Long considered the blue-collar workhorse of the winemaking process, operating sub rosa, yeasts have recently taken center stage in many conversations about wine and the desire to emphasize the expression of vineyard apart from human and technological influence. At the essence of the debate is the decision to inoculate with commercial yeast or to allow the ambient yeast from the grape skins, the vineyard and the winery environment to start the fermentation process “naturally.” Quite often the opposing philosophies square off like a pay-per-view fight card: Romantic vs. Realistic, Chance vs. Control, Variety vs. Consistency and Risk vs. Safety.

Some Facts About Yeasts & the Big Ferment

Yeasts are fungal micro-organisms which are responsible for the fermentation process of transforming sugar into alcohol when producing beverages such as beer and wine. There are many different types of wine-related yeasts. Those that are found on grapes and in highest quantity in the vineyards, like Hanseniaspora and Kloeckera, can often start fermentations; but due to their intolerance to alcohol (they falter at about 3-4%), they can’t finish the job. Species from the more well-known Saccharomyces genus will eventually take over to complete the fermentation because they can tolerate much higher levels of alcohol and out-compete other yeasts for nutrients.

Of course, yeasts have been worker bees in winemaking for millennia, so what has changed? Start with the fact that wine today is a business. Many winemakers choose to inoculate their fermentations with commercial yeast strains to reduce the risk of “stuck” fermentations and develop a more consistent product, which helps protect the significant investment in their business.

Commercial yeasts are not synthetic, notes Tim Keller, a UC-Davis graduate and a winemaker of over 10 years currently consulting for Alta Ridge Vineyards in Sonoma. He says, “They are just selected from nature, grown and packaged into a format where they can be re-used.”

According to Karien O’Kennedy, a technical consultant from Anchor Yeast, the yeasts that wind up being produced commercially are picked precisely because of their ability to keep a fermentation going. Now we are getting closer to the crux of the current debate: Many people attribute rising levels of alcohol in modern-day wines to commercial yeasts, whose greater efficiency ensures that cuvées ferment completely. These yeasts “have been isolated from great natural ferments,” O’Kennedy explains. “Wines produced with commercial yeasts just often have higher alcohols because they are actually dry. Many natural ferments are not.”

An important point here: Yeast alone, commercial or native, cannot cause the higher alcohol levels in wine. From the biological perspective, final alcohol level is still driven by the sugar present in grapes at the time of harvest. When producers wait for more ripeness and pick at 28 Brix, which represents the sugar content in the berries, they can expect about 15% alcohol after fermentation to complete dryness.

Keller notes that winemakers are conscious of the their choice of yeast, just as they are of many other aspects of the vinification process. He says, “Selecting [commercial] yeast strains that can finish high-alcohol fermentations allows us to make a wine style that was never possible before.”

Wine as a Business: Big Market for Big Wines

But who is really responsible for that “style,” which detractors of high-alcohol wines are apt to call “Parkerized?” Is it Robert Parker himself, and/or other gatekeepers who heap high scores on full-bodied wines. No doubt the debate has been intensified by subjectivity: one person’s “highly extracted” is another’s “over the top.” If consumers buy these wines—in essence creating demand for the style—shouldn’t wineries supply it?

This is where I think the true source of the divergence between these two schools of thought emanates. When someone decides to get into the wine business, he or she faces a fundamental decision to style wines toward the mass market, or to make wine of “terroir,” representative of its site, at the risk of appealing to a much smaller market.

Expression and Passion of Terroir

While there are many factors during the process of making wine that have an impact on the final product, natural ferments are considered to be one, if not the, top qualifier in holding what some call the “DNA” of the vintage. According to the noted author Alice Feiring, “using native yeast ferments is essential to a terroir-expressive wine.”

To be successful, the winery must possess very healthy grapes, grown in well-managed soil that has not been chemically farmed, followed by expertly clean winemaking. Indeed, the cliché “great wine starts in the vineyard” applies more pointedly than ever to the challenge of making wine naturally.

For some, the idea of natural wine does include a level of romance… of allowing the grapes to turn to wine practically by themselves with just a watchful, mothering touch along the way only intervening when absolutely necessary. “I am in for the game and the adventure and the passion and yes, the taste. I love wine. I love variety,” expresses Feiring.

Cory Cartwright, host of saignée, is adamant that he does not favor natural-yeast wines based on philosophic loyalties, but rather to enjoy what is in the glass. He explains, “Sometimes it can be sublime, sometimes it can be bad, but it is rarely ever boring or standard.”

It comes down to the personal preference and taste of the wine consumer once again, as it always should. But can the average wine consumer taste the difference in a natural wine? In a natural ferment, there will be more diverse fermentation dynamics due to the many yeast species that are coming from the vineyard and the winery as opposed to a ferment inoculated with a single strain. Studies at Kumeu River Wines in New Zealand, who naturally ferment all of their wines, identified upwards of eight different species present throughout their fermentations. Natural ferments will often occur at lower temperatures and take longer to finish, which allows yeast to increasingly facilitate the development of texture and finesse in the wine, which one might be able to detect by way of mouthfeel or unique esters.

