Spruce Porter Fermenation Problematic or Slow? Help us save 10 gallons of beer!

[rockgineer]

We have brewed a Spruce Porter with an og of 1.060 and so far have a fg of 1.048. Fermentation seemed to come to an end after 7 days, we got the same fg reading at 13 days and repitched the yeast and at day 20 the gravity reading was still 1.048. The problem is we planned to have a fg of 1.016 and right now the beer has the consistancy of a warm 10w motor oil than a porter.

We used the yeast bed from the previous brew of red ale that was take from the fermenter and put into the keg the same day. That red ale fermented fine.

We have had a hard time keeping the fermenter at a constant temperature due to the winter time and it may have gotten up to 80 degrees once or twice (due to an awesome wood stove) but we have never killed the yeast at these temperatures before. What are some other things that can cause the yeast to stop or slow fermentation?

Is there anything special to do when repitch yeast?

We were hoping we could salvage the beer and force carbonate but its too thick and sweet. The beer isnt very cabonated at the moment. Is it possible to repitch again? do we need to let the beer go flat before we try again? or are we boned?

What is the average time a beer of this style should be left to ferment?

We used White Labs Irish Ale Yeast (one vile per 5gal fermenter) and this is our recipe:

Thanks for the help,
Brad

 

[afr0byte]

First, one vile per 5 gallons, while it may work, is under pitching your yeast. Second, no 80 degrees wouldn't kill the yeast. If anything, it'd help in this case. It's possible, if this is an all grain batch, that you didn't convert much of the mash and you simply have no fermentable sugars left. Other people might be able to give you better answer in terms of how to fix it though.

EDIT: Also, when you repitch, you should (based on advice from Jamil Z) get the yeast in a starter and wait until they get to high kreusan.

 

[storunner13]

Did you try a different hydrometer? Yours might be broken. Unless you've tasted it and it's still really sweet, then maybe forget about a new hydrometer.

 

[davesrose]

So you first said that this was from a yeast slury from a red ale...the Irish yeast vials were for that beer, and this was from that slurry right? Looks like you're doing all grain, which can make this a bit more complicated. More often, slow or stalled ferments come from stalled yeast....every so often, stalled ferments come from a bad mash (where there wasn't a total starch to simple sugar conversion). I'd first see if you can rouse the yeast and see if your gravity goes down any....barring that, then adding nutrient, then more yeast. Only after you've tried everything else, and the gravity is still the same as it is now, should you consider amalyse then.

 

[rockgineer]

we first used the Irish ale slurry from our previous batch. We re-pitched with new vials of the same white labs Irish ale yeast with no reduction in gravity.

How to we rouse the yeast?
In my online shopping cart I have some Servomyces Yeast Nutrient 6 pack and Amylase Enzyme 1.5oz.

Since we have kegged and attempted to carbonate this brew is there anything special we should do to bring the yeast back to life?



It is possible we didn't convert our starches during the mash. The beer is thick and sweet but doesn't taste as sweet as it probably should, is this a sign of poor starch conversion?

 

[jfowler1]

I looked at your recipe, and thought I had the answer. Some quick searches on Wikipedia may have confirmed my thought. I do not believe you convered any/many of the starches in your mash to fermentable sugar. The bulk of your grain is amber malt, which does not self convert.

From Wiki:
Amber malt - Amber malt is a more toasted form of pale malt, kilned at temperatures of 150-160 °C, and is used in brown porter; older formulations of brown porter use amber malt as a base malt (though this was diastatic and produced in different conditions to a modern amber malt). Amber malt has a bitter flavor which mellows on aging, and can be quite intensely flavored; in addition to its use in porter, it also appears in a diverse range of British beer recipes. ASBC 50-70/EBC 100-140; amber malt has no diastatic power.

Munich has a very difficult time self converting due to kilning temp, which is why you typically have to pair it with Pilsner or 2-row. Carapils, black, chocolate, and crystal are for the most part unfermentable. As you see above, Amber malt has been kilned at a very high heat, so I assume that the enzymes have been completely killed off, and have no ability to convert (amber malt has no diastatic power).

I am afraid that you have 10 gallons of starch water.

Sorry I couldn't offer a solution,
Joe

 

[rockgineer]

Joe, thanks for sharing your tid bit of research that really sheds some light on things.

So are we totally boned or can we add Amylase Enzyme and turn this starch to sugar and add some new yeast?

 

[afr0byte]

Huh, I should have looked at the recipe I suppose. You could add the enzyme to convert the starch. I have no idea what amount of enzyme you'd use to get which fg. Also, you have no way (that I know of at least) to denature the enzyme if the fg is getting too low.