Crazy low attenuation with 1968

[rippajak]

I recently brewed a London Brown Ale using Wyeast 1968, my first experience with this strain. Here is the recipe, for reference.

5.5 Gallon

• 5 lb 8 oz Maris Otter
• 1 lb 60L Crystal
• 12 oz Special B
• 5 oz Chocolate Malt

I measured an actual mash-in temperature of 155*F.

Beersmith estimated the O.G. at 1.038 and F.G. at 1.014. My efficiency came in unexpectedly high, likely due to this being the smallest grain bill I have used to date, and I measured an O.G. of 1.045.

I used a 1L starter made a day ahead of time, aerated the cooled wort for 30 minutes using an aquarium pump, and agitated the fermenter every day or two for the first week of fermentation. Everything that I had been told was necessary for this extremely flocculant British strain. Nevertheless, the beer finished at 1.019 (!), for an apparent attenuation of 57%. I was expecting a high final gravity for this style, but that is just outrageous.

I have a few theories. I have considered that the numbers that Beersmith gave me may not be accurate. Perhaps it did not properly account for the high proportion of specialty grains in the bill, or else for the high mash temperature.

1L is a smaller starter than I typically make. I assumed that for such a low gravity brew it would be sufficient, but maybe I should have bumped it up a bit.

I also ferment in my unfinished basement. I run a space heater to keep temperatures up, but it has still stayed in the low 60's during the winter. Furthermore, it was only after a dozen or so brews in this space that I realized sitting the fermenters on the concrete floor probably leaches another few degrees out of them. Temperatures may have been too low for the yeast to properly attenuate.

For what it's worth, the beer was excellent. I took it to an after-work party, and most of the keg disappeared in an evening. I would like to rebrew it, but part of that for me is identifying and correcting the problems I saw in the first run. I have considered using a different yeast, but 1968's reputation encourages me to troubleshoot before giving up on it.

Any thoughts from more seasoned brewers than myself?

 

[FVillatoro]

How old was the yeast? Did you use a yeast calculator?
I did a 2L started for a 1.054 OG brown ale using this same strain and it attenuated to about 82% - which I was not anticipating!

However, I re-pitched it as slurry in 4 consequent batches and I got about 74% attenuation without agitating the bucket (1 did agitate the brown ale at least once a day).

It could be that you got a low cell number even though you made a starter, and the yeast viability will have a big affect too on the total cell count.
The yeast I got was 2 days old so that possibly contributed to it's naughty performance.

 

[dcbw]

Special B is a caramel malt. That means you have 23% caramel malt in this recipe, *and* you mashed pretty high *and* 1968 is not a great attenuator at 69% avg. I'm surprised you got as low as 1.019 on it.

 

[m00ps]

Special B is a caramel malt. That means you have 23% caramel malt in this recipe, *and* you mashed pretty high *and* 1968 is not a great attenuator at 69% avg. I'm surprised you got as low as 1.019 on it.

This x100

I would recommend to not go over 20% specialty malts in general, even for something like a russian imperial stout. Also mashing that high is somethign I'd also only save for a stout

 

[mrdauber64]

Careful with that yeast. It's known to flocc out early. This yeast really needs to be ramped up to the high 60's, low 70 toward the end to encourage it to finish. I've had a couple batches with this yeast that I fermented cold and they ended up starting up again after bottling causing one batch of bottle bombs and the others to be overcarbonated. Since I've had better temp control I haven't had this issue.

Try rousing the yeast and moving to a warmer location to try and encourage a couple more points out of it. If it doesn't start again after a couple days you should be good!

 

[rippajak]

Special B is a caramel malt. That means you have 23% caramel malt in this recipe, *and* you mashed pretty high *and* 1968 is not a great attenuator at 69% avg. I'm surprised you got as low as 1.019 on it.

Yeah, it's a substantially higher proportion of specialty grains than I would normally use. I was shooting for the toffee, caramel flavors and residual sugars that I'd read to be characteristic of the style, but I guess I went a bit overboard. On a rebrew I think I'll pull back the crystal malts to get back under 20% or so and lower the mash temperature a couple of degrees.

 

[micraftbeer]

Yeah, it's a substantially higher proportion of specialty grains than I would normally use. I was shooting for the toffee, caramel flavors and residual sugars that I'd read to be characteristic of the style, but I guess I went a bit overboard. On a rebrew I think I'll pull back the crystal malts to get back under 20% or so and lower the mash temperature a couple of degrees.