Tim Keller believes that one should be able to taste a difference. However, Linda Bisson, professor of Viticulture & Enology at UC-Davis, disagrees, stating, “Most of the time they cannot [taste a difference] unless it has strong ‘off’ characters.” Alice Feiring thinks it’s easier to tell the difference in white wines, but in many cases it’s more about being able to identify what is not natural in the wine, as in, for example, a Verdejo seemingly manufactured to impart Sauvignon Blanc-type aromas. She knows people who “can put their nose in Nebbiolo and smell the typical laboratory yeast used from Piemonte.” Michael Brajkovich, winemaker at Kumeu River, acknowledges he has been able to “tell what [commercial] yeast was used in a fermentation, but could not distinguish the variety or vineyard” in those same wines.

How to Find Natural Wines

Unfortunately, there are no labeling laws requiring ingredients on the label, and even if a producer identifies their wine as being made from natural ferment or native yeast, there is no way to know that the native yeast wasn’t supplemented with some commercial yeast after fermentation started. So, it takes footwork by the consumer to find producers who are legit; following blogs that focus on natural wine can help identify wines that have been enjoyed.

In the end, I believe it is simply a matter of style and taste rather than of right vs. wrong. As wine lovers, we should be open to experience what raw flora can deliver and make our own decisions that further define our individual styles and tastes as well as advance intelligent conversation about differing wine styles. To each his own.

Recommendations

Favorite Natural Wine Producers of Cory Cartwright:

Paolo & Giampero Bea

Pierre Overnoy

Jacques Selosse Substance

Natural Wines I have recently enjoyed:

2007 Edmeades Zinfandel Mendocino

2006 Yangarra Shiraz McLaren Vale Single Vineyard

2007 Kumeu River Hunting Hills  Chardonnay

* This article was also published at PalatePress: The Online Wine Magazine

Depending on how deep your passion is into the world of wine, you may find yourself yearning for further understanding of how wine is transformed from clusters of fruit in a vineyard to a bottle of yummy goodness.  Or not.  As somewhat of a science nerd, you’ve probably read some of my posts about making wine in my basement and the winemaker’s certificate program I am current studying.  Or not.  In my blogging “travels” over the interweb I stumbled across the natural wine movement, which very much intrigues me, and found that my love for wine science and the focus on less human interaction in the winemaking process cross at a point involving the single-celled organisum that is significantly responsible for making wine what it is: Yeast.

To further delve into this intersection, I wrote a piece about yeast and it’s fresh starring role which is published over at the Palate Press, the new online wine magazine.  Check it out!

Cheers!

Michael Brajkovich, Winemaker

When you think of wines from New Zealand what comes to mind first?  Probably something with a strong tart pink grapfruit and cat piss smell in most cases… but, not from Kumeu River Wines near Auckland.  They are touting some pretty fantastic Chardonnay these days because they have found this variety performs best in their vineyards as opposed to the more well-known regional varieties of Sauvignon Blanc and Pinot Noir.  I had an opportunity to sit down with Michael Brajkovich, the 2nd generation winemaker of Kumeu (pronounced Koo-Myew), during his visit to Hinton’s in Atlanta and received a wonderful history lesson as well as some insight into the world of natural wine and native yeast.

The family emigrated from Dalmatia, a region in present day Croatia, to New Zealand in response to Government control of the region and the regulatory requirement that all males 16-18 enter the army.  Once in their new home, the family made ends meet by farming their orchards, raising cattle as well as fishing before eventually planting wine grapes.  Initially, Michael’s dad produced fortified wines including Sherry, however, he was more partial to dryer wines and eventually started growing and producing Muller-Thurgau, a white variety of German origin, in the 1960’s though it was still in the style of an aperitif.  Michael knew at an early age he would stick with the family business of making wine and joined the team as a winemaker in the early 1970’s after attending university.  By that time, the new cafe style dining trends of the time led to increased demand for completely dry wine styles.  Kumeu had 60 acres consisting of Cabernet Sauvignon, Cabernet Franc, Sauvignon Blanc and Chardonnay and worked with different trellising designs throughout, with the Lyre design becoming most prominent.

By the mid 1980’s Kumeu was devoted to using natural ferments, which means they let the ambient yeast from vineyard and winery start each fermentation batch.  Studies of ferments at the winery confirmed that upwards of 8 different species of yeast were present throughout fermentation, with the well-known S. cerevisiae completing the job.  Additionally, Michael allows his Chardonnay to age sur lie with battonage for an extended period of time by implementing a Bordeaux technique that includes taking the wine off the lees for a week before putting it back in and then oxygenating.  This process counters disulfides that can build up during sur lie aging and allows for extended time on the lees allowing the yeast to facilitate more distinctive aromatics and other varietal characteristics.  Additionally, it keeps the buttery notes to a minimum since yeast consumes diacetyl, the major contributor of butter-esque characteristics.  Ultimately, Michael employs a Burgundian style of winemaking, especially the use of an older barrel regime, as he never wants his wine to smell or taste like oak, as well as malolactic fermentation (MLF) as a means to reduce acid and round out the wine and never to add buttery notes!  All of the fruit for every wine is hand-harvested and whole-berry pressed as well.

