- Joined
- May 22, 2020

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- 90

Mashed the following in 5qts of water for 60 minutes at 152 (held pretty steady between 148-154˚ in a nylon bag, in a 3 gallon kettle on a gas stove).

2.25 lbs (2 row) pale malt

1.25 lbs Crystal 80L

6 oz Chocolate Malt (420srm)

1 oz Black Patent malt (500srm)

At 60 minutes I moved the bag into a 5 gallon pot with another 5 quarts of 168˚ water for 15 minutes (I did not maintain temp in this pot so it cooled down to 152 or so). After 15 minutes I poured a final 2 quarts of 168 degree water over the bag and then removed the bag and poured the wort from the 3 gallon kettle into the 5 gallon kettle. At this point I had approximately 3 gallons of wort in my 5 gallon kettle which measured 1.040 gravity.

I brought the wort to a boil and made the following hop additions:

1 oz East Kent Goldings @ 60m

1 oz Willamette @ 11 minutes

1 oz Mt Hood @ 11 minutes

When the 60 minute boil was completed, at flameoff I added 4.95lbs Briess Golden light DME and stirred for about 10 minutes until it was dissolved. Then I cooled to 68, added another 2.5 gallons of water and pitched a decanted 1.5 liter starter of London ESB 1968 (about 500ml went into wort). OG ended up at 1.056 and 5.25 gallons in the fermenter.

Here is my question:

The flameout DME addition is something Palmer mentions in the partial mash section of How to Brew. He basically extends his Palmer Method to work with partial mash by using grains up front and extract at the end. But Jamil and several others mention adding the extract at the start of the 60 minute boil. I played around with Beersmith and noticed that changing the timing of the DME addition had a pretty big impact on the IBU and I'm not sure I understand why:

From Beersmith using above ingredients:

DME addition at start of 60 minute boil: IBU 21.9

DME addition at 5 minutes (from end): IBU 28.4

DME addition at 1 minute (from end): IBU 31.4

DME addition at 0 minutes (Whirlpool): 32.3

I assume 0 minutes at whirlpool is the same as saying right after flameout. Also, I noticed that if I chose 0 minutes in the boil, the IBU dropped back to 21.9, but this may be a Beersmith bug because .1 minute stayed near 31.4.

Can someone help me understand why the IBU (I assume this relates to Hop utilization) changes so much as I move the DME addition time further towards flame out. I've read a lot of threads over the last day or so and still don't fully grasp what is happening. I do like doing late extract additions, particularly for partial mashes, but I want to be sure I understand how the grains, hops, and extracts are working together. If the answer is too long, point me toward a good source.

Thanks