Toward better wine science communication (and my PhD)

If you’re a winemaker, a vineyard manager or viticulturist, or in a similar role, and if you have ten minutes to help a PhD student gather some data (and improve the state of research communication in the wine industry), I’d be most grateful for your response to this survey on your feelings about winemaking and growing information and where you go to find it. Find the completely anonymous survey here: http://fluidsurveys.com/s/winescienceinformation/

How to replicate a wine from 1500 year-old grape seeds

How to replicate a 1500 year-old Negev wine: 

  1. Unearth 1500 year-old grape seeds from the famed Byzantine-era city Halutza. (Done; credit Israeli archaeologists.)
  2. Extract DNA; sequence. (This is the easy part.)
  3. Check sequence against known contemporary grape genomes (to infer evolutionary relationships, and to double-check that seeds really weren’t refuse from archeologist’s lunch before proceeding).
  4. Realize that DNA sequence from seeds doesn’t represent DNA sequence of original cultivated vines, because Vitis species are notoriously mutation-prone, Halutza vignerons would probably have worked with grafted vines and selected varieties the way we do now (cf. Theophrastus who wrote about grafting in Athens in the 3rd c. B.C.). Deal, because we can infer a lot about the parent vine from the seed DNA but the stuff we can’t infer can definitely change wine quality (cf. reason why every contemporary commercial grapevine is propagated by cutting and not from seed).
  5. Synthesize fresh, lab-manufactured DNA from the old sequence (there are companies for this).
  6. Get someone like Dr. Andy Walker at UC Davis to (get his grad students to) clone new DNA into grape stem cells.
  7. Plant lots of babies. Watch lots of them die. Wait.
  8. Try to find a climate similar to c. 500 AD Halutza for vine cultivation (consult archeological meteorologist?) Hope that soil types also have something in common, or try to replicate historically appropriate soil.
  9. Accept that since grapes are subject to lots of somatic mutations, the new grape vines may change a bit along the way and not be exactly like the original Negev wines. Keep dealing.
  10. Consult Dr. Patrick McGovern (biomolecular archaeologist specializing in fermented beverages; Dogfish Head collaborator/co-creator of Midas’s Touch, etc.; outstandingly nifty person) about mimicking historical winemaking. Do what he says.
  11. Hope that Dr. McGovern has advice on how to handle the problem of modern Saccharomyces cerevisiae being a darn sight different than whatever might have been around to ferment things in the Byzantine Negev.
  12. Option A: Backtrack 15-20 years and clone person using DNA from bones found at Halutza dig. Raise in a bubble (consult designers of The Truman Show) to mimic growing up in Byzantine Halutza. Make sure he doesn’t try any wine until the replicated stuff is ready, then get him to write tasting notes. Option B: Accept that even if we’ve perfectly replicated an ancient wine (see above caveats about genetic variation, yeast, etc), we won’t actually have replicated the wine because we, the drinkers, will be different, and the wine only fully exists in its drinking and enjoying via the participation of complex sensory and thinking apparatus attached to a subjective human being.
  13. Drink the darn wine anyway. Invite Robin Trento over to make dinner (ask her to bring her own garum). Look up retirement residence addresses for the journalists who were “ready for a taste of the Byzantine Empire’s favorite wine” back in 2015 and make sure they get a bottle.

Story and strategic choices in talking about Central Otago subregions

Central Otago went from zero to international recognition in less time than it takes to test the merit of a great Burgundy vintage. Good for them. It’s occupants had the advantage of a favorable climate, enthusiastic pioneers, and in many cases an enviable lot of capital investment, but they also experimented generously and — most importantly — became polished storytellers. The stories may in fact have outpaced the wines, which is less a criticism of the latter than an acknowledgement that they are very much still figuring out what they’re about. And so, while it’s obvious that subregional differences are dramatic enough to shout about, not much shouting actually happens on that account. One: they don’t yet have the maturity for more than broad subregional outlines. Two: it might not be part of the story they want to tell in any case.

