Day 30.1: Yeast
latecomer Ed Thralls over Wine Tonite! is figuring out the whole natural wine thing and wanted in on the proceedings, so i had do some research on yeast. Enjoy!
Part of the natural wine movement is one of the ongoing philosophical battles regarding the question to inoculate the must/juice with a starter culture of wine yeast or to allow the native, or “wild,” yeast to do its thing all by itself, with minimal to no human intervention.
Wild yeast is believed by some to enhance quality and certain characteristics of the wine. To be more specific, it is said to reflect the particular vineyard’s character in the wine more closely. This has to assume that the vineyard has some fairly distinctive qualities to begin with. For example, bacteria, which often accompany native flora, have a higher chance to take over during the longer fermentation, so the fruit will need good acid and good tannic structure to help battle this situation because native yeasts will be less tolerable to SO2. A wild yeast fermentation takes longer to start since the quantity of yeast in the vineyard and on the berries will be much less than when inoculated, will take longer to finish and will do so at a generally lower temperature. On a positive note, longer and slower fermentations can allow the yeast to have more of an impact on the fermentation adding enhanced texture and finesse to the wine. This is due to the fact that, in addition to converting sugar to alcohol, yeast also produces esters and compounds that contribute to flavor and aroma.
But, what is wild yeast, really? Most feel they aren’t really wild at all, but rather the well-known Saccharomyces that has set up residence in the winery or in the vineyard, often as a result of winery hygiene habits or pomace being recycled back amongst the vines. Regardless, native yeast is less predictable, less consistent and can often result in off-odors and flavors. Yeah, we all know, what might be off for me or you may taste like gold to someone else. Check out my post about petrol aromas caused by TDN in Riesling for another example.
On the other hand, fermentations inoculated directly with Saccharomyces increase the winemaker’s confidence that fermentations actually start and complete, are expedited in a timely manner, and are more predictable. This is mostly due to its tolerance to high alcohol and SO2 and its minimal negative by-products. These fermentations also will fun faster and often much hotter than those of native yeast. When you think about the investment and economics of growing and making wine this seems like a better insurance policy.
In an effort to see if I could distinguish the impact of wild yeast in natural wines, I tasted two fairly well-known offerings and compared them with wines of the same varietal, vintage and region but made with inoculated wine yeast. Note: this by no means was a scientific study, so draw your own conclusions. I just needed an excuse to drink some more wine. [Like that’s necessary]
2007 Edmeades Zinfandel Mendocino – This wine was very, very much fruit-forward on the nose that was almost “sweet,” but not in the residual sugar meaning, of course. There was absolutely no heat on the nose even though the ABV was a whopping 15.2%. The taste brought forth some very big blackberries, vanilla and medium spice at the finish. Overall, this was very smooth, velvety and full of fruit. The comparable wine displayed a lot of heat (15% ABV) and chocolate on the nose and was very smoky, jammy and finished with much bigger spice on the palate.
2006 Yangarra Shiraz McLaren Vale Single Vineyard – Right off the bat it was like I dove head first into a rosemary bush and got a few sprigs shoved up my snoz. I love rosemary and it’s a very distinctive aroma of the Syrah grape. Add that with some black olives and this was getting very interesting, indeed. The taste was also herbaceous with black fruit, slight minerality and medium spice on the finish. That was awesome! [Think The Chris Farley Show on SNL] The comparable wine from the same region displayed lavender, spice, blackberry and chocolate on the nose. The taste brought on more black fruit, jam with a shit ton of more spice, but a fabulous mouth feel, like you grew hair on the tongue.
So, were the fruitiness and distinct varietal characteristics of the natural wines due to the native yeast? Think about the Zinfandel where both contained 15% alcohol, yet I could only detect the heat on the faster/hotter fermenting wine yeast. Or think about the highly distinctive varietal characteristics of the Shiraz. Did the slower/cooler native yeast fermentation allow the yeast to pull more of these attributes from the fruit? I think I’ll need to do some more studying on this topic.
Ultimately, this sounds like the classic risk/reward scenario, where the significant economic risks of a stuck fermentation, off-odors and off-flavors are believed to be outweighed by the reward of more significant vineyard characteristics, elegant texture, pride in following a principle of less human intervention and marketability of the product to others sharing the same principles.
Yeast is as yeast does.
Cheers!
