Fermenting low

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WildKnight

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I cannot seem to get my beers to ferment low in gravity.

I read articles about people who get their 8 and 9% big-bodied beer to ferment low. Triples that ferment down to 1.010 (or lower). I've seen some 10% stouts that go down to 1.018. What is the trick?

I always pitch a starter. It is active and usually contains 100ml of yeast slurry when it settles. I always aerate the carboy using a 0.5 micron stone. I've even pitched champagne yeast at the end to try and get it lower.

I generally mash low, 148-152. Sometimes I even add some cane sugar to add alcohol and get the gravity low. Most often, I mash for 90 minutes up to 2 hours.

Generally, my beers stop fermenting at 1.020-22, regardless of the recipe - 10 lbs 2-row, 15 lbs 2-row, 18 lbs 2-row. Some recipes have crystal and some have none - all end above 1.020. With a 75% attenuation yeast (i use WLP001 - 73-80%), anything under 1.080 should ferment below 1.020, which is 95% of the beers I brew.

I've only ever gotten one beer below 1.020, and it was a recipe with 9 lbs of grain, no crystal and I pitched a whole yeast cake from a previous beer. Everyone who tried it said "good flavor, but kinda light." How do you get a full bodied flavor while getting the gravity low so it doesn't taste too sweet?

Is it even reasonable to expect recipes with that average 10-12 lbs of 2-row with 1lb of crystal (plus minor percentages of other grains for color) to ferment below 1.020?
 
I cannot seem to get my beers to ferment low in gravity.

I read articles about people who get their 8 and 9% big-bodied beer to ferment low. Triples that ferment down to 1.010 (or lower). I've seen some 10% stouts that go down to 1.018. What is the trick?

I always pitch a starter. It is active and usually contains 100ml of yeast slurry when it settles. I always aerate the carboy using a 0.5 micron stone. I've even pitched champagne yeast at the end to try and get it lower.

I generally mash low, 148-152. Sometimes I even add some cane sugar to add alcohol and get the gravity low. Most often, I mash for 90 minutes up to 2 hours.

Generally, my beers stop fermenting at 1.020-22, regardless of the recipe - 10 lbs 2-row, 15 lbs 2-row, 18 lbs 2-row. Some recipes have crystal and some have none - all end above 1.020. With a 75% attenuation yeast (i use WLP001 - 73-80%), anything under 1.080 should ferment below 1.020, which is 95% of the beers I brew.

I've only ever gotten one beer below 1.020, and it was a recipe with 9 lbs of grain, no crystal and I pitched a whole yeast cake from a previous beer. Everyone who tried it said "good flavor, but kinda light." How do you get a full bodied flavor while getting the gravity low so it doesn't taste too sweet?

Is it even reasonable to expect recipes with that average 10-12 lbs of 2-row with 1lb of crystal (plus minor percentages of other grains for color) to ferment below 1.020?

I would start with checking your thermometer. What type of mash tun are you using? How are you making your starters? Are you reusing yeast?
 
I would also check to see if your hydrometer is calibrated and correct the reading for temp. If using a refractometer check for calibration and correct the reading for alcohol in fermented beer.
 
Agree with Clonefarmer - calibrate your thermometers and hydrometer. Also, are you fermenting within the recommended temperature range of your yeast?
 
Yes do the above checks, also, how long do your fermentations typically take to reach final gravity? I wouldn't check for final gravity until about three weeks for standard brews.
 
Agree with Clonefarmer - calibrate your thermometers and hydrometer. Also, are you fermenting within the recommended temperature range of your yeast?

66-68F

I would start with checking your thermometer. What type of mash tun are you using? How are you making your starters? Are you reusing yeast?

8 gallon stainless steel pot with false bottom and ss ball valve. Thermometer reads 212F at boiling, mash at 150 is consistent with my cooking thermometer. Starters are made from washed yeast from previous batches. They are mixed with 500ml of 1.040 wort and spun on a stir-plate for 12-24 hours.

I would also check to see if your hydrometer is calibrated and correct the reading for temp. If using a refractometer check for calibration and correct the reading for alcohol in fermented beer.

Samples are held at room temp for before reading. Should be very close to hydro calibration.

Yes do the above checks, also, how long do your fermentations typically take to reach final gravity? I wouldn't check for final gravity until about three weeks for standard brews.