Driving through Central makes it clear that subregional differences should be important. Driving in from coastal Otago (the Dunedin area, where I live), the first substantial growing area you encounter is Alexandra, a dry, flattish valley with a large (for this area) town. Cross the hill and drive past the dam and you’re in Cromwell, where many vineyards enjoy the mitigating effects of Lake Dunstan. North at the top of the lake, the Bendigo vineyards are widely known as seeing both the hottest and the most extreme weather. Go east toward Queenstown and the Bannockburn vineyards are perched above the Kawarau river. Through the pass further toward Queenstown, the Gibbston valley has the highest elevation and the coolest climate. And then there are the outliers: dear Nick Mills at Rippon in Wanaka; vineyards in Waitaki closer to the coast. These are obvious differences. Central Otago doesn’t tend toward subtle.

Plenty of conversation is happening about subregions, none of them questioning whether they’re significant. The questions instead are about what is significant. Are site differences principally related to soil differences as you move up the “terraces” from the valley floor? Or is the elevation more significant? Maybe it’s enough to talk about those big subregions. There’s that first problem: it’s hard to tell in part because vines are young, but maybe even more so for want of continuity. Vineyard managers, winemakers, owners, directions, and styles have flexed enough here that two challenges become significant: creating distinctly regional pictures independent of those other factors, and passing down sensibly kept records and knowledge gained from experience. The openness to experimentation and international flux that has helped these folk find a niche in the pinot world so quickly has, at least in some cases, come at the expense of some stability. Point the first.

Point the second: wine, and Central Otago, is all about story. Subregions may not be the story people want to tell here. Yet. Adept storytelling is a stand-out feature of many successful wineries here: to justify selling $70 pinot noir with nearly no history behind them, it has to be. Telling a story doesn’t mean talking about everything that goes into making a wine; it means carefully curating elements that create a specific image. Subregionality may not be part of that story. In some respects, that choice is about market readiness, which is obvious. They’ve succeeded when someone in Louisiana or Newcastle knows where Central Otago is; talking about Bannockburn is too much.

But it’s also a choice about style and direction. Some wineries here bottle from estate vineyards. Many blend fruit from different vineyards for balance and complexity and, no doubt, economy and ease. Matt Kramer told producers in 2013 that using many clones was (one; he had a few other interesting points) key to making exciting pinot noir, and it could be said that blending across multiple vineyard sites is similarly looking for complexity. As those vineyards age, and maybe as they’re planted with increasingly diverse clones, maybe

Back to choosing a story. Wineries here have mostly built their identities around concepts other than subregions. If that’s working for them, serious investment may not go into defining, refining, and emphasizing subregional stories.

Since differentiating yourself is ever necessarily the new world winery game, it makes sense that a (but not all) winery here is built expressly around exemplifying subregional differences. That’s Valli, where Grant Taylor bottles separate pinots from Gibbston, Bannockburn, and Waitaki. Tasting those three wines, made by the same winemaker in essentially the same ways, is an education that makes me wish Taylor’s portfolio included bottles from Bendigo and the other subregions as well. The Gibbston wine is the sharpest with the highest acidity, the Bannockburn the biggest and smokiest, the Waitaki the spiciest with the most prominent tannins. The Waitaki stands out to me as the most interesting wine, possibly because it’s the least standard and, dare I say, maybe the most complex: while the Gibbston and Bannockburn are well-made and enjoyable wines, the Waitaki has the thing that makes me want to keep coming back to the glass.

That’s the direction I hope Central Otago pinots take as they grow up: not just well-made wines with fancy labels and nice stories, but intriguing and maybe even intellectually satisfying wines. Whether they find that intrigue in multiple clones on single vineyard sites, blending across regions, or even just older vines under winemakers who decide to stay put, I’ll hope that Valli keeps doing what Valli does, and maybe more of it.

**By the by, “Central Otago” is a “district” within the “region” of Otago, where a “region” is roughly equivalent to a province or a state. Central Otago is a recognized Geographical Indication — it can be used on labels going to the EU, with a defined meaning — and various subregional names are allowed as “Appellations of Origin” on labels going to the States.