Follow day by day here: https://saignee.wordpress.com/31-days-of-natural-wine/
Up next: Dard et Ribo with Linecook415; or: VLM was WRONG (Day 30.2)
saignée 
Nice post! I just found your blog and you have made my bookmarks!
I’m a CA winemaker – and I’ve played with native fermentation and come to the resolution that the people who are doing it successfully are “cheating” with saccharomyces.
True native yeasts cant live past a few % alcohol – so they will ferment down until maybe… 18 brix and then peter out – at which point the saccharomyces will take over. I dont think that the saccharomyces needs to be out in the vineyard – its all over the winery – no matter how well you clean.
I lost a couple of tons of Pinot to a native yeast experiment back in 2005 – and I wont do it again.
That said, I DO let native yeasts START the fermentation process for me – But then I put in the yeast that I know will finish the job. The result is “maybe” some more complexity but definatley a longer maceration. I dont have a scientific reason for doing it that way but then again.. this is winemaking.
Thanks for a good blog… Im gonna read through your previous posts now…
Cheers
Tim, a very good point you made there. With the more vigorous Saccharomyces, I like the idea of starting native and then letting Sacch takeover (because it can) to finish the heavy lifting of completing the fermentation, etc… while you hope to get the presumed varietal characters from the slower native part of the process up front… very cool.
Hi, my name is Karien and I am a fermentation (wine yeast) specialist. I find the whole concept of natural fermentation quite interesting. Especially the whole marketing behind it. I have attended many wine tastings where one of the things that impress the tasters is if the wine was made with “natural” fermentation. It is just so much more romantic than saying I used a specific commercial yeast to assist me in obtaining this aromatic profile. It is the belief that natural fermentations express terroir the best. The same argument goes for using neutral yeasts like pdm. Natural, or more accurately put – uninoculated fermentations, can be great if the yeast population you have in your vineyard and cellar comprise of aromatic yeasts. So one can create exquisite wines this way, however all yeast populations are not created equal and you might end up with a bottled wine that has a huge amount of unlocked potential that you could have had if you used aromatic commercial yeasts. So, its a catch 22. Yeasts differ greatly in their ability to enhance varietal character. For instance, your yeast choice for S. blanc production is critical because the varietal character comes from thiols that is influenced by the yeast you use. Chardonnay, Riesling and red grapes are more forgiving because their varietal character comprise mostly of compounds not influenced by yeast. However, yeasts produce esters that can smell the same as this varietal character and thereby enhance it. Esters are formed from amino acids in the grapes – so technically it is also varietal character. Now the great news is that yeast companies are not blind to the potential benefits of “natural” fermentations. The challenge is to get the right mix. A lot of research are being done on non-Saccharomyces yeasts isolated from natural ferments. Some of these yeasts have been commercialised. One yeast company has commercialised two yeast blends of Saccharomyces yeasts. The yeasts in the blend interact with each other’s metabolites to enhance varietal character expression, so it is mimicking what is happening in natural ferments. So winemakers are now starting to have the option of having the benefits of more than one yeast conducting the ferment – in a controlled manner, i.e. the fermentation will finish. Still not very romantic though, but then again how romantic is the addition of tartaric acid or alcohol removal?
Here Here. Karien!
The one winemaker that I have spoken at length with who does this… also uses a lot of SO2 – which “wild” yeasts are especially sensitive to. This winemaker was a protoge’ of a more famous winemaker who is known for this technique.
What he is REALLY doing is modifying the fermentation kinetics – still “really” using the saccharomyces strains that are native to his winery (and controlling the competition) – essentially reducing the innocculum level so that lag phase (the slow starting phase) of the fermentation is longer.
I do the same thing by getting the grapes below 50 degrees after crushing – and then let it slowly warm up on it’s own… When the vat starts smelling like fingernail polish (aldehyde) I know that a native fermentation has begun, and I add my commercial yeast (which by the way will consume the aldehyde – so I’m not worried about that)
At the end of the day, most winemakers who use native yeasts will concede that it’s “mostly marketing” – which irks me, because I HATE the notion of having a marketing play dictate how the wine is made. I’d rather make the BEST wine I can for my customers and then explain why I made those decisions openly and honestly.
