All grain potential calculation

[TheRoadrunner]

There are some old folks in my neighborhood, who have restored a fascinating old 18th century farmhouse.
The farmhouse has its own malt loft, that has also been brought back to a working condition.
I help them by converting their pilsner malt into beer for a yearly event at the farmhouse.

The yield of their malt have been somewhat unstable, but over the years I've been able to adjust the potential of their pilsner malt to 1023 (compared to 1036 for commercial 2 row pilsner malt),
which when added with smaller amounts af commercial malt gives a fairly predictable result.
This year I thought I would be more scientific about the process so I made a sample mash in an ordinary pot on my kitchen stove.
I added 400 grams (0.882 lb) of grain to 1 liter of water and mashed for a little over an hour at 65?C (149?F) and heated up to 78?C (172?F)  for the last 10 minutes.

I sifted 700 grams litres of 15.2 Brix (SG 1060) from the mash and added another half litre of water, which was succesively sifted out as 530 grams of 5.1 Brix (SG 1020)
When mixed, I now had 1230 grams of 10.8 Brix (SG 1042)
I guess the 1230 grams converts into (1230/1042*1000=) 1.180 lires or 0.3118 us gal.

How do I convert this to a potential to enter in BS to properly calculate my recipes?

[brewfun]

First, big kudos for taking on the daunting task of analyzing home malted barley! The skills of maltsters are truly amazing and largely unknown by most brewers.

In the US, Malt potential is based on the extract of 1 pound of malt to make 1 gallon of wort. In your experiment, you had 400g or malt to yield 1.18 liters.

1230 ml yield = 0.3249 gallon

gm/gallon = 400/0.3249 = 1231.

This equates to about 2.71 lbs/gallon to yield 1.043 or 1.015 to 1.016 per lb.

The extract percentage number is based on solubility vs. sugar. 1 lb of sugar is 100% soluble and yields one gallon at 1.046 (100%). Your malt percentage is 15/46 = 32.6%.

There is more to the analysis you can do. What that percentage represents is what's called "as-is, coarse grind." This means that the yield number isn't based on absolute dryness (kiln dried commercial malt is usually 4% moisture weight). Also, your number is limited to what you strained and should have gone until you had zero gravity in a rinse, then got boiled down to a liter.

The numbers we get from maltsters is based on a "congress mash" where you'd grind the malt to flour, extract it by boiling, then dry the solids and weigh them against the original amount. This process tells you the absolute solubility of the malt, which would be your max potential. We infer that this is mostly sugar in calculating how much to use in a recipe.



 

[TheRoadrunner]

Thank you for your answer, I know this is a big unknown for most brewers, my self included, but one never stops learning 

I should probably have done a few extra washes to get lower than 1020. And I never thought of drying and weighing the residue. Good input

The recipe I normally use, contains about 80% of this homemade barley malt and the rest is commercial malt.
If the homemade is somewhat low on enzymes to break down carbohydrates and protein, I guess it might benefit from mashing alongside commercial malt with a higher level of enzymes.

So all in all my empiric value of 1023 may not be that far off after all. I look forward to seing the efficience of this upcoming brew.

Maybe I should see if I can attend their next malt production, I might learn more 

[brewfun]

It would be very interesting to see them malt the grain! I remember a Zymurgy article by Fred Eckhardt about home malting. It looked like a terribly complicated process to my extract brewer's eyes. I wish I still had those old Zymurgy magazines.

If they're using a heritage malting variety, your malt may lend itself to decoction mashing. I suspect that the malt may simply be undermodified and would benefit from an acid rest and protein rest. Noonan's "New Brewing Lager Beer" has complete directions on this classic mash.

I think the addition of commercial malt is wise. If you decoct, you don't have to add it until after the first decoction from protein to saccharification. you wouldn't want to lose the enzymes.

[TheRoadrunner]

Good point 

I've spent a lot of time reading about decoction mashing, and it makes perfect sense: To use heritage methods for heritage malts.
Obviously the malt is undermodified given the tools these old folks have at hand.

I have planned a full triple decoction mash for tomorrow, where the commercial and highly modified malts are not added until the 3rd decoction is extracted and temperature is at 65 ?C (149?F). It will be a long day, but a thrilling experience.

The rest of my ingredients came today, but the brewshop forgot to add the yeast, Safale US-05 (not on the bill though). 

My batch is 60 litres (15.8 us gal) and I planned to ad 3 packages. I have 1 package in stock, slightly passed 'best before'.

My grains are all crushed and ready. Should I pospone the brew, or add the 1 package of yeast at end of brew and the additional yeast one day later? 

[brewfun]

Why not go to a local brewery with a sanitized mason jar and get yeast that way? If they balk, I think explaining that you're doing more of a historical recreation than a homebrew project, they'll be happy to help out.

You want to pitch all of your yeast at once and as soon as possible. Barring the above, you're best to postpone the brew day until you have everything.

[TheRoadrunner]

The brew was postponed until the yeast was there.
I had an exciting but long brew day (7.00 AM until 9.00 pm).
The size of the batch was limited by the size of my decoction pot, and that made the total amount a little too small for optimal lautering.
I am using a copper pipe at the bottom of the mash, using the grain as a natural filter, but that works best if there is a little more grain present, than was the case here.
Effectivity was decent though, far better than the previous single infusion brews.

The recipe was calculated for a 60 litres batch and I had 55 with the expected OG of 1049.
 
Having learned a lot, I might have another go at it next time I brew with undermodified malt.

Thanks for all your advise.