 

On Palate Press: why authenticity makes most of us hypocrites, and why globalism makes it worse

My Palate Press article for this month is about why wanting authentic wine makes most of us hypocrites. I’m not talking about preaching wines of place in public and then buying Cupcake when no one’s watching at the grocery store, though there’s that. I’m talking about saying that we want wine to taste of its place, probably even truly believing it, but then really wanting wine to taste like the stuff we’re accustomed to liking. Drinking wine you like is fine — more than fine, in fact — but we run into real problems trying to compare or rank (formally or informally) wines from around the world: some authentic wines will always be underprivileged because their authentic flavors either don’t look like the established gold standards or just aren’t as nice. it leaves you one of three choices. 1. Drop ideas about wine tasting authentically of its place and look for producers who are just trying to match the global gold standards. 2. Burn the democratic wine flag and accept that some wines are the poor and downtrodden. 3. Stop comparing wines from different regions and love each in its own special, unique way. The argument in more detail, and with a cute dog picture, is here.

Studying sulfur dioxide effects with better DNA technology suggests we may not need much of it

Fast: In a new study using better-than-ever microbiology, 25 mg/L SO2 added after pressing was enough to “stabilize” yeast and bacterial growth during fermentation, and higher concentrations actually seemed to slow fermentation. Inoculating the must with commercial S. cerevisiae had a very similar effect, even without adding SO2, which looks really, really good for no-added-sulfur wines. BUT (and this is a big but) the study only included one wine (a California chardonnay) made in one way, in smallish (19 L) lab volumes. Goodness only knows if their results will generalize, but let’s hope this encourages someone to look.

More: Sulfur dioxide is the single most commonly used winemaking chemical worldwide. That familiarity probably has something to do with our not understanding it better: we know it’s safe, we know how to use it, and so we don’t have much reason to study it.

In all fairness we do understand SO2 well, but microbiology keeps changing. The publishing dynamo* of Nicholas Bokulich and David Mills – responsible for really excellent recent research on how microbes are spread around a working winery over space and time – plus UC Davis wine microbiologist Linda Bisson (and another Davis student and a Japanese collaborator have published a new American Journal of Enology and Viticulture article on how SO2 affects bacteria and yeast populations in fermenting wine.

The question isn’t new, but the technology they’re using is. Short story: better DNA detection techniques let them pick up on the presence of a bigger range of both bacteria and yeast than previous strategies.

Longer story: Microbes in wine (and elsewhere, for that matter) can be “viable but nonculturable” (VBNC), a new idea ten years ago when microbiologists could still think that agar and Petri dishes were a reasonable way of identifying bugs in a sample. Until better DNA technology made clear a serious issue: yeast and bacteria might be stressed out enough by environments (like wine) to not grow on command but still be alive and able to multiply and cause problems, aka VBNC. (The unculturables who won’t grow in dishes at all are trouble, too.) The details of the high-throughput DNA sequencing they used to ensure that VBNC bugs weren’t left out of their survey aren’t important except to note that it lets them detect more microbes than previous studies.

The other great = new element of this study is its looking at multiple SO2 concentrations, from 150 mg/L down to nil. More work for them; more data for everyone. They also included ferments inoculated with commercial S. cerevisiae and not, which ended up being important.

Their results say that the most important factor in determining what grows in fermenting wine seems to be the degree to which a single strain has the opportunity to take over. One way of encouraging dominance is inoculating with commercial yeast: it more or less takes over and overall microbe diversity declines. But another way is adding SO2, which knocks down some microbes and gives tolerant ones (S. cerevisiae strains included) an opening. Adding SO2 and inoculating S. cerevisiae even without SO2 had similar effects on overall microbial diversity. And, moreover, 25 mg/L was enough SO2 to “stabilize” the ferment. In other words, sulfur-free wines may be less risky than winemakers are generally inclined to believe if they inoculate (which plenty of people inclined not to use sulfur are also inclined to avoid).

The obvious problem: one wine, one vintage, one set of processing techniques, and 19 L volumes. All of these are major reasons to question whether these results will hold for any other set of circumstances. pH and a slew of sulfur-binding compounds affect SO2 efficacy. Fermentation temperature, oxygen, clarification, means of harvesting…the list of processing steps important to microbial diversity is too long to list. And it’s well-known that fermentation volume is important to microbial kinetics.

In short? This article is almost certainly more important to wine microbiologists as a methods paper than to winemakers. (It’s not incidental that the methods section abbreviates the winemaking protocol — “grapes were harvested, crushed, and pressed according to standard winemaking procedures,” whatever that means – and uses nearly a full page of text to describe the DNA sequencing technique.) Nevertheless, it may well serve as impetus for more experimentation with low- and no-sulfur wines, and a good reminder that we always have more to learn about SO2.

