DMS Where does <140F come from?

I have many of the classic brewing science books and can't find validation of this temperature so commonly used in the beer forums. I do see:

1. Lager malt is kilned to 158F which is not high enough to destroy enough SMM that ultimately can become problem DMS in our lagers.

2. Briggs, et. al Brewing: Science and Practice, mentions cooling the wort to 192F to "usefully slow" the reactions with fewer volatiles being formed; p. 344

3. Lewis and Bamforth in Essays in Brewing Science, state that SMM breaks down to DMS >176F

My other books are next door (Lewis, Fix, DeClerck, Noonan, Bamforth, Hardwick, Jansen, Boulton, Palmer, Goldammer, Hornsey, etc.) but I don't think any of them give this 140F figure as being the magic number we need to cool below quickly to diminish DMS formation.

If memory serves, Korzonas might give this number referencing Fix's 1st edition as the source, but the 2nd edition does NOT have this information in it.

Where DOES this number come from? Is it correct?

Here is what I found in Homebrewing Volume I by Al Korzonas, page 90.

When wort is above 158*F S-methyl methionine (SMM) in the wort rapidly breaks down to dimethyl sulfide (DMS). As long as the wort is boiling the SMM is converted to DMS and is boiled off. When you turn off the heat and the boiling stops, DMS begins to increase in the wort. If you cool quickly, the DMS created will be below the flavor threshold and the finished beer will not have a detectable amount. However, if the wort spends a long time between boiling and room temperature (where DMS production is virtually nil), then the DMS level will become excessive. This is the primary reason that cooling the wort quickly is important.

Another reason for chilling quickly is that it produces a better cold break, which is made of clumped protein-polyphenol complexes that begin to form as the the wort drops below 140*F. If you dont get a good cold break the protein remaining in the wort can later cause problems for the yeast during fermentation and contribute to haze in the finished beer.

The 2 references given for the above paragraphs:

Fix, G J, Principles of Brewing Science (Brewers Publications, Boulder, 1989), 142.

DeClerck, J., A Textbook Of Brewing, Vol. 1 (Chapman and Hall, London, 1957), 300.

I had always heard somewhere between 150-160 to stop SMM conversion. The only person I have heard say 140 was Jamil on BN shows, and I take everything that guys says with a grain of salt. It's good to note that Fix only mentioned 140 when referring to cold break.

Hmm did I say 60C was the conversion temp or that getting below 60C ensures no conversion is happening? Two different things. (Or was I just screwing up my C to F conversion like usual? )

Conversion happens around 70C. Rapid conversion happens around 80C. I've seen information that says the conversion of SMM to DMSO occurs "above 60C." (I'll put a link at the end of the post if I can find it.)

Keep in mind, 158F is not some magic number where conversion of SMM isn't happening anymore. Just like a lot of other brewing numbers, we're just picking the closest increment of 10C, in this case 70C.

I think you're fine if you can get the wort below 170F rapidly, then you keep cooling after that. Everything slows down and you'll be OK. However, to be certain that no DMSO is being formed, get below 60C (140F) and you're absolutely certain that no DMSO is being formed.

Brewing: science and practice - Google Books

Thanks for the link, good to see where the 140 number came from. I have never put that much thought into it because I always figured it good practice to chill your wort down as fast as possible. That way where ever the magical conversion stopping point is you will reach it as quickly as you are able anyway.

Yes, exactly. The point being chill the entire wort as quickly as possible. If you can't, make sure you go with an extended boil to eliminate as much SMM and DMSO as possible.

Ok, I have to ask. What about hop backs or whirlpooling. You are purposely keeping the wort at near boiling temps for 10-15 minutes before you start to cool.

Is this not much time in the grand scheme of things and as long as you can cool it quickly after that 10-15 minutes, your good?

I ask because I whirlpooled on my last 2 brews and haven't tasted the final product yet.

humann_brewing said:

Ok, I have to ask. What about hop backs or whirlpooling. You are purposely keeping the wort at near boiling temps for 10-15 minutes before you start to cool.

Is this not much time in the grand scheme of things and as long as you can cool it quickly after that 10-15 minutes, your good?

I ask because I whirlpooled on my last 2 brews and haven't tasted the final product yet.

Click to expand...

Two questions:

1. Did you use a lot of lager/Pilsner malt in your grain bill? If not, this shouldn't be a problem almost ever in ales-just lagers.

2. If you did use Pils malt, what are your last 2 brews and can you respond back here with your taste results when done? We can all learn from your experience.

ipscman said:

Two questions:

1. Did you use a lot of lager/Pilsner malt in your grain bill? If not, this shouldn't be a problem almost ever in ales-just lagers.

2. If you did use Pils malt, what are your last 2 brews and can you respond back here with your taste results when done? We can all learn from your experience.

Click to expand...

Last 2 brews were a Cali Common but no pilsner malt and a pretty standard Pale Ale malt bill with no Pilsner. I am fermenting with WLP810 SF lager yeast and stayed at the 57-58 low end of the recommended range.