Karien,
I would rather winemakers not add or subtract anything to try to reach some imaginary “unlocked potential” because i think that is the reason we have have reached a point where a lot of wine from around the world has started to taste the same. Over oaked, too big, too much extracted fruit all in the name of “unlocking potential” or trying to reach some standard that doesn’t actually exist. So what if wine is different from year to year, or some of it has more fruit on it, or others have more acid. Do we need standard yeasts to flatten out wines, or can we accept that wine is different from a can of coke and homogenization might just be a bad thing.
I wouldnt blame the yeasts for all the wines in the world starting to taste the same – I would blame the fact that we only make wine from 6-7 different varietals out of the thousands avaliable.
But it’s a false economy to wish that people used native yeasts – the native yeasts cant really make the wine. Its the yeasts that are picked up in the winery. So as a winemaker, I can either choose to pick the yeast that works best for the style i want to make – or I can leave it to chance? Romantic notions of “native yeast” aside, I’d rather have control over my wine and make the best product I can. If anything, commercial yeast strains promote diversity in the yeast flavors because there are hundreds of options for yeast – otherwise we would by default all be using the yeast that happened to be the best at clinging to winery equipment.
The problem is even varietal distinctions are dissapearing under the weight of technology. I can buy a roussanne, an albarino, a vognier, a muscat that taste mysteriously the same. Why is that? Is it because people can’t stop fucking with the wine to “enhance” the flavors? It isn’t just innoculated yeast i’m talking here, it’s enzymes and 200% oak treatments, and RO and all other manner of technology brought to bear on wine that ends up leaving you with a big mouthful of (IMVHO) bland wine. It may sound like bullshit, and i’m not a winemaker but I do know what I like and even before I even knew a single thing about innoculation vs. wild yeast i had tended towards natural yeast without even realizing what i was doing.
As someone in the trade who tastes 50-100 wines a week, and, as importantly, drinks wine often outside of work, I agree with Cory’s assessment. That is, that Spain’s 200, France’s 2,000, Italy’s 2,000,000 (ok I exaggerate) very different indigenous grape varieties tend to not only show similarities when treated in similarly heavy handed manners in the cellar (of which cultivated yeast is just one treatment) but also are just a whole let less pleasant to drink.
Many wine drinkers (retailers in particular, who typically taste a wider variety of wines than anyone else), often times get to a point in their palate evolution where they personally seldom drink Californian, Australian, South American, Bordeaux, Spanish and other particularly ‘market driven’ regions’ wines. No coincidence that these areas continue to apply a cookie cutter, commodity approach to winemaking. Wines from, say, the Loire valley are hugely popular amongst my peers because they are low alcohol, highly complementary with food, and show loads of personal character for pennies on the dime compared to other bigger, more ‘serious’ wines.
preach it brother! preach it! YES!
I think that’s a good insight Joe. Im a california winemaker – so I definatley have a specific horizon of wines that are on my radar. But I think we have two seperate issues here connected only by a filament.
1) is heavy-handed wine styles. And I totally agree with you there. It is easy to whack a wine with too much oak and a high alcohol etc and make something that is more enjoyable from lesser quality fruit. Part of that I think comes from all the levers that we can throw these days to make exactly the wine we want – instead of letting the grape talk for us. When you have a hammer – everything looks like a nail… So I totally agree with you there.
2) Is about “commercial yeast strains” vs Native yeast. My point there is that I dont think the existence of commercial strains is to blame for the homoginazation you speak about – it’s how they are used.
The connection between the two is that the more robust yeasts allow winemakers to complete high-brix fermentations that might have gotten stuck just 20 years ago. But a lot of that also has to do with our increased knowledge of how to feed a fermentation with yeast nutrients as well…
For me, commercial yeast strains gives me the abillity to have a diversity of yeast-derived flavors in various lots around the winery. And it does make a difference, and I do make better wine from it. I think the key is having the restraint to use the right tools at the right times, but otherwise let the wine be itself.
Joe? Let me get this straight: you jumped from decrying heavy-handed winemaking to lauding wines that “show loads of personal character for pennies on the dime compared to other bigger, more ’serious’ wines.” What’s important to you – “natural” or “value”? :-)
Karien is a technical consultant for a yeast company. Earlier in my career I was technical director for one of the two North American wine services laboratories. We are brought in when clients’ wines have gone wrong. Sure a retailer may taste 50-100 wines a week – generally finished, successful wines. Try 50-100 a DAY (on a bad day) wines that are unfinished and more or less flawed – wines that might not ever see the light of day if we can’t fix them. Karien and I have a very different view of “natural” winemaking.
