Extended Maceration and Acidity

Does extended maceration lower acidity?

Whole cluster pressed red grapes for rose will have higher acidity (TA) than fermenting/macerating them ‘normally’ for red wine because of the potassium (potassium + tartaric acid = potassium bitartrate, which lowers acidity).

My question is…once a red fermentation is dry, is there any/enough potassium left in the skins to have any (meaningful) drop in the TA?

I’m assuming the answer to this will be either no (that the heat of fermentation has extracted all the potassium that’s going to come out of the skins, assuming a typical fermentation, e.g. cold soak + fermentation of ~2 weeks and a peak temp in the 80s)…or that it depends (i.e. EM might lower the TA, depending on the starting amt of potassium in the grapes, the heat of fermentation and many other factors). But maybe someone has thought about this and has a better answer?

I think the answer is yes, though I’m no kind of diploma having enologist. Based on the fact that even with extended maceration pre and post ferment free run has a lower ph than press and hard press has the highest pH. Leading me to believe there is still enough potassium left to effect pH in an upward direction. However I am not sure how TA would be effected changes. When you say acidity the TA and pH are related but not directly. With pH being the power of the acid on the solution and TA being the amount of acid in that soloution.

Ive heard burgundy winemakers say that extended maceration can “round the tannins”. I suspect that’s really is going on is that acid is being lowered and tannins are less sharp with less acid. I guess it could be tannins chaining up though.

And Eric, if you were a real man you would be adding potassium via stems.

I have herd the same and agree. The tannins could be chaining up but only if little to no so2 us used. Once a big hit of so2 is added polymerization slows/stops.

Well by this standard I guess I am a real man, thanks for that Berry. Lots of stems the last couple years as they are the best I have seen them drought related I would guess. All lots get some every year on my Pinot Noir.

Erick what kind to total time on skins are you looking for? I get 21-26(even up to 28) days on skins with no temperature control or adjustment. Just start with cold fruit, native ferment, and partial whole clusters in the bottom of my Tbins, and press at cap fall. Punch downs are 1 early and late 2 in the middle stages and 3 during peak.

I was just kidding with Eric. The root of the joke is that we both have pulled fruit from the same vineyard this year. He destemmed and I whole cluster foot stomped. It should be interesting to try the two wines side by side after they are bottled.

Thanks for the great responses/discussion/ideas!

Excellent point about the press wine pH…esp the hard press wine. Seems like a good answer to me!

I understand that TA and pH are loosely connected, since we’re dealing with weak acids. I believe going from tartaric to potassium bitartrate lowers the TA. This is because tartaric has two potential hydrogen ions (H+), where potassium bitartrate otoh I believe only has one potential H+ (pH measures the number of dissociated H+ currently in solution, TA measures (indirectly) the total number of potential H+ available). That might be incoherent…sorry. Anyways, I believe potassium bitartrate has a lower TA contribution than Tartaric does.

A bit of both your reasons makes sense to me Berry.

Hey, it’s all about what my babies (grapes) want to be when they grow up…not if I’m a real man or not :slight_smile:

Interesting, I didn’t realize that sulfur stops polymerization…any references where I can read up on that? I’d done a fair amount of reading on tannins, and the more I read, and it appears the more research folks do into tannins, the less I/we understand and more questions come up. I stopped reading about this a year or two ago, so might be behind the times (this is intended as a general comment on tannin understanding, not about sulfur and polymerization).

My fruit starts as cold as it comes in (i.e. is picked at)…ideally in the 50’s, but sometimes things conspire against that. I don’t use a huge amount of sulfur at the crusher, so I’m reluctant to chill fruit down much, if at all, below its picking temp. I ferment natively as well. Everything’s different of course, but usually ferments are dry or close to it by ~2 weeks. I suspect the air temps in my winery is a bit warmer than yours, which encourages things along.

It’s more that I’m curious about the impact of EM…rather than looking for a certain number of EM days, or total days on skins. That’ll vary depending from wine to wine and year to year…but I decide it based on past history with the wine/vineyard, how the wine tastes in the fermentor, the juice to skin ratio + others.

Definitely looking forward to that!

My head hurts from contemplating that chemistry. We do not actively pursue cold soak or do extended maceration. In at cool (7:00 a.m.) picking temps, into the destemmer, and into the tank.

We inoculate on day 2, rather than rely on native yeast. 9 days and we are “dry,” at 0. Day 11 are at -1.6 and sending a sample in for a complete lab. It seemed “still” to me this afternoon, but what do I know. Color is gorgeous - I will get a photo up over on Weather Thread.

I expect we will press on Wednesday and barrel on Thursday or Friday. 2 weeks, in and out.

+1. This makes me wonder if people favor uninoculated ferments because it means less sulfites leading to better polymerization. And they just naively attribute it to the yeast.

The mechanism here may be that SO2 scrubs up aldehydes, which are important (for reasons I don’t exactly remember at the moment) in building tannin-anthocyanin structures, which produce rounder tannins.

To be clear so2 at destemmer wont matter much as it binds so fast, not that I usually add any or if i do 10-20ppm. Though so2 post pressing to retain free during inoculated malo is pretty normal. Many malo strains can handle free so2. Thus other techniques ate used to soften/advance tannin development.

I prefer none of the above and keep an eye in va, malo completion and cellar temps (sub 60) during winter. If i can hear bubbles from bung hole popping (think rice krispies in milk) im ok with co2 keeping the wine safe.

Just read this in The Science of Wine, pg 140:

Oxygen reacts with anthocyanins and other phenolics present in the must, enhancing color stability and accelerating phenolic polymerization.

So it seems the lack of SO2 is allowing the oxygen to have more of an affect on the wine.