1 week primary, 1 week secondary. a big beer will sit for 3 weeks before checking.
 
As far as thermometer calibration, is the theory that I am mashing to hot due to an wrong thermometer reading?

I would imagine even if off by 2-3F, shooting for 148-150 leaves me at 145-153 which is not that high. This shouldn't be enough to make unfermentable wort, should it?
 
I just switch between stirring and recirculating a pot at a time by hand for the 90 minutes. I only add heat for about 1 minute every 15 minutes of mash time.
 
taking the beer off the yeast after 1 week would be my guess.

Yeah, this would be another thing to look at. I've only had 1 stuck fermentation and it was due to a low fermentation temp and poor wort aeration. I also use a stir starter and never had issues until this last beer. I fixed it by agitating the beer every so often over a period of 6 days to get the yeast back in suspension - it finally dropped to within 1 point of my predicted FG. I also don't utilize secondaries any more, so I still had my beer resting on the primary yeast cake, which helped alot.

So other than fermentation temp, hydro and thermo calibration, proper wort aeration and keeping the beer in the primary longer or until you bottle/keg, I got nothing else. Hopefully you figure it out!
 
If your mash pH is off, you may not be getting proper enzyme activity. Do you do a starch conversion test? Do you test with a pH meter?
 
If your mash pH is off, you may not be getting proper enzyme activity. Do you do a starch conversion test? Do you test with a pH meter?

No and No. I'm thinking of trying the mash pH buffers available. We have fairly alkaline water in Louisville, but folks in my homebrew club don't seem to have a problem with pH.
 
if you're getting good conversion (hitting your OG) then mash pH shouldn't be a concern, should it?
 
No and No. I'm thinking of trying the mash pH buffers available. We have fairly alkaline water in Louisville, but folks in my homebrew club don't seem to have a problem with pH.

Either could be your problem. Starch conversion testing is incredibly easy. I just pull a thin layer from the mash in a white coffee cup and put a drop or more of iodine (or iodophor) into the coffee cup with it. If the edges of the iodine that are contacting the mash remain amber colored you are fully converted. If it turns black or purple, you have unconverted starches. Unconverted starches will lead to a high FG.

Managing mash pH has been made easy as well but you absolutely need a pH meter. Don't waste your time with the buffers, they don't work. Water chemistry can be very complicated but the following thread contains a very simplified, results oriented process. If you have any questions, ask in the thread. The author is a great guy and is great about answering questions.

https://www.homebrewtalk.com/f128/brewing-water-chemistry-primer-198460/

We have fairly alkaline water in Louisville, but folks in my homebrew club don't seem to have a problem with pH.

Don't assume that just because other brewers are not reporting problems that you don't have any. It sounds like you have your bases pretty well covered as far as the common causes of high FG. I absolutely wouldn't ignore this one. If you have highly alkaline water, I can pretty much guarantee that managing mash pH will improve the flavor of your beer, even if it doesn't fix your FG issue. I have highly alkaline water as well and when I started adjusting mash pH my beers went from OK to excellent! Since I started using a pH meter they went from inconsistent to excellent EVERY TIME! Water chemistry is paramount. If you were the only brewer in your club that tested and adjusted mash pH I would go out on a limb and guess that you make the best beer in your club. It's that important, especially if your water is alkaline.
 
if you're getting good conversion (hitting your OG) then mash pH shouldn't be a concern, should it?

Not necessarily. You can have unconverted starches or sugars that are insufficiently broken down due to poor pH conditions in the mash.

Here's a chart from Palmer's How to Brew that shows typical enzyme ranges in the mash.

f79.gif


link to page: http://www.howtobrew.com/section3/chapter14-1.html
 
So, how do you accomplish getting fermentable sugars, low final gravity and still having a beer with a little roundness to the body. Not wee heavy body, but a sufficient backbone.
 
It sounds like you are doing most everything right (ie. proper mash temps, pitch rates, ferm temps etc.). I would let it sit in primary longer as someone suggested earlier or even better, verify with a hydrometer that it is indeed finished fermenting before moving to secondary. Recipe is something to look at as well. Crystal malts are great for adding body.

