final gravity

[joemama]

I've got a bourbon mash (12lb cracked corn, 4lb 2-row, 1lb rye, final vol 6gal) that started at 1.080 and it looks like it's going to finish fermenting around 1.014 (8.7% abv). Yeast used was BRY-97 dry ale yeast.

I've read a bunch of people here saying they get around or below 1.000. Is that what people get with all grain mashes, or is that more applicable to washes that include sugar? Does distiller's yeast or bread yeast attenuate better? I put my recipe in beersmith and it shows an estimated FG of 1.014. Just wondering how people are hitting 1.000?

[jb-texshine]

Bry-97 is rated at medium alc% perhaps you just maxed out it's potential. Or maybe the temp is out of its range and its just stalled out.

[joemama]

Maybe. I wanted to use US-05 but the brew shop was out of stock. Just looked and US-05 is rated low to medium alcohol tolerance so that actually might have been a worse choice.

[jb-texshine]

I don't care for the way they rate the alc tolerance of yeast. How much is medium? 5% 9%? 12%? Anyway... what's your ferment temp? Maybe its out of its range. 1.010 ain't too bad,rum gets run at that sg.all the time.worst case,fill boiler only half way and put a bit of real butter in the boiler to help stop it from foaming.
jb

[S-Cackalacky]

I don't know the yeast you used, but if the sg is still above 1.000, it still has sugar in it. Could have stalled for a variety of reasons - low PH, alcohol stress, temp, etc. The only other reason might be unfermentables, but that usually only happens with something like a rum ferment. If you decide to go ahead and run it, give it plenty of head space and maybe add some anti-foaming agent. Good luck with it.

Posted with jb.

[der wo]

When you mash with such low malt content, you need a good plan. Low temps, the same temp in the whole mash, much time, no boiling at the end and, if you use backset, pH correction. And the 2-row must be a high-dp one. Why did you take no 6-row? I would always mash low malt whiskeys with 6-row (if it was available in my country).
If the 2-row is high-dp, FG under 1.000 is definetly possible with your grain bill and without adding enzymes.

[joemama]

I read at Williams brewing that BRY-97 has 73-77% attenuation. 1.080-1.014 is 82.5% attenuation. Do these things apply to beer but not whiskey mashes for some reason?

[joemama]

@jb ferment temp was temp controlled starting at 67f and slowly increased to 70f. Just checked it and it's at 68, probably just because the house is cold and it's about finished fermenting.

[joemama]

@der wo - I buy 2 row in bulk for beer brewing, so I just use that and make sure I have 40 dp for the entire grain bill, as I read that a 60 minute conversion is possible as long as you have more than 35 dp or so. When I mash I add the barley and rye at 145-150 and insulate, then let it drop overnight. Iodine test showed complete conversion. I did a post mash boil and I'm going to run a split batch next with half boiled and half not boiled and see what differences there are in fermentation and flavor. Maybe I should put the barley in at a little lower temp. Still, ale yeasts aren't supposed to be able to attenuate to 100% so I'm still surprised you guys hit 1.000 with all grain.

[corene1]

Just a thought , I believe that is why most AG distillers shoot for a potential 8% with a starting gravity of around 1.060. So it will ferment out to 1.000 at 8%. I am not well versed in the yeast department and use primarily bakers yeast, but I always adjust my starting gravity down to 1.060 if it is higher than that before pitching yeast. My typical finishes are between .999 and 1.003.
You recipe has almost 3 pounds of grain per gallon of water so it will definitely have a high SG. Maybe next time cut it down a little and see where it finishes at.
As the others have said if you run it at it's current state prepare for some foaming, but I am sure it will taste great.

[der wo]

I don't think, that your problem is about the yeast. But about yeast other members here have much more knowledge than me.
Low abv sugar washes normally go down to 0.990, fruit mashes also, except very thick mashes. Grain normally go to 1.000, but only, if you achieve, that all or almost all sugars are fermentable.
All measurements with a hydrometer of course! Refractometers give out much higher results for a fermented wash.
In beer brewing you want to get a mixture of fermentable and unfermentable sugars. If you fail, you end with a too sweet and low abv or too dry and high abv beer. For whiskey you want the too dry and strong beer.

@der wo - I buy 2 row in bulk for beer brewing, so I just use that and make sure I have 40 dp for the entire grain bill, as I read that a 60 minute conversion is possible as long as you have more than 35 dp or so. When I mash I add the barley and rye at 145-150 and insulate, then let it drop overnight. Iodine test showed complete conversion. I did a post mash boil and I'm going to run a split batch next with half boiled and half not boiled and see what differences there are in fermentation and flavor. Maybe I should put the barley in at a little lower temp. Still, ale yeasts aren't supposed to be able to attenuate to 100% so I'm still surprised you guys hit 1.000 with all grain.

