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Fermentation won't start

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M

Malkav

NewBee
Registered Member
Jun 22, 2010
2
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Hello everyone, I am a mead making enthusiast from Slovenia (Central Europe).

Yesterday I've made a simple hydromel batch:

1.8 kg acacia honey

15 raisins

1/4 tsp. generic yeast nutrient

enough spring water to bring the must to 4 litres (I'm going to ad 0.5 L after racking)

Lalvin/Uwaferm 71B

SG: 1.123

I have aerated the must by heavily shaking the carboy.

I rehydrated the yeast for 20 minutes in warm water (37-38°C) as recommended by the manufacturer.

The temperature of the must at pitching was 28-29°C.

The temperature in the basement is currently around 22°C

18 hours later is still see no action in the carboy. The only change that I noticed was that some of the raisins have floated to the surface (they have most probably absorbed some the water). And it seems like there's some white sediment forming in the bottom (yeast?), but I see no bubbles (neither in the carboy, nor in the airlock), nor do I detect any alcoholic smells.

About 12 hours ago I made a starter out of the yeast form the same packet (they only sell it in 100g bags), just to see if the yeast is alive, by putting a tsp of the yeast in some lukewarm apple juice (the real cloudy stuff bought from a farmer) and covering it. As farm as I know this should be yeast heaven, but after 10 hours with barely any signs of life, the yeast accumulates at the bottom each time after I stir it up. 2 hours ago I decided to put this starter into a warmish oven and now it has formed a little foam, but yeast still stays mostly at the bottom. At this point I decided to taste this starter and I detected something that could be start of a ferment and just a slightly fizzy effect on the tongue (but very weak). And I am now not even sure if it was my yeasties that did the job, or some kind of spontaneous ferment.

I checked the yeast package and it is almost two years old, and when I bought it yesterday I noticed that the store keeps them at room temperature.

So could it be that the yeasties or maybe most of them are already dead, or am I just paranoid?
 
C

ckbryant

NewBee
Registered Member
Jun 6, 2010
15
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0
Atlanta, Georgia, USA
I think you've probably identified the problem. I have read that dry yeast can lose half of its potency when stored at room temperature for a year. At two years old, your yeast is very suspect.

You're also putting it into a _very_ hard environment with so much honey. That much sugar can make for a difficult start. My experience has been that anything over 1.3 kg of honey in the batch size you are making, with similar procedures, can be difficult to get working.

I think your best bet would be fresher yeast...if that is not an option, you might consider diluting to 6 L total volume, aerating again, and re-pitching yeast (after hydration).
 
Medsen Fey

Medsen Fey

Fuselier since 2007
Premium Patron
May 23, 2007
9,004
53
48
Fusel Shack, in the swamp west of Ft. Lauderdale
Welcome to GotMead Malkav!

While the potency of the yeast definitely declines over time unless it is stored cold, I'll be surprised if yours doesn't work. It seems like the yeast you used in the apple juice started, and I expect your mead will as well. With 71B you can get sometimes get a very long lag phase (72 hours in some cases), so be patient with it, and continue to aerate it to allow maximal yeast growth.

Medsen
 
M

Malkav

NewBee
Registered Member
Jun 22, 2010
2
0
0
The mead is now fermenting very slowly, but now I'm thinking, if I should add 10 more raisins (cut), to help the yeasties.

I was a bit suspicious about SG (it was supposed to be a semi-sweet mead), but since, I lack the experience in this field I really didn't know what to expect, so I decided to trust my calculations. But now that think about it I see the most probable reason for such a high SG. I calculated the required amount of honey using the "5 gallons of must should contain 1 pound of honey per % of desired ABV". So I translated this equation into metric measures for a 5 L batch, but in the last minute I've found out that my carboy can hold about 4.5 L

So now I checked and found out that 1.123 is the average SG for a quality sweet late harvest dessert wine. So it seems like this is going to end up closer to a sack mead. (I know a few people who'll enjoy it, and I imagine that it will go along nicely with a nice cherry pie.) Lalvin recommends this yeast strain for (among other things) for late harvest wines and residual sugar wines, so in theory this yeast should be able to work in this environment. I'll also add some spring water after I rack and I hope that this should allow the remaining yeasties to eat up some more sugar.

So what would be the recommended SG for a semi-sweet or off-dry mead that would finish around 14%? And how should I calculate these things in the future?
 
P

Pewter_of_Deodar

NewBee
Registered Member
Sep 23, 2004
1,867
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68
Cedar Rapids, IA
With the combination of a high SG and a likely high pH, you have created a challenge for your two year old yeast. The slow fermentation is a good sign and will hopefully continue until the batch is done though it may be a long time.

Let the experts agree with me before you try it, but I would be tempted to add the juice from one lemon or orange to the must to bump the pH in the right direction. I did not notice anything in your recipe to add any significant acidity to the batch.
 
Medsen Fey

Medsen Fey

Fuselier since 2007
Premium Patron
May 23, 2007
9,004
53
48
Fusel Shack, in the swamp west of Ft. Lauderdale
I don't think you should have too much of a problem now that it is going. A gravity of 1.123 is not excessive for 71B, and if it ferments to completion you should end with a final gravity of around 1.015-1.020 which is nicely sweet, but certainly not syrupy. To help it get to completion, aerate it at least daily until the gravity gets down to about 1.090. You may also want to give it some more nutrient - at least 1/2 teaspoon (roughly 2.5 grams).

The pH of traditional meads sometimes drops too low (below 3.0) and I would not add acid that may worsen this tendency until the fermentation is complete. Adding orange juice (which usually has a good pH for fermentation) will provide some buffering which prevents pH drops, but it may add some orange aroma/flavor that you might not want. The pH of lemon juice is usually so low that it may exacerbate the potential for the fermentation to stick. Generally speaking, I find it better to add the acids after the yeast have finished fermenting.

If the pH does drop too low, the fermentation may get very slow after initially showing good activity. It is best to make adjustments to the pH after taking measurements, so it is a good idea to have (or to borrow) a pH meter or some pH test strips.

In some cases the pH does not create problems, and hopefully your fermentation will run to completion without delay.

Medsen
 
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