The 5 Chardonnays we tasted on this evening were just phenomenal and nothing like I’ve experienced before.  At times when I felt I experienced a toasty like aroma, Michael assured me that it was most likely caused by the extended yeast contact and less from oak, since they use well-used barrels that were more than 5 years old and not giving off much oak characteristics anymore.

2005 Kumeu River Estate Chardonnay – completely barrel fermented in French oak.  2005 was a cooler vintage and as such will age faster.  If you can get your hands on the 2004, it is looking really good and will have a longer life.

2007 Kumeu River Village Chardonnay- from the lower end of the vineyards, this was a little sharp with significant minerality.  2/3rds were fermented in stainless steel with the rest in barrel and spent 6 months on the lees with battonage.  Slightly toast notes on the nose, again, from the yeast as explained above.

2007 Kumeu River Coddington Chardonnay- this vineyard is owned by a grower/filmaker and the first harvest was in 1998.  We get much more apricot and peach fruit and they do use more and stronger oak with this one.

2007 Kumeu River Hunting Hill Chardonnay – this vineyard overlooks the more infamous Mate’s vineyard and has a South and West aspect.  There is much more fruit on the nose with some white flower.  The mineral is barely detected.  This was my favorite.

2007 Kumeu River Mate’ s Vineyard Chardonnay- the creme de la creme and the vineyard is named for Michael’s father.  We got much more mouthfeel and texture with this wine, which uses 30% new oak.  The grapes in this vineyard are from the Mendoza clone developed by H. Olmo of UC-Davis, labeled UDC-01.  Unfortunately, the vineyard has the leafroll virus, but is still able to produce fantastically high quality fruit.  Not sure how much longer this will be able to happen, so get it while you can.

Michael is a great story teller and passionate winemaker making some fantastic Chardonnay from a region more well known for other wines.  If you’re looking for variety, texture and wines that melt in your mouth, look no further than Kumeu River.

Cheers!

(no relation of this topic to the title… I just had the Foghat song running through my skull for some reason) 

It’s now Day 5 (Day 3+ of fermentation) and the yeast are really doing their thing.  You can see from the chart below that the temperature has risen quickly to around 75F (23.9 C) and the Brix, or sugar level, has dropped dramatically, down to 6 ( or 1.023 SG).  If it keeps going like this, I may be racking to the carboy this weekend.

All along I have been punching down the cap twice a day to continue extracting color and tannins, though you won’t get much more color extraction past about 3 days.  When we are ready to rack into the carboy, we will siphon the “free-run” out first which is the plain wine juice.  This is generally considered the premium part of the wine and often some winemakers will only use the free-run for their wine.  However, we will also take the rest of the must (or lees) and press the remaining juice out of them to a certain level.  This is generally done in fractions which include differing levels of pressure.  At each fraction, more and more of the phenolics and tannic characters are extracted from the seeds and skins, which can get bitter pretty quick.  So, this means I will taste the resulting juice each time before I decide to add it to the carboy.  Once (or if) I get to a point where the pressed juice is too bitter, I will not add it and it will be tossed.  Since I am doing the pressing by hand, I am not sure I will have much of a problem here.

It’s day 2 of fermentation (day 4 of the whole operation), but who’s counting?  One of the main pointers I ever got about making wine at home is “BE PATIENT” which is very tough for me.  I am definitely an instant gratification kind of guy.  So, I waited patiently as my frozen cabernet sauvignon must thawed and eventually reached the 60’s in temperature and I was finally able to throw some yeast into the mix.

Within 12 hours I could see a difference and by the time I got home from work yesterday, there was a full “cap” on the must along with some obvious bubbles and a snap, crackle and pop… we are definitely in business.  To summarize, here is what’s been done so far:

1. SO2 after the must thawed and was able to move it around

2. At around 60F I added some pectic enzyme which will help remove/prevent any haziness as well as increase juice extract from the grapes

3. At around 65F I added one package of Lalvin RC 212 wine yeast, which is good for 5-6 gallons of wine

4. Right after that I added some Yeast Energizer according to the manufacturer’s instructions, which was 1 tsp per gallon of must in this case

5. Then I added 1 ounce of oak cubes

6. Each day I will punch down the cap, which is the grapes, seeds, stems, etc.. that get pushed to the top as a result of the fermentation activity, at least once (maybe twice for more extract, color and tannin).  I will also measure the temperature and Specificy Gravity (SG), which is basically sugar density.  Remember, we are trying to ferment until the wine is “dry”, or there is no sugar left.  This will occur when the SG is about .995-.998.  Right now I am at 1.100

Video:  Day 4