Mead Stuck Fermentation

Question

So, I made a 5 gallon batch of mead on 10Apr2015. I used 17 lbs of pasteurized clover honey and 4 gallon of spring water (no-boil method). OG = 1.130. I used D47 Lalvin yeast (3 packs) with 1/4 tsps of Ferm K and 1/2 tsp of DAP 4 times in the first 3 days. Temperature is pretty stable at 68-70F.

I as planning to add some strawberries at G=1.050 (ABV~10%) to make it a melomel, but...

After 7 days of strong fermentation it stuck around 1.090. It took 3 weeks to move it from 1.090 to 1.060. After that I racked the mead into a clean new bucket and re-pitched another packet of D47... No changes. The gravity is dropping by 0.002 per day at best... Right now it is on 1.050 and I am planning to add some frozen strawberries (5-7 lbs)...

Is it normal? Would adding berries boost the fermentation? I want to drop it at least to 1.025. Should I increase the temperature to speed up the process? I'm afraid that it will stop at 1.035-40 or something. Could it be because of the honey? I haven't had any issues with my other meads. Usually I have to manually stop the fermentation at 1.010-15 before it dries out.

Any suggestions?

UPDATE (8 May 2015):

It's been 3 days since added 1tbs of yeast energizer (mix) yeasts, 1tsp of potassium carbonate and 7 lbs of frozen Wild Blueberries (that's how much space I had left in my carboy). For the last 2 days it's been fermenting like crazy. Previously I had bubbles going through airlock one per minute. Now I actually had to get a blow-off tube, because it is bubbling every 2 seconds. Maybe there is hope after all :)

You know what... since I restarted this mead on the Star Wars Day (May the 4th), I'll call it "the New Hope". :)

Answer 1

So, first things first, 1.130 is a pretty high starting gravity for some yeasts, and can cause some additional yeast stress, unless you are diligent with nutrients and your yeast is hearty enough to handle it. I'm not saying that this is necessarily a problem for D47, but its something to consider. The more work you expect the yeast to do, the more help you need to give it. If you want it to finish sweet, most meadmakers around the web recommend fermenting 100% dry and then backsweetening to the desired gravity. That way, the yeast can operate within a comfortable range, and you have more control over the final outcome.

Next, for five gallons, those nutrients seem pretty low. 1/4 tsp DAP and 1/2 tsp Fermaid K 4 times is about 1 tsp DAP and 2 tsp Fermaid K for a five gallon batch (3 tsp total). Typically, you'll see about 3/4 tsp DAP and 1.5 tsp Fermaid K for one gallon (2.25 tsp). If you scale that up to five, that would be about 11.25 tsp, which is almost 4 times what you used for your batch. Most likely, your yeast is nutrient starved. Right now, you're sitting at about 62% of the sugars consumed, but your yeast has done about 73% of its potential workload. If you didn't provide enough nutrition, then your yeast will have nothing to help it reach the end and will begin to slow down substantially. Adding berries will provide some more nutrients for the yeast, so you could see it pick back up a bit, but it also adds more sugar. If you add berries, I'd add some more nutrients as well.

Finally, did you do anything to buffer the pH? Typically this is done with some small additions of either potassium carbonate or potassium bicarbonate up front. Some will say this in not necessary, but if your pH drops too much during fermentation (and it will drop), then your yeast can start to throw off-flavors or stall out. Degassing during primary to get rid of some of the dissolved CO2 will also help with this, as CO2 is acidic.

So at this point you can try:

• Adding additional nutrients (nutrients only, no oxygen at this point; berries might help a little)
• Degassing
• Raising the pH if your pH is close at or below 3.0

If you're really worried about it being stuck, though, you can pitch a packet of EC-1118. Restarting stuck fermentations is basically its job. It would probably take you 100% dry, sure, but you can always backsweeten.

It's worth noting, though, that as long as you're still seeing the gravity drop, the yeast are still working. Slowly, sure, but they're still at it. Racking was likely unnecessary, and just lowers the yeast cell count. Pitching additional D47 may or may not have done much.

Whatever you do, do not raise the temperature anymore. You're already sitting at the top of D47's temperature range, and increasing it anymore is just asking for it to start throwing off fusels.

For more info on current meadmaking techniques and some other possible ideas, check out this article on homebrewtalk.com:

http://www.homebrewtalk.com/current-mead-making-techniques.html

Answer 2

If I had a beer dropping 0.002 per day, I wouldn't call it stuck, I'd call it "nowhere near ready to bottle".

I don't make much mead, but I have had mead go about that slow and still finish dry. But it did take a while. Try adding more nutrients, that seems to be a standard procedure. And I think stirring up the yeast is an acceptable practice too.