Wines, Naturally

Many wine experts are very skeptical about natural winemaking techniques. They say natural fermentations lead to unreliable or stuck ferments and regard doing away with sulfite additions — a requirement of certified organic wines in the United States — as handing over the wine to spoilage microbes.

But in recent years, a small but growing number of winemakers are using less chemical intervention and turning it into commercial success. Their techniques vary, but the inspiration is often a desire to craft wines that are unique and more natural, coupled with environmental concerns. These wines, say the advocates, have an originality and depth of flavor unmatched by the results of a more conventional winemaking process.

And let’s face it, if the superstar Bordeaux winery Château Pontet-Canet can go not just organic, but biodynamic, then you should be able to hold back on those chemicals just a little, don’t you think?

As I researched organic winemaking, I wanted to hear about the pros and cons directly from the winemakers who have bought in. So I consulted with three professionals who make wines more naturally than the norm.

Defining Organic, biodynamic, and Natural WInemaking

Before diving in, let’s define what we’re talking about. In the US, a bottle labeled as certified organic wine must satisfy United States Department of Agriculture (USDA) rules governing what you can do to the grapes in both the vineyard and the winery. Certified organic grapes cannot be subjected to any synthetic chemical, pesticides, or herbicides. For the wine made from these grapes to be certified organic, no added sulfites are allowed (350 parts per million (ppm) are permitted in conventional wine) and anything added (like yeast) generally must be certified organic, or, like bentonite, be on the USDA’s approved list of additives. (For both grapes and wine, domestic producers can turn to OMRI Listed products: Those reviewed and listed by the Organic Materials Review Institute. That listing is accepted in the USDA National Organic Program.)

In contrast, European organic wine standards allow sulfite additions. Winemakers can add up to 100 ppm of sulfite for reds and 150 ppm for whites.

Biodynamic grapes and wines push organic concepts to another, some might say, esoteric level. According to Demeter International (the world’s biggest biodynamic certification body) guidelines, grapes should be hand harvested from vineyards where “the farm is managed as a living organism.” No herbicides or pesticides of any kind are permitted and growers are encouraged to base vineyard decisions on lunar cycles (yes, you read that correctly). In the winery, natural ferments are used while acidity adjustments, micro-oxygenation, and even plastic containers are not permitted. Interestingly, sulfites are allowed but cannot exceed 100 ppm at bottling.

Compared to the rules and regulations for organic and biodynamic wines, natural winemaking is more of a philosophy. Supporters generally advocate organic and biodynamic vineyard practices and less to no chemical intervention in the winery. Alexandre Bain, the only natural wine producer in France’s Pouilly-Fumé wine region, put it this way in Decanter Magazine: “Organic and biodynamic are the tools, natural is the philosophy.”

Natural winemaking can also come with attitude. The international Raw Wine Fair advocates more transparency in winemaking including labelling bottles with the details of any processing or additives. As for specifications, “natural” has no legal or regulatory meaning.

Goodbye Intervention

So the winemaking options range from less chemical intervention to more extreme forms of natural winemaking that involve no intervention at all. The common denominator is the use of healthy, quality fruit, often grown organically or biodynamically. So home winemakers interested in holding back on the chemicals need to be able to source or grow disease-free, high-quality grapes.

As a more natural winemaker, the shopping list of possible chemical additions you might give up includes: Pectic enzymes to help break down the must; tannins added before, during, and after fermentation to take out proteins and provide grip and mouthfeel; acid additions to lower pH and raise acidity; oak chips and powder to add oaky aromas, and glycerin to enhance body. Chemicals for clarifying and fining include bentonite, kieselsol, isinglass, gelatin, and casein. There’s also lysosome for protection against spoilage and stopping malolactic ferments, egg whites to reduce astringency. Copper sulfate additions can deal with hydrogen sulfide (rotten egg gas) aromas that can result from nutritionally stressed yeast.

“We have limited our toolbox,” says Sebastian Donoso, where at Bonterra Vineyards (Wine Enthusiast Magazine’s 2016 American Winery of the Year), he says everything about their winemaking is less reliant on chemical intervention and more natural.

“For whites you’re talking about bentonite, tartaric acid, KHT, which is cream of tartar, and sulfites. That’s about it,” says Donoso. For reds, Bonterra, located in Mendocino County, California, adds some tannins, bentonite, egg whites, sulfites and, if necessary, acid.