If you're re-brewing and changing something, I'd think about what it was in the final TASTE that you want to change. I frequently get caught up chasing numbers rather than thinking about what it is in the finished product I want to change. Who knows, maybe you came up with the next craze- uncommon high percentage of specialty malts and then fermenting cooler with 1968 yeast. Don't write off the recipe/process if the numbers didn't turn out what you expected if it still made a beer you enjoyed and your work colleagues. Unless of course your co-workers are all 20-somethings fresh from college where favorite beer = free beer...

 

[Natdavis777]

Agreed with the crystal malt % and mash temp in conjunction with this yeast. I average 75% with 1968, but I start at 65F and start to ramp up after 24 hours. This yeast has always finished within days. My first time using it though, I stayed low (like I do with 1056) around 62F, and I had poor attenuation.

 

[rippajak]

Unless of course your co-workers are all 20-somethings fresh from college where favorite beer = free beer...

Woah, it's almost like we work together...

In seriousness, though, those of us with more... shall we say, discerning, palates thoroughly enjoyed the brew. Paradoxically, I found it to be on the thin and watery side. At 1.019 FG, I expected something heavy and cloying. But the sweetness was fairly restrained, and I actually found myself wishing for a little more body in the beer. Maybe alcohol content has more of an effect on mouthfeel than I thought?

 

[pdxal]

Were you measuring final gravity with a refractometer, by chance?

 

[rippajak]

Were you measuring final gravity with a refractometer, by chance?

I was not. I do not own a refractometer, as a matter of fact. Does it provide a worthwhile advantage over a hydrometer?

I rebrewed this beer over the weekend. I cut the C60 addition in half, substituted 12 oz of Munich for a pound of Maris Otter, and lowered the mash temperature to 152*. It's fermenting away happily in my basement. Hopefully this round comes out a little closer to right.

Thanks for the advice, everyone!

 

[FatDragon]

I was not. I do not own a refractometer, as a matter of fact. Does it provide a worthwhile advantage over a hydrometer?

A refractometer can take gravity measurements with just a drop or two of wort, which doesn't typically need to be chilled, so it makes for a much easier gravity readings on brewday (or so I'm told by people who use them).

The downside is that refractometers get mixed up when there's alcohol in solution so refractometer readings are inaccurate with finished beer. It's common for new brewers to take OG and FG readings with refractometers and wonder why their FG seems to be way too high, so the common response to "why is my FG so high?" is "are you measuring it with a refractometer?"

 

[oceanic_brew]

I've only recently started using 1968 on my IPA's but have since started using it on a number of brews. I usually ferment at 62-64 for a few days and then ramp up to 70 to help finish and haven't had any issues.

I'm currently fermenting a Barleywine with an OG of 1.106 using an entire yeast cake of 1968 from a heavily hopped IPA. I'm actually very interested to see how this yeast performs since I started the fermentation high at 70, cooled to 63 but during the cool my temp controller crapped out and kept on chilling to 57, luckily I caught it and now it's out of the chest and going for a free rise to 70 to finish.

I checked the gravity after it dropped to 57 and it was 1.055 so I'm having some faith that this yeast won't floc out on me before its finished. I've read that even a 2 degree drop in temp can cause some yeasts to floc out and finish early. I'm really lucky that I used a yeast cake and the fermentation was extremely aggressive for the first couple days.

Interesting yeast, love the flavor.

 

[fun4stuff]

A refractometer can take gravity measurements with just a drop or two of wort, which doesn't typically need to be chilled, so it makes for a much easier gravity readings on brewday (or so I'm told by people who use them).

The downside is that refractometers get mixed up when there's alcohol in solution so refractometer readings are inaccurate with finished beer. It's common for new brewers to take OG and FG readings with refractometers and wonder why their FG seems to be way too high, so the common response to "why is my FG so high?" is "are you measuring it with a refractometer?"

My last brew was a zombie dust clone with 1968 where I got 74% attenuation, which is just slightly above predicted attenuation on their website. I fermented at 64 degrees for three days then ramped up to 72 for about a week. Krausen began falling on day 3. Very flocculent yeast- was pretty clear at the 2 week mark before I dry hopped.

Few people use refractometers correctly for beer homebrew and there is the long standing myth that they can't be used post fermentation often peperpetuated by people who have never used them. So no wonder so many noobs make mistakes- myself included until I looked more into it. The benefits are as fat dragon says- read sg quickly with 1-2 drops of wort without having to spend time cooling the sample. They are a lot less fragile and easier to clean than hydrometers.

What most people don't realize is that do get an accurate reading you need to determine the wort correction factor specific to your refractometer and use a special calculator for post fermentation sg. You can google brewers friend refractometer calculator to read more about how to do this.

 

[FatDragon]

What most people don't realize is that do get an accurate reading you need to determine the wort correction factor specific to your refractometer and use a special calculator for post fermentation sg. You can google brewers friend refractometer calculator to read more about how to do this.

