Using Amylase Enzyme to Drop My FG?

[robbyg]

I brewed my second-ever partial mash a few weeks ago, which also happened to be my first-ever 5 gallon batch (I did a dozen or so 2-gallon batches first). It was a Northern English Brown Ale cobbled together from various recipes on HBT that finished at a respectable OG of 1.047.

However, I had a terrible time determining and maintaining a consistent mash temperature -- I was stovetop mashing (following DeathBrewer's wonderful instructions), and my obviously crappy digital thermometer would read 130F in one spot and 180F an inch away, so I got newbie-nervous and fiddled with the temp a lot. So I was already a little worried about how this would ferment out.

I pitched a packet of S-04 at 72F had activity within 24-30 hours in my 65F basement. I took a gravity reading at day 14, and it was sitting at 1.017, which was higher than I'd hoped. After reading a bit in the forums, I decided to give the bucket a gentle swirl a couple of times a day for a couple of days to reintroduce yeast into suspension, and I moved it to a warmer corner of my basement (closer to 70F than 65F).

I tested this morning, on day 20, and I'm still sitting at 1.017. So now my suspicion is that my poor mash temperature control resulted in an overabundance of complex sugars that didn't ferment out.

So my question is this: If I were to add, say, a half teaspoon of amylase enzyme to my primary, what could I expect the result to be? Ideally, I'd like to see this finish around 1.010-1.012. Could I conceivably hit this mark, or will the amylase drop me lower (say, all the way to 1.005 or something)?

I appreciate any and all input here. I've not used amylase before, though I have some sitting at home.

 

[KellyK]

I agree with your diagnosis that your mash probably caused issues with too many non-fermentable (or less than desireable fermentable sugars) in your wort. However, my 2 cents, I would never use amylase on any beer that had an OG of under 1.080. Once you add the enzyme on the finished wort side, it doesn't really stop. It will keep breaking down and could readily drop your beer to 1.005 or even worse. The way to keep the enzyme in check, at least in my experience, relates to the alcohol tolerance of your yeast. If you use it in a 1.080+ beer, even if the enzyme keeps breaking down the remaining sugars, your yeast will reach terminal on their alcohol tollerance and will stop of their own accord, even if there is more for them to eat. Not so for lesser gravity beers.

Taste it, even if it finished higher than you wanted, if it tastes good I'd call it a day. If you're worried about overall alcohol content, you could try mixing up a sugar syrup solution (1 cup corn sugar to 1 cup water, boiled then cooled) and adding it to the fermenter to boost the overall gravity a bit. The addition of sugar could even jumpstart the yeast into more muching of the less fermentables, but that doesn't always work.

If you have the amylase around, try using it on the mash side. It will help give your mash an extra boost in converting the sugars and the enzyme will denature during the boil.

I've had plenty of beers that finished higher than I wanted them to and they still tasted great.

Also, I should probably double check this, you're sure your hydrometer is calibrated correctly. Sometimes it's the hydro that's off and not the wort. Double check your calibration, it should read 1.000 in ~60 degree water.

 

[nilo]

Amylase convert starch into sugars at specific temperatures, not long chain sugars into short ones. Your mash is done and you got the sugars already, so not much you can do.
I think you fg is not far from what you should get, for a partial mash recipe.
What is your recipe by the way?

 

[wonderbread23]

Amylase convert starch into sugars at specific temperatures, not long chain sugars into short ones.

Not really. The first response is correct. Amalyse will break down the long chain sugars (the ones initially created in the mash). The reason this doesn't happen if your mash temp drops is because at that point the enzymes have been denatured. A bone dry brown isn't what I'd enjoy, so I'd just chalk it up to experience and enjoy the beer.

 

[nilo]

I think I got it. So in this case, one should add "beta amylase" to a fermenter, increase temp to 140F to activate the enzyme so it can covert the long chain sugars, keep it there for let's say 20min, then cool to pitching temp and re-pitch yeast?
Re-pitch would be necessary since the increase to 140F would have killed then all, right?

 

[robbyg]

Thanks for the detailed feedback, KellyK. That's what I was looking for -- an understanding as to whether the amylase would stop on its own after a certain point, or if the quantity I added would merely speed/slow the conversion process. And my hydrometer IS significantly off... but I knew that going in, and my numbers took that into account (my beer read 1.021 at 68F, but my hydrometer is 4 points high in water at 60F, so math ensues each time I take a reading).

I'm not ~overly~ concerned about the alcohol content, though this will work out to be my lowest ABV beer to date, and 3.9% seems pretty low for a brown. I think in the future I'll give the amylase a try in the mash, at least until I can get around to building a cooler-based MLT for better temperature control.

And Nilo, here's the recipe I came up with. I called it "Cheerio", as it's a honey-nut English brown ale.

Recipe: Cheerio
Style: Northern English Brown Ale
TYPE: Partial Mash

Recipe Specifications
--------------------------
Batch Size: 5.00 gal
Boil Size: 3.50 gal
Estimated OG: 1.047 SG
Estimated Color: 17.1 SRM
Estimated IBU: 24.5 IBU
Brewhouse Efficiency: 73.00 %
Boil Time: 60 Minutes

Ingredients:
------------
Amount Item Type % or IBU
2.50 lb Extra Light Dry Extract (3.0 SRM) Dry Extract 34.72 %
2.00 lb Pale Malt (2 Row) US (2.0 SRM) Grain 27.78 %
1.50 lb Caramel/Crystal Malt - 60L (60.0 SRM) Grain 20.83 %
0.50 lb Brown Malt (Crisp) (65.0 SRM) Grain 6.94 %
0.20 lb Pale Chocolate Malt (Crisp) (200.0 SRM) Grain 2.78 %
1.00 oz Fuggles [4.00 %] (60 min) Hops 12.4 IBU
1.00 oz Goldings, East Kent [5.00 %] (25 min) Hops 10.8 IBU
0.25 oz Goldings, East Kent [5.00 %] (10 min) Hops 1.4 IBU
0.50 lb Honey (1.0 SRM) Sugar 6.94 %
1 Pkgs SafAle English Ale (DCL Yeast #S-04) Yeast-Ale

 

[Yooper]

I think 1.017 is fine for that recipe! Using amylase (and no, it's not heated and all that stuff) would probably cause it to finish superdry and not be as good as it is right now.

 

[nilo]

So the amylase from the barley malt needs to go to 140+ temp to be activated but the one you buy doesn't and works at room temp?

 

[Yooper]

So the amylase from the barley malt needs to go to 140+ temp to be activated but the one you buy doesn't and works at room temp?

Right.

Some people have used crushed Bean-0 tabs when their homebrew store didn't have amylase powder, and we've heard stories about their beers NEVER finishing until under 1.000!