What gives?

[NorthernBrew]

Hi guys, i'm new to homebrewtalk.com. On my 5th allgrain right now and i'm noticing a rather annoying trend. Everytime my FG is 6,7,8 points higher than i'm aiming for. Fermenters are 5 gallon buckets w/ airlocks. I keep my temps around 70, or as close as I can, maybe a 5, 6 degree swing. I've let it sit for as long as three weeks. Tried slightly raising the temp, rocking the bucket (a bit torn on that one) and once added sugar after boiling it in water although that was not to lower the FG but only to raise the alc level to about 4%.
Any tips or outrage to throw my way? Most appreciated.
Thanks guys

 

[h-bar]

What are your mash temperatures? If you mash too high (above 158F), you'll extract out a bunch of unfermentable sugars that the yeasts can't consume. By 6 FG points, do you mean 1.016 rather than 1.010?

 

[NorthernBrew]

My mash temp right around 153. Yeah my OG was right on the money, at least the last three times. Right now i should be looking at a 1012 and i'm scratching my head on 1020

 

[Barley_Bob]

What yeast are you using? And have you zeroed your thermometer to make sure the temp it shows is correct?

 

[NorthernBrew]

It's fermentis us 05 this time. Says on the bag that 70 is ideal for it. Or 20 celsius.I have a pid controller for the temp plus a handheld thermometer.

 

[BierMuncher]

The lower the mash temp the lower the FG.
The longer the mash rest, the lower the FG.

My driest beers (1040-1050 range) rest at around 149 for 90 minutes and dry out to well under 1010.

Lower the temp and let that mash sit for an extra 30-40 minutes. You'll be golden.

 

[KurtB]

Welcome to the forums.

There are a lot of reasons possible, and not a lot of information to go on from your first post.

Information that could be helpful includes what yeast was used, how high was the starting gravity (even posting the recipe may help us to figure things out), was the yeast re-hydrated (dry) or was a starter used (liquid), was the wort aerated (shaken) before pitching, etc.

However, probably the first thing I would check is to make sure your thermometer is accurate. You may think you are mashing at 153, but could really be at a higher temp.

 

[duboman]

Have you calibrated your thermometer and hydrometer? Are you correcting for temperature? Are you rehydrating your dry yeast or making starters if using liquid strains?

FG per recipe is a crap shoot and not always accurate depending on conditions and recipe as well as process but ideally it's close, not as far off as yours appear to be so my guess there is something in your process or poorly calibrating measuring devices causing poor attenuation or perceived to be poor attenuation

You could also not be getting full conversion of the mash leaving a lot of less fermentable sugars behind. Do a conversion check. Water can also play into conversion as well as mash pH. Lots of things to consider here...

 

[NorthernBrew]

Alright. I mashed for 60 min at 153 ish. Mash out at 170 for10 min. Boiled for 60 min. Cooled to room temp with immersion, tapped in buckets. Did only sprinkle yeast over the wort after giving the bucket a good shake. Gravity measured with a refractometer on multiple occasions during the brew. Was very happy with the OG, right on 1054. Yeast is fermentis us 05. Going by the info on the bag the ferm temp was right. Although i worry always about the swing in temp, which is about 5,6 degrees.
thermometers agree and are calibrated. The refractometer shows 1000 with clean water, so i'm pretty confident with the numbers.

 

[mrwizard0]

Were you using the refractometer to take the FG? They are not accurate with alcohol present.

 

[NorthernBrew]

Were you using the refractometer to take the FG? They are not accurate with alcohol present.

I did not know that. That could definately be a factor. Thanks

 

[SuliBrew]

+1 with alcohol present. Lots of calculators that will give you the correct FG reading based on OG and current FG.

 

[NorthernBrew]

Good to know

 

[duboman]

Were you using the refractometer to take the FG? They are not accurate with alcohol present.

+1
Take a reading with a hydrometer, you'll be surprised

 

[NorthernBrew]

The lower the mash temp the lower the FG.
The longer the mash rest, the lower the FG.

My driest beers (1040-1050 range) rest at around 149 for 90 minutes and dry out to well under 1010.

Lower the temp and let that mash sit for an extra 30-40 minutes. You'll be golden.

Sounds good. Is a 90 min mash good for all styles?

 

[NorthernBrew]

Using the beersmith calculator, using the original brix reading and the fg, i seem to be in better shape than i thought. Thanks everybody. This is definately the place to go for quick responses

 

[Demus]

Sounds good. Is a 90 min mash good for all styles?

90 minutes is simply not necessary with today's highly modified malts. 60 is probably even more than they need but is a well accepted, conservative practice. Adding 30 minutes would just lengthen your brew day.
Besides , your beer attenuated fine. You just didn't measure the FG properly. There are spreadsheets online to convert post ferment refract readings, or simply use a hydrometer for FG...


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[BierMuncher]

90 minutes is simply not necessary with today's highly modified malts. 60 is probably even more than they need but is a well accepted, conservative practice. Adding 30 minutes would just lengthen your brew day.
Besides , your beer attenuated fine. You just didn't measure the FG properly. There are spreadsheets online to convert post ferment refract readings, or simply use a hydrometer for FG...


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The evidence in my brewshop after several hundred batches is empirical. The identical grist mashed at 149 Degrees for 90 minutes will definitely attenuate lower than one mashed at 154 for 60 minutes. Does this make it suitable for all styels? Certainly not. I cut my OctoberFAST Ale down to just 45 minutes to retain some unfermentables and give that rich malty backbone.

 

[Demus]

Temperature control is just as effective and would save you :30...


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[mrwizard0]

The evidence in my brewshop after several hundred batches is empirical. The identical grist mashed at 149 Degrees for 90 minutes will definitely attenuate lower than one mashed at 154 for 60 minutes. Does this make it suitable for all styels? Certainly not. I cut my OctoberFAST Ale down to just 45 minutes to retain some unfermentables and give that rich malty backbone.

Isn't this comparing two different things? The same grist mashed at 149 for 60 min should attenuate lower than one mashed at 154 for 60 minutes.

 

[Demus]

Isn't this comparing two different things? The same grist mashed at 149 for 60 min should attenuate lower than one mashed at 154 for 60 minutes.

Yes, this is an apples oranges comparison. Temperature effects attenuation by favoring one enzyme over another. Lower temps favor beta amylase which creates more strait maltose, while alpha amylase creates more dextrins and less fermentable sugars. While a lower temp like 145 FAVORS beta amylase, alpha amylase still does some work. Enzyme activity is not an on off switch, but a bell curve. A mash at 145-155 has BOTH enzymes active so mashing longer will ALWAYS result in greater fermentability because beta amylase will have a chance to "catch up" even in a warmer mash. This however is not the easiest way to affect fermentability. More commonly brewers simply vary the temperature, and keep the time consistent...


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