I don’t see why you can’t have “natural” and “value” in the same wine. That is predominantly what I drink.
And maybe those wines that you and Karien “fixed” shouldn’t have seen the light of day.
Emma that’s a pretty bold statement. Personally I agree with you on some level, and I will take it a step or two farther: this winemaker should not have been hired, that owner should not have delusions of grandeur, this vineyard should not have been planted. Not up to me to decide these things though. Or you.
I’ll add this… My little experiment with a “truly” native yeast fermentation where I lost a few tons of pinot… that was over 10k worth of fruit I ruined… Add that to the perspective…
The real problem? My crew did TOO good a job of cleaning the equipment and I didnt get cross-infection with a saccharomyces strain that could take the fermentation over and complete it. Truly using “native” yeasts is fiction.
Have you been to France? really… pfffffff
Marketing of native yeast. Let’s see, most of the wines heavy collectible wines were made with only uninoculated must until….the 1970s. How do you account for that? This is a grossly uninformed conversation. It is not the ‘marketing’ of native yeast (like–marketing? Where’s the PRODUCT being sold for it?) it is the yeast manufacturer that has a stake in marketing of the product.
Yeast strains have a profound effect on not only how ‘clean’ the ferment is (and that is debatable) but the flavor, which is why so many white wines taste like NZ sauvignon blancs, or profound fruit salad. I prefer to see what the vineyard and place where the wine is made, and the winemakers hands, have to say.
Thank GOD you posted! YES!
Sorry – not misinformed. I have a Degree in Viticulture and Enology from UC Davis and have been a commercial winemaker for over a decade.
TRUE: Innoculating wines with yeast directly is a modern practice. But that does not mean that “natural” or “native” yeasts ferment older wine styles. Only Saccharomyces Cerivicae can accomplish that. The isolations that have been done of the “bloom” on wine grapes is yeasts of the species Kloeckera or Hansineospora – species which are not nearly as alcohol tolerant (like 6-8%) as Saccharomyces.
That yeast that makes the wine (or at least finishes is) resides in the winery. Over time old world wineries would be totally infected with their house strain of yeast. If your house strain ended up being something that didnt make nice wine…
Your call as to whether this can be included in a notion of “terroir”.
Commercial yeast strains – where did they come from? Isolations from wineries. They are captured and reproduced from wineries who have made great wines in the past. There isnt anything “unnatural” about them. Its just that winemakers use them to take control over which strain does the job for them. As a result, we all make better wines.
marketing of native yeast – the product is the wine. Winemakers talk about native fermentation as a quality differentiator – even when they themselves know that it’s mostly BS. That is the problem that I have. As I said above, I myself do a “partial native” to increase complexity – but I put the yeasts I know will give me the quality and complexity in so that the job gets finished and so that I don’t end up with a sweet wine or vinegar (or both)
And by the way alice… Im a fan, and Im glad to see you in this thread because it really is “parkerization” that is the subject of debate – too ripe, too high alcohol, too much oak…
DIrectly innoculating yeast isnt the cluprit here – it’s winemakers who play for ratings first, and drinkability / authenticity etc… second or third.
Tim, First of all, thank you. Yeast isn’t the culprit but it is a signifiant part of the picture. But trying to control the fermentation through selected yeast has an impact on flavor and texture.
Correct?
That is trying to influence the outcome, and then there are all the other tricks one can use.
Going native—AND —Im assuming gorgeous vineyard practice and a healthy winery situation—shows the vintage and the vineyards hard years work. In some years the ferment goes slow, in some cases fast and in the hand of an experienced winemaker, the result is different but hardly ever–wine gone wrong.
This is what I’m after. This is what people who hunt the best in natural wines are after. Yeast is a big part of the story of today’s white wine (in particular) samenss.
And even though you hold a degree from UCD, (ive talked about this issue at length with Roger) unless you have years of only working with Native under your belt, and truly immersing yourself in these wines and walking the vineyards and talking with the winemakers, you aren’t informed enough to persuade me.