Even more: find the full paper, with many more details on which specific yeast and bacteria species were detected and when they peaked (unfortunately behind the AJEV‘s lovable paywall) here. Read the full paper if you can; it contains plenty of potentially idea-generating details that I’ve not even attempted to summarize here.

*Hackneyed maybe, but, seriously, what else do you call them? Bokulich’s CV, as a PhD student, could put to shame plenty of tenured professors. When I’m not just feeling horribly inadequate, I’m wondering where this guy will end up post-graduation. Barring his speaking French and fancying living overseas – or starting a lucrative consulting firm – he’s probably lined up to make tenure at Davis in record time. Heck, he probably already qualifies for tenure.

Finding unboring wines in Marlborough, part 1: Seresin Estate

If you don’t live in New Zealand, Seresin Estate is a producer you should know, or know better. They’re a largish (if you’re not comparing against Yealands) biodynamic producer in Marlborough, and the biodynamics is one reason you should know them: Seresin proves that fresh, approachable, frankly delicious biodynamic and even no-sulfur wines are possible. But you should also know them because their wines are worth drinking with no labels attached, like the vegan carrot mole salad good enough to make the omnivores reject their roast chicken.

Perhaps the best way to describe Seresin’s core wines (the winery also produces a second label, Momo, and several higher-end pinots hovering around NZ $100) is that they’re easy to drink without being boring. These are biodynamic wines you can serve to people who don’t like weird wine. More importantly, these are interesting wines you can serve at a dinner party: you won’t be bored; your non-oenophile guests won’t be turned off. And you can probably even find them whereveryouarenotMarlborough.

The following are rough-cut notes from the tasting room; more important than the specifics is that all were delightful and eminently drinkable.

2011 Memento riesling – Seresin has in the past produced a dry riesling but has (at least in part because the style is such a hard sell in New Zealand) scaled back to this single sweeter bottling. Robustly aromatic with a rich honey apricot nose accurately foreshadowing its dominant flavors. Rich and honeyed, but well-balanced by bright acidity (and lots of it). Something to pour with the lovely array of chêvre- and nut- and fruit-adorned salads in perpetual vogue.

2013 sauvignon blanc – One of three S.B.’s Seresin produces under its main label, and the most regionally typical. Combines classic sweaty armpit, passionfruit, and asparagus notes with typically bracing acidity, but underpinned by enough body to keep things pleasant. A simple grilled fish kind of wine.

2012 Marama barrel-fermented sauvignon blanc – Easily the most challenging wine on this list, in part because it strays from easily recognizable styles. Obviously sister to the stainless S.B. in aroma, though bigger and rounder. Clear oak presence especially in the mid-palate with some oiliness lasting through on the finish. I’d like to see it after another few years’ integration time.

2012 pinot gris – Splendid bright acidity carries throughout without being overwhelming over apple-dominant fruit. Slightly sweet, but on the crisp rather than the oily side of what gris does. More roast pork tenderloin than seared salmon.

2012 chardonnay – Light, fresh, relatively understated aroma emphasizing the green apple-lemon side of the chardonnay spectrum. Crisp, fruit-focused but still with some dimension, and lots of acidity on the finish.

 2013 Osip pinot noir – Osip is Seresin’s sulfur-free line: no sulfur sprayed (as a de rigeur anti-fungal) in the vineyard; no sulfur used in the winery. Proof-of-principle that a sulfur-free wine can be (here, at least) fresh, fruity, and easy-to-drink. Fresh, bright raspberry aroma with an equally exuberant impression in the mouth. Not wanting for intensity, but light on its feet. At the risk of using the word “yummy,” it is. I’d like to try this with sushi.

2012 Leah pinot noir – The flagship and least expensive of six (excepting the Osip) pinot noir bottlings. More intense, darker, and brambly than the Osip, but still unquestionably fruit-driven. Silky up-front but with prominent tannins dominating the finish. Duck pastrami comes to mind, though an herby smoked-salmon pasta is a lot more likely in my kitchen.

If you could learn which yeasts actually ferment your natural fermentation, would you?

