Big problem with new batch!

[MrFightGuy]

I made a 6-gallon batch of mead on March 4th using 17 lbs of mostly clover honey. The only other ingredients I added were 1 tsp of energizer, 2 tsp. of nutrient, 3/4 tsp. of acid blend and a pinch of powdered grape tannin. I used Lalvin 71B-1122. It took two days for fermentation to really pick up, but after that it was smooth sailing.

Two and a half weeks out, I racked it, and it tasted fantastic! Fruity, full-bodied and light at the same time, just delightful!

One month out and my mead is developing an extremely chemical odor and and flavor. I wouldn't quite describe it as medicinal, more like paint thinner or rocket fuel. It smells like it would blow sky high if you lit a match over the airlock. Fermentation is still proceeding slowly, but the stuff's kinda revolting. Not toxic, but the few drops I tasted had to be choked down. This flavor/odor doesn't seem to be really matching the profile of the usual off-flavors and smells that people seem to get on this board. Any advice?


-Nathan

 

[Medsen Fey]

Hi MrFightGuy,

That does sound troubling. A couple of questions -
1. What temp are you keeping?
2. What was you starting gravity
3. What is the gravity now? Is it still dropping?
4. Can you check the pH?
5. What was the gravity when you racked?

You can get some paint thinner/nail polish from ethyl acetate (from acetic acid bacteria) but that seems unlikely if you still have fermentation going and CO2 being produced. There are contaminant yeasts such a Hanseniaspora that can compete with S. Cerevisiae and produce ethyl acetate along the way.

You may have a lot of fusel alcohols. It is likely that this is the result of some yeast stress - I get this with high temperature batches for example. Undernourished yeast could be a factor here, and I am curious if pH stress may be a factor.

Perhaps with a bit more detail, we can zero in on the cause.

Medsen