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skunkboy
01-17-2011, 10:46 PM
Anyone smelled/tasted diacetyl in mead before? Is DMS the only precursor for diacetyl, or maybe citric acid as well? Does DMS exist in fruit, like blackberries?

http://forum.northernbrewer.com/viewtopic.php?f=8&t=50603

Wondering because a blackberry mead at a recent club meeting had a diacetyl offtaste detected by a couple of other club members, I am begining to think that I can't detect this stuff very well...

akueck
01-18-2011, 12:40 AM
Unless I have been misled, diacetyl and DMS are unrelated. DMS is created by heat from SMM precursors in malt. Boiling will drive it off, and a 60-90 minute open rolling boil should be enough for most grists. Diacetyl is a natural by-product of yeast fermentation as it is one of the possible intermediate products on the way from sugar to ethanol. Yeast will usually clean it up after the sugar source is depleted.

Causes for excess diacetyl in beer include moving the beer off the yeast too soon and poor yeast health. The same could cause it in mead, though I haven't experienced it there myself. I have had acetlyaldehyde in mead for a few days during fermentation, but it also cleared up on its own.

DMS tastes like cooked corn, diacetyl like movie theater butter.

Medsen Fey
01-18-2011, 10:03 AM
Diacetyl also get produced by lactic acid bacteria (malolactic fermentation). In winemaking this can be very desirable such as in those nice buttery, barrel-aged chardonnay wines. They produce even more if sugar is available (but also produce VA in that case).

So it is possible that if you used fruit, you had some MLF occur causing more diacetyl.

skunkboy
01-18-2011, 08:20 PM
Unless I have been misled, diacetyl and DMS are unrelated.

Doh, yeah, my mistake on that... getting my off flavors confused again... ;-)