Silver Thread Vineyard’s Paul Brock makes 12 different wines per year in New York’s Finger Lakes region, six of them are Rieslings. He aims for wines that express the vineyard and minimize actions in the winery that might take something out of the wine.

“I’m really focused on doing all my winemaking in the vineyard and through fermentation, and once fermentation is over just getting a stable product into the bottle.” Brock says his main tools are small amounts of sulfite and argon gas to top up tanks and barrels.

The vineyard held an organic certification during most of the 1990s but dropped the certification over environmental concerns about using copper sulfate fungicides for the mold-related diseases more common in cooler and humid climates like the Finger Lakes.

The cooler climate, says Brock, can however have its advantages for more natural winemakers. His grapes generally come in with a pH of 3.6 or lower — good levels to help control spoilage microbes — allowing him to comfortably use less sulfites. He usually uses 120 ppm and with some low pH Rieslings as little as 45 ppm.

Brock doesn’t use fining agents as varieties he works with, apart from Gewürztraminer, don’t have the high level of protein instability that might call for a fining agent like bentonite.

“Consumers, I’ve always felt, want to be able to taste and feel things in the wine and know that they came from the vineyard, and as a winemaker if I start taking things out then that’s not being true to my vineyard, so I’m not looking to fine my wines in any way.”

He uses basic pad filtering (three times) and membrane filtering (once) for all his varieties to ensure microbial stability before going into bottle.

“Bonterra doesn’t make organic wines, we make wines made with organic grapes,” explains Donoso. Bonterra also uses some sulfites during the winemaking process, adding up to 100 ppm to ensure the longevity of their bottles and to better guard against spoilage.

Like Brock, Donoso underlines the importance of pH in facilitating a more natural winemaking process.

“Some varieties you can pick very ripe and still have a very low pH, like Petite Sirah for example. Those varietals, even ripe, over 25 °Brix, will have a pH of 3.3 or 3.4 compared to Cabernet. If you pick Cabernet at 25 °Brix you’re talking about 3.7 or 3.8,” he explains. “The pH is really your determining factor when it comes to bacteria.”

As soon as the grapes are harvested, Bonterra sends a sample to the local laboratory. “Whether it’s organic or conventional, it’s just a good practice,” says Donoso. “Get a baseline for your nitrogen status and also run some chemistry to find out pH and titratable acidity.”

“If your pH is really high on red grapes then you may want to consider acidulating with tartaric acid before primary fermentation.” Donoso says acidulating before fermentation, rather than afterwards, not only improves bacteria control but the acid absorbs better, producing a better tasting wine.

Providing Nutrients

At this pre-fermentation prep stage, many conventional winemakers would be adding artificial sources of nitrogen, like diammonium phosphate, commonly called DAP. Unhealthy yeast can produce hydrogen sulfide aromas in the wine but DAP ensures the yeast has enough food to remain healthy and complete fermentation. Winemakers who prefer more natural techniques do this differently as well.

Rather than DAP, Bonterra adds organic yeast nutrients, which can cost four times more than artificial DAP. Some experts say organic nitrogen versus fertilizer-based DAP can be as much as four times more effective in nutrient values, but there is no peer-reviewed research to support these assertions.

Donoso says picking balanced fruit, rather than overripe grapes with very high Brix, will bring down the amount of nitrogen you may need to add and reduce stress on the yeast.

“So we focus on making sure that the yeast is fed, that we’ve supplied that difference in nutrients and also the temperature of the fermentation, that it doesn’t get too cold, that it doesn’t get too hot. Also the pump over regimen, there’s a lot of yeast in the cap, in the skins, so you have to pump it over to make sure that the yeast is in solution,” explains Bonterra’s winemaker.

However, if you’re keen to go natural and confident in the quality of your grapes, you could do what Australian natural winemaker Wayne Ahrens does and not add any yeast nutrients to the must at all.

“To me as a farmer, those sorts of nutrients come from the soil,” says Ahrens, owner of organically and biodynamical certified Smallfry Wines. “So when we’re working with our vine nutrition we’re using minerals to adjust any shortcomings in the soil and that should result in good, healthy must coming into the winery.”

