How to use this blog

This blog consists of pieces on various wine technology topics. These are sorted into Categories: Postmodern Winemaking, Natural Winemaking, Terroir, Alcohol Adjustment, Social Responsibility, and so forth. The Search function will bring up titles discussing your keyword: sulfites, micro-oxygenation, chips, allergens, fining, and reverse osmosis are rich in content. I also recommend the Postmodern Winemaking Calendar Mandala or the the Postmodern Winemaking Glossary which ties all the concepts of postmodern winemaking together.

Smoke Taint Treatment

Hi Clark:

I have a wine with smoke taint from a grass fire. What remedial treatments are available?  What is the efficacy, have you seen successful results on Pinot Noir?



Hi Dave,

Pinot Noir generally has little tannin structure, which in other wines can absorb and integrate smoke taint, so it’s particularly difficult to treat without losing the essential perfumes that make Pinot attractive, because the membranes required are much looser than those that can be used for removal of smaller molecules like ethanol and acetic acid and tend to strip mouthfeel and floral aromatics.

While the phenomenon is far from well understood, here’s the scuttlebutt.

Our reverse osmosis sublicensee David Wollan of WineNet Australia (now MemStar) first developed an offshoot of my patent to treat smoke taint.  We now know that it is a large complex of compounds and every fire is different, but guaiacol and 4-methyl guaiacol are used as an index.

In my invention, a tight RO membrane (around 80 daltons porosity) passes permeate containing pretty much just water, ethanol and acetic acid.  Ethanol can be removed by distillation and the water recombined, or VA can be removed by a resin and the alcohol/water solution recombined.

These membranes are too tight to pass smoke taint, so he employed looser ones in the 100 – 150 dalton range, running the permeate through activated charcoal and returning to the wine.  The looser the membrane, the more efficient the removal, but also the more you lose good stuff, particularly in a fragile wine like Pinot Noir.

It seems that in some treated wines, the taint recurs. It is believed that this happens if the taint elements are glucosylated, which it seems only happens early on, during the pre-veraison or immediately post-veraison cellular division time.   So if your grass fire happened in the fall, you might be okay.  If not, you might check with Peter Salamone at Laffort, who has been looking at glucosylase enzymes to hydrolyze the bound form.  I believe ETS can analyze for what you have.

Your toughest choice is who to trust your wine to.  There are four companies: WineSecrets, Winetech, VA Filtration, and Mavrik.  I have had good and bad experiences with all of them.

Direct fining with carbon can also be tried:

Additional reading:

California Pyra-noia in 2023

Noted columnist Dan Berger is writing a book on Cabernet Sauvignon, and he and I regularly discuss a common mental ailment among my winemaker colleagues that I call “pyra-noia,” a morbid fear of Cabernet varietal character and in particular, the bell pepper aroma attributed to 2-Isobutyl-3-methoxypyrazine, or IMBP.

The history of this ailment is interesting. Like Type 2 diabetes, it was nearly unknown until skyrocketing in the early 1980s in response to the quite high levels of bell pepper in plantings in the Salinas Valley in Monterey County. This is thought to have been related to the fruit shading caused by the high vigor of own-rooted, virus-free vines in a cool climate.  When in 2008 my panel at tasted 126 wines from this area, we found that the viticultural practices (canopy manipulation, leaf pulling, deficit irrigation) and  winemaking techniques (whole berry fermentation, flash détente) had completely eliminated the problem.

Yet the mental disorder remains, and has spread to Napa Valley, where common practice is to mask varietal and terroir character through excessive hang time, resulting in high alcohol raisiny, pruney wines that all taste the same at breathtaking prices that appeal to the unwashed rich.

The average brix in 1976 for Napa Cabernet was 22.9, resulting in legendary wines from BV, Mondavi, Clos Du Val, Souverain and Burgess with distinctive character and astonishing longevity, many still wondeful today, half a century after they were made.  Today’s “clown wines,” which are harvested at an average of 25.6 brix, not only lack character but fall apart in the cellar by five years of age, to me a betrayal to the consumer.