The Australian Wine Research Institute (AWRI) has launched a new winery service. Winemakers can now submit samples from natural/wild/native/non-inoculated ferments (or, conceivably, from an inoculated one if they wanted to) and, courtesy of “next-generation DNA sequencing*,” receive a profile of the yeast species present along with approximate percentages. An additional step can give them more specific strain information, and the AWRI can also isolate, freeze down, and store the main yeasts from your sample as “insurance” if you need them in future vintages.

This sounds like marvelous geekery. Winemakers who don’t inoculate probably wonder about what’s going on in there at least occasionally. What I’m unsure of is whether this yeast profile is a useful management tool beyond a fun way to satisfy your curiosity (or give even more detailed information to very well-heeled consumers). I imagine the following scenarios:

Good natural ferment — You like what’s happening with your uninoculated wine. You’re going to keep making it even if you learn that some generally undesirable bug has part of the action because you know you like the results. Maybe having a yeast profile sets you a benchmark so that if the ferment stops working in some future vintage you can send in a sample for comparison and see if the microbial blend changed, but how does that information then change what you do?

Bad natural ferment – You’ve tried not inoculating a wine and it isn’t working for you for whatever reason. You send in a sample from one that didn’t work (too slow, undesirable flavors, or didn’t finish fermentation). Maybe you’ll learn that some toxic bug is out-competing the yeasts you need to grow, or you’ll identify the source of that high volatile acidity you’ve been combatting. What then? The natural ferment still doesn’t work. Can you tweak pH or how much sulfur dioxide you use or your oxygen management to encourage more favorable microbes against the enemy? I don’t know how likely someone is to successfully adjust or amend a natural ferment to work better at that level — from the perspective of philosophy as well as how likely it is to work — but if you’re going to try these strategies, you’ll likely know to try them without knowing which yeast species are involved.

Planning a natural ferment – Maybe you run a test natural ferment to see whether you like what it does, and you want to “double-check” that it’s okay. The primary information you need stays the same: does it ferment to dryness? does it move fast enough to satisfy your economic needs and peace of mind? does it taste good? These will remain the primary drivers of your decision to move ahead or not, independent of what you learn from that yeast profile.

This service can help answer that perennial question of whether the yeasts in your “wild” ferment are really wild or just commercial yeast strains that have colonized your winery, and to some extent (especially if you go down to that extra strain level sequencing) the degree to which your ferment is different from some other winery’s. But the question — the AU $275 question for running a single sample, or AU $792 for the recommended panel of three samples per ferment — is this: will the extra information change what you do?

Nevertheless, forward-thinking actionability isn’t everything. Even if a winery never tries to replicate a previous successful wine by inoculating with its bespoke mix of strains banked through the system (that seems unlikely to succeed simply given the enormous variability in other parameters affecting wine quality directly and indirectly via influencing yeast growth), a retrospective look at yeast mixes in multiple vintages of the same natural ferment could be interesting. Did a change in viticultural management practices, or source of grapes, or fermenting conditions correlate with a clear change in microbial populations? That prospect makes me hope for two things. First, that a winery (or a dozen or two) will use this as a tool for looking back at the path they’ve taken and not just down at where they’re standing. Second, that when they do, they’ll share.

 

*Next-generation DNA sequencing (this introduction from Nature is dated and technical, but it’s also open-access; the article on Wikipedia is also quite good) is a collection of methods so called because they rely on new strategies for sequencing DNA — not just tweaks of the old traditional way, but really new ways of solving the problem — that let us do things differently, faster, and more efficiently. The most important things to know about next-generation sequencing are that, 1) it’s not a method, but a general term for a whole bunch of methods; 2) the idea has been around since 2008, which doesn’t mean that any of those methods can’t be cutting edge but which does mean that they’ve “trickled down” to the general market by now; and 3) they allow for pulling many sequences from many different organisms out of a single small sample. Old sequencing methods required a relatively large sample of (preferably) a single pure target sequence or else the signals would get so jumbled up that the whole instrument read-out would just look like soup (as I recall well from my first sequencing experiments as an undergrad in 2002-3). Now, we can sequence even single stretches of DNA, and even many different single stretches all hanging out in the same sample from some real-life microbe-rich setting: soil, seawater, or an active ferment. And we can do it quickly and inexpensively enough, now, to offer it as a commercial service. Remember those predictions about what genomics would bring us back around 2000, when sequencing genomes really hit the news? We’re getting there.

