US05 question

[fattox]

Hey guys,

Just a quick one - I've recently done a couple SMaSH APA's - both based around El Dorado with one being BB Pale and the other MO.

I pitched one pack of US05 on the MO Smash and 2 on the BB Pale, however both seem to have finished around 1.030 which seems quite high considering they both started around 1.055 (3-3.5%).

Any particular reason?

Info - both rehydrated with water boiled then let come down to right temp.

Sanitary

Temp control on the fridge was showing a solid 20 degrees, as were both the independent gauges.

I don't actually mind that they're lower on the alcohol, but is there anything that could've caused this? I was shooting for around 1.010 as a target.

 

[fattox]

Info - both rehydrated with water boiled then let come down to right temp.

what I meant to say here is that the water used to pitch the yeast was boiled, let down to room temps, the yeast was put into that water and rehydrated, then that was sat in the fermenter fridge at ~20 degrees and pitched.

 

[CrookedFingers]

How long have they been fermenting ?

 

[Yob]

What was your mash temp?

 

[Tahoose]

Ferment temp, if ambient maybe it's a bit cold and the yeast has gone to sleep?

 

[manticle]

Are you measuring gravity with a refractometer? If so, are you correcting for alcohol?

Why do you think they are finished?

 

[carniebrew]

Did you try a forced ferment test? Take a ~300ml sample of your wort in a jar, shake the crap out of it every half hour or so for 24 hours (you're allowed to sleep), then check the gravity again. If it hasn't changed, there's likely no fermentables left in your wort...or no yeast left to do the fermenting, but I'd suspect the former first.

EDIT: But I'm betting on the refractometer thing Manticle suggested...

 

[fattox]

Thanks for the replies guys

@Carnie and Manticle - I've been using a hydrometer, I only use the refractometer up until the point where I'm fermenting, then the hydro comes out.

@Yob - 67 degree medium body BIAB. I hit 1.055 on both with OG measured on refractometer/converted from Brix

@Crookedfingers - one has been going for near 2 weeks, the other 3 weeks.

My thinking is that maybe the fridge got a bit too cold for them. I will put the heating gear into the bigger fridge, as I'll need the fridge it's in to chill for when I keg them anyway.

I'll do a forced ferment test though, like you said Carnie. Will report back once I have a result.

 

[carniebrew]

Didn't you have the fridge at 20C though? That's probably even considered high for US-05, I ferment with that yeast closer to 17/18.

How old were the US-05 packs, and were they well treated/stored properly before you used them?

If the forced ferment test shows no change in gravity after 24 hours, try adding some yeast into the jar (kit yeast, or even bakers yeast will do in a pinch), and shake it again for 24 hours to see if the gravity's dropping.

 

[A3k]

Are you sure that your thermometer is right? Mash temp could have been 70C if only 3deg off. The fact that both batches have stopped at the same FG seems to indicate a problem here. if it was yeast, I would've thought there'd be a fair discrepancy in the gravities due to the doubling of yeast in one batch.

If the yeast have slowed down/stopped, you can raise the ferment temp. These days I start a little cooler than I want, then raise the temp to the desired ferment temp, then finish warmer, always increasing. Probably not [SIZE=10.5pt]necessary with US05, but I think it's good practice. I seem to do it since [/SIZE]I went through a Belgian phase, and it worked with them. Yeast seem to like temperatures increasing.

 

[fattox]

@carnie I did, but I went out yesterday to check them and it was reading 13 for some reason. I think because we had a huge cold snap up here, coupled with my heating gear being in the other fridge it could have been a few days since.

As for mash temps, I usually have a little probe that sits in the whole way through the mash. I think the BB Pale one started a bit high, and I only got 1.025 after the first hour but then I let it cool down a bit until it hit the right temps and let it mash for another hour or so until it hit OG. I'm looking into a herms setup for the BIAB system though purely for that additional temp control.

