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Stuck fermentation

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jd_tighe

jd_tighe

NewBee
Registered Member
Feb 3, 2008
24
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Ontario
Hello everyone, I think have a very stuck fermentation and was wondering if anyone can help, this is my first mead attempt.

I started a 5 gallon batch of traditional mead back in November and racked to a carboy when it hit 1.020 after about 3 and a half weeks (Dec.03) and it quickly stopped fermentation and has stayed at 1.020 since then, this is quite a bit sweeter than I was hoping for. My recipe was as follows:

15.5lbs white clover honey
water to 5 gallons
2tsp yeast nutrient
1tsp yeast energizer
3tsp acid blend
lavin ICV-D47 yeast

O.G was 1.100

I added more energizer and nutrient after the fermentation had seemed to max out and a little more when I racked to the carboy. On Jan. 27 I re-pitched with a D-47 starter which I made with must, more honey, water, and about a tsp each of nutrient and energizer. I left the starter for a few hours and it started to bubble pretty good, but when I stirred it into the carboy all activity stopped, it's been a week and nothing at all is going on in there. Is there something I did wrong, maybe racked to soon? Is there anything I can do to salvage this batch?
 
Welcome to Got Mead?

Ok there are a couple of things here.

1. Stop adding acid up front. This is unnecessary and probably is what caused your sluggish/stopped ferment, in other words, check your ferment and echo back what the pH is in this thread.

2. I don't see any mention of aeration or supplemental nutrient dosing.

Also, we'll need some more information.

1. Are you aerating this ferment
2. How much yeast did you use
3. Did you add supplemental nutrient to the fermentation after the initial addition to the must.
4. Was this batch heated?
5. What is the ambient temperature?
6. What is the temperature of the must?
7. What does the must taste like?
8. Are there any mold colonies growing on the surface of the must
9. What were your expectations of this batch before you started?

Your original gravity should ferment out to about 15% ABV which puts you right at the alcohol limit for this yeast. I'm guessing your OG was a little higher (maybe 1.11x). So this batch should be about done, I wouldn't consider this stuck.

Cheers,

Oskaar
 
Hello and thanks for replying,

I don't have the things for a pH test, I was following directions that said the acid blend was for taste, I didn't realize that could stop a fermentation, good to know. I will have to pick up a pH test kit.

I was aerating the must in the primary several times a day but not since racking (unless you count stirring in the starter last week), for yeast I used 2 5 gram packets of D47.

Nutrient and energizer were added after the fermentation in the primary started to slow, and again at racking

No heater was used, but the containers are kept in a room with a pretty constant temperature of 22 C, which I think is about 72 F

There's no mold or off smells, the must is semi-clear and tastes fairly sweet, I was aiming for a semi-dry mead and expecting this batch to go a little lower with that OG. I was pretty certain of the 1.100 O.G but I guess I could have made a mistake. If its done I guess I'll just age it and enjoy a sweet mead instead.

Thanks for the help

Justin
 
Well I finally got to a brewing shop, all I could get there was an acidity test kit, one that uses a titration with a colour indicator. The problem is that it gives a result in grams of acid per litre, and it's been way too long since I took a chemistry course to translate that into a pH value. The kit gives desired values for red and white wine starting and finishing acid concentrations. My mead read 6 grams/litre of acid which seems within normal range for wines, but I'm not sure about mead. If anyone has any experience with this type of test I would appreciate any imput.

Regardless, I'm going to go on the assumption that if the acidity is at a normal starting concentration for wine, it probably wouldn't have inhibited fermentation. So I probably messed up on the OG or my calculations were off for ABV, and the fermentation is actually finished. After some further tasting my girlfriend and I have agreed that's it's drinkable and I'm sure aging will do wonders. With that in mind I am currently cooling it down to help it settle before racking it to a clean carboy for bulk aging.

One more thing, what calculation do you use to determine ABV?
 
Hello jd,

At the risk of going into a chemistry lecture, an Acid titration kit essentially measure the total acid including the acid molecules that are still attached to the H+ ions. The pH is a measure of the free H+ that are no longer attached to the acid molecule. The two do not necessarily go hand in hand - you can have wine that contains a lot of acid but the H+ is mostly bound, so the pH remains high. On the other hand you can have solutions that don't have a lot of buffers that can have relatively little total acid, and still have a lot of free H+ floating around which then gives a low pH (more acidic). Honey musts tend to fall into the latter category with little in the way of buffers, which is why it is usually not a good idea to do acid additions at the beginning of fermentation, because even small additions of acid may drop the pH down to a level where the yeast stall out (they generally like it best between 3.4-4.0). I would not make the assumption that if the titratable acid is similar to the level found in wines that the pH is okay for the yeast.

In mead making, monitoring the pH is probably more important so that you can insure that the yeast stay in their happy zone. I think it is well worth it to have a pH meter - it is my second favorite tool next to my hydrometer. Dan McFeely has a number of posts that address the unique issues and short-comings of acid titration kits with honey musts due to gluconic acid (and its lactone) being the prevalent acid in honey. Perhaps he will chime in to share more info, but if you do a forum search on gluconic acid, you'll find plenty.

Dan has also been kind enough to point out a link that really explains ABV calculation quite well. It is the root of all the short cut formulas you will find. Thanks Dan.

I hope this is helpful,

Medsen
 
Well that'll teach me to make assumptions, thank you for all the chem information.
I'll have to keep an eye out for a pH meter, do you mean the digital type with the electrode on the end, or is there a simpler/less expensive option? And I will definately not be useing acid pre-fermentation again.
Thank you also for the link, that was a very helpfull explanation.
 
Great, that's significantly cheaper then the ones I found when I googled "pH meter"

Thanks again for all your help :notworthy:

Justin
 
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