DMS and Boiling

I guess the best way to describe my attitude towards pilsner malt recently is: wary or afraid. Everyone says that you HAVE to boil it for 90 minutes in order to drive off DMS. As such, I have been just using american 2-row instead of pilsner malt (with decent results), but it seems to be cramping my creativity.

Anyways, I was thinking about it earlier today and I get a ton of boil-off with my beers, I boil off around 2 Gallons per hour (26%). With this amount of boil-off, do I really need to worry about DMS? Unfortunately, my wort collection method doesn't allow me to collect more wort than the 7.5 Gallons I already collect, so boiling for 90 minutes is rather unfeasible and I want to be able to brew worry free with pilsner.

So what are peoples thoughts? Is DMS a red herring? Could I get away with a 60 minute boil with my setup? Should I just stay with American 2-row whenever anything calls for pilsner malt?

DMS isn't a red herring. It's a volatile chemical compound and pilsners are more prone to it.

The boil length isn't some magical number though. The goal is to drive the concentration of DMS below the taste threshold. Boiling longer is an obvious way to do that. Boiling vigorously is a way to do that. Fermenting vigorously is a way to do that. (Quick cooling also minimizes the DMS production) The combination of those things is going to determine how much DSM is left in the finished product.

You might have no problems with a 60 minute boil for a belgian that practically jumps out the carboy while fermenting. If your boil is vigorous enough, you might not even have DMS issues in a pale lager that just kinda chugs along.

Pilsners are more prone especially since they are much milder flavored and it will stand out more.

What is the diameter of your pot? At 2 gallons/hour, you must have a short and wide pot. Are you sure your boiloff is that high?

I get 1.2 gallons per hour boil off with a 13.5" diameter pot in a very humid state.

IMO/IME if you maintain a vigorous boil AND can chill the wort very quickly (<15 minutes), create the proper sized starter, properly aerate the wort and have a healthy fermentation DMS is not an issue. I have successfully brewed beers with up to 80% Pilsner malt following these best practices.

duboman, is that with a 60 minute boil?

Topher, since I brew on the stove top, I can't get a rolling boil with a single 8 gallon pot. As such, I boil in 2 separate pots, which doubles my surface area. I think one of my pots has a diameter of 11" and the other has a diameter of 13". I was originally planning to go gas 6 months ago so I could boil in one pot, but my apartment doesn't allow stoves on the patio.

In theory, you are boiling off as much DMS in your 60 minutes as others do in a 90 due to the 2 pots/higher evaporation rate thing you have going on. The only way to know if that transfers over to practice is to try it.

billl said:

In theory, you are boiling off as much DMS in your 60 minutes as others do in a 90 due to the 2 pots/higher evaporation rate thing you have going on. The only way to know if that transfers over to practice is to try it.

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I'm not sure about that. I remember reading that DMS boil off is a function of time. When the boil is vigorous, you boil off 50% of the DMS precursor every 40 minutes. So at 80 minutes...75% is removed. So on and so forth. I will try to find a link.

Here's a pretty good explanation:
http://www.picobrewery.com/askarchive/dms.htm

And yes, to answer your question I do a 60 minute boil but keep in mind I ensure a very vigorous boil when using Pilsner malt and experience greater boil off in these batches as well. I also use a CFC and can chill my wort down in less than 15 minutes on a 6.25 gallon batch. Both of these practices have proven to be effective in eliminating my concern for DMS issues. Also, as mentioned DO NOT USE A LID!

I'm not sure about that. I remember reading that DMS boil off is a function of time. When the boil is vigorous, you boil off 50% of the DMS precursor every 40 minutes. So at 80 minutes...75% is removed.

Click to expand...

To a degree this is correct however there are other factors involved such as vigor of boil and ability to rapidly chill the wort. These are discussed and referenced in the article I linked as well as a helpful graph illustrating it.