Stuck Ferment, Or Is It?

[Kai]

I brewed a low gravity APA last week, OG 1.035. It is currently sitting at around 1.014, or 60% apparent attenuation.

While I would normally love such a high FG on a low %ABV beer, I am concerned because I do not think I was using a wort that was specifically poorly attenuative. The wort was from the dregs of a well-known local microbrewery's mash tun (SG 1.028), so it was essentially third runnings, and was intended for their Genuine Pale Ale.

Is there a difference in fermentability between runnings from the mash? That is, do the first runnings attenuate as much as second or third runnings, or more, or less? If latter runnings are less attenuative, then it might explain the current stopping point on my ferment. Do any partigyle brewers (or anyone else) have an answer on this one?

 

[Gulf Brewery]

Kai

Quick possible solution - The beta-amylase acts on the starch molecules to break it down primarily to maltose which is highly fermentable.

By the time your wort was extracted, the beta-amylase would be denatured and so leave longer unfermentable starch molecules in the wort.

That is all speculation, but should start an interesting discussion.

Cheers
Pedro

 

[Darren]

They were my thought Pedro. Either that or most of the enzymes were washed away in the first/second runnings.

cheers
Darren

 

[Kai]

That sounds like good speculation to me. I'll have to ponder it a bit more, I'd rather be sure that I'm going to bottle any grenades.

Although, I can think of no real reason why this ferment would have stuck. I've only had a couple stuck ferments in past and in each one I've been able to think of a possible reason.

 

[Darren]

That sounds like good speculation to me. I'll have to ponder it a bit more, I'd rather be sure that I'm going to bottle any grenades.

Although, I can think of no real reason why this ferment would have stuck. I've only had a couple stuck ferments in past and in each one I've been able to think of a possible reason.

[post="107589"][/post]​

Kai, rack it with a bit of yeast from the primary. That should startit up if its going to. Either that or drink it straight from the fermenter

 

[roach]

another idea might be to chuck in a pack of dried yeast and see what happens. would not affect flavour profile but will get it down a few more points if there are any fermentables left.

 

[tdh]

Of course I'll add my 2 bobs worth

They were the second runnings from the batch sparge process and the mash bed temp only got raised to the low 70's. So I'm thinking that enzymes didn't get totally denatured but excruciatingly precise temp measurements weren't taken.

My ferment of the similar wort ( the 1000 litres of GPA) stopped at 1.011 (OG = 1.045).

The dried yeast addition could be your best bet seeing that no additional aeration will be required.

tdh

 

[Mr Bond]

Straight from the horses mouth.

 

[Darren]

Of course I'll add my 2 bobs worth

They were the second runnings from the batch sparge process and the mash bed temp only got raised to the low 70's. So I'm thinking that enzymes didn't get totally denatured but excruciatingly precise temp measurements weren't taken.

My ferment of the similar wort ( the 1000 litres of GPA) stopped at 1.011 (OG = 1.045).

The dried yeast addition could be your best bet seeing that no additional aeration will be required.

tdh

[post="107638"][/post]​

TDH,
What were the first runnings coming in at?

cheers
Darren

 

[tdh]

~1.080

tdh

 

[Kai]

I was considering adding more yeast, although the first yeast I used was US-56 and it's still actively in suspension. Drinking from the fermenter I have covered for the moment.

Thanks for the advice, tdh.