On Palate Press: Machine vs. hand-harvesting (and our future with robots in winemaking)

A few years back, a group of Auckland-based researchers established that machine-harvested Marlborough sauvignon blanc has higher aromatic thiol concentrations = tastes more intensely Marlborough sauv blanc-y = is better than wine from hand-harvested grapes. I don’t know how widely that logic is known amongst wine consumers, in New Zealand or elsewhere. Reading back labels in my local wine shop makes it clear that the hand-picked grapes = superior wine logic rules in the minds of marketers and, if they’re any bellwether (a worthwhile question), at least some consumers.

Marlborough sauvignon blanc aside, is that prejudice justified? My January piece for Palate Press addresses that question. The short answer is that hand-harvested grapes are in many settings more about feeling good about purchasing genuine artisan wine than about quality or flavor. The longer answer is here.

Saying that hand vs. machine harvesting is becoming less and less of a quality issue, with better equipment in the field and in the winery, isn’t the same as saying that the difference doesn’t matter. It does, to our perceptions of what we drink. But it’s also impossible not to see this as one more instance of Robots Will Take Our Jobs, and a particularly hard-hitting one with wine such a cultural icon. A lot of vacuous dithering takes place in the media around this topic (even in outlets like The Atlantic, though this piece from The Economist might be an exception) and, to be honest, I’m not sure that I have anything worthwhile to add. We’re headed, I think, for a major shift in how people work, earn money/obtain necessary resources, and spend their time. That shift may come in the form of an organized political (maybe governmental, maybe by large companies) decision to redefine work and money, or it may come as a necessary post-degenerate organic movement after the fall of Rome. Either way, being human, we’ll continue to find meaning in our work whether that means choosing to harvest grapes by hand because it’s meaningful to do so, even when a machine/robot can do a better job, by redefining wine quality such that the robot can’t do the job as well, or by understanding human winemaking as a conceptual art independent of the physical work of our hands.

 

The value of cold soaks for red winemaking; the value of cold soak research for winemakers

Cold soaking seems to be an especially divisive winemaking technique, at least in the Pacific Northwest, and that’s saying something in an industry full of strong personalities. Cold soakers say that allowing crushed red grapes to rest for one to several days in an environment too cold for Saccharomyces activity, before warming everything up to yeast-pleasing temperatures and allowing fermentation to begin in earnest, deepens color and augments flavor and tannin extraction. The anti-cold soak camp claims that these benefits aren’t real and sometimes adds that cold soaks allow for the dangerous possibility — dangerous, that is, if you’re also in the anti-spontaneous ferment camp — of illicit microbial growth before winemakers inoculate commercial yeast strains at the soak’s end.

Research to date has been unhelpfully mixed. Some studies show increased phenolic (color and/or tannin) extraction, some don’t, some even show lower phenolics following cold soak, and the variables responsible for the differences haven’t yet been worked out. Adding to the confusion is the inevitable mess that follows pro-spontaneous from anti-spontaneous fermenters, since the non-Saccharomyces activity that might occur during cold soaks is a source of desirable complexity to some and unconscionable spoilage to others.

I would love to say “until now” and herald the arrival of a brilliant, conclusive paper outlining a robust explanation for how and why and where and when cold soak works. My inability to do so isn’t likely to come as a surprise. Nevertheless, there is new research and, while far from once-and-for-all conclusive, it helps, if perhaps not in the expected way. A new study from an Argentinian team* tested cold soak on cabernet sauvignon, merlot, syrah, pinot noir, malbec, and barbera d’asti, looking for differences both when the wines were pressed and after a year of bottle aging. Cold-soaked wines saw four days of 6.5-11.5ºC (44-52ºF) courtesy of periodic dry ice additions, then 10-day fermentations at 21.5-26.5ºC (71-80ºF); control wines went straight to 14-day fermentations. All varieties were made in the same way: same full twice-daily pump-overs, same twice-daily punch downs. All were inoculated with the same commercial yeast strain five hours after crush. Regrettably, the study didn’t include multiple variations on the cold soak theme — different times, temperatures, or techniques — that might have helped to suss out where any cold soak differences are happening and given much more information to winemakers. In particular, it’s important to emphasize that chilling with dry ice meant as much as a 10ºC (18ºF) difference in temperature between different parts of the tank because the dry ice clumped. Jacketed tanks would have applied a more uniform treatment.

