View Full Version : sour smell

10-12-2011, 03:06 PM
15# honey, water to five gallon, used lalvin k1v-1116, pasteurized honey in a gallon of water, added nutrient to the rest cooled, added honey to cooler water, stirred, constituted yeast and pitched.

the fermentation started by mourning and was violent, cleaned up the trap etc. let go, day two a sour smell was very strong, liked rotting apples.

after 4 days the smell has eased up considerable and the fermentation is still very strong,

has anyone had this happened before? will it clear up? did it ruin in that short period ?

There is nothing floating in it, looks like all the other batches I have made so far.

10-12-2011, 03:19 PM
You may have been smelling one (or both) of two things, acetaldehyde or acetic acid (vinegar acid). As we've discussed in other threads on the forum, acetic acid is produced in great quantities when acetobacter bacteria take up residence in an alcoholic liquid, and they will metabolize (eat) the alcohol and produce volatile acids (VA) such as acetic acid as a byproduct. Acetobacter require oxygen to survive, so if you have an acetobacter infection in your must it will show up as a slimy surface cap (called "vinegar mother" by the folks who intentionally make vinegar from wines) in your fermenter or aging carboy.

However, some yeast strains can also produce VA when subject to excessive stress during fermentation. In addition to the relatively small amounts of VA that yeast may produce, acetaldehyde is an intermediate byproduct of yeast's metabolism of sugars. Often (again most often during a stressed fermentation) the yeast don't complete the biochemical conversion of sugars all the way to ethanol at one time; they will instead form acetaldehyde as an intermediate step, and then later on (once all the sugars are gone) they'll go back and finish the conversion of that left over acetaldehyde to ethanol.

So, if you smell the familiar aroma of green apples along with the sour smell (which kind of sounds like what you are describing), then it is more likely than not that you are experiencing some acetaldehyde production in your fermenter. Especially since you describe a rather violent and quick ferment, I'd suspect acetaldehyde production first. The good news is that it will virtually vanish as fermentation finishes, once those yeast run out of sugars and start to hit the acetaldehyde as a secondary source of energy.

10-12-2011, 11:41 PM
Just out of curiosity (im a newbie meadie) how long did it take to start fermenting rapidly after pitching the yeast and all? Thanks.

10-13-2011, 05:42 PM
Just out of curiosity (im a newbie meadie) how long did it take to start fermenting rapidly after pitching the yeast and all? Thanks.

it was over night, and it was violent, pushed up through the trap, was a real mess

10-13-2011, 05:44 PM
out of five batches, only one that did that, same process on all, but used 1116

10-13-2011, 05:47 PM
as predicted by the mentor, the smell has tapered off to not noticeable day 4