High jinx with high brix

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BarrelMonkey

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I thought I would post this to share my experience of this year's harvest, and also to hopefully start some discussion around the best way to go about pre-fermentation adjustments when brix comes in a bit (or a lot!) high. I have followed with interest @NorCal's thread on making petit syrah from high brix grapes, and I'm sure there are others out there with similar experiences.

This year I bought a 1/2 ton of pinot noir; it was a weird ripening year and, long story short, my grapes came in at 27.5 brix. pH was 3.59 and TA 0.64%, which seemed in an acceptable range given that (based on starting brix) I was heading towards making a 'bigger' style of pinot noir.

A note about sample preparation and measurement: for pre-fermentation measurements using a refractometer I took a scoop of grapes + juice and blenderized it before straining/filtering and measuring. (Centrifugation would have been ideal, but I didn't have access to a suitable sample centrifuge). I think this is particularly important in high brix/later-harvest samples; if there are dessicated/raisiny grapes, they are likely to have a substantial fraction of sugar bound up in them which will not register in a pure juice sample - more on this later.

Day 1: destemmed and added 30ppm SO2, left to cold soak for 2 days
Day 2: Brix = 27.5 (blenderized sample, refractometer)
Day 3: With a goal of 24.5 brix (14.7% potential alcohol) I figured I would want to add ~30L of water (with 6g/L tartaric acid to maintain pH level). Wanting to be conservative, I started out with 25L. After thorough mixing, and taking another blenderized/filtered sample, I had brix = 24.0 (by refractometer). Notably, brix from juice alone was just 22.5 at this stage (refractometer and hydrometer). I also submitted a sample for lab analysis of glucose-fructose, which should give a more accurate measure of fermentable sugars and hence potential alcohol. This came back as 258g/L, which is high; using the most widely accepted conversion factor of 16.8, it gives a whopping 15.3% alcohol (though the exact value depends on various things including yeast strain and could be higher or lower). I pitched my yeast today (but before I received the Glu-Fru lab results). I was worried about ending up with a stuck ferment since my yeast of choice (AMH) craps out above ~15%.
Day 4: Brix (juice alone) = 24.5 by hydrometer! Clearly grapes are still soaking up and releasing sugar into the juice. AMH yeast is known for having a long lag phase and while there were signs of bubbles, no overt fermentation. I decided to bump up the water again, adding another 12L with 6g/L tartaric. After thorough mixing, I measured 22.5 brix by hydrometer. Had I overdone it?
Day 5: Brix (juice alone) = 24.5 by hydrometer! Cap starting to form but still no temperature rise. I decided at this point to leave it alone and call my starting brix as 24.5
Day 6: Brix (juice alone) = 20.5. Temperature rising so we are off to the races. I'm hoping that, even if my potential alcohol is still a bit high, I will be able to reduce it by (a) having a high surface area in my primary fermenter (1/2 ton macro bin) and (b) frequent aeration (punching down 2x/day). Plus the bin is now outside and the weather is getting hot again, so I hope that will blow off some alcohol too.

This was quite the adventure and a learning experience for me. I'd be curious to hear how others have approached this sort of challenge, and I'll update on my final brix reading when my ferment is done, hopefully within the next 4-5 days.
 

CDrew

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High brix all over California this year!

I picked a 27 brix Primitivo this last weekend. Sulfited to 30ppm in the vineyard. I watered back with a total of 8L acidulated water. It's in 3 Brutes with pH range from 3.48-3.65. EX-V enzyme. I was shooting for 25 brix and hit 24.5 (I do have a 20-30 brix hydrometer so this number is accurate). Fermenting with a yeast that is known to tolerate 17% alcohol (Bravo). My lag phase was only 12 hours. Don't know if good or bad, but it is what it is. Tuesday evening, 72 hours post pitching I was at 15 brix and vigorously fermenting.

I have to say that 5 days without fermentation would make me nervous. Regarding alcohol levels, I've come up about 1% short of theoretical max (measured by LWL), likely due to evaporation (that's a guess).
 

Boatboy24

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Hearing all these crazy high brix reports is making me want to order more tartaric acid, just to be sure I can water back sufficiently. I may pay through the nose for shipping, but better safe than sorry, I guess.
 

Steve_M

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This year I measured 26 Brix. Blend of Cab Sauv, Cab Franc, Merlot and Petit Syrah. Leaving it alone, Ph was 3.47. TA not sure, forgot to order new batch of chemicals to test so reading I got was low at only 5.1 g/l. Will test/adjust post MLF. Definitely the highest starting Brix I have had.
 

BarrelMonkey

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This year I measured 26 Brix. Blend of Cab Sauv, Cab Franc, Merlot and Petit Syrah. Leaving it alone, Ph was 3.47. TA not sure, forgot to order new batch of chemicals to test so reading I got was low at only 5.1 g/l. Will test/adjust post MLF. Definitely the highest starting Brix I have had.
Yeah, I'd probably leave it as is with those numbers and those varietals. Hope the fermentation goes well, what yeast are you using?

My pinot noir went negative brix today so I'm hopeful that I'm going to ferment to dryness... 👍
 

CDrew

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A friend of mine(owner of the vineyard), who picked the same 27 brix Primitivo that I did, on the same day, and did not water back. He used RP15 yeast which can tolerate a high alcohol finish. But my 24.5 brix watered back fermentation with Bravo is done, in fact, I racked off the gross lees today, so I'm done plus 2 days! He's still at 15 brix and chugging along. It's been an interesting year, and my guess is this year will teach us a lot about high brix fermentation. I'm comfortable now with acidulated water additions and pH corrections. I can't detect any dilution of flavor in the finished wine, despite an 8L(2 gallon) water correction out of 25 gallons . The real lesson is that having several pounds of tartaric acid on hand before harvest is a good idea. My Syrah took 12 days to go dry, not sure why. That's long for me. The Primitivo took 7. But I racked 46 gallons total of new wine today, so pretty happy. It's time to complete MLF.
 

Chuck Rairdan

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Several fermentations this year in the 25 Brix range. A Tannat finished dry in a little over a week, while a Teroldego started at the same time is at about 10 Brix a week and a half along, still chugging steady. Both were innoculated with VRB yeast. A old vine Carignane is finishing at a little over a week while a Cab is at 10 at about a week. I'm thinking one of the main factors explaining this is the available nitrogen and other nutrients naturally available in the grapes. I add Fermaid O as directed and monitor for fermentation speed and sulfur odors along the way, although the Teroldego had a very low available nitrogen level at harvest. A question I have is, if the primary is taking longer than expected, how long generally is it okay to leave the fermenting wine on the skins before pressing? I've seen no longer than 7 days as a rule of thumb.
 

Steve_M

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Yeah, I'd probably leave it as is with those numbers and those varietals. Hope the fermentation goes well, what yeast are you using?

My pinot noir went negative brix today so I'm hopeful that I'm going to ferment to dryness... 👍
This year we switched from using BM4X4, to BDX.
 

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