Very good point. I rushed out that last reply because something else came up in the real world so I didn't get time to mention correcting for the refractometer reading with alcohol in solution. That said, how accurate is it? I've heard varying opinions; some that you can usually get a decent read but it's no substitute for a hydrometer, and others that it's totally on point.

 

[pdxal]

Very good point. I rushed out that last reply because something else came up in the real world so I didn't get time to mention correcting for the refractometer reading with alcohol in solution. That said, how accurate is it? I've heard varying opinions; some that you can usually get a decent read but it's no substitute for a hydrometer, and others that it's totally on point.

I've compared >20 refractometer FG readings to my hydrometer and using Sean Terrill's calculator they're never more than 1-2 gravity points off, generally spot on.

 

[fun4stuff]

Very good point. I rushed out that last reply because something else came up in the real world so I didn't get time to mention correcting for the refractometer reading with alcohol in solution. That said, how accurate is it? I've heard varying opinions; some that you can usually get a decent read but it's no substitute for a hydrometer, and others that it's totally on point.

Now that I use the wort correction factor I'm usually spot on. Been off 1-2 points a couple times. I quit comparing now as much though.

 

[rippajak]

To perform a bit of threadomancy, here's an update.

I did another run of this recipe a while back, and racked the beer into a keg earlier this evening.

I backed off the C60 addition by half to try to bring down the finishing gravity, and lowered the mash temperature from 156*F to 152*F. I also swapped a pound of Maris Otter for 12 oz of 10L Munich to try to build up the maltiness a bit. All in all, that left me with the following.

4 lb 8 oz Maris Otter
12 oz Munich 10L
12 oz Special B
8 oz Crystal 60L
5 oz Dark Chocolate Malt
Mash @ 152*F for 60 min

My original gravity came in lower than the original batch at 1.039.
Final gravity was, again, a shock, rolling in at 1.009. Substantially drier than I had expected, or intended.
My frustration is mounting.

However, I made two discoveries today which lead me to believe that I have been tilting at windmills with regards to attenuation. The first is that tonight was the first time I have ever degassed a beer sample before taking a final gravity reading. It had never occurred to me before the last week or so that dissolved CO2 could potentially throw off a gravity reading. Anecdotal evidence from other homebrewers on the web suggests that it can alter the reading by as much as 12 points, leading me to believe that my final gravity readings on all of my brews have been substantially higher than reality.
The second came when I decided to calibrate my thermometer for the first time. I made up an ice bath which was ultimately destined to cool a yeast starter that I was cooking up, and stuck my trusty digital thermometer in it on a whim. It read back at 40*F and change. After doing a quick Google search on proper calibration procedure, I made another ice bath in a smaller glass, using a higher ice-to-water ratio. After waiting several minutes for the temperature to stabilize, I inserted my long-used, faithful instrument. It slowly crept down to about 50*F, then leapt to -38*F and began to crawl slowly up toward 0. I pulled it out, and it continued to read in the range of -10* to -20* in room temperature air, occasionally bouncing up to 50* or 60* for a moment. I believe it to be what scientists call completely FUBARed. Only the gods know at what temperatures I have actually been mashing my beers.

TL;DR Degas your post-fermentation samples, and I just ordered a Thermapen.

 

[FatDragon]

The second came when I decided to calibrate my thermometer for the first time. I made up an ice bath which was ultimately destined to cool a yeast starter that I was cooking up, and stuck my trusty digital thermometer in it on a whim. It read back at 40*F and change. After doing a quick Google search on proper calibration procedure, I made another ice bath in a smaller glass, using a higher ice-to-water ratio. After waiting several minutes for the temperature to stabilize, I inserted my long-used, faithful instrument. It slowly crept down to about 50*F, then leapt to -38*F and began to crawl slowly up toward 0. I pulled it out, and it continued to read in the range of -10* to -20* in room temperature air, occasionally bouncing up to 50* or 60* for a moment. I believe it to be what scientists call completely FUBARed. Only the gods know at what temperatures I have actually been mashing my beers.

I did a brewday a couple years ago when I discovered that all three of my thermometers were in the same boat. I ended up estimating the tap water temp and adding a certain volume of tap water to a certain volume of boiling water in order to hit my mash temperature. It was not a good beer, but I suspect mash temp was the least of its problems.

I've done three other brews that for one reason or another, whether equipment or user error, were mashed at completely unknown temperatures. They're three of the top ten beers I've brewed. I know mash temperature is important to making a good beer, but I've also discovered that a mystery mash temperature is not necessarily the death of a beer.