Fermentation stopped

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winemaker81

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I purchased 180# each of west coast malbec, merlot, and zinfandel this fall. I inoculated with Red Star Premier Rouge and initial fermentation went as expected. I did a light press and have ~35 gallons of wine in carboys.

I started a 2nd run from the pomace of all 3 -- fermented as separate batches, using Wal-Mart brand sugar. When each batch dropped below 1.010 I did a light press to get 5 gallons of wine. All 3 went together into a 54 liter demijohn and a spare gallon.

I hard pressed the remaining pomace and got an addition 7 gallons, which I kept separate from the free run/light press.

The first runs are kept as varietals while the second runs are homogenized into 1.

Here's the oddity -- the first run wines all fermented down to 0.994 to 0.996, as expected. No problems here.

All containers of the second run fermented to 1.000 and stopped. I added EC-1118 to kick start the wines with no change. Temperature remained fairly stable so that doesn't appear to be the problem. Each of the containers is at least somewhat different -- demijohn is mostly malbec and merlot wtih some zin. The spare gallon is all zin. Of the hard press, the carboy is almost totally malbec and merlot, and the extra gallons are zin. Yet each fermented to exactly 1.000.

I brain stormed with guys at my local shop and the only thing we could think of was non-fermentable sugars.

So, does anyone have any idea if cheap sugar (Wal-Mart brand) has more unfermentable sugars in it than name brands, and does anyone have any other ideas regarding the source of the problem?

This is curiosity on my part. If the SG remains the same at bottling time I'm going to stabilize. Both the free run and hard press taste good for green wines so I'm fine with making no changes.
 

stickman

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The brand of sugar shouldn't matter. My first guess would be lack of nutrients if you didn't add any.
 

sour_grapes

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How do they taste? Do the second-run wines taste at all sweet?

Also, just curious how high you took the SG when mixing up the 2nd run wines?
 

winemaker81

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I wouldn't think the brand of sugar would matter, but figured it was worth asking, in case someone knows more about it than me.

I added 3 tsp Fermax to each of the 3 batches, then added another couple of tsp more when adding the EC-1118.

For each second run batch I added 5 gallons of water, 13 lb 4 oz sugar, tannin, acid blend, and fermax. Initially I added 10 lbs sugar to each batch, but the SG was around 1.050-1.054. After adding additional sugar, SG jumped to 1.075-1.078.

This surprised me, but I expected to get about 18 gallons initial post-press volume from the second run. When I got nearly 23, I realized there was far more juice left in the pomace than I realized. The sugar was diluted in far more liquid than expected.

The first run merlot & zin started at 1.110 (YOW!) and the malbec at 1.093. This is my first experience with west coast grapes. Previous experience is with NY Finger Lakes and NC grapes. The initial brix of CA grapes is an eye opener.

The second run has just a hint of sweetness to it. It might be fruitiness, but my palette says "sugar".

Here I'm thinking out loud (well, through my keyboard). 10# sugar should push 5 gallons of water up to 1.090. Yet I added an addition 1/3 of that to get the SG to ~1.075. Messing up the calculations, the mix includes a total 7 gallons of unpressed wine that is around 15% (average). Let's call that 2.5 gallons/batch.

This explains why I had to add so much sugar, as the water was diluted by 50% with a fairly hot wine.

Is this enough to push the wine up to a level that EC-1118 can't handle? It might. I'm have no idea how to do the math on that one.

Yet the wine does not taste that hot. I've made a few high alcohol wines and certainly have drank enough. The wine does not taste that hot. Which doesn't preclude me from being wrong.

I'm going to use a vinometer on my first runs to see what I get. If I have sugar in the second run, I won't get an accurate result, but I will try it anyway.
 

winemaker81

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This year I purchased 5 lugs each of 3 grapes. Next year I'm thinking I'll do 8 lugs each of 2 grapes.

I'll do another second run, but I'm thinking I'll do the free run/light press for the first run. Then press the heck out of the grapes, which goes into a separate batch). Then do a second run on the pomace. If nothing else, the math will be easier.

;-)
 

sour_grapes

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This explains why I had to add so much sugar, as the water was diluted by 50% with a fairly hot wine.

Is this enough to push the wine up to a level that EC-1118 can't handle? It might. I'm have no idea how to do the math on that one.
If I have done the math right, I have your 2nd-run wine at about 14.5% now (i.e., at SG=1.000).
 

winemaker81

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Paul, thanks for doing the math. At first blush it appeared that the second run had produced enough alcohol to exceed the limits of the EC-1118. However, even if I could not figure out the correct math, that did not appear to fit the facts. Even if your calculations are off a bit, that's still far short of the 18% the EC-1118 can produce.

This leaves me wondering why the wine did not ferment to dryness ... but as the wise old owl said, the world may never know. :)
 
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