But Mother Nature seems this year to be on the side of folks like Dan and me.  The freakishly cool growing season is giving us full maturity at less than 23 brix.  It’s basically a French year, with low brix, low malates, rich fruit and low pHs, hastening picking due to the threat of rain and botrytis rot.  We are all going to make elegant, balanced, distinctive wines in 2023 whether we want to or not.

ETS Labs just sent out a hilarious article offering cold comfort to the pyranoid entitled Why is monitoring IBMP important this year?  In essence, it says that this will be a high varietal character year and there’s nothing to be done about it except to send samples to ETS to measure the extent of the calamity. Here’s yet another supplier promoting pyra-noia.

Join Dan and me in rejoicing.  Who knows — when Napa winemakers see how wonderful these wines will be, some of them might even decide to make them that way on purpose, as André Tchelistcheff smiles down from Heaven.

Dissolved Oxygen parameters for bulk wine shipping

Hi Clark,

What’s a good rule of thumb for O2 levels before filling tankers?



Hi Matt,

Short answer is, you’ll do well to get below 1 ppm, and 4 ppm is where most wineries panic and sparge w N2 upon receipt.  I hate this procedure, which strips volatiles, so let’s avoid pickup in the first place.

Let’s first talk about how you achieve this, then some debunking with theory.


Tips for loading a wine while minimizing DO pickup:

  1. Always ship full compartments if you can.  If multiple compartments, top the biggest one and go partial on the other smaller volume.
  2. Lay down a layer of inert gas approximately 1 foot high.  Calculate the number of standard cubic feet this will take by measuring the length and width of the compartment at its widest, for example 20’ long X 8’ wide x 1’ deep = 160 SCF.  The best way to lay down a layer is with pelletized dry ice.  This disperses in a small amount of wine, so it doesn’t boost your dissolved CO2 very much, and is still a good practice for reds.  One pound of dry ice converts to 30 SCF, so in this example, throw in 5-6 pounds. Next best is to deliver this gas in a laminar fashion through the sending line.
  3. Always inert the lines. Any gas will do, but the heavier than air  (CO2, Ar) are better blanketers. Go right through your centrifugal pump.  Any flow up to 1000 SCFH will lay laminar into the truck, creating a blanket because the gas is cold.  This layer will persist long enough for the pumping to occur.
  4. The best loading pumps are magnetic-driven closed housing centrifugals.  Your standard winery centrifugal has a spring-compressed carbon seal which sucks in air, especially if the seal has been scored by particulates.  If you have one of these, keep your seals ground smooth and replace your springs every year or two.
  5. If you have a partial tank, your blanket will disperse in transit, so you have to gas the headspace.  Laminar argon is best for this because it’s faster to deliver 1.25 volumes of argon than 4 volumes of N2 (see Argon, What A Gas).  CO2 may be used if you don’t mind the pickup.
  6. Measure, measure, measure.  Measure the wine in the tank at start and in the truck at finish.  Measure the top of the headspace as you evacuate with laminar flow.  Measure the DO upon arrival.


What is missing from all this standard dogma?  The simple question: “Why do you care?”  Big young reds will gobble up 4 ppm in a few hours, and often benefit from the experience.  A delicate Sauvignon Blanc, however, may be completely transformed by that amount of pickup.  Know your wines’ Oxygen Appetites, which vary 10,000-fold.  Yes, that’s a plug.  But as you well know, oxygen is not always the enemy.

The Basics About Acids


The same red wine shows the following chemistry in adjacent years:

’11 pH: 3.65 TA: 6.2 g/l
’12 pH: 3.45 TA: 5.9 g/l

How does the Total Acidity level AND the pH rise at the same time (since higher pH indicates less acidity)?



Dear Ron,

An acid is any dissolved substance that can release a proton.  Since the element hydrogen is just one proton with one electron in orbit around it, we also call this a hydrogen ion (H+).

The acids in wine are weak acids, which means they can dissociate a proton (HA –> H+ + A-) but can also take it back (HA <– H+ + A-).  We write these together as an equilibrium (HA <=> H+ + A-).