Healthy Fermentations

Ahrens says they don’t get reductive issues during fermentation, like the hydrogen sulfide production that results from poor yeast nutrition. The Smallfry website boldly states their natural winemaking philosophy in colorful Aussie slang, “bugger all intervention,” it reads.

“So it means no packet yeasts, no packet bacteria, not opening packets really at all, and hand-harvested grapes, organically biodynamically grown,” explains the Aussie winemaker.

Ahrens says the only packet he ever opens during the winemaking process is for sulfite and he uses very little, even compared to Donoso and Brock. He sticks to less than 50 ppm, which is recommended by many natural winemakers and under half the amount allowed under Australia’s organic standard.

“We’ve made zero-sulfur wines and they’ve worked out quite successfully but our distributors are more scared of it than we are, really.” He says distributors sometimes regard natural wine as a risky investment.

Ahrens does not believe the conventional view that sulfites are necessary if you want to age your wine is necessarily the case.

“I think the elevated sulfur levels that were being used were measured to deal with faulty corks,” he contends. “It depends a bit on how the wine is made as well. If you make your wine entirely reductively during the process, they’re more hungry for oxygen. If you give them oxygen during the fermentation process then they’re much more stable.”

Smallfry’s winemaker says an ample supply of oxygen is fundamental for a healthy fermentation.

“As soon as I’ve got free juice under the cap, very early in the process, I’ll rack off that juice and splash it through a sieve, give it lots of oxygen, then pump it back over the cap,” says Ahrens.

Packet yeasts are designed to be good fermenters and often start vigorously. By contrast, the phobias surrounding natural winemaking picture a hapless winemaker waiting many days, even weeks, for a natural fermentation that might never start. Ahrens says oxygenation techniques help a natural fermentation get started within 48 hours.

Smallfry uses multiple half-ton fermentation containers that stand about 2.5 feet (0.76 m) high, which he drags into the sun to get things going, claiming that the sunlight itself has antimicrobial activity.

During that first 48 hours Ahrens and his helpers literally hand mix the must to make sure the grape skins circulate. “It’s good to do with your hands or feet because you can feel little warm patches of the ferment starting to get going and you can mix them through. Generally by day 3 there’s a cap forming and free juice under the cap,” Ahrens said.

Fermentations last about two weeks for reds and for some whites, in contrast to conventional methods that encourage minimal skin contact, up to one month on the skins. Ahrens says a longer fermentation is ideal for stabilizing the wine.
Ahrens says serious spoilage issues are rare. “We had a stressful year in 2016 and I had three wines where I had to intervene and that was more than I’d had in the previous 10 years altogether. So it doesn’t happen very often,” he says.
If an issue comes up he takes the necessary remedial action and sells the wine under a different label. The problem could be something as routine for a conventional winemaker as an acid adjustment. For example, the 2004 vintage was a little out of balance so they adjusted the pH with 1 g/L of tartaric acid.

“We’re not in the business of making bad wine,” says Ahrens. He monitors pH levels during the winemaking process and takes careful notes of temperature. “We’re trying to create a situation conducive to the microorganisms we want to grow . . . so temperature is fundamental to that.” This starts by picking the grapes in the morning so they are cool when they come into the winery. This not only discourages spoilage organisms but can also give the best opportunity for yeasts like Hanseniaspora, a wild yeast commonly found on grapes, to start the fermentation, adding complexity before Saccharomyces yeast strains kick in and dominate.

While oxygenation is used to encourage the primary fermentation, the secondary or malolactic ferment is allowed to proceed at its own pace, but Smallfry does run tests to track their progress. Two years ago their primary and malolactic ferments were happening together. “Whereas this year the malos have fired up again now that the weather has warmed up,” says Ahrens.

Ahrens doesn’t know exactly what his yeasts are. “No. I’ve got no idea,” he confesses. “We’ve never used packet yeast in that shed but like I say, killer strains occur naturally and I think most likely it is a killer yeast that ends up conducting our fermentations, but we’re starting off with a whole grab bag of different yeasts.”

By contrast, Bonterra doesn’t use natural fermentations and has invested considerable effort finding the right inoculated yeasts that will complete fermentations at a high alcohol level with minimal use of nitrogen.

