Help Converting Full Boil to Partial from BCS Recipes

[strawbalebrewing]

Hi there. I am an all grain brewer, but a friend recently asked to brew with me because he wants to learn more and move from brewing kits on the stove top.

I recommended trying a few of the recipes out of Brewing Classic Styles, but I was actually a bit stuck trying to convert the recipes for a partial stove top boil using a 3 gallon boil as opposed to the 7 gallon boils in the book. I followed the step-by-step calculations in the book (assuming 44 pts for DME), but when I plug my results into beertools, the OG seems too low.

Could anyone take a look at my results for converting Jamil's Wittbeir and Lefse Blonde recipes for partial boils and let me know if they look janky?

Thanks BN crew. You guys rule.


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Lefse Blonde

1.065 OG

3.5 lbs Pilsener DME
.75 Wheat DME
1.5 lbs Cane sugar

Steeping grain
.5 Lb Aromatic Malt

1.6 oz Hallertau 60 mins

WLP500 Trappist Yeast

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Wittbier

1.050 OG

2 lbs Wheat DME
.25 lbs Munich DME

1.13 lbs Flaked Oats
1 Lb Pilsener Malt

1.5 oz Fresh Citrus Zest 5 mins
.4 oz Coriander seed 5 mins
.03 oz Dry Chamomile Flower 5 mins

.25 oz Sorachi Ace 60 mins
.25 oz Sorachi Ace 15 mins

WLP400 Wit Yeast

[Fugglupagus]

They are 7 gallon boils, but the recipes account for one gallon of boil off. So the fermentables in the recipes are based on a 6 gallon batch. He drains 5.5 gallons out of the kettle to ferment. He discards the other 0.5 gallon as it is laden with trub and hops. So the recipes needs to be adjusted from 6 gal to whatever you batch size you plan to ferment.

Are you shooting for 5 or 5.5 gallons?

[strawbalebrewing]

I would be shooting for 5.5 gallons into the fermenter.

Also, I'm a little bit of a moron for not reading the partial boil chapter more carefully. After re-reading it, I think I now realize that this calculation for figuring the fermentables for this boil is for the purposes of designing the boil only – and that at the end of the boil, I'll then need to add the balance of the extract from Jamil's full recipe.

Am I right about that?

Thanks for responding.

[Fugglupagus]

Also, I'm a little bit of a moron for not reading the partial boil chapter more carefully. After re-reading it, I think I now realize that this calculation for figuring the fermentables for this boil is for the purposes of designing the boil only – and that at the end of the boil, I'll then need to add the balance of the extract from Jamil's full recipe.

Am I right about that?

Yup. The book recommends limiting the gravity of the partial boil to no more than the recipe's OG. According to theory this method will give results as close as possible to full boil volume worts. You can compute the boil gravity if you want, and add extract accordingly. Or if you want to RDWHAHB, add half at the beginning and the rest at the end.

Generally speaking, BCS partial boils ending with a 5.5 gallon fermentation need to reduce the recipe amounts by (5.5 gallons)/(6 gallons) = 92%.

FYI, both recipes you selected are slightly not standard from an extract brewers perspective. The wit is actually a mini-mash recipe. The pilsner malt and flaked oats are mashed like a small batch of all-grain (instructions in appendix C). Then the extract is added to make up the balance of the fermentables. The blond calls for steeping aromatic malt. You will likely get 0 ppg from steeping aromatic. Since the recipes are straight conversions from all grain where aromatic may bring something like 26 ppg to the party, you may need to add additional extract to make up the difference.

[Fugglupagus]

The blond calls for steeping aromatic malt. You will likely get 0 ppg from steeping aromatic. Since the recipes are straight conversions from all grain where aromatic may bring something like 26 ppg to the party, you may need to add additional extract to make up the difference.

Or convert the recipe to a mini-mash.

This is how I'd convert the blond assuming I was getting LME in a standard package from someplace like Northern Brewer and that I was gonna stick with steeping the aromatic:

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Lefty Blonde

1.065 OG

6 lbs Pilsener LME (36 ppg)
15 oz Pilsner DME (42 ppg)
14.6 oz Wheat DME (42 ppg)
1.4 lbs Cane sugar (46 ppg)

Steeping grain
7.3 oz Aromatic Malt (0 ppg)

1.5 oz Hallertau 4%AA (adjust for actual AA) 60 mins

WLP500 Trappist Yeast
***********

Frankly, I'd add full pounds of both DMEs and take the extra gravity point. Unless I needed the DME for my next brew.

[strawbalebrewing]

Great! So, this confirms for me that I was planning correctly, which is good.

I was planning pretty much as you outlined above, except I was going to go with 6.2 lbs Pils DME rather than the Pilsener LME/DME split as you have. I'll take a look at my local HBS and see what they have and plan accordingly.

I've done plenty of partial mashes, so this will be a nice way to show another homebrewer a new technique.

Thanks again for the help. Much appreciated.