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Brews & Views Bulletin Board Service * Brews and Views Archive 2003 * October 10, 2003 * Tip for AG'ers with High FG Problems < Previous Next >

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Shawn Duggan (216.195.139.173)
Posted on Friday, September 19, 2003 - 04:25 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

After going AG I used to have continual issues with high FG. It really annoyed me because I'm pretty anal and did things by the books...adjusted my water properly, kept temps right, pitched lots of yeast, aerated with O2, made sure my thermometer was accurate....etc. I usually never miss an OG by more than a point. So it was killing me that I never hit the FG I wanted.

I don't mill my own grain. So I decided it was the crush my LHBS was giving me. Not much I could do there. So after doing a little reading I decided to thin my mash to 1.25 qts/lb for my usual pale ales and mash longer (2 hours). Seems to work quite well.

I've learned a lot from this board and thought I would pass this along. It might help someone else out.
 

Jim O'Conner (63.164.164.115)
Posted on Friday, September 19, 2003 - 08:51 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Wow. That's the longest mash time I've ever heard. Hey, but if it works, the proof's in the pudding, or in this case, the beer.
 

Brandon Dachel (63.238.222.190)
Posted on Friday, September 19, 2003 - 11:23 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

> So I decided it was the crush my LHBS was
> giving me.

Crush will effect efficiency but will have no effect on FG. It's a function of unfermentable sugar content.

How high is a 'high' FG? You say that your water is adjusted properly so I assume you know what your doing with water chemistry.

At what temp are you doing your sacc. rest? A longer mash will produce a more fermentable beer, but the same results can be achieved by simply mashing at a lower temperature.

Then again there are some things that just defy explanation. Like when people talk about beers that drop from 1.085 to 1.020 in 2 days with a half gallon starter at 65F. I do the same and NEVER see fermentation that fast. Oh well.

Oh - are you using alot of crystal malts or carapils?
 

Magnus Graham (148.177.161.211)
Posted on Friday, September 19, 2003 - 11:54 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I keep trying to sort this out. Maybe it isn't stuck.

For example a 1050 OG beer:
What is the range of FGs you could expect taking into consideration Mash composition and Yeast (proper brewing yeast).

All sugar brew would get pretty near 1000 but what about the top end e.g. hot mash and low attenuation yeast??

Anyone out there worked it out.
 

Bill Pierce (24.141.63.119)
Posted on Friday, September 19, 2003 - 12:59 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Mag, the short answer is "it depends." There are a number of factors affecting fermentability. I would say the three most important are yeast selection and management, malt selection, and mash temperature.

The attenuation range of most yeast strains is published. These are ballpark figures based on an adequate pitching rate and aeration, but they at least provide some idea of what to expect.

You are correct that pure sugar is nearly 100 percent fermentable, as anyone who has made dry mead will attest. Pale malts are up to perhaps 88 percent fermentable, such as in a mash with 100 percent pale malt converted at 148 F and fermented with a highly attenuative strain like champagne yeast. Caramel malts are more like 50 percent.
 

Dave Witt (205.188.208.73)
Posted on Friday, September 19, 2003 - 01:52 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

"Caramel malts are more like 50 percent."

Bill, I always wondered, why wouldn't the mashing process change the fermentability of high dextrin malts like crystal and carapils? What if you had a high % of crystal malt and mashed at 148F? Wouldn't those dextrins be broken down to simpler sugars along with the rest of the starch from the pale malt? I understand the effect of Crystal malt in an extract beer from a mouthfeel standpoint, but in a mash, doesn't the high dextrin/low fermentability issue kind of go out the window, if you mash it low enough, long enough?

I rarely use Carapils anymore. I use crystal malt thinking more of its flavor contribution than its body/sweetness contribution. I feel I can alter the body of my beer enough by mashing at various temps.

Can caramel/dextrin malt be made more fermentable by mashing lower, or does amylase not effect these dextrins? Am I missing something?
 

big earl (209.222.26.27)
Posted on Friday, September 19, 2003 - 03:10 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

It's been my experience that the 1st thing to look at when getting high F.G.'s is Proper AERATION ..........
 