I am obsessed with the new world/old world disconnet, I guess I call it. I don’t know where this comes from, and I address it some in my book–the winemaking from fear–place. I still need to delve in deeper, find out. To me, it’s like when I wrote about Aubert saying, as he looks out at La Tache, to deny terroir exists is to deny that the sun rises.
This issue is as deep for me.
You know?
I do. And I think we actually agree on most things.
I think that the new/old disconnect stems from the lack of our own winemaking tradition and the varietal paradigm. We are stuck in this rut of making wines that imitate the old world – and are too afraid to do the decades of work, and trial and error that it takes to develop a native authintic wine tradition. Winemaking from fear-place indeed!
Too many winemakers and winery owners think that terroir means “good winemaking soil” – which we have in spades here in CA, but true terroir as “a sense of place” is something that is almost universally lost on us. (reference the statistics about what varieties we plant and where)
I would agree that the yeast that is native to a winery could be considered part of that terroir over time – as would I think the culture and cusine of the people who drink the wine. That will take decades to develop – but in CA, we aren’t even TRYING.
Like you I’m deeply passionate about the lost “soul” of wine – to the point where the wine project I am starting now on my own (what is probably my life’s work) is dedicated to JUST THAT – trying to bring some authenticity and real respect for terroir to Ca.
I have gotten to the place working for others making soulless wines… I’d rather not make the wine at all.
It is scientifically incorrect saying that there is no Saccaromyces
Cervisiae (SC) naturally in/on the grapes; Saccaromyces Baianus is
not there (yes it has been observed in France and Hungary but in the
cellars), Saccaromyces Cervisiae is (which one of the SC is another
story will write more later about that). There are some scientific
researches that state otherwise but those in realities are more
sponsored writings published from some famous yeast manufacturers,
let’s call them for what they are brochures passed as scientific
research. It would be more correct saying that SC is rarely
observed: better said – you need to take a hard look to find it, BUT
THERE IS. Technically speaking the presence of yeast (ANY STRAIN)
around the grape is very small (usually about 10 @ exp 4 per grape) and the
main strain present at harvest is the Kloeckera apiculata (KA) with
that you will find SC as well also others with KA there are also
Pichia, Candida, Brettanomyces , Dekkera, Torulaspora,
Zygosaccharomyces strains. And it is true that you are going to add
strains from the environment no matter what (including your hands
while you harvesting the transportation to the cellar the cellar
machines etc.) but guess what that is the normal / natural
environment; it is an act of nature not a human act that wants to play
God. SC is everywhere and as per your curiosity residues inside one
of the earliest known wine jars from Egypt contained ribosomal DNA
from S. cerevisiae, indicating that this yeast was responsible for
wine fermentation by at least 3150 B.C .
Back to the yeast fermentation: many try to get rid immediately of
the bad boys: Kloeckera apiculata (KA include in this also there are
also Pichia and Candida Brettanomyces and Dekkera), are commonly
referred as the “bad ones” because they risk to spoil the fermentation
at starting giving you with acetic acid esters acidity and bunch of
things you don’t want (including heavy headache and sleep
deprivation) with KA; and you need to watch out for those because
they can stay there and be dormant even after the malolactic . In
reality KA can be an alley at starting as help starting the process
(with a big IF tell you after) and they cease their activity at about
6% of alcohol (but they start stalling at 4% as they don’t like
ethanol). And here is the IF:
IF you harvested the grapes at the right time, IF you have healthy
grapes at the right yield that should be not more than 0.6t/ha =
0.27t/acre (and yes you need to work in the vineyards to do so you
need to be a damn good vine assistant) you reached phenolic maturation
(remember Yves Glory curve?) and you are not over 21 brix, right PH…
THEN you can afford to do a natural fermentation : the yeast strains
we will pretty much do it for you yeasts after yeasts, SC will take
over and it will go over starting slowing down at about 12% opening
the door to his majesty Oenococcus Oeni bacteria for the MLF and
everything will be quite smooth. If you are not in the target you
need to go commercial: selected yeasts enzymes to keep it up
lactobacilli and modified Leuconostoc Oeni (that many call still
O.Oeni is like saying that Obama and I are related) then and you are
making mass marketing wines period; you can claim that you are organic
biodynamic or whatever you can put on the labels but is just paper not
reality.
