I have done a few kettle sours and in some cases, a wild yeast or heterofermentative bacteria ferments out quite a bit of the sugars. In the past, I've used DME to bring the gravity back up for the boil, but it would be good to have the option of just skipping the boil, however, there's way too much DMS in the wort at this point.

1 Answer 1


Yes there are sulphate-reducing bacteria. These are mostly found in marine biology. I don't know of any of these bacterium useful in brewing though (maybe just ignorant).

In your case DME will have low SMM and DMS, because it has already been mostly boiled out in proccesing. Though I would still do a short boil 5min boil and chill for sanitation.

Fun Facts Some yeast can convert DMSO into DMS.

DMS can be scrubbed with cO2.

DMS can be perseived with at very low levels.

DMS at high levels can smell and taste like shrimp / seafood water.

DMS has half life of 40 minutes at it's boil temp (99 21°F) so a 90 minute boil or wort usually is enough to get the levels below the detection threshold of most palets.

Once DMS turns into DMSO it can't be boiled off. Its boil temp is > than waters.

  • I'm not concerned about the DME, rather the existing wort has noticeable levels of DMS from the mash. It also has some alcohol content. If I boil it, I'll need to use the DME to bring the gravity back up to ferment.
    – Wyrmwood
    Jul 8, 2017 at 22:21
  • @Wyrmwood well if you boil the beer up the alcohol will be gone. But I was referring to boiling a DME solution and chilling, then adding that to your beer. Jul 8, 2017 at 22:24
  • Yeah, boiling just the DME doesn't do anything to reduce existing DMS levels though. I've either got to find an alternative to boiling to reduce DMS or add DME since the sugars are now much lower and fermentation will essentially be restarted.
    – Wyrmwood
    Jul 10, 2017 at 14:48

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