The agglomerated results were straightforward enough. Cold soaks increased color density, but didn’t increase phenol or tannin concentrations. Cold soaking also didn’t make a statistical difference to any basic wine chemistry parameters: ethanol concentration, pH, acids, glycerol, and residual sugar. Tasters found that the most important difference between all of the wines was driven by grape variety, though that’s hardly meaningful and says nothing about cold soak. That’s the big picture.

The details in the supplemental data attached to the main paper show something more interesting. Each variety responded a bit differently to the cold soak treatment. In the barbera and the syrah, tannin concentrations actually were higher in the cold-soaked wines. The opposite was true for the pinot noir, where cold-soaked wines measured tannin concentrations statistically significantly lower than the control. Cold soaking related to increased total phenols in cabernet, decreased in pinot noir.

What this says to me is that we’re measuring the wrong construct at the wrong level of detail. Asking whether “cold soak” works seems to be the wrong question. Instead, we need to be testing out different potential cold soaking parameters in specific grape varieties to identify what precisely makes a difference and what is moot. This is the kind of data that could really help winemakers who through the lens of their communal experience are saying that cold soak sometimes makes a noticeable positive difference and sometimes doesn’t, and who might reasonably look to science to help them figure out what features separate the worthwhile instances from the useless ones. Unfortunately, if the research question continues to be “Does cold soak increase phenol concentrations?” instead of “Under what conditions does cold soak make a difference to phenol concentrations?” we’re likely to continue seeing confused yes-no-or-maybe reports instead of useful, applicable explanations of what winemakers seem to observe.

 

*Including Federico Casassa, who has in the past published excellent phenol-related research with James Harbertson at Washington State University, including the American Society of Enology and Viticulture’s 2014 Best Enology Paper of the Year, on the phenolic effects of extended maceration and regulated deficit irrigation, the full text of which is freely available here.

On Palate Press: Water footprints and Waiheke (and chickens, again)

My Palate Press piece for this month (which I really wish was entitled something involving “water” to make the subject more clear) is a bit about Waiheke Island, just off the coast of Auckland, and a bit about water footprints in the wine industry. The relationship between the two is that Waiheke — shockingly, for a North American accustomed to consistent public amenities like central heating and easy wi-fi (both unlikely propositions in New Zealand) — has no public water supply. In good years, residents and businesses and wineries meet their individual needs either by collecting and filtering rainwater (most folk) or with a “water bore” into the under-island aquifer (large and/or resource-full folk). In bad years, all of the above buy water from private companies with private water bores, and do laundry less often.

Waiheke is a good reminder, though, that whether water comes out of a tap or off the cistern parked next to your car, it’s always coming from the same two places: the sky, or underground (which isn’t to say that the two aren’t connected, but only that it’s helpful to think of the two compartments). Tap water is a bit like packaged boneless skinless chicken breasts from the grocery store. Someone else has done all of the hard work for us. Both distance us from the hows and wheres of the stuff we use. Butchering chickens is a pain*. It makes endless sense to divide labor, specialize, and let someone else with better equipment and skills and economy of do it for you. And bake your bread, change your car’s oil, and collect and filter your water. Still, all of these things make it easier to abuse the system. We don’t pay as much attention to our dinner’s living conditions when it didn’t live with us before it appeared on the table, nor to how it died if we didn’t kill it. I’d never really thought about water that way before wandering around on Waiheke; I try to conserve it, but I don’t usually think so graphically about what my convenient kitchen faucet implies. I’d never wish drought on anyone (and California and its people have my sympathy). But maybe it’s no bad thing to look for a drinking fountain in a place with no public water and find none, and remember that I should be just as conscientious about my water as I am about my free-range, local, organic Sunday supper.

More about my Waiheke visit, and about water, is on Palate Press.