Another thing that tells you how the notion of indigenous yeast is
crucial if you claim making natural wines. Saccaromyces cerevisiae
(SC) is a very ample family of different yeasts. How wide? Consider
this: there are 0.6% differences in the DNA between a human being
from a chimpanzee… while between strains of SC there are more than 2%!
And we are talking just the natural strains not the “laboratory
enhanced”.
Sure you can use artificially cultured yeast but you cannot call those natural wines anymore as part of the identity of its uniqueness gets lost.
Wow Paolo… Impressive! Formidable! Thanks for posting!
Tim AND Paolo, …wow indeed.
I’ve spent some time mulling about this issue as… And while I wanted to refrain from posting in this column again, cause the horse is probably dead, and beating it isnt likely to yield results, I do think I know why it was so hard for me to communicate my position: Cause I’m not at either pole – Im in the middle – and it’s hard to communicate centrist arguments – they are much less amenable to simple / soundbyte arguments.
(the fact that this is a highly multi-faceted, scientific issue doesn’t help either)
I think that perhaps the best way to explain my opinion (and my winemaking approach) is this:
I believe in letting a wine be it’s own animal, and I subscribe to the notion that the wine will be it’s best when it is left to it’s own devices.
But there is the conflict. Without human intervention, grapes will turn into wine – and THEN into vinegar. Or if the wrong bugs come from the vineyard such as lactobacillus – it will go straight from grapes to vinegar.
Winemaking is the art of controlled spoilage (maybe not romantic, but nonetheless true) I think that the winemaker’s hand should be much like that of a good parent – let it do it’s thing – but encourage it in the right direction and only stepping in when really necessary.
I’m sorry if that doesnt fit into either category tidily, but I would be a worse winemaker if I trended twoards either extreme.
As i said above – I let a “wild” fermentation start, and only add yeast once the wild yeasts are well established. When I DO add the known yeast, I dont put anywhere near as much yeast into my ferments as the manufacturer reccomends – maybe 1/8th the amount. But I DO put them in there. Why?
Because it is one thing to have the fermentation temperature and kinetic profile of a native fermentation (which is good) and it is good to try to let the wild yeast have their “say” in the fermentation (which is also good) – but it is another thing to blindly assume that a yeast will be present that can finish the job.
As I’ve said before, being wrong about that assumption once cost my employer over ten thousand dollars, and almost cost me my job.
By putting just a pinch of commercial yeast, and putting it in only after the native fermentation has started, I get to … send a chaperone with my kids to the school dance. I know that if something weird happens… there is someone I can count on to step in to keep everyone safe.
But I also get a fermentation that gives me the quality and charachter of an uninnoculated fermentation.
Now…. seperate issue….
To the point of ‘uninnoculated” what I was trying to point out earlier was that “uninnoculated” doesnt exist. The winemakers who are successful with this are very aware of the fact that they are, in fact, letting their barrels etc do their innoculation for them.
I would make wine this way too (use concrete tanks that will permenantly harbor my resident strain etc) but extending the notion of “terroir” to the usage of yeast (at least in CA) is premature. We dont even know what varietals are best. (we are too busy pretending to be Burguntuscandeaux instead of establishing our own authentic tradition) The yeasts that we should encourage to take up residence in our wineries should be those that work best with THOSE wine styles… but until we have that nailed down… expecting “soul” or “terroir” from a California wine in ANY context is going to leave you disappointed.
It’s sad, but that is where we are in my part of the world.
Tim Keller & winetegrity – thank you. Voices of reason. Paolo – I PRAY for my native Pinot ferments to take off on Kloeckera. When the Saccharomyces takes over it can take up the ethyl acetate and incorporate it into more interesting aromatic compounds. But 0.27 tons per acre? I think you slipped a few decimal places. Grand cru designation requires yields of under 45 hL/ha, which is about 3 tons/ac assuming a press yield of 160 gal/ton.
Winetegrity and Tim Keller are one and the same… I think there is a different “remember me” cookie on the laptop i used for the last post…
John; my mistake. Indeed I slipped a decimal there and I saw it after. And yes yields of about or lower than 40hl/ha are necessary to really play that game.
Tim, Alice, Cory et al…
Sorry to be late to this party, but these posts are very interesting and I’d like to throw my own two cents in the mix.
The winery I work for has a policy of yeasting everything. No native anything. For the owners, educated by UC Davis, it is just too “dangerous” and “inconsistent”. So every lot of syrah, for instance, gets D21 or D80. The results are good, very predictable and everything always finishes primary and malo by Thanksgiving.