Magnus Graham (148.177.161.211)
Posted on Friday, September 19, 2003 - 04:22 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Yes Bill but I haven't sussed the fermentation/attenuation stuff yet and am being lazy. It is possible to brew a 1050 beer that bottoms out at 1020 but is it probable and what would a beer like that have to be.

I accept that it is more probable that there wasn't enough aeration....

I have done some meaty high end mashes and these seem to stop around 1020. I feel that I have maybe hit the slow fermenters but beacause there are a lot of them, I still need to wait a month or so to keg.

Make sense?

Mag
 

Shawn Duggan (216.195.139.173)
Posted on Saturday, September 20, 2003 - 02:12 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Brandon - my rests are between 152-154. OG around 1.60 and the high FG I was getting is about 1.018-1.020 with American Ale yeast. The beer was good, but none of us settle for good, do we? I do not use much crystal or carapils (< 4% in my recipes that use them). And my starters are a gallon-ish for the 10 gal ales I make. And I aerate with pure 02 generously.

I was varying a lot of things trying to make things better. One day I got busy with my son and ended up mashing for 2 hrs. That beer finished at 1.012 which made me very happy. Been doing it since.

I agree with what one person said. 2 hours is long. I might drop to 150 for my next mash. Maybe I won't. I only brew every 2 months or so these days (10 gal). So its whatever works. It's all about the beer.
 

Denny Conn (140.211.82.4)
Posted on Saturday, September 20, 2003 - 07:41 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

You said your thermometer is accurate, but how did you test it? Did you test at mash temps or just at boiling and freezing? I've had problems similar to yours in the past, and tested my thermometer the old "boiling water and ice water" method. It looked OK. Then I got a lab calibration thermometer and tested it at mash temps...discovered it was off 5 degrees! Just a thought...
 

Guy C (67.169.98.103)
Posted on Saturday, September 20, 2003 - 07:57 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

When you say you aerate with pure O2 generously, how long is that?

Dr. Cone recently mentioned that too much O2 puts an oxidative stress on yeast cells, which can produce unhealthy cells.
 

Shawn Duggan (216.195.139.173)
Posted on Sunday, September 21, 2003 - 01:51 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Denny - I did the ice water and boiling comparison. Maybe it is off at mash temps. I had not thought of that. Thanks.

Guy - About 90 sec per 5 gal fermenter, with a strong flow. I think to have too much O2 the amounts would have to be quite extreme.
 

Andrew Bales (65.28.61.181)
Posted on Sunday, September 21, 2003 - 10:31 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I have done 4-5 hours for hefeweizens. I do 1.5 to 2 hours for basic beers, but I like good extractions and my direct fire system has never done well with 1 hour mashs, they are pretty hazy even when stepped to 120F,155F, 168F. The last wheat-rye-wine I did I mashed overnight and it was still slow running off.

What kind of heat do you see during mashing? Mine goes up over time from the thick steel sides of a keg half bbl. You might well be above your starting point by 10F if you use one as well.

I found that if I want low finals from my mash kettle I need to mash in at 120F and slowly raise it to 148F (1.33 ratio) and let the latent heat of the keg kettle's steel sides raise it slowly to 155F; covered with no fire on its own. I used to just race to 152F, but overshoot when removed & covered was well to 162F, the heat build up at the bottom of the kettle was just too hard of a decoction mash, boiling, darkening, for a 1060 beer. Not a grainy beer even tho boiling up from the bottom was seen (and still is just not as much), but a very malty taste and high final. Great for lagers, heavy porters and non-nitro stouts, and such. Terrible for pale ales and dry stouts on nitro, kolsch, and belgains. The body comes out way too wide.
 

Timothy Wulfers (56.0.84.111)
Posted on Monday, September 22, 2003 - 04:45 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I agree with Denny , I had the same problem with my 10 to 20$ dial type thermometers . they checked good at both extremes but could be off by 10 degress at 150 ! Also once I started using my digital thermometer I noticed lots of hot and cold pockets in my mash bed . I made a mash paddle that allows me to stir the mash verticaly . This helped alot .
 

HEU Brewer (80.78.102.253)
Posted on Monday, September 22, 2003 - 05:38 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I found out that while brewing and listening to Led Zeppelin Presence my OG is right on. That must be the trick.

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