View Full Version : An observation on yeast nutrient and potassium carbonate

03-13-2014, 07:17 PM
Recently I noticed a very odd smell and taste in my must after attempting to restart a stuck fermentation as reported here (http://www.gotmead.com/forum/showthread.php/22772-Stuck-Fermentation) in an earlier thread. While re-acclimatising the yeast in a sample taken from my must I added potassium carbonate. The smell that suddenly arose from the must was of what I can only describe as peroxide. However, as I found that the peroxide smell coming from the sample dissipated and the yeast appeared to be doing fine, I added it to the main 1 gallon batch and forgot about it.

Having recently tasted my must, which is still peroxide smell free, I have noticed a very strange bitterness. I reported this on the previous thread and Wayneb advised that he thought it was just the taste of the new yeast doing their thing, but it got me thinking about the peroxide smell again and I want to make sure that I didn't have a bad batch of potassium that's contaminated my mead.

To eliminate or confirm my theory, I mixed the K2CO3 with honey, apple juice and water: No peroxide smell. I then added a 1/4 teaspoon of vinclasse yeast nutrient to the mix which caused the solution to fizz and give off an acrid peroxide smell; it appears that K2CO3 and yeast nutrient react in this very peculiar manner. The solution was also very bitter to the taste. I tried this with just water, K2COS and the nutrient and got the same result.

I'm hoping that eventually the bitterness will fade as the yeast continue to use the nutrient and K2CO3 or through aging but I'm worried that the reaction has caused irreversible damage to my mead. In any case, are there any chemists out there who know what the reaction was that occurred?

03-14-2014, 01:54 AM
Well not knowing what peroxide might smell like (not routinely used/available except in small quantity - cosmetic etc), I can only conclude that its more likely nucleation of carbonic acid as gaseous CO2. Which is known phenomena.

I haven't noticed the bitterness you allude to, but given some of the materials used in nutient/energiser type products, it wouldn't surprise me to know that some have a bitter taste.

Plus I wouldn't directly taste potassium carbonate/Bicarbonate......

03-14-2014, 07:42 AM
The place i remember having a strrong peroxide smell was a womans hair salon, from the dye used to color hair. A 3% peroxide solution has no odor i can detect

Sent from Arthur Dent's towel smothering a volume of Vogon poetry, some of which just leaked out.

Kansas Mead
03-14-2014, 09:57 AM
I once tasted yeast nutrient it was very bitter. So it could have been the nutrient you were tasting.

05-08-2014, 11:11 PM
OK, I know that this is WAY late...

Potassium (the K in K2CO3) has a very bitter taste/after-taste to us humans and free potassium could be accounting for the bitter taste. This potassium will more than likely be metabolized by the yeast at it is one of their major nutrients and should not show in the finished product...