In juice, the two acids involved are tartaric, which is stronger, and malic, which is weaker.  This means that at any given pH, the tartaric acid will be more dissociated than the malic.  Both of these acids contain two acidic protons, so we write H2Ta and H2MA.

The titratable acidity (TA) measures how many dissociable protons there are without regard to whether they are actually dissociated or not at the moment.  In other words, the H’s on both sides of the equilibrium.  This is like the cops on the payroll.

We care about TA because it tells us how the wine tastes.  That’s because when we put wine in our mouth, our glands keep secreting basic saliva until the wine is neutralized completely.  That’s called a titration.  We get the sensation of sourness or tartness, and also the palate-cleansingness of all that saliva.

The pH measures only the free H+.  You can’t taste pH (only its effects, and only if you are very, very good).  But the free protons are the cops on the beat, out there fighting crime.  The pH determines all the chemistry and microbiology of the wine: how fast it ages, how prone to spoilage, how reactive with oxygen, how effective SO2 is – everything.  The sourness of TA has nothing to do with any of this.

pH is regrettably upside down. Higher free H+ means lower pH, because it’s really the negative exponent.  pH 3.0 means the ratio of water molecules to free H+ is 10-3, or one in a thousand, whole pH 4.0 means 10-4, or one in a ten thousand.

The A- parts left over when the H+ departs are called conjugate bases.  In juice, these will be tartrate (Ta2), bitartrate (HTa-), malate (Ma2) and bimalate (HMa-).  These can hook up with other positively charged elements besides hydrogen ions (H+), principally potassium (K+).

The wine’s resistance to pH change is its buffer capacity, which has to do with how much of these potassium salts are around, providing conjugate bases over and above what is paired with the available H+.  The effect of these is to pull protons away from the free pool we measure as pH.  If there’s a lot of buffer capacity, we will have a high concentration of K+ and a high pH even if our TA is also high.

The other thing that matters is the ratio of tartaric to malic.  A pure tartaric acid solution has a much lower pH (higher free H+) than a pure malic acid solution, thus the higher the tartrate component, the lower the pH.  When the pH and TA are both high and the potassium is low, the cause is high malic acid.

This happens in certain varieties like French Colombard, Petit Verdot and Norton.  It can also happen because of drought. Low soil moisture in winter causes early budbreak and grapes maturing too early in the season, when there is not enough time for the malic acid to be metabolized.

Hot weather can shrivel the grapes, causing the acid to be more concentrated and the TA to rise.  This has happened the last two years in California.

Think of the cops analogy.  If you have lots of cops on the payroll (high TA) but few on the street fighting crime (high pH), where are the cops?  They’re in the donut shops!  So either you have a whole lot of donut shops (high K+) or just a few very good Krispy Kreme donut shops full of cops (high malate).

More about pH and TA in my blog about acid adjustment.

If you have a real Jones for this kind of stuff, and for anyone wishing to enter winemaking, let me shamelessly plug my Fundamentals of Modern Wine Chemistry course, which tackles this as a foundation and goes on to address much of the stuff you really need to know from an Enology degree from Davis or Fresno.  There’s also a 500 page syllabus loaded with articles on a wide variety of practical winemaking topics, with the entire first 50 pages dedicated to pH and TA.

Why doesn’t tartaric acid addition lower my pH?

Hi Clark,

I have been working a blog post to the PA wine industry regarding how winemakers can deal with high potassium wines.  For the past few years, we’ve been dealing with wines that have an extremely high pH (4.0+) and usually the TA is low, too (<6.0 g/L).

Now, I’ve tried to make tartaric acid additions to these wines, but often, the TA will go up and the pH will hardly move.  Of course, then I am dealing with a high pH, high TA situation.  Ironically (or perhaps, no so), we have been getting more phone calls regarding high potassium levels in the vineyard or in harvested fruit, so I’m currently guessing many are dealing with high potassium situations.  I recalled that the use of ion exchange or ED may be applicable for high potassium wines to reduce the potassium concentrations and potentially alter the pH to a more reasonable level in the wine.  I’m contacting you to 1) see if this is the case, 2) if there are any great resources that you can recommend for winemakers to alter this problem in the cellar, and 3) if there are any companies on the eastern part of the U.S. that can offer these services (ion exchange, ED) to winemakers in the region?