As far as ensuring that you have the proper amount of fermentable sugars, you want to mash at an appropriate temperature for the recipe, mash in the acceptable pH range (5.1-5.5) and insure that all of your starches are converted with a simple starch conversion test.
 
Not necessarily. You can have unconverted starches or sugars that are insufficiently broken down due to poor pH conditions in the mash.

Here's a chart from Palmer's How to Brew that shows typical enzyme ranges in the mash.

f79.gif


link to page: http://www.howtobrew.com/section3/chapter14-1.html

that chart just shows me what ranges enzymes work best at.

it doesn't say, "at pH 5.1 beta-amylase converts starch to unfermentable sugar"

if he's converting starch to sugar, which it sounds like he is, I still don't see it as a pH problem.
 
i tested my hydrometer in distilled 60* water.... it was .04, instead of .00.
so that explained my "high" FG readings.
 
that chart just shows me what ranges enzymes work best at.

Don't you want your enzymes to work at their best?

it doesn't say, "at pH 5.1 beta-amylase converts starch to unfermentable sugar"

100% true, but it does show the "sweet spot" (pH of 5.1 to 5.5) where you can get the best performance out of all of the important brewing enzymes. These are the enzymes that convert starches into fermentable sugars.

if he's converting starch to sugar, which it sounds like he is...

Without a starch conversion test, it isn't safe to assume that his starches are 100% converted.

It sounds like his other brewing practices that affect FG are pretty well in line. Do you have a better theory as to why his beers are finishing so high?
 
taking the beer off the yeast after 1 week would be my guess.

This is your problem, Leave a standard gravity beer on the yeast 2 weeks MINIMUM, three is better then check the gravity, to get more body, mash higher, up to 60F.

Keep on brewing my friend:mug:
 
Don't you want your enzymes to work at their best?

100% true, but it does show the "sweet spot" (pH of 5.1 to 5.5) where you can get the best performance out of all of the important brewing enzymes. These are the enzymes that convert starches into fermentable sugars.

Without a starch conversion test, it isn't safe to assume that his starches are 100% converted.

It sounds like his other brewing practices that affect FG are pretty well in line. Do you have a better theory as to why his beers are finishing so high?

if he's hitting his OG, that means he's converting starch to sugar. right?

i believe his problem is 1 week primary - most of my mid-high gravity beers don't hit terminal in under a week.
 
Yes, but it doesn't mean that he is converting all of the starch to sugar.

so? he's not chasing efficiency.

are you saying that two beers made with exactly the same grainbill, OG, and mash/ferment temperatures but two different pH's will ferment differently?
 
so? he's not chasing efficiency.

I'm not talking about efficiency. Unconverted starches are unfermentable. Unfermentable starches in your wort lead to higher than desired final gravities. I'm not sure you understand what unconverted starches are.

are you saying that two beers made with exactly the same grainbill, OG, and mash/ferment temperatures but two different pH's will ferment differently?

I'm not saying they will, that depends on the pH difference, but they absolutely can. I'm not saying this is absolutely his issue, but it is a very good possibility. If racking were his sole issue, I would imagine at least a few of his beers would have finished fermenting before he racked in one week and would have had normal final gravities. Most of my beers reach terminal gravity in a week or less.
 
I will cast my vote for the 1 wk primary being to blame. I only do two week fermentations too, but I just do a 2 wk primary unless I am dry hopping or the like. Try a 2wk primary and I think you will be happy.
 
I'm not talking about efficiency. Unconverted starches are unfermentable. Unfermentable starches in your wort lead to higher than desired final gravities. I'm not sure you understand what unconverted starches are.

lol, i understand what unconverted starches are

i'm under the assumption that unconverted starches don't affect a gravity reading. if that's wrong, and unconverted starches affect specific gravity, then i agree with you.
 
Starches are soluble at 130* and can thus affect gravity. :mug:

are you sure?

http://cartwright.chem.ox.ac.uk/hsci/chemicals/starch.html
Water solubility: slight (a clear solution of starch is most readily prepared by adding a slurry of about 1g starch in 10 ml of water to a large volume (ca 500 ml) of boiling water, then immediately allowing the solution to cool to room temperature)

i hate to quote wiki, but:

http://en.wikipedia.org/wiki/Starch
Solubility in water: none

unless i'm doing it wrong.
 

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