things this weekend to see if they have an effect. First, as mentioned, mash higher. Perhaps decreasing the fermentability of the wort should reduce attenuation. The other thought was to get my runnings boiling as soon as possible. I am wondering if because I wait for my runnings (and don't do a mash out) that I may be continuing conversion. So, I am going to get my first runnings boiling while I sparge for my second runnings. I think also making a starter of appropriate size and using O2 helps increase attenuation. I'll let you know how it works.

 

[joe4444]

I like the mash-out idea. It is one of those things I never saw the benefit in, "locking in the sugar profile", I didn't see the downside in a higher mash efficiency. But now that I know that a longer mash leads to a more fermentable wort, a mash-out is a great idea.

It is also good to know that others with sound fermentation techniques are having the same issues with 002/1968. Maybe a switch to an even less attenuating strain is in order.

Is anybody able to get an attenuation in the lower 70's with these strains? If so, how?

Also, any other ideas for creating a less fermentable wort?

 

[MachineShopBrewing]

mash around 158 and use some carapils. The carapils should help you quite a bit.

 

[ArcLight]

What is your original gravity?
Maybe it's lower than expected, say due to a poor crush, and the attenuation is thus less than you realize?

 

[joe4444]

I based the attenuation off of a 1.049 OG.

81.6% = (49-9)/49

 

[opiate82]

Rather than mashing higher, try mashing shorter. https://www.homebrewtalk.com/f36/controlling-attenuation-through-mash-times-60576/

 

[joe4444]

I agree that the length of the mash was probably the culprit. After a 60 min mash at 157, followed by a 45 min fly sparge of 170 water, I essentially did a 105 min mash. In the future for beers I want a little more residual sugars left behind, a shorter mash followed by a mash-out seems the way to go. With mash temperature also playing a role, but a smaller one.

Thanks for everybody's help.

 

[nopride]

The amount of O2 definitely affects your attenuation, so maybe the easiest thing to change is next time hit it with the O2 for 30 seconds instead of a minute. Between these two examples you should be able to dial in the oxygen level you want for lower gravity beers.

 

[ArcLight]

157 (if your are dead certain that's accurate) is rather hot.
It will denature the Beta Amylase.
At that temperature a 60 minute mash wont differ from a 120 minute mash.

But at 149, a 60 minute mash vs a 120 minute mash would make a difference. At this lower temperature both Alpha and Beta amylase are working without being destroyed, though the alpha is working slowly, compared to at 157F.

2 weeks ago I brewed a Blonde Ale, and mashed it for a long time, and it was at 149 and dropped down to 145.
OG = 1.060 (aerated by shaking - very tight double crush, BIAB)
FG = 1.005
using S-05 (rehydrated)