Any help that you can provide will be GREATLY appreciated.  I’ve already referenced your book and few online articles that I have found regarding the situation.  Otherwise, I hope this harvest is treating you well.  Best, Denise Gardner, Penn State Enologist


Hi Denise,

How very fine to hear from you.  I am quite impressed with the program you’ve put together and read your weekly blog updates with relish.

Your question involves a basic tricky problem which confronts winemakers all the time.  They often report adding tartaric acid to no effect.  This is an illusion.  No need for IX or ED technology – the solution is easy once you understand what’s going on.  This is the first thig I deal with in Fundamentals of Modern Wine Chemistry and it takes a while to explain.  Let me try.

Tartaric acid has the following dissociation equilibria:

H2Ta  <=>  H+  +  HTa-  <=>  2H+  +  Ta2– , with pKas of 3.0 and 4.2.  The bitartrate curve (HTa-) peaks at pH 3.6 and is rather low at pH 4.0.

Let’s break these down into the two separate equilibria:

Eq1:    H2Ta  <=>  H+  +  HTa-               pKa = 3.0

Eq2:    H+  +  HTa-  <=>  2H+  +  Ta2–   pKa = 4.2

In the normal case, K+ has been exchanged for H+ so you have a lot of bitartrate buffer but K+ is the counter ion.  This combination should precipitate as KHTa, but it doesn’t because the pH is so high that much of it is in the TA2 form.

Now think about what happens when you add a little more tartaric acid (H2Ta).  Say you add 1.0 gm/L.  Initially, the pH will shift down, but you have a lot of buffer present, so maybe you get to 3.85.  Now you have a even more tartrate present and a higher percentage in the bitartrate form, plus lots of K+, so you get a precipitation.

Since you’re lowering the TA by removing a titratable proton (in KHTa), the TA comes back down.  At the same time, you are removing material from the left side of Eq2.   Mass action will make this equilibrium shift to the left to compensate like any buffer.

Notice that this decreases the free H+ from 2 to 1.  A decrease in H+ is the same as an increase in pH. Net effect is that your TA goes down and your pH goes up.  It’s entirely possible to end up back where you started.

Now Eq1 mass action would make your pH go DOWN, but it only operates strongly at low pH.  In sum, when you cold stabilize (precipitate KHTa) above 3.6, your pH goes up.  If you start below 3.6, your pH goes down.  Magic.

So basically, your problem is that you aren’t adding enough tartaric.  Because you chickened out and added less tartaric than you need, you think nothing happened. But that’s not true, because you have removed a lot of potassium.  You just need to keep going.

Generally speaking, the right addition is to 3.6.  At this pH, you get the maximum KHTa precipitation and no pH shift.

Note:  If the TA is higher, sometimes the cause is high malate rather than high K+.  In that case, double salt (aided by crossflow clarification) or a malic-loving yeast is the solution pre-fermentation, or ED afterwards.  But always test first by correcting a sample to pH 3.6 with tartaric and doing an overnight freeze/thaw.

Let me know if this needs further clarification.

Winery Water Bandits


Took your course at UCD, discovered then that we overlapped at college.

I am a Cab grower for a high end Napa winery, 10 years.  We are re-negotiating price, and I am advocating a higher price because they want very ripe fruit, 28-9 Brix.  Obviously this reduces my yield.  Are they getting more wine by adding water to the must, or is there another way to ferment dry at high Brix?




Dear Fred,

As you suspected, you are being robbed.  Gives new meaning to the term “stick-up.”