*As I know from recent experience. The Great Chicken Experiment is, regrettably, over. The first two hand-me-down hens lived happily with us until the neighbor’s rooster discovered them and decided that they were his, after which they lived happily with the neighbor until she decided she was done with poultry and she invited me to dispatch the lot of them (after which they lived in my freezer and my stockpot). Save the (charming, darling) several month-old chicks, who we adopted. Unfortunately, having been raised entirely outside in our mostly fenceless environs, they’d learned to be very freely free-range. A trip through someone’s spinach was more than anyone was willing to tolerate (save, maybe, the chickens) and we handed them on to someone else. We miss them, though my garden does not.

Authenticating icewine: closer, if not quite close enough

Scenario #1 – You’re sitting next to your fire after dinner, relaxed, with a few ounces of fine Canadian or German icewine, maybe a few slices of blue cheese and a ripe comice pear, and the current evening reading book. You enjoy all three for an hour or so and retire, happy and sleepy, to bed.

Scenario #2 – You’re sitting next to your fire after dinner with a few ounces of icewine and an active mind in search of a target, maybe two active minds if you have a companion. Conversation turns to the wine, how desperate those first Germans must have been to salvage their inadvertently frozen grapes and how arduous and expensive repeating the process on purpose now is. You speculate that cutting real icewine with something else must be mighty tempting, and the gaze you cast on your glass turns wary. And then you cast your gaze on Google and find this new article in the American Journal of Enology and Viticulture on a new strategy for testing the authenticity of icewine.

Icewine production is very expensive and no International Body of Icewine Authenticators polices producers to ensure that they’re doing it right or in good faith. Canada produces the bulk of the world’s stock (though I also enjoyed some fine examples in the Finger Lakes, not too far south of Ontario), and the Canadian Vintner’s Quality Alliance (VQA) legislates use of the term: a Canadian bottle with “icewine” or “ice wine” on the label must be made from approved varieties, from grapes harvested during “sustained” temps of at least -8°C, naturally frozen on the vine, coming in at at least 35°Brix, with no added sugar or alcohol, all overseen by a VQA representative. European producers employ similar standards, but the Asian sweet wine market is apparently well-populated with “Iced wine” and other unauthorized and fraudulent variations on the theme. Having a reliable means to verify that an “icewine” is really icewine made from frozen grapes seems prudent.

Per Armin Hermann’s new research, tracking oxygen isotopes could be that way. The idea is clever and conceptually simple. When grapes freeze, water partitions unequally between the part that turns to ice and the part that remains liquid. That’s the point of icewine: more water freezes, leaving sugars and other dissolved molecules concentrated in the syrupy liquid that remains. The naturally occurring isotope 18O, present in the water, will also distribute into the frozen and the unfrozen parts unequally. Since the frozen ice is more or less excluded from what ends up in a bottle of true icewine, then, icewines will contain a characteristic amount of 18O. All we need to do is determine — theoretically, using mathematical equations, and empirically, by measuring a bunch of icewines — what the “icewine” versus the “not icewine” 18O ranges are. Simple, elegant, and probably effective.

The plots of 18O measurements Hermann created show what looks like reasonably convincing separation between the ice- and non-icewine samples (understanding that judging how convincing is outside my expertise). BUT, there are two important caveats. First, the comparison was lab-frozen grape musts against the unfrozen originals. Again, it’s simple: “Frozen grapes, when pressed, will produce a must that is always depleted in 18O relative to its marc and also to their unfrozen counterparts.” The study didn’t include creating a database of icewine samples from various regions to establish reasonable 18O ranges. That’s solvable in theory, though the success of the whole method still depends on finding good, clear separation between real live ice and non-icewines.

Second, the method provides no way of determining how the wine was frozen. The 18O-depleted wine could have just as easily been frozen after harvest, in the winery, illegally. So, no matter how successful that empirical database is, the method won’t perfectly solve the how-do-we-detect-fakery problem. It is, as Hermann notes, an “additional” means giving a “strong indication” of authenticity. I wonder: is there a detectable chemical difference between the kind of slow freezing that would happen naturally on a grapevine in a cold Ontario winter and fast winery cryofreezing? Until then, looking for the Canadian VQA mark on the bottle — and avoiding anything labeled “iced wine” — remains the safest option, North American privilege notwithstanding.