Stabilization and yeast tolerance - an anecdotal tale

[MightyMosin]

If you read through this forum you will periodically see posts that state that they don't want to use chemicals or why should I stabilize? There are a variety of members on here that pasteurize to avoid using additions and they do so very successfully; I believe there is a pinned post on the cider forum about how to do this. For myself, I use the K-Meta and K-Sorbate to stabilize the mead and to prevent further fermentation.

I started a mead on 03/16/2023 with SafAle S-04 yeast. This yeast is tolerant to 9-11% according to the manufacturer. After ~ two months it stopped at 1.004 SG with an estimated ABV of 13.65%. I wasn't surprised by this as I have previously used the ~11% yeast and have gone to 14%.
What I was a bit surprised by is that it didn't finish dry, but it was over tolerance.

I stabilized the mead with K-Meta but no Sorbate and I back sweetened it to 1.019 and left a comment in my notes that said "will fermentation start?". That mead has sat in the carboy for about 17 months since and I finally circled back to it as I'm trying to get a bunch finished out for the end of the year. I racked and checked it today. The pH was the same at 3.6 and the SG was sitting at 1.006. It had obviously started fermenting again once the condition (probably temperature) were more favorable to the yeast and it went through most of that added honey and then finally tapped out. It is now at a calculated 15.36%, but with the added honey volume I'll round that down to 15%.

None of this is new for me, but the takeaways from this:

• Published yeast tolerances are just rough guide lines and the yeast are horrible readers and if well fed they will go above and beyond for you.
• If you are trying to game where a yeast will stop based on published tolerances, be prepared to be disappointed in either direction of that tolerance, though it will usually exceed published tolerances based on my experience if you provide the nutrients that mead needs.
• I purposefully did not use K-Sorbate at the first racking as I was pretty sure that the yeast would start up again. If I had, it probably, but not assuredly, would have stopped where it was at.
• I've seen a few posts where some members have used only the K-Sorbate without the K-Meta; that is setting up the potential for bacteria that might use the sorbic acid as food and ruining your mead. Always use K-Meta if you will use K-Sorbate.
• If I had trusted that fermentation was done at that 1.004 and bottled without the use of K-Sorbate and only used the K-Meta, every single bottle would have exploded violently.
• At this point, even though I am confident that the yeast has tapped out at >15% ABV I am still using stabilizers as there is still sugar left there. I will almost certainly add some more honey in to back sweeten next week and those stabilizers are my long term insurance against a super yeast strain that might continue higher, even though unlikely at this point.
• Pick your poison for mead stability: ABV tolerance tap out, chemical stabilizers, or pasteurization... but pick one to use.

I use chemicals for stabilizing as ABV tolerance means three general paths: to take:

• A dry mead that has used all the honey up and you don't add any honey after. This can be any ABV. A nice dry traditional mead fits well here.
• A high ABV that has used all the honey it can and you can now back sweeten with honey to get the flavor you want. Not a bad approach, but I do enjoy the carbonated session meads that use honey as the sweetener. I also don't want all my meads to be a high ABV.
• A dry mead that used all the honey and you back sweeten with a non-fermentable sugar. A good approach but you have to find a sweetener that you enjoy. I want honey as my sweetener to help keep/enhance that aspect.

For myself, I haven't tried pasteurization. It it more work than I want to entertain at this point and I am leery of what those higher temperatures may do to the flavor, though I don't really know as I haven't done it yet.

 

[bernardsmith]

Here's the thing about yeast specs: They are very similar to the specs that manufactures of project critical hardware publish - think, chains, ladders, ropes, elevators, and the like. If a manufacturer states that the weight an elevatorr can take is 400 lbs, you KNOW that it MUST take more weight before it will break. BUT if you enter an elevator and te load is 401 lbs and it crashes 20 floors ... You and not the manufacturer is responsible. On the other hand, if you NEEDED that elevator to crash when it carried 450 lbs and it worked perfectly, again, you and not the manufacturer is to blame Labs are merely telling you the most conservative specs that THEY will take responsibility for when the yeast FAILS.
On another note, pasteurization, in my opinion is rarely if ever a good option. Sure, heat will kill the yeast, but it will also destroy volatile aromatics and flavor molecules, and you spent good money on honey and not table sugar for those aromatics and flavinoids. and that is the BEST scenario. The worst scenario is that the CO2 in bottles of mead will expand upon heating and unless the bottles are designed to withstand the pressure of that expanded gas, you may find that the heat creates bottle bombs. Here, the best case is that you lose only the contents of the bottles. Worst case, is that flying shards of exploding glass behave just like shrapnel.