I'm not sure how accurate my probes are though, I might test one vs my meat thermometer vs my STC probe on boiling water and see what difference that makes

 

[fattox]

Also with the forced ferment test I've taken samples of each into spare PET bottles as I didn't have a jar handy, the initial result looks promising. Every time I shake there's a reasonable krausen on each for quite a while anyway, but will test them around 12pm (which is when I pulled the samples as I finished work)

 

[manticle]

As for mash temps, I usually have a little probe that sits in the whole way through the mash. I think the BB Pale one started a bit high, and I only got 1.025 after the first hour but then I let it cool down a bit until it hit the right temps and let it mash for another hour or so until it hit OG.

This doesn't sound great. High temps for an hour might have led to significant denaturing of beta amylase.
Also, unless you are constantly recirc ulating wort or stirring/raking mash, there will be hot and cool spots throughout most mashes so a temp probe in one spot may not give the whole picture.

 

[verysupple]

I've never mashed higher than about 69 C (except if doing a step mash where some steps are higher) but the difference in FG between mashing at, say, 65 and 68 C hasn't been that big for me. Maybe 3- 4 gravity points. So is accidentally mashing really high, say over 72 or something, going to result in an FG of ~1.030? It seems like a big jump in FG for a relatively small jump in mash temp. I'm just thinking the OPs problem sounds more yeast related than mash temp related to me. There seems to be plenty of info on the effect of mash temp on attenuation, but does anyone have a source I can have a read of that looks at attenuation from really high mash temps? (manticle usually knows of a paper or a book ) Even anecdotal evidence if people have accidentally mashed really high would be good to have a look at.

 

[manticle]

I'll have a look at some stuff later on - going away this weekend (leaving tonight) so won't have access to any texts until Monday.

Mashing at 70 for 30 minutes with a 1040ish OG and a full pack of liquid will see me hit 1016-1018. However, as you know denaturation of enzymes is a function of time and temperature. 72 is well outside the optimum range for beta and from memory it is rapidly destroyed once the temp hits about 75 (de Clerck). Different texts give slightly different ranges.

Anyway - I agree that a slightly too high mash temp wouldn't necessarily result in 1030s (although I had a beer stick at 1030 and never move till I threw Brett at it - beer was the result of a complicated step mashing routine going horribly wrong when my element blew) but it could be contributing and it does depend on how high is high - especially for an hour.

 

[Lord Raja Goomba I]

A bit of anecdotal evidence here, if you'd like.

I've mashed at 72 in the past with a British Pale Mild (sort of a bitter, but not quite). It's the beer that got another member on the AG bandwagon in Brissie.

Used Windsor - a notoriously poor attenuator.

It finished at 1.020.

Hopefully that helps with the 1.030 problem - methinks yeast.

 

[fattox]

Yeah I did end up running a forced fermentation test and the results were completely inconclusive. The MO Batch seems to have gone up to 1050 which is dumb as it tested at 1030 last night (but it was quite carbonated!) and the BBP batch seems to have dropped a couple points. I have a couple packs of US05 handy as it is, is it worth pitching one each to see what happens?

The yeast was handled as normal - let rise in ferm fridge to ferm temps, rehydrated in sanitary water, then pitched. It might have sat a day or so in the packet but I've done it this way a dozen times before without a drama at all.

So yeah, worth pitching a fresh pack each?

 

[r055c0]

The gravity went back up? I'd be getting a new hydrometer...

Is there another AHB member that lives nearby who might be able to pop over and test your beer with their hydrometer / refractometer?

 

[verysupple]

You should de-gas the sample before taking the hydrometer reading because the CO2 bubbles tend to cling to the hydrometer which makes it more buoyant. Pour the sample back and forth between two glasses or stir it to get most of the CO2 out. It might not be the only problem you have but it's contributing to the confusion.

 

[hoppy2B]

What's the temp of the hydro sample you are measuring? If you are measuring your sample colder than the standard then your attenuation will seem less than it really is. Warming your sample to 20 C will give you a lower gravity reading.

That said, its still a high final gravity.