Poor Attenuation- any help would be great

My last 4 batches have attenuated very poorly. Prior to this I was averaging about 75% attenuation. Could be the winter months but I keep my brews in an insulated closet with a space heater set at 65 degrees and the door is insulated as well.

My last failure was the best laid plans (however the sample tastes FANTASTIC!) My og was 1.055 and FG was 1.028. here is the recipe

% Amount Name Origin Potential SRM
-----------------------------------------------------------------------------
79.2 4.00 kg. Munich Malt Germany 1.037 8
8.9 0.45 kg. Flaked Oats America 1.033 2
5.9 0.30 kg. Chocolate Malt America 1.029 350
5.9 0.30 kg. Roasted Barley America 1.028 450

Dough in at 138 and rest at 127.4 for 30 minutes, raised temp to 148 for 20 minutes, 158 for 20 minutes. I don't know why but I brought it to 168 for 10 minutes before vorlauf. Then I fly sparged and went to a 90 minute boil. I sent my wort through a SS strainer and aerated the wort a bit more before pitching Danstar Nottingham dry yeast (not rehydrated, no starter since it was dry, no yeast nutrient) at about 72 degrees. My OG was 1.055 and FG is 1.028. It sat in the closet for 5 weeks with no secondary. The temps varied from 72 at start to about 65 after 5 days. I never saw a ton of krausen.

My previous 4 brews have finished at 1.018-1.020 which is high compared to the 1.012 I saw in the summer months.

I am going to force Carb this one and drink since it still tastes good. I am checking samples at 60 degrees and have checked my hydrometer. I have had success with doing a rest at 127 , 148 and 158 in the past Can someone please help me out?

 

Not that it should have much effect on the attenuation, but a protien rest with that recipe isn't necessary. However, you only have 20 minutes at 148. Try doing that recipe with a simple infusion mash at 148 for 60 mnutes. Or at the very least, I would reduce the protien rest time to 20 minutes and increase the beta rest (<154) to 30 minutes.

 

Agree with BigB, you don't need the protein rest there and would benefit from a longer beta rest. Also,have you calibrateted your thermometer recently? Simplest explanation is that you don't have as fermentable a wort as you were predicting which would point to mash temp or posibly poorly modified base malt.

 

Thanks all-

My Thermometer has been Calibrated recently. I'm brewing a brown and a Honey IPA this wekend. I'll only rest at 154 for 60 minutes and report back in a few weeks to see if that does the trick.

What kind of a ingredients would be in a recipe where a protein rest is needed?

 

Most of the malts today are highly modified and don't require a protien rest. A pilsner malt would still benefit from the rest and bring out the more complex back end maltiness, but even that is debated.

Has your water source changed?

I would also double check the thermometer against another.

Rehydrate your yeast for 30 min before pitching in 100 degree pre boiled tap water.

your temps are fine. I typically attenuate from 1.060 -1.075 to 1.010 @ 62 degrees.

Good luck and I hope this helps.

Bull

 

If you had a large portion of adjuncts... like raw/torrified wheat, corn, rice, and to some extent malted wheat too.

Another thing to remember when mashing... if you want a thinner/more dry/more attenuated beer, you should mash at a lower temperature. A higher temp will result in a more full bodied/sweeter/less attenuated beer.

 

This is all great info! I have been trying to search and read up on improving attenuation a lot recently.

I am going to try a Pilsner here pretty soon so at least I can go into it with a little experience with the rest. Thanks for the heads up bullinachinashop. I'll also start to use my digital Themrometer against my brew pot's Thermometer just to double check them against each other.

BigB- what's the acceptable range for each. I'd venture to guess 148-154 for thinner/more dry/more attenuated beer and 155- 160 for full bodied/sweeter/less attenuated beer? Total stab in the dark on that one though.

 

Well the range would be more of a sliding scale than a strict range. If you mashed at 145 it would be thinner and more fermentable than if you mashed at 150. And likewise thinner at 150 than 156. Obviously you have to keep it within reason. Generally, IMHO (and I hope others will chime in) if you kept your mashing range between 146 and 158 you would get a good range to work within. If I was making a Belgian Triple and really wanted as much attenuation as I could get, I would probably mash at 146-148. Now if I was after a fuller beer like a Stout or a Porter, I would mash 154-158. There are several things that affect attenuation though. Here is a couple good resources:

http://www.howtobrew.com/section3/chapter14-6.html (pretty straight forward)
http://braukaiser.com/wiki/index.php/Understanding_Attenuation (more technical)

 

I really can't wait to build my fermentation chamber. I have been keeping a close eye on craigs list for a cheap mini fridge and then I will get to it. I get pretty even temps in the closet for now but it is not perfect.

I have used liquid yeast in the past as well. I made my starter and it took off quick! I will use liquid on the Pils for sure. Thanks for the heads up on that one.

 

Just switching to liquid yeast will not affect attenuation unless you are switching from a poor attenuating dry yeast to high attenuating liquid yeast. Nottingham's average attenuation is 75% and is commonly used for many beers including English Ales. Now say you switch to WLP011 European Ale (liquid) which is also used for English Ales... But guess what? The average attenuation on WLP011 is only 67.5%. You certainly aren't going to improve attenuation by switching to that liquid yeast.

Fermentation temperature would also only have a substantial effect if you were fermenting too cold. However, 65 F for Nottingham is just fine. Don't get me wrong, I'm not advocating ignoring fermentation temperatures by any means... I'm just saying that only if you keep it too cold or too hot will it affect attenuation.

 

Thanks Big B- I am going to go over the links you sent earlier when I get home from work with a fine tooth comb. I expect I'll learn a lot. I may have a question or two for you after tonight after I read up a bit more. Again much appreciated!

 

I am doing a brown today and I think I can fix this.

Here is the recipe:

8.25 lbs Pale Malt 2 row
1 lbs Victory Malt
1 lbs Special Roast Malt
1 lbs Crystal 60L
0.25 Chocolate Malt

I plan on setting my temp at 154 for an hour and doing a 90 minute boil. I am using safale 05 and rehydrating this time. If anyone has anything to add, feel free to let me know. I am starting now. I will update with OG at the end of today and FG in a couple of weeks.

Thanks all-Cheers!

 

Do you monitor the fermentation temperature, or just the ambient temp? A cold floor could be bringing your fermentation temps down.

 

As mentioned earlier, rehydrating dry yeast would certainly help. I know many go without rehydration with success, but it doesn't always turn out that way. According to Palmer and JZ, pitching dry yeast directly on wort kills about half the cells. Also, going the liquid yeast starter route should help as well.

 

Yes, but your premise seems to infer that by switching to liquid yeast, you will get better attenuation. Or more directly that liquid yeast "with a proper starter" will give better attenuation than dry yeast. This is not accurate. Even if you make a huge starter, liquid yeast will not get you any better attenuation over dry yeast unless the yeast can reach that attenuation level and all other things being equal. Remember that most dry yeast packets, including Notty, are 11.5g packs and have approximately 225-300 billion cells. Now compare this to an activator pack which has approximately 100 billion cells. Using a fresh pack and a 2L starter on stir plate will only get you to the low end of the cell count in a pack of Notty.