Sunday, January 07, 2007

My First Partial Mash!

I just finished my first brew with a partial-mash and I think it went very well.

I used two sources to help me out, Ken Schwartz presentation 'Converting All-Grain recipes to extract/partial mash and Ray Daniels 'Designing Great Beers'.

Ken's presentation shows you how to take an all-grain recipe and convert it to a partial-mash and extract recipe

The recipe that I decided to copy was a Sierra Nevada Pale Ale clone (it didn't turn out that way, but I'll get to that later).

The original recipe called for the following malt bill:

11.9lb 2-row pale ale malt
1.7lb of Crystal 60L

I ended up using 3lb of 2-row pale ale malt and 2lb of Crystal 60L in the partial-mash.

How I came up with this is that I wanted to do a 5lb mash (recommended in Ken's paper). I had to buy 2lb of the Crystal (it comes in 1lb bags) so I figured I would just bump the 1.7lb up to 2lb. This leaves me with 3lb of 2-row to make the 5lb of grain for the mash.

You take the 11.9lb from the original recipe and subtract the 3lb used in the mash and you get 8.9lb that you have to make up with extract. Ken gives a conversion rate of .67 to convert from grain to dry extract. That would give me about 6lb of extract to make up the difference (This is not how much I ended up using, I'll explain later).

So I built a mash tun out of a 16qt Colman cooler. I drilled a hole in it and make a filter with a rubber stopper with a 4" piece of 3/8in OD copper tubing through it. to the inside end of the copper tubbing I attached a piece of SS Braid with a hose clamp. To the outside end I attached a 4" piece of clear tubbing with a valve at one end.

I went to the LHBS to get the ingredients but they did not have the US-56 Dry Yeast that the recipe called for so I picked up a pack of US-04 Dry Ale Yeast instead. I picked up the wrong hops by mistake and got Challenger instead of Cascade for the flavor/aroma hops. So at this point I decided that I'm not making a SNPA Clone, but just some kind of pale ale/IPA beer.

The mash went well. I heated water up to 173º and racked to the cooler/tun. When the temp had dropped to 165º I added the grains. This soon brought the temp down to about 150º. I let that rest for 60min, stirring at 30min.

Next it Vourlofed about 8 cups (one at a time)until the wort ran clear. Then I started sparging the 170º water into the mash tun to keep about 1/4 to 1/2 inch of water above the grain bed. It says in Ken's paper to do this very slowly (about one or two cups per min) so it took some time to do.

Once I had the wort from the mash (just over 2gal) I took a gravity sample. It gave me a corrected reading of 1.065 S.G..

If I'm following Ray Daniels 'Designing Great Beers' correctly that means I have 2 x 65GU = 130GU in the wort

So to reach my target grav of 1.053:

53GU x 5.5gal = 291.5GU in the whole batch

291.5GU - 130GU = 161.5GU needed from extract

161.5GU / 40GU (per lb extract) = ~4lb extract.

So this is what I went with. I did the rest of the brew like normal. I did a late extract addition putting in about 1lb of DME in with the wort and top off water at the start of the boil.

When all was said and done after the 60min boil and cooling the wort I came up about 1/2gal short of the 5.5gal I shoot for so I topped off to get to 5.5.

I took a S.G. reading and found I'm getting about 1.051 O.G.. This is a little bit short of what I was shooting for but not too far off.

The gravity sample looks very nice to me and it tastes very good as well.


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