Wild Fermentation With Capturing and Using Natural Yeasts

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Discover the art of wild fermentation and learn how to capture, cultivate, and brew with natural yeasts. This comprehensive guide covers techniques for creating unique fermented beverages with complex flavors that commercial yeasts can’t match.

Introduction to Wild Fermentation

In a world dominated by commercial brewing yeasts, there’s a quiet revolution happening. Brewers and fermentation enthusiasts are increasingly looking to the past—to wild fermentation techniques that have been used for thousands of years before the invention of pure yeast cultures. This return to ancestral methods isn’t merely nostalgia; it’s about exploring complex flavor profiles that can’t be replicated with laboratory strains.

Wild fermentation involves capturing and cultivating the natural yeasts and bacteria that exist in our environment—on fruit skins, in the air, on grain husks, and virtually every surface around us. These microorganisms have been our unseen partners in food preservation and alcoholic beverage production since before recorded history.

“Working with wild yeasts connects us to brewing traditions that span millennia,” explains Jeffrey Maranian, founder of the Wild Fermentation Project. “Before pure yeast cultures were isolated in the 19th century, all fermentation was wild fermentation.”

This comprehensive guide will explore how to capture, cultivate, and brew with wild yeasts to create unique beers, wines, meads, and other fermented beverages with character and complexity that commercial yeasts simply cannot match.

Understanding Wild Yeasts and Bacteria

The Microorganisms Behind Wild Fermentation

Wild fermentation relies on a diverse community of microorganisms, primarily:

1. Wild Yeasts
   • Saccharomyces species: Relatives of brewing yeast that occur naturally in the environment
   • Brettanomyces: Often called “Brett,” known for creating complex, funky flavors
   • Pichia, Candida, Hanseniaspora: Less common yeasts that contribute unique flavor compounds
2. Lactic Acid Bacteria (LAB)
   • Lactobacillus: Creates lactic acid, providing sourness and preservation
   • Pediococcus: Produces distinctive acidity and sometimes diacetyl (buttery flavor)
3. Acetic Acid Bacteria
   • Creates vinegar-like acidity when exposed to oxygen

According to research published in the Journal of Applied Microbiology, a typical wild fermentation can contain dozens of different microbial species working in succession or in concert. This diversity leads to flavor complexity that’s difficult to achieve with single-strain commercial yeast.

Wild vs. Commercial Yeasts: Key Differences

Understanding how wild yeasts differ from their commercial counterparts helps explain their unique effects:

Characteristic	Wild Yeasts	Commercial Yeasts
Diversity	Mixed cultures with multiple species	Usually single isolated strains
Attenuation	Often highly attenuative (drier finish)	Predictable, strain-dependent attenuation
Flavor Profile	Complex, evolving, sometimes unpredictable	Consistent, predictable, style-specific
Fermentation Time	Usually slower, sometimes months	Typically faster, often 1-2 weeks
Alcohol Tolerance	Variable, often lower than commercial strains	Usually selected for high tolerance
pH Tolerance	Many wild strains tolerate low pH	Variable pH tolerance by strain

Commercial yeasts offer consistency and predictability, which is why they’ve become the brewing standard. Wild yeasts, however, offer something different: adventure, complexity, and a connection to place and tradition.

Capturing Wild Yeasts

Natural Sources of Wild Yeast

Wild yeasts exist virtually everywhere, but certain sources are particularly rich:

• Fruit skins: Especially unwashed organic fruits with their natural bloom intact
• Flowers: Particularly fragrant varieties like dandelions, elderflowers, and fruit blossoms
• Raw honey: Contains natural yeasts and bacteria from flower nectar
• Tree bark: Especially from fruit trees and oaks
• Grain husks: Unmalted grains carry natural microflora

According to Dave Logsdon, founder of Wyeast Laboratories, “The best wild yeasts for brewing often come from the same places we get our brewing ingredients—fruits, grains, and honey all harbor microorganisms that have co-evolved with these fermentable materials.”

