knockout hop additions

[KidHop]

After listening to some of the recent CBYI shows I decided to I add an ounce of Columbus and whirlpool hot for 20 minutes on the IIPA I brewed a week ago. So far as I can tell 1 week into it, the whirlpool hop addition adds a very smooth hop character to the beer.

I just made sure I kept the wort temp no lower than 200F. I seem to remember that DMS is most likely to form in the 180F - 140F range when cooling. There is no detection of DMS in the beer. Actually, the only thing I detect is hops.

Also (unrelated to this thread), I was able to drive the attenuation from 1.080 to 1.010. 1.5lbs of sugar and healthy yeast starter helped.

[Hoser]

Comparitively speaking, did you get more intense aroma from doing the WP for 20 minutes or from a 0 minute addition that is quickly cooled?

It is hard to answer that question since I have not done any side-by-side comparisons. Also, I have dry hopped all of the beers where I have done a WP addition so that would cloud the picture further. If I had to guess, probably not since some of the volitile aroma compounds are lost due to the heat. But, the only way to tell would be to do the split the beer into 2 batches and WP hop one and crash cool the other and then do a blind taste test.

Hoser

[Mills]

I wonder how big of a necessity it is to actually even whirlpool those late additions. I know there is more contact with the wp, but you might achieve the same or similar thing by dumping in the hops and covering. Just a thought.

Mills

[animaldoc]

I remember from one of the shows JZ said the precursor of DMS was produced between a certain temp range, like 180-130. Can anyone verify these numbers for us?

If you are whirlpooling at the end of boil you would be above the DMS precursor upper limit, so no DMS later on.

I think the main thing working in the whirlpool's favor re:DMS --we're talking pale malt based beers here which have most of the SMM precursor to DMS driven off during the kilning process with the remainder driven off during the boil. The "upper limit" temperature of 180F -- I don't think DMS stops being formed at this temperature, it's just less of an issue because above this temperature it's being volatilized. That would actually be a problem for us whirlpooling, because if we are going to cover the kettle at this stage, we would actually trap the DMS and it would return to the kettle thru condensation on the underside of the lid.

My take? Don't worry about DMS in these beers. Or if you are going to worry, whirlpool uncovered.