A previous winery I worked for used a modified approach – every lot was allowed to start spontaneously, but then was yeasted with a commercial strain 3 or 4 days later at a low rate. The results were always better than the straight yeasted lots. But again, the fear that has been instilled in winery staff about “native” yeast fermentations won over, and we never even experimented with a totally native ferment.
For my own project, I can allow the native yeasts to work at their leisure. And sometimes it IS leisurely! I often have lots that finish in July. But the resulting aromatic and flavor complexity is heads and shoulders above what a commercial yeast would give me. So I’m happy.
Incidentally, I find that the more naturally the grapes are grown, the better a native fermentation will work. I purchase some grapes, and they are always slow to finish. My own, naturally farmed, grapes, on the other hand, are always finished by winter. So there may be something going on regarding the grapes giving the right environment (completely free of sulfur, pesticides, whether organic or not, and herbicides). My feeling is that soluble fertilizers also effect the rate of fermentation.
So, that’s why the gods of wine invented commercial yeast strains, no? If your grapes are full of systemic fungicides, soluble minerals (which the plant has no choice but to take up), and/or sulfur, etc., you pretty much HAVE to use commercial yeasts in order to have a complete fermentation, and insure a consistent product.
There’s really no right or wrong in this issue – only a choice.
I must say as a technical consultant for a wine yeast manufacturing company I look a bit like the antichrist in this conversation. Fortunately I know I am not seeing that I have to deal with the flip side of the coin a lot, i.e. natural fermentations gone wrong. Alice I agree with you that one should keep winemaking as natural as possible. If you have good quality grapes and a good natural flora on your grapes and in your cellar then natural fermentation (if it goes to dryness) will give you a wine that is head and shoulders above a wine inoculated with a single strain. It is not rocket science to figure out that if you have a combination of yeasts conducting the fermentation, each one producing its own set of flavour active compounds from the precursors that the grapes provide, that you will have a very complex wine where no one particular aroma will dominate over the rest. Every single person that contributed to this blog so far will choose a wine like this because we are all wine connoisseurs. It is the ideal world. Unfortunately we do not live in the ideal world. The biggest amount of wines produced in the world are drunk by non-connoisseurs and the wines were potentially produced from average quality grapes. A winemaker, as noble as he wants to be, can only work with what he is given. If you have average quality grapes with an average natural yeast population then you will end up with an average to below average wines, possibly semi-sweet. However, if you choose a commercial yeast strain that is very good in enhancing varietal character and you use modern winemaking techniques such as cold fermentation on white wine, then you can make the best of an average situation. You can produce a bottle wine instead of a cask wine. In the end winemaking is a business and one has to make a profit – you have to sell your wine. The average consumer does not care if the wine was fermented with native yeasts or commercial yeasts. The wine is aromatic or not. They like it, or not. If you have very good quality grapes and a new winery, or if you have very strict cleaning procedures, then you are also not going to have a high enough population of natural flora in your cellar. Also in the case of white wine production where you have very little skin contact time with some varieties then your inoculum in the juice will be too small and you can have delayed onset of fermentation and a stuck fermentation character. The other much bigger contributor to the fact that people are moving towards inoculated fermentations is the issue of phenolic ripeness. For some vineyards in some years it will be at 24°Brix and some years 27°Brix. Personally I find picking at such high sugars ludicrous and it is my opinion that, that vineyard is planted in the wrong place or you are trying to make the wrong style of wine with it. Very few yeasts can ferment such high sugars to dryness. This is why natural ferments were possible for all the great vintages from the past when people used to pick at 21°Brix. Even in Bordeaux they pick at 23 and 24°Brix nowadays. So one does not always have a choice. If you pick at high sugars – then opting for a natural ferment is a huge risk, a huge financial risk and a huge career risk. Personally I think one should not waste energy on whether or not a winemaker uses native populations or commercial yeasts. The commercial yeasts have been isolated from great natural ferments. It is still natural. Rather worry about the amount of DAP people add to fermentations unnecessary or the massive amounts PVPP, egg white, gelatin, isingglass, casein, gum arabic, wood alternatives to name a few. Some winemakers add CuSO4 standard to every finished wine. Some people adjust pH with sulphuric acid. That is unnatural.