There are a lot of reasons why winemakers do this.  Many are paranoid about vegetal characters from pyrazines (we call it “pyranoia”), and other just want highly impactful and fruity (raisiny) aromas.  These “clown wines” age very poorly, and I consider them a betrayal of consumer trust, but they are very popular today with the ignorant rich, especially the affluent Chinese, who are very new to this game but surely will wise up soon.  I know $200/bottle producers who pick at 30 brix and then add sugar and high proof alcohol.  It’s a disgrace.  Hopefully the trend will pass.

In the pursuit of density, many winemakers believe their wines will be more concentrated at higher brix.  That seems to make sense if you don’t know how colloid chemistry and volatility work.  The elements critical to Cabernet quality, the color and tannin, are not soluble in solution and can only be extracted into copigmentation colloids – little balls of apolar goodge which are held together and stabilized by the driving force of water, i.e. the dielectric constant.  The higher the alcohol, the lower this driving force, and at 20% alcohol, there are no colloids at all.

The higher alcohol also suppresses aromas, partly because the esters and other aromatics in wine are hydrophobic but alcohol-soluble, thus increased in volatility by low alcohol solutions and decreased as the alcohol rises, and also because the trigeminal nerve irritation of the alcohol solvent masks aromas generally.

So in fact, lower alcohol wines have more extraction, more stable structure, greater longevity and fruitier aromas.  But some consumers just want a wallop of alcohol, some nice raisins and maybe some sugar.

Whatever. But they shouldn’t be robbing you in the process.  You should negotiate based on an agreed brix such as 24.5 (that’s still 15% alcohol) and make the winery pay a sugar bonus based on the shrinkage.  Being a work-crazed techie, you recognize that brix is a weight percentage, not volume, so build in your adjustments accordingly.

Here is a density table you can use. In shrinking from 24.5 to 29 brix, you should be compensated a bonus of 16.9% on the tons you delivered. The winery, if they diluted to 14.5, gained 40.5 gallons, so they ended up with 210.5 gallons wine instead of 170 GPT.

This doesn’t factor in the losses from unharvestable raisins and other losses such as bird damage, but it’s something. This calculation is for hand-picked fruit.  The loss for machine picked is 8% higher because of destemming.  If you like, I could help you complete a table to insert in your contract.

Turrentine Wine Brokerage likes to talk about the Manic/Depressive Wheel of Fortune that’s supposed to turn every eight years or so.  Unfortunately, the Growers were supposed to be on top starting in 2007, just when the recession hit and everybody started trimming inventory.  As a result, wineries have gotten used to screwing growers through the last 15 years.

But finally your turn has come.  Napa Cabernet is hot as a pistol.  You can pretty much name your price and terms.  Use this opportunity wisely.  Were I you, I would start by trying to get into a relationship that has long-term sanity and win-win prospects with some winery you like and trust.

If you want to stick with your current client, you are going to have to man-up.  Try this meditation.  Find a mirror to stand in front of, pretend you’re looking at your winery partner, and spend fifteen or twenty minutes telling them to go bugger themselves.  Then you can tone it down when you actually talk to them, but still have some fire in the belly.

Good luck!

Game changer for DTC shipping for small wineries

This sounds like an ad, but I swear I have no interest in VinoShipper other than to wish them success in freeing us from our chains.

I met recently with Steven Harrison of, who has, for eight years, been operating a DTC compliance and tracking tool which I think has become a real game changer.  VinoShipper’s strategy is to take title of wines, under their network of licenses and relationships.  This transfer effectively allows VinoShipper’s DTC licenses to be utilized in most states, obviating the need for individual wineries to obtain and maintain their own direct ship licenses, thus allowing wineries of all sizes to compliantly sell to many more states, with no investment from the wineries.

I was quite skeptical at first. Doesn’t Granholm vs Heald restrict itself to interstate shipment of wines produced by the shipping entity? But Steven pointed out the flaw in this thinking. What, exactly, is meant by “production?” Take a look at your monthly 702. In the Federal definition of wine production, the same wine can, on the monthly form can be produced by a dozen different actions: by fermentation, by sweetening, by blending, each over and over. The designation “produced and bottled by” requires 75% of the wine to be produced by fermentation on the premises, but this designation is in use on only a small minority of wines. Nothing Gallo bottles in its vast Modesto plant is fermented there, thus the flexible designation “Vinted and bottled by.” Wineries buy and sell bulk wine all the time and bottle it as their own, and there is even a lively trade in “shiners,” bottled unlabeled goods.

