Islay Style Whiskey

[hanon]

I'm working on my Islay Style Whiskey. Last time I did 10 lbs in my 8 gallon kettle with bakers yeast, this time I'm doing 20 pounds in my mash tun with high gravity ale yeast, which is a very strong English yeast.

Here is the recipe:

20 lbs Heavy Peated Malt
4 oz Acidulated Malt
4 tsp Gypsum
Added 10 gallons of 155 degree water and mashed for 90 minutes at 145.
Cooled to 90 degrees and pitched 400 billion cells of WLP099 Super High Gravity Ale Yeast. pH was 5.55.
1.056 SG

I'm fermenting in my mash tun on the grain at room temperature.

[SoMo]

That sounds pretty tasty, should make a smoky malt for sure. What are your plans for aging?

[hanon]

I plan to age it on light toast oak chips at 125 proof for 4-6 months. Eventually I need to get a small barrel.

[SoMo]

That's my kinda drink with the light toast, should be a great sipper

[hanon]

Gravity is still over 1.040. This is the first stuck ferment I've ever had and I've been brewing beer for a long time. I pitched enough yeast and the pH was fine, so the only thing I can think of was that it didn't have enough oxygen because of the grain and the nature of my mash tun. I'll probably try this again with ale yeast using only 10 pounds of grain and fermenting in my kettle at 70 degrees, but for this batch I'm just going to pitch a half pound of bakers yeast on top of it. That should get it done.

[Odin]

Half a pound should be enough for 250 liters ...

Why not try to up the temp a bit?

Odin.

[Terryv]

How was the peat flavor last time?

Is it true that they have to have lots of heads to have it?

[hanon]

Room temp is high 70s, it's definitely not too low. 400 billion cells of WLP099 should smash 10 gallons of 1.055 ale - which is basically what this is - at 70 degrees. I think it has to do with being on the grain in the container it was in, my mash tun is a 50 qt cooler. 1/2 lbs of bakers yeast costs me less than a dollar. I used 1/4 lbs on a 10 pound batch last time and it was fine, but I do want to try a few different yeasts with this. I'll probably try 300 billion cells of the White Labs yeast on 10 pounds of grain in 5 gallons of water in my kettle next time. I plan to start in the high 60s.

Terryv - I think it needs to age before I can really evaluate it, it's still pretty rough. I also think I over-oaked it by using dark toast oak chips. I'm using light toast oak chips from now on and will eventually get a small barrel. All commercial Scotch puts most of the heads back to feints, and I know Laphroaig definitely does this. I think they collect from 70%-55% for hearts, which is definitely more tails than heads.

[frunobulax]

This is a guess, but the stuck ferment may be due to a low PH due to the phenols in peated malt, plus you added acidulated malt and gypsum, both lowering PH. Do you have a meter?

[hanon]

It was 5.55 pH after the mash, but when I pulled some out to mix the bakers yeast in, it was down to 3.4 after barely attenuating 10 points. You may be on to something about the phenols in the peated malt, and I was thinking fermenting on that grain may have done it, but CO2 signifiacntly lowers pH, and the CO2 probably doesn't escape so well from my mash tun, so I'm thinking that's what lowered the pH so much.

[hanon]

Did this again with some White Labs Scotch Whiskey Yeast. Have been aging 2250 ml on light toast wood chips for a few months at 125 proof. I also have a few hundred ml of the white whiskey at 86 proof and have been drinking that. It keeps getting better and if I mix it 50/50 with quality non-peated scotch it's better than Bowmore or even Ardbeg IMO, much closer to a Laphroaig, Talisker, or Lagavulin. We'll see how my aged stuff turns out, but I would definitely do this again just for the white whiskey.

[Alchemist]

It was 5.55 pH after the mash, but when I pulled some out to mix the bakers yeast in, it was down to 3.4 after barely attenuating 10 points. You may be on to something about the phenols in the peated malt, and I was thinking fermenting on that grain may have done it, but CO2 signifiacntly lowers pH, and the CO2 probably doesn't escape so well from my mash tun, so I'm thinking that's what lowered the pH so much.

Not that I have a solution, but I would say it isn't the phenol. I've done multiple 100% peated malt mashes and had zero fermentation issues. Both on and off grain.

I kind of wonder about your aciduated malt. Why did you add that? 3.4 isn't crazy low. But clearly something is up.

I'd also toss out that you are over thinking the pH issue. The grain is naturally very buffered. CO2 may lower in an un-buffered system, but you have both grain and gypsum. You are well buffered.

That all said, I'd adjust up with bicarb to the 4.5-4.8 range and see what that does.

[hanon]

Like I said this last one with the White Labs yeast turned out great. I think fermenting in my 8 gallon kettle instead of my 50 quart cooler might have made a difference as well. I aim for a post mash pH between 5.4-5.6, if I didn't add the acidulated malt it would be higher than that.