DMS
Term from the Brauwerkstatt brewing glossary, category “Faults and hygiene”.
Explanation
Dimethyl sulphide, smells of cooked corn or vegetables. It comes mainly from Pilsner malt and boils off, so boil vigorously without a lid for at least 60 minutes.
Test your knowledge
What does the off-flavour DMS smell like?
- Butter
- Cooked corn or vegetables
- Green apple
Show answer
Correct: Cooked corn or vegetables. DMS (dimethyl sulphide) comes mainly from pale malts. A vigorous, uncovered boil drives it off.
Why is the wort boiled?
- So that the yeast can grow
- To create alcohol
- To sterilise it, to get bitterness from the hops and to drive off unwanted compounds
Show answer
Correct: To sterilise it, to get bitterness from the hops and to drive off unwanted compounds. Boiling sterilises the wort, turns alpha acids into bitter iso-alpha acids and drives off DMS.
Why should the wort be chilled quickly after the boil?
- Less risk of infection and less DMS
- To make the hops more bitter
- To produce more alcohol
Show answer
Correct: Less risk of infection and less DMS. Warm wort is an ideal breeding ground for microbes, and as long as it stays hot, DMS keeps forming.