PDA

View Full Version : over attenuated. . . a lot.



laporterouge
08-20-2008, 09:15 PM
I was trying for a sweet blackberry mead.
My batch size was supposed to be 4 gallons, but since the thawed blackberries contributed lots of water I have about 5 gallons.

ingredients:
17.4 lbs of wildflower honey (I suspect that maybe the 3kg pails of honey I had may have had less than 3Kg. I don't have a scale)
13 lbs of frozen blackberries
Lalvin D-47 yeast 2 litre DME starter that was decanted prior to pitching.
OG: 1.122 (was hopping for 1.157)

Followed the stagered nutrient addition method as I read in BYO in July.
Managed the PH by adding a 5ml of acid reducer (potassium carbonate) after yeast pitch.

10 days of fermenting and my gravity is now 1.002, when my target was 1.035.
So I guess I will be back sweetening this batch a lot.

My questions are:

-Should I use some sorbate and sulfite now since I know for certain I do not want this to ferment any more?

-Why did I miss the mark so horribly? Was it the additional water that came from the frozen blackberries?


Thanks in advance for you time.

Medsen Fey
08-20-2008, 09:37 PM
Welcome to GotMead? laPorteRouge!

13 lbs of honey in a 5 gallon batch will be taken dry by just about any wine yeast. If you want it to remain sweet you need to either backsweeten, or to start with a high enough gravity to exceed the yeast's alcohol tolerance. In the case of D47 that is about 14% so you need a starting gravity a little above 1.110 for there to be residual sugar - this would typically be around 15lbs of honey (but your hydrometer will tell you for sure). To have it semi-sweet I would typically start at about 1.115, and for sweet 1.130. Obviously that would change with a different yeast.

In your case, 13 lbs would leave you sweet with 4 gallons, so I'm guessing that the extra volume is what threw it off. That is why it is so important to measure the starting gravity with the hydrometer - to make sure you are where you want to be.

An easy way to figure these things out is to use the GotMead Calculator. (http://www.gotmead.com/index.php?option=com_content&task=view&id=745&Itemid=16) It is a truly handy tool.

As for backsweetening, you will probably want to stabilize the mead with sorbate and sulfite before adding more honey as this will probably restart the fermentation otherwise.

Good Meading!
Medsen

wayneb
08-21-2008, 12:02 AM
Let me add my welcome, too!

Medsen, I think you misread the initial post. There are 13 lbs of blackberries in it, but there are also 17.4 lbs (give or take) of honey, and the total batch size is 5 gallons. From my quick calculations (albeit made under the influence of mead tonight :drunken_smilie: ), I think the starting gravity would be more like 1.135. If you measured it at 1.122, then I'm inclined to agree with your speculation, LaPorteRouge; either you used frozen berries that had a lot of extra water frozen with them, or your honey pails may have been not quite filled. It is always best to measure the quantities of your ingredients for yourself rather than trusting a commercial supplier's contents spec. Those nominal measurements can differ from reality by more than 10% in many cases.

In any event, this is a good starting point for a fruit melomel. If you fermented to dryness from the 1.122 starting gravity then you have almost 16% ABV. That exceeds where D47 would normally give up the ghost, even with proper rehydration and the best possible fermentation care. So you did nothing wrong; you merely had a great batch of yeast and you treated it perfectly well! ;)

Medsen's advice about backsweetening is absolutely correct, laPorteRouge. Even though at nearly 16% ABV odds are that all your D47 is kaput, I'd recommend that you add sulfite and sorbate if you want to absolutely ensure that no fermentation re-starts. It is always best to let the fermentation finish completely, and only then to add the sulfite and sorbate. They work well together to kill off residual yeast and to make sure that any surviving stragglers will never reproduce, but the chemicals often aren't enough to completely stop a robust fermentation in-process.

laporterouge
08-21-2008, 07:11 AM
Medsen read correctly. He responded while I was editing my first post. Thanks for both of your posts, I feel much better about my way forward.

wayneb
08-21-2008, 11:58 AM
Ahhh... that explains it. I was surprised -- he's usually even more of a stickler for detail than I am! ;D

Glad we could be of help!

Medsen Fey
08-21-2008, 07:58 PM
yeah, I'll stickle'er anytime, anywhere! :tongue1:
:sex:

Wolfie
08-22-2008, 12:12 AM
I agree with everything above, aside it's worth noting that some fruits may give a yeast an extra boost and push it beyond it's tolerance. The best I can figure is that there are additional nutrients in fruit as well as complex sugar and added turbidity.
I believe that Oskaar has a couple of Cysers with D-47 that end at %16 as well.

Welcome to Gotmead!