Low Attenuation (S-05) in Milk Porter

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rifraf

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Hello all. I recently got back into brewing and after a few batches went to make a milk porter based on a beer I had at a brewery in NC. They were willing to share the grain ingredients with rough notes but no exact amounts, so that part was up to me. Ingredients:

Here is the Beersmith info:

***
1 lbs 8.0 oz Chocolate Wheat Malt (400.0 SRM) Grain 1 13.3 %
1 lbs Caramel/Crystal Malt - 60L (60.0 SRM) Grain 2 8.8 %
5.0 oz Black (Patent) Malt (500.0 SRM) Grain 3 2.8 %
5.0 oz Oats, Flaked (1.0 SRM) Grain 4 2.8 %
3.0 oz Roasted Barley (300.0 SRM) Grain 5 1.7 %
7 lbs Extra Light Dry Extract (3.0 SRM) Dry Extract 6 61.9 %
1 lbs Milk Sugar (Lactose) (0.0 SRM) Sugar 7 8.8 %

1.00 oz Magnum [12.00 %] - Boil 60.0 min Hop 8 24.8 IBUs
0.50 oz Northern Brewer [8.50 %] - Boil 15.0 min Hop 9 4.3 IBUs
0.50 oz Northern Brewer [8.50 %] - Boil 0.0 min Hop 10 0.0 IBUs

1.0 pkg Safale American (DCL/Fermentis #US-05) [50.28 ml] Yeast 11 -


Gravity, Alcohol Content and Color

Est Original Gravity: 1.065 SG
Est Final Gravity: 1.020 SG
*******

Fermented at about 69* (fermenter temp) in my basement for 3 days before I moved it upstairs for another 5 days (73* fermenter temp).

My actual measured OG was 1.081. After 1 week of fermentation, I'm at 1.030. In the past, the bulk fermentation was always done by a week and FG didn't change much with S-05. This puts me at an apparent attenuation of 65% which seems low for S-05. Is the lactose throwing me off? Do I need to be more patient with the yeast? I was planning on giving it at least another 2 weeks anyway to clean up.

Thanks!
 
How big was the batch size? Using extract and those grains to get up to 1.081 would be around 3.75 gal. If it was larger, like a typical 5 gallon batch, I would question the instrument making the gravity readings.
 
1.081 is about right for 5 gallons; the extract will give you 63 points + the lactose will give you 7 + 3lbs of grain will give you about 10 points = 1.080.

The reason you have such a high FG is because you have a lot of unfermentable sugars. The lactose and speciality grains are 17 points that will mostly not ferment. If you took this number from both the OG and FG, you would have 1.064 to 1.013, which is 80% attenuation of fermentable sugars.

Put the recipe in BeerSmith, and select partial mash with a 40% efficiency, and you should be close to your OG.
 
1.081 is about right for 5 gallons; the extract will give you 63 points + the lactose will give you 7 + 3lbs of grain will give you about 10 points = 1.080.

The reason you have such a high FG is because you have a lot of unfermentable sugars. The lactose and speciality grains are 17 points that will mostly not ferment. If you took this number from both the OG and FG, you would have 1.064 to 1.013, which is 80% attenuation of fermentable sugars.

Put the recipe in BeerSmith, and select partial mash with a 40% efficiency, and you should be close to your OG.

Awesome thanks. I didn't mash any base malts, I thought it wouldn't get any fermentables from the specialty grains unless they had a 2-row in there with them?
 
Awesome thanks. I didn't mash any base malts, I thought it wouldn't get any fermentables from the specialty grains unless they had a 2-row in there with them?

Most speciality malts have sugars. And when you steep them you are dissolving these sugars. Crystal will give around 18 to 20 points/lb, while the more roasted malts are somewhere around 8 to 12 points per lb. These are mostly unfermentable sugars.

If you mash them, you will get a lot more from them. These additional sugars, converted from starch, are mostly fermentable.
 
Ah ok. So I'm getting sugars, just not fermentables ones. I must have misunderstood How to Brew and everything I've read. Thanks for the tips, I'll adjust Beersmith accordingly.

Now that I know that, why doesn't Beersmith automatically add non-fermentables when you add grains to the recipe? Or more accurately...what does it think I'm doing when I select extract and add grains?
 
My original miscalculation was based on beersmith number. It's why your target OG was 1.065 and you actually had 1.081. If you plug in the same exact numbers as all grain you get the correct starting gravity of 1.081. Not sure what this is all about though. Beersmith is a good tool, but it definitely has it's limitations. Best thing to do, in my opinion is to write the recipe with extract only. Then add in all the unfermentables to the recipe. What ever the OG jumps from those addition, figure them as unfermentable. Hope that helps and hopefully someone else can add more.
 
In Beersmith you do need to manually set check the "unfermentable" box for a grain. On the options > advanced tab you can also change the percentage steeping efficiency, it seems like folks get more like 50-60% yield for crystal and roasted malts so you probably want to change that. That will help with getting the OG right for extract batches, it will likely still underestimate the FG as I think many calculators do because they go by a set % attenuation for the yeast.
 
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