amylase in the secondary?

someone in the local brewers group has an imperial stout that started at 1.098 and is sitting at 1.035. dark extract batch (with specialty malts; no additional crystal) and fermented with wyeast scottish ale yeast.

he's moved it to a secondary and is wondering if amylase will help effect further attenuation. i personally have my doubts due to the low (and tired) yeast population that is left.

anyone know if this is likely to work/help?

 

It would probably work, you may have to pitch more active yeast but it would break the long chain sugars down and make them a lot more digestible for the yeast. The problem is there is no way to shut it off, so you will end up with a bone dry RIS. A 1.098 - 0.098 beer is gross, trust me it just tastes like ethanol.

 

IMO, the 1.030 range is good for a RIS. Like Tonedef siad, a dry RIS would be quite disgusting. The best solution would be to pitch a starter, or a dry pack of a neutral yeast. That might help get you a little below 1.030 but not dry it out.

 

thanks for the replies. this is not my beer, actually. i recommended that he rack the beer onto a yeast cake from another batch, but i think he's inclined to try amylase instead, as someone else suggested.

thought i'd check here for some additional opinions. thx.

 

I'd try a little yeast nutrient, but not amylase, for the reasons outlined above. But his efficiency thus far is 62%, which isn't super high, but it's not too off for a scotch ale yeast.

 

I'd be inclined to do both. Pitch a fresh, high-tolerance yeast, then rack off a gallon and add some enzyme. How much that will dry it out depends on the extract, but since alpha amylase has a de-branching limit, it won't dry it out completely.

 

That was going to be my comment... Amylase wont take it all the way down.. Just stay away from beano..

 

Jamie why would you suggest so highly against beano? I read a BYO article which concluded it was sufficent in decreasing FG by .002-.004
cheers

 

Amalayse can only do so much. Beano is a completely different enzyme. In your body, its made to break down oligosaccharides. These are the long chained sugars found in beans and similar food that makes you fart. It will break down all of the long chained dextrins in your beer also. Since there is no way to denature it, beano has the possibility of converting all of the long chained sugars, which yeast in turn will metabolise. Amalayse on the other hand is "debranching". That means it only breaks down long chained sugars so far. It leaves them big enough so the yeast still can't get to them.

 

Is beano glucose amylase?

 

Beano is alpha galactosidase

 

Exactly... Short and sweet = Amalayse will stop at it's debranching limit where the different enzymes in beano will not, leading over time to a much drier product..

 

Thanks for the great info

 

Rehashing what everybody else said a bit, but there are two viable techniques:

1) Pitch on a cake of something like cali ale, which is sure to take it down into the 1.020's;
2) Add amylase powder and pitch a yeast like EC-1118 or WLP099 which is good at restarting stuck fermentations.

A third method, but is more work, is to build up a starter of a highly attenuative yeast like cali ale, and after 48 hours or so feed it a bit of your beer every day for about a week. This will adapt it to fermenting the beer. Then you can pitch in the starter and it should finish fermenting the beer to a more reasonable gravity.

That said my Imperial Stout was 1.102 OG and finished at 1.028 and 1.031 this year (two English yeast strains in two fermenters). It's very tasty. 1.035 is sweet but still very drinkable.