Stuck Fermet

[Dustin Kerr]

It has never happened to me and thought it never would but I have a stuck fermentation on my hands. I am stumped on how to get it going again.  It is a stout that started at 1.048 and is stuck at 1.019. I used Safale S-04, It started like a rocket and went hard for a couple day then calmed down.  I would guess its been at 1.019 for 2 weeks now. A week ago I added some Vintners Harvest SN9 hydrated with some sugar. I have aerated it, warmed it up  and still nothing.  

What should I do now, I kinda want the beer to be higher than 3.9%

I tastes great almost like a milk stout with some toasted notes in the background.

Just bottle it, more yeast?

Any feedback would be greatly appreciated.

[Peter Church]

What was your mash profile and recipe, may well be done. If its tasting great and wont move then I'd bottle. 

[Dustin Kerr]

5KG Gladfields Ale Malt (*Base Malt)

1.4kg roasted oats

550G Gladfields Roasted Barley

550G Gladfields Chocolate Malt

380G Weyermanns CaraMunich T2 Malt

185G Gladfields Medium Crystal

[Kevin Sharp]

That's 17.4% oats and only 62% base malt. Normally 10% oats is considered a lot. I would expect pretty low attenuation with that malt profile.

If it tastes good, I would either just bottle it or consider brewing a higher gravity stout and blending them.

[Rhys Williams]

You could add  "Dry Enzyme".

This will break down the more complex unfermentables, and make them fermentable.

It could then go as low as 1.004 or so.

You might want to split the batch, and do this to half, and then compare the two batches once bottled to see which you prefer....

[Kevin Sharp]

Chris White mentions this in his "Yeast" book, but he doesn't recomend it. Most enzymes are commercially produced using bacteria so adding them post-boil is asking for trouble.

[Rhys Williams]

I have used the Mangrove Jacks Dry Enzyme (3g pack) on a Croucher Low Rider Clone that finished too high, with no I'll effects. It look it from 1.018 to 1.005, so works as advertised!

[Damon Colbert]

He doesn't recommend it, because you can't control or stop the enzyme (not very well at least, you can slow it down with crash cooling).

No risk of bacterial contamination (from the enzyme), as long as you operate with your normal clean procedures.

I've used dry enzyme on a couple of occasions to rescue over-temp mashes that finished too high.  Works well, as long as your style suits a dry finish.

[Kevin Sharp]

Lack of control is one problem , but on p34 the book states ...

The manufacturers propagate these enzyme preparations from a a microbial source, so they may contain a small quantity of bacteria. Adding these enzymes to the beer, without the benefit of the boil, has the potential to spoil the beer. From a food and safety perspective, the quantities of bacteria are small and harmless, but from a brewer's perspective , it is unacceptable. The allowable levels of bacteria in these enzyme products often range in the area of 1000 to 5000 CFU, and that is just not acceptable in beer (Briggs, et al 1981; Mathewson 1998; Walker 1998).

You may well get away with poor sanitisation, but that is not to say that there is no risk, or to put it another way - how do you sanitise the enzymes without denaturing them?

[Damon Colbert]

By dehydrating them, and sealing them in a foil packet  ;-)

I have to admit, I haven't read those references. They are fairly old, and possibly reflect out-of-date purification procedures.  But I'll try to remember to have a look when I get home.

That said, almost any kind of enzyme purification would remove/inhibit most microorganisms.  Otherwise the enzyme would not remain intact and functional for very long, as they would be degraded and reabsorbed for their nutrients.  Plus, the enzyme producers wouldn't do well to sell contaminated enzyme.

It would be interesting to try plating out a sample of dry enzyme.  I don't work in a lab anymore, but I might try and swing it with some friends of mine.  Would be interesting to know for sure.  :)