“The key is not stressing out the yeast,” says Donoso. “You want to be able to finish the fermentation. So we work really hard to make sure that the yeast can carry out the fermentation from beginning to end and leave zero sugar behind. The only way to do that is to work with your growers when it comes to your nitrogen levels in the fruit and that varies year to year, from vineyard to vineyard, appellation to appellation, there’s a lot of variation.”

For white wines, he says there are two strains that are very good and widely available. For Sauvignon Blanc he recommends VIN 13. “It’s a good style and ester-releaser, which are really positive things for Sauvignon Blanc so you get the grapefruit character.” It also has very low nutrient requirements, can handle low fermentation temperatures of around 50–55 °F (10–13 °C) and doesn’t produce any hydrogen sulfide. For Chardonnay, Donoso uses DV10, which facilitates a clean fermentation and doesn’t impart any flavor characteristics.

For reds, Bonterra often uses UV 43 — a mixture of yeast strains including Saccharomyces bayanus, which devours fructose better than Saccharomyces. “So that’s very important for varietals like Zinfandel that have a higher level of fructose and glucose at the very end because you want to be able to finish the fermentation.” UV 43 is a good fermenter for big, fruit-forward reds and can handle up to 18% alcohol with a low nutrient requirement.


The aging process can be the undoing of wines, not just those made naturally or with less sulfites. The need to top up barrels because of liquid loss from evaporation exposes them to the air and can cause oxidation and spoilage.

Donoso says the undoing of the home winemaker, especially if they are going a more natural route, can be the temptation to open their barrels or carboys too often.

“You don’t want to open the barrel — you want to have that vacuum there.” He says with a vacuum and minimal sulfur levels, opening the barrel to top up every one to two months is sufficient. (The vacuum develops naturally as water and ethanol vapors evaporate from a tightly bunged barrel through transport between staves or through the wood.)

Keeping their barrel room at 80% humidity through the use of a misting device and keeping it between 55–58 °F (13–14 °C) means that they don’t lose too much wine through evaporation from month to month.

Before bottling, Bonterra puts the wine through a cross-flow filter and then a sterile filter to guarantee removal of bacteria and yeast.

Cleaning & Sanitation

One last question I had about organic winemaking is the use of cleaning and sanitizing agents. I have a soft spot for stomping grapes in the ancient Greek and Roman tradition, but the thought of must in contact with feet as Ahrens says is employed at Smallfry does bring thoughts of cleaning and sanitation to mind.

“We don’t use sanitizers in the winery at all, we just use water,” says Ahrens.

I was astonished. In the world of modern winemaking, if there’s one concept that gets repeated ad infinitum in this magazine and in any enology lesson, it’s the importance of cleaning and sanitation.

“Yeah,” says Ahrens in an Aussie drawl. According to Ahrens, sanitation regimes using chemicals like potassium metabisulfite are not as widespread in the wine industry as you might think.

“I worked at Jacobs Creek Winery, did my trade as a cellar hand there, and they talk about if it looks clean, it is clean. It was only when we were working specifically with post-sterile filtration that we actually had to sterilize and sanitize [with chemicals].”

Ahrens says even a number of conventional wineries in the Barossa Valley of South Australia don’t use chemical sanitizers on their winemaking equipment. One primary consideration, he says, is the damage these chemicals can do in the wastewater stream.

But if you think this might be your chance to justify less time cleaning or sanitizing, you’ll be disappointed.
“We certainly wash things immediately after use; we’re always cleaning,” says Ahrens. Smallfry uses cold water to rinse and flush out lines, pumps, hose out tanks and containers, and then repeats this process just before the next winemaking session.


So does going natural and foregoing chemical tools used by more conventional winemakers improve the flavor of the wines?
“I don’t believe that organic wine or biodynamic wine tastes better than a conventional wine,” says Donoso. “For me it comes down to a feeling. It’s a belief system, biodynamic specifically, and I do believe that the energy and forces are going to help the fermentation and that the wine is going to be more sound and more true to its terroir than a conventional wine.”
Ahrens believes wines put through a natural fermentation have a broader profile with more complexity. “It’s a width to the palate that I don’t see much in wines that have been fermented with a single packet yeast.”

His advice to the home winemakers interested in going natural: Take your time.

“We went at it very slowly and carefully at the beginning and worked out what we needed to do to make sure things didn’t go wrong. So I’ve got a pretty strong recipe in my mind now that I’m really quite comfortable with.”