High FG

[Capecodwhale]

So I brewed an AG recipe close to Beirmunchers Black Pearl Porter, except for some additional grain I had. My Efficiency came out as 93% according to iBrewmaster. OG was 1.075 and FG stopped at 1.030. I do not understand why the FG was so high. Mash target was 150F, but I was initially low and had to decoct 2 quarts to bring the mash up to temperature. Mashed for 55 minutes, with mash out temp of 170F. Boil was 90 minutes, 6.4 gal start with target of 5.5 gal. (I don't have notes on final volume, but would estimate 5-5.5 gal.) Yeast was Wyeast 1028, a couple months past best use date, stepped up into a 2L starter. 7 days @ 60F, then 2 days @ 65F, then 5 weeks @ 60F. I had another brew that finished high also. I would like to know why? My thermometers are calibrated, as well as my hydrometer. Is it because I did a decoct that changed some of the first runnings sugars, making them less fermentable? Is it because the yeast was too old, even though I made a starter? The hydro sample taste ok, if not a little thick on mouthfeel. Could I add some simple sugars to lower the FG? What do you all think?

Grains & Adjuncts
Amount Percentage Name Time Gravity
8.00 lbs 60.09 % Crisp Maris Otter 60 mins 1.038
20.00 ozs 9.39 % Caramel/Crystal Malt - 10L 60 mins 1.035
17.00 ozs 7.98 % Chocolate Malt 60 mins 1.028
13.00 ozs 6.10 % Caramel/Crystal Malt - 60L 60 mins 1.034
1.00 lbs 7.51 % Oats, Flaked 60 mins 1.037
8.00 ozs 3.76 % Cara-Pils/Dextrine 60 mins 1.033
3.00 ozs 1.41 % Barley, Flaked 60 mins 1.032
8.00 ozs 3.76 % Special B Malt 60 mins 1.030

 

[jdauria]

Ah good old Cape Cod! How's things along the mid-Cape? I have answered a few of these similar type questions over the last few days...long story short, I am guessing you under pitched your yeast. I use MrMalty.com yeast pitching calculator myself to determine the amount of yeast to pitch. While you made a starter, did you use a stir plate or just stir it occasionally?

Using MrMalty, a 1.075 OG, 5 gallon batch, with ale yeast "a couple months old"...using 12/1/12 as an estimated date...and assuming you just did intermittent shaking of the starter, you would have needed to pitch 3 vials of yeast that old in a 1.84 liter starter (using a growth rate of 3, the standard I use). If it was simple starter, you just let it sit around, you would have needed 3 packs in a 3.18 L starter, if a stir plate, 3 packs in a 1.19 L starter.

Also 60F is the low end of the fermentation range for that yeast, so you probably did not want to keep it that low for that long either.

Not sure about the simple sugars, but you could always pitch some more yeast and let it go another few weeks.

 

[Capecodwhale]

Thanks for the quick reply neighbor!
I made a 1L starter and stepped up into a 2L, all with a stir plate spinning. Aerated of course. And as soon as I read your reply I remembered that I used White Labs 007. (I don't know how Wyeast got into my notes.) Brewed the first of the year with yeast best by October, so a little old. Looks like I will have to buy the Mr Malty app.
It's racked into a keg now. When I get home I might throw some dry yeast in to finish the job... Lesson learned with not keeping track of my yeast on hand.

 

[latium]

Did you include the malto-dextrine and the lactose which are in the Black Pearl Porter recipe? I didn't see that you'd listed them, which is why I ask. If you did, that would be why, as those ingredients are unfermentable.

Looking a little closer at what you posted, the grain bill lists 20 oz of C10 and 13 oz of C60. That's nearly three pounds of crystal malt, which contribute mainly unfermentable sugars. Also add in the half pound of dextrine malt, which also contributes unfermentable sugars (dextrines for mouthfeel).

If my math is correct (doing it by hand with a spreadsheet rather than brewing software), about .016 of your FG is coming from those three sources, meaning that if you hadn't added those, your SG would be about 1.014. To my knowledge, brewing software doesn't take unfermentables into account when estimating an FG.

 

[jdauria]

Thanks for the quick reply neighbor!
I made a 1L starter and stepped up into a 2L, all with a stir plate spinning. Aerated of course. And as soon as I read your reply I remembered that I used White Labs 007. (I don't know how Wyeast got into my notes.) Brewed the first of the year with yeast best by October, so a little old. Looks like I will have to buy the Mr Malty app.

MrMalty online is free, iPhone version cost be $5, but well worth it because when at Brew shop I can check yeast date and determine the number of vials I need.

Yikes the yeast was very old. If it's best By October...that means you need to go back 4 months I believe it is, for Wyeast, so that is June. Just for kicks, I checked with MrMalty again and putting in a date of 6 months ago for the yeast, it says you needed TEN packs of yeast, 27 without a starter! That would cost a pretty penny! 6 month old yeast only has a 10% viability rate.

 

[stpug]

33 oz of combined Crystal
8 oz Special B
41 oz of semi-sweet finishing grains

16 oz oats
8 oz carapils
3 oz flaked barley
27 oz of body building grains plus the extra creamy/oily oat texture

WLP007 fermented basically at 60F when it's low end should be 65F.

I believe that a combination of heavy sweet-grain usage coupled with a fermentation too low for that strain of yeast is what is leaving you a little high on the residual sugar. You basically forced the yeast to perform it's full fermentation about 5 degrees lower than it's optimal range and it probably crapped out early because of that. I would guess that your pitching rate was sufficient for the gravity of your beer, even considering the older "use by" date.

Additionally, I believe the thick mouthfeel would be a direct result of the body building grains you used in the recipe, regardless of the mash temperature. A thick mouthfeel for a high-strength porter might actually work out very well once it gets some carbonation.

If your gravity reading is accurate (in the 30s) then it might be worth pitching a new stepped starter at high krausen with a beer temp of 70F to finish it up. The reason for the stepped starter is to provide an abundance of yeast cells to work on the remaining sugars since they'll likely want to flocculate quickly. The reason for 70F beer temp is to encourage their activity with some warmth.

Another option is to use a different yeast strain that doesn't floc too well and is known for finishing stuck fermentations. The less flocculant the strain, generally the better the yeast is at consuming the maltotriose (complex sugars).

 

[Capecodwhale]

Thanks All for the replies.
I did not add malto-dextrine and the lactose which are in the Black Pearl Porter recipe. The previous time I brewed the BPP recipe, it turned out good but had a little sour milk type note to it. My brews usually come out pretty clean tasting and I don't think it was infected or anything. So I attributed the sour note to the Lactose and replaced it with more oats
and grains. But what you guys are saying makes total sense. Ibrewmaster is saying the ABV is 5.9%, but the brew wasn't 'hot' tasting as far as alcohol. Since I like Big Beers, I think the only thing to do is to pitch more yeast starter after I warm the beer up a little. A little bit more alcohol and less mouthfeel might put this beer in its place. I thank you all for your contributions and thoughts!
Cheers!