So where is the line? There are fifty different answers, buried in the licensing language drafted by fifty State legislatures, most of whom understand very little about winemaking law.

Steven’s approach is to review, for each State, exactly what the law states, and to comply with it. I spent three hours going over these individual strategies with Steven, and it sure looks like he has done his homework. A few important States remain where it seems a license must still be obtained, but one by one, he has worked out methodologies for most of the country.

The best news is, there is no installation or monthly recurring fee and he only charges 4.75%-8.75% plus a per-bottle fee for the service, and that includes full compliance, filing most State excise tax reports (that’s right – the winery doesn’t have to file), 3rd party age verification, merchant processing fees and more. No wonder over 500 wineries have joined.

Holding lees prior to addition

Hey Clark,

We have been using PM Winemaking as a topic of discussion. My crew tells me I’m post modern.

So … lees. If we don’t want them with some wine for a while, what do we do in the interim? Have you cleverly figured a system for storing lees? As a tiny producer options like freezing would work for me. I use freezers regularly, 55 gal drums are great for cryo- extraction.

Thanks for putting out the book, good food for thought.

Regards, Paul

Hi Paul,

Glad you are finding the book useful.

Lees can be left at the bottom of the tank or barrel, and do not cause trouble in young red wines unless they are stirred, in which case they will attack monomeric anthocyanins and lead to dryness.

Be sure to distinguish fine lees from gross lees, which should be racked off of at the earliest moment post fermentation. The fine lees are anything that moves.

Some wineries consolidate lees in bruts or drums. They will take care of themselves remarkably well if stirred each day with a paddle.  Sometimes an aeration bubbler is set up on a timer to kick up the lees every six hours or so.  The key is to prevent clear wine on the top.

Generally lees can be recombined after 100 days or so.  If you don’t have a spectrophotometer, just acidify 50 mls of the wine in a glass to pH 2.0 with sulfuric acid and compare with a glass of the unacidified wine.  When there is little or no change, your pigment polymerization is complete and it is safe to add lees back to coat the structure.


The Way Winemaking Is Supposed to Be

My favorite corollary of Murphy’s law is “Nothing is impossible for the guy who doesn’t have to do it himself.”  Today’s case in point, this time a person rather than a guy, is Sheila Donohue’s astonishing blog in which she touts the virtues of fiscal irresponsibility in the name of Natural Wine.  Check out…

These guys sound great. Yet I imagine that if you ask the Soccis if “not producing a vintage” is “the way winemaking is supposed to be,” they might just demur.

Surely even a fledgling blogger can communicate love for a family winery without attacking all the rest.

The plain fact is that the “many of today’s winemakers who strive to match the expectations of the mass market” constitute less than 1% of my colleagues who are working for the 250 or so national brands. They are good at what they do, and do not deserve Sheila scorn.  She should avoid their wines, as I do, when seeking anything beyond a standard beverage.

The other 99% of wineries make extremely small amounts of wines that strive for diversity and uniqueness in order to build personal connections with their tiny (often local) following.  They have to do this to survive, and they represent the vast majority of players, unless you restrict your shopping to Dean and Deluca.

If your winery is located in sunny Tuscany and your family has worked out the fine points over a thousand years, it’s easy to follow the practices of la dolce vita she describes, and Lord love them for it.

The real heroes, in my view, are the Mom and Pop in Des Moines who sold all but 3 acres of the family farm to Cargill ten years ago and are experimenting with a few hundred cases of La Crescent, Brianna and Marquette at 40 below zero, literally betting the farm on something that’s never been done before. This is the story of the 100 or so new wineries established in Iowa in the last decade.

Most U.S. States have similar untold stories. If they want to use a little technology to stay alive, I think the Lord will love them too. I hope Sheila will not wrinkle her nose and scoff at their efforts.