Your iodine test says nothing about, if all is fermentable.
I normally sacrifice 1/7 of the malt before boiling the corn. Then, when it cools down to 165 I put in again 1/7 of the malt. At 130 I put the rest 5/7 in and let cool over night. Altogether 20% high diastatic 2-row in the grain bill is enough this way. The FG varies between 1.005 and 0.998. I ferment and distill on the grain.

FG 1.000 is not 100% fermented. For a 10% wash 0.987 would be 100% fermented. But this is theory not practice.


Edit: I use this complicated mashing procedure, because I want to mash with as little as possible water, so I can add much backset after conversion.

[still_stirrin]

...When I mash I add the barley and rye at 145-150 and insulate, then let it drop overnight. Iodine test showed complete conversion. I did a post mash boil...

Here's the difference...most that terminate at or below 1.000 do not boil their mash, thereby denaturing any remaining enzymes in the mash. When you do, you essentially stop any subsequent starch to sugar conversion which would be available to the yeast to ferment.

Also, grain bill has an effect on the final gravity. (discussed below)

...Maybe I should put the barley in at a little lower temp. Still, ale yeasts aren't supposed to be able to attenuate to 100%...

Fermentation is typically "attenuate", meaning that it reaches conclusion asymptotically....it continues at an increasingly slower rate as the sugars are consumed. If the yeast is approaching it's alcohol tolerance limit, then it begins to slow down on the consumption of sugars...as you guessed it...asymptotically.

Also, the way you figured attenuation is correct: (OG - FG)/OG x 100 = % attenuation,
where OG = (original gravity - 1.0) x 1000, or in your example: (1.080 - 1.0)x1000 = 80
and FG = (final gravity - 1.0) x 1000, or in your example: (1.014 - 1.0)x1000 = 14

Then, % attenuation is: (80 - 14)/80 x 100 = 82.5 %...pretty good for any ale yeast to accomplish. As you can see, it will approach 1.000 asymptotically, likely never to fully reach 100% attenuation without a very long secondary fermentation duration.

Another thing to consider in your final gravity reading is the beta glucans present from the rye malt. Unless you do a mash step to reduce them, many of those remain unbroken in your ferment. Beta glucan rest is below the normal protein and saccharification steps you normally use. The glucan rest is best between 90-110*F, with a 15-20 minute hold at that temperature.

While beta glucans won't increase the gravity reading directly, the viscosity will tend to keep the hydrometer from properly sinking into the solution. It's very "sticky" and syrup-like.

In conclusion, you made your "distiller's beer" just like you are used to making your drinking beer, which is good. The mashing processes are very similar. However, temperatures of the saccharification rest is usually lower when making "distiller's beer" because the desire is to keep all the sugars fermentable instead of retaining some of the carbohydrates for body and flavor (non-fermentable).

Many of the distillers here also opt for elimination of the post-mash boil as it does denature the working enzymes. Also, boiling is advantageous to the beer brewer because it knocks out proteins in the boil which result in a cleaner wort for fermentation. For the distiller, that protein represents yeast nutrients which will affect the aggressiveness (and termination) of the yeast to ferment.

The bottomline is that what you got represents your protocol very well. And differences between yours and many of the distillers here are exactly that....differences in protocol...not necessarily poor (or exemplary) performance.
ss

[Jimbo]

Still, ale yeasts aren't supposed to be able to attenuate to 100%...

They will if you feed them maltose by mashing in the mid- high 140's. That's my protocol, and always use ale yeasts.

[CharliePattonsSon]

On my second all grain Corn Whisky mash now.
Flaked Corn and 2 Row Malt Barley (what can I say I'm a cheap ass ) I mash 20 litres bottled water to 8.5 lbs flaked corn and 1.5 lbs malted crushed barley. No sugars added at all. Old fashioned style Corn Whisky!
My first OG was around 1.061 after correction to temperature and FG of 1.008 after 3 and half days fermentation (that's post strain/squeeze and just before into the still)
Now my second fermentation of this recipe is almost ready (will be squeezing and stilling tomorrow) Original gravity of 1.058 and just took a reading of 1.005 an hour or so ago.
Should be a touch lower tomorrow before I strain, squeeze and take my actual FG.
So it sounds about right Sir for your mash if you aren't adding any refined sugar etc