Mead Lover's Digest #1412 Wed 11 March 2009

Forum for Discussion of Mead Making and Consuming
Dick Dunn, Digest Janitor

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I'm sorry in advance for the long question, but I've done a lot of up front
work to try to answer this question myself, and it's starting to look like
*nobody* really knows the answer here.

This evening, I racked a 5 gallon batch of maple mead from the primary into a
carboy. This batch started with 6 lbs medium amber grade A maple syrup, 2 1/2
lbs buckwheat honey, 6 1/2 lbs light clover honey.

The OG was exactly 1.120, which was my target, so I was pretty happy to have
it land right there. This was taken after warming (no more than 130 degrees
F) and mixing, then giving the must a night to "set". I then mixed it well
(not worrying about aeration yet) and checked the gravity before pitching and
churning.

This evening marked 15 days of activity, and 2 days after the real slowdown.
I tested the gravity and found it to be exactly 1.010, which gives a gravity
variance of -0.110. Now to figure out ABV.

There are a lot of calculators online, including rooftop, gotmead, and a half
dozen others – all impressive enough in their own right. But out of about 6
different methods, no two seem to agree.

The question is how do I *really* calculate ABV from the gravity variance?
According to Schramm, 1 lb of honey gives a gravity increase of 0.008 to a 5
gallon batch. I've found this to be pretty accurate. He also says that that
1 lb honey will give a potential of 1% in alcohol. By that formula, I've got
13.75% ABV.

My hydrometer shows the 1.120 SG point is almost exactly 16% potential, where
1.010 is almost exactly 1.25% potential, giving 14.75% ABV.

If I run through Charlie Papazian's formula, I multiply the variance by 105
for 11.55% ABW, then multiplying that by 1.25 for 14.43% ABV. I seem to
remember somewhere else said multiply by 131 to get ABV, where Charlie's
formula is actually multiplying by 131.25. That's close, anyway – and is
actually very close to the calculator at
http://www.angelfire.com/wi3/johnsons/abv1.html. In fact, this is the only
two methods I've found that even remotely agree.

According to the online calculators, I've got somewhere between 14.44% and
16%. The one on gotmead suggests I have 15.37% – arrived at by subtracting
the potential for 1.010 from that for 1.120.

I've also found elsewhere (can't remember where just now) that it is actually
0.00753 in gravity variance for a 5 gallon batch that gives 1% ABV, which
suggests just over 14.6% ABV.

So, now the kicker: The yeast I've used here is Lalvin D-47. The info sheet
from Lalvin says this yeast has a typical ABV tolerance of "up to 14%" (though
some folks claim it is a 15% yeast). Now I realize this is only "typical" and
it is entirely possible to push the envelope here, but this only just slowed
down 2 days ago, and was still showing a little activity. Surely it should
just be approaching it's tolerance?

I'm confused: do I have 13.75%? 16%? Something in between? What's the "real"
magic number to use for a 5 gallon batch? And who's the authority on this?

I'm aware this is far less important than actually enjoying the stuff (and I
*was* surprised how good it tastes), but hey, I'm a numbers guy, so …

Thank you all

Lou

End of Mead Lover's Digest #1412