Some believe in a cold soak, where you cool down the grapes (also called must) with dry ice to delay the start of the fermentation. Fermentation generally starts when the must warms up into the 65degree range. This does have some risk of creating volatile acidity (think a smell like nail polish), so you need to keep an eye on things. Another way people try to increase skin contact is to leave the skins and juice together post fermentation. The risk here is the alcohol can extract harsh, bitter tannins from the seeds.
So, after 12 days, fermentation was underway. My general protocol this year was to only do one hand punch down and to do a few "pump overs" per day. I didn't add yeast, so this was a native or natural fermentation. I also decided to not add any yeast food or nutrients or anything else to must.
A punch down is a fancy term for pushing the grapes down, back into the juice. During fermentation, the skins rise to the surface due to the creation of carbon dioxide, so you need to push the skins back down into the juice. The yeast that convert sugar into wonderful alcohol, need oxygen to do their job, so the punchdown also adds oxygen into the must.
A pump over is when you take juice from the bottom of the tank,and "pump it over" the top of the must. It was too much of a pain in the ass to clean and hook up a pump every night, so I just used a bucket to empty juice from the bottom valve and pour it over the top. I decided to give this a whirl when I read about this being done by several big name Burgundy houses. It also,gave me the benefit of being able mix up the juice, to even out the temperature in the must and mix in some oxygen. It's hard to keep the temperature even in the tank with so many whole clusters, because it makes it pretty damn hard to mix things around.
During fermentation, you keep track of the temperature and brix, which is a measure of how much sugar is left to ferment. You do this to make sure you don't get a stuck fermentation, which can have a real negative impact on the final wine (assuming you can get it unstuck).
Here we're the stats over my too brief seven day fermentation. This ended up being a pretty healthy fermentation to give you an idea of how it should go.
Sept 29th
Fermentation starts, temp still at 69 degrees
Sept - 30th
brix 23.5
pH 3.45
Temp 70 degrees
Oct 1
Brix 22.2
Temp 71 degrees
Oct 2
Brix 20.0
Temp 76 degrees
Oct 3
Brix 10.0
Temp 84 degrees
Oct 4
Brix 3.6
Temp 90 degrees
Oct 5
Brix 0
Temp 86 degrees
I was happy to see the temp peak at 90 degrees for a day, which isn't too hot for Pinot and gives me confidence that I will get a ton of the good stuff extracted from the skins. The highest I was able to get my Pinot to hit last year was 84 degrees. I think the difference was having more mass in the tank. Last year I only had about 250lbs of grapes, this year I had 400+. Good stuff.
The only thing I wasn't able to get was a reading on brix and pH pre fermentation. Generally it takes a few days of the juice to get to a point where you can get a real reading on both. I'm not too worried about it based on how well the fermentation went. The final wine will be what it will be and that is how I wanted it anyhow, as little human intervention as possible.
October 6th, I pressed the wine off, since brix hit zero. Zero here doesn't mean the wine was completely dry, you need the brix reading to be a negative number for complete dryness. I'd prefer to get the skins out the wine at this point to prevent extracting harsh tannins from the seeds.
Next post will be all about pressing and "barreling down"
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