I will still post back but I am optimistic that the results will be good. I tasted the Pale Ale this morning to see if the dry hop is done and it was mighty tasty.

jamilz said:

Hmm did I say 60C was the conversion temp or that getting below 60C ensures no conversion is happening? Two different things. (Or was I just screwing up my C to F conversion like usual? )

Conversion happens around 70C. Rapid conversion happens around 80C. I've seen information that says the conversion of SMM to DMSO occurs "above 60C." (I'll put a link at the end of the post if I can find it.)

Keep in mind, 158F is not some magic number where conversion of SMM isn't happening anymore. Just like a lot of other brewing numbers, we're just picking the closest increment of 10C, in this case 70C.

I think you're fine if you can get the wort below 170F rapidly, then you keep cooling after that. Everything slows down and you'll be OK. However, to be certain that no DMSO is being formed, get below 60C (140F) and you're absolutely certain that no DMSO is being formed.

Brewing: science and practice - Google Books

Click to expand...

First off I have learned much from Jamil's book and hundreds of hours of podcasts. Immense respect. and appreciation. Coming in second at this year's AHA is a profound feat for this two-time Ninkasi winner, who certainly has his plate full with lots of other commitments.

However, his reference to the formation of DMSO above 140*F is not particularly important in producing DMS as I understand it. Cf. Briggs, Brewing Science and Practice, DMS is our focus, not the much less important DMSO.

p. 165, "Surviving DMS, SMM and small amounts of DMSO reach the fermenter."

p. 546 "DMS can arise during fermentation to a limited extent from the reduction of DMSO."

In other words, DMSO is the least of our worries compared to SMM and conversion to DMS and the focus on 140*F (which is for DMSO) is misleading when attempting to reduce DMS formation from SMM.

SMM conversion and breakdown to DMS occurs at 80*C/176*F, a much higher temperature:

Hornsey, Brewing, p. 47 says, "...a significant breakdown [of SMM to DMS] will only occur at temperatures above 80*C (85*C seems to be optimum)."

p. 138 (referring to the boil), Bamforth, Tap Into the Art and Science of Brewing, says "...it's only when the temperature gets much above 80*C [176*F] that SMM breakdown occurs."

Lewis and Bamforth, Essays in Brewing Science agrees with the 80&C/176*F figure (p. 103)

In addition Hornsey, Brewing, p. 47 says "DMS has a boiling point of
37*C [99*F] and so is easy to remove during wort boiling." Thus volitization continues at a very low temperature indeed.

I bring it up for a couple of reasons. There seems to be an emphasis on ultra quick cooling below 140*F to reduce DMS. It seems that the correct figure is almost 40*F higher - 80*C/176*F. That matters for many without sophisticated cooling systems (e.g. ice in the sink or bathtub).

Since professional brewery (primarily making lagers, BTW) coolships, sedimentation tanks, and whirlpools all take a minimum of 30-60 minutes before cooling, is our focus on rapid cooling faster than that really important or has it become a solution to a problem that doesn't really exist? Papazian's dictum, "Relax, Have a homebrew" ???

Finally, for those interested in the no-chill method for lagers: You can use an immersion chiller or sink to cool hot wort in the kettle to below 176*F in seconds, do a whirlpool for 20-30 minutes, and transfer to the no-chill [O.K., LESS CHILL ;-) ] container having:

a) removed most of your hot break
b) eliminated conditions for significant SMM conversion to DMS
c) kept temps high enough to reduce bacterial growth maintaining a high pasteurization temp range.

Briggs, et. al. above, suggests the importance of keeping the temperature between 160*F to 180*F to reduce bacterial growth (pp. 319, 344). If you follow the commonly quoted 140*F threshold, you are getting below the pasteurization temperature which is also 140*F (De Clerck, A Textbook of Brewing, Vol. 1, p. 514) and increasing the liklihood of putting more bacteria into your no-low-chill container.

The oft mentioned 140*F doesn't refer to the greatly feared breakdown of SMM to DMS, but the formation of DMSO, a much lower priority that has confused the issue. For the purposes of DMS reduction and reduced bacterial growth, the temperature of 80*C/176*F should be the focus, not 60*C/140*F.

At least that's my understanding right now.

P.S. HOPS AND DMS: Briggs, Brewing Science and Practice, p. 693-4: "Late or dry hopping with whole hops will add as much as 15 ppb to the beer DMS level..." So pellets for late hopping with lagers addresses DMS as well.

As Jamil has said, there is no magic number, although I would think that the majority of homebrewers could almost as easily get their wort down to 140F as they could 176F (ok, maybe a FEW minutes longer).

The question still remains, how fast is fast enough?

It's all subjective IMO. Your sources indicate 176 is more of a concern than 140, but you also have to consider the amount of time it takes, and what volume of the wort is being cooled. Even if it takes 10 minutes for my CFC to chill the whole volume, half of that (actually more since the siphon is faster at the start of the transfer) is done in about 5 minutes. So only half of my volume takes 10 minutes, and then half of that is down in like 7.5 minutes...

This might be more valuable to those brewing with pilsner, or using the so-called "no-chill" method of brewing. Those who use a chiller are already likely chilling as much wort as they can, as fast as they can.