Simple Capture Methods for Beginners

For those new to wild fermentation, these three methods offer accessible starting points:

1. Fruit Mash Method

This technique harnesses the natural yeasts present on fruit skins:

Ingredients:

• 1 cup chopped organic fruit (berries, apples, or grapes work well)
• 1 cup water
• 2 tablespoons raw honey or unrefined sugar

Process:

1. Lightly crush fruit in a sterilized glass jar
2. Add water and honey/sugar, stir with a clean utensil
3. Cover with cheesecloth or coffee filter (allows air but keeps insects out)
4. Stir twice daily and watch for bubbling
5. Once actively fermenting (usually 3-5 days), strain and use the liquid

2. Flower Capture Method

Particularly effective in spring and summer using nectar-rich flowers:

Ingredients:

• 2 cups organic, unsprayed flowers (dandelions, elderflowers, or fruit blossoms)
• 2 cups water
• 2 tablespoons raw honey or unrefined sugar
• 1 organic raisin (optional, provides additional nutrients)

Process:

1. Place flowers in sterilized glass jar
2. Add water, honey/sugar, and raisin if using
3. Cover with cheesecloth and secure with rubber band
4. Stir twice daily
5. Look for bubbling and yeasty aroma (typically 4-7 days)
6. Strain and use liquid starter

3. Backyard Capture Method

For the truly adventurous, this method captures yeasts from your local environment:

Ingredients:

• 1 cup wort or sugar water (10% sugar solution)
• Small shallow dish

Process:

1. Place sugar solution in shallow dish
2. Set outside in garden, orchard, or woodland for 4-8 hours
3. Transfer to sanitized jar and cover with cheesecloth
4. Watch for fermentation signs over 3-7 days
5. If mold appears, discard and try again
6. If successful fermentation occurs, use as starter

When capturing wild yeasts, patience is essential. Ambient temperature impacts success rates—aim for 65-75°F (18-24°C) for optimal results. Remember that not every capture will be successful or produce desirable flavors, so be prepared to experiment.

Advanced Capture Techniques

For experienced fermenters seeking more control:

Stepped Propagation Method

This method selects for alcohol-tolerant yeasts through progressive feedings:

1. Start with basic fruit or flower capture method
2. Once fermentation begins, add equal volume of fresh sugar solution (10% concentration)
3. Allow to ferment for 48 hours
4. Repeat step 2, gradually increasing sugar concentration to 15%
5. By the third or fourth feeding, you’ve selected for stronger yeasts

Selective Media Technique

Borrowed from microbiology, this approach discourages unwanted microbes:

1. Create capture wort with low pH (add lactic acid to reach pH 4.0-4.5)
2. Add small amount of alcohol (1-2%) to discourage bacteria
3. Add hop extract (IBUs 15-20) to inhibit some bacteria
4. Proceed with normal capture method

According to microbiologist Dr. Linda Harris from UC Davis, “Selective pressures like low pH and the presence of hop compounds can help isolate yeasts that will perform better in brewing conditions while discouraging spoilage organisms.”

Cultivating and Maintaining Wild Yeast Cultures

Building a Strong Wild Yeast Starter

Once you’ve captured wild yeasts, building a viable starter is crucial:

1. Initial Feeding:
   • Add your wild yeast capture to 4 oz (120 ml) of wort with OG 1.040
   • Incubate at 70°F (21°C) for 24-48 hours
   • Look for signs of fermentation (bubbling, foam, yeasty aroma)
2. Step-Up Feedings:
   • Add 8 oz (240 ml) of fresh wort (OG 1.040)
   • Allow to ferment for 24 hours
   • Repeat with progressively larger volumes until you have sufficient starter
3. Sensory Evaluation:
   • Smell the starter after each step-up
   • Desirable aromas: fruity, floral, spicy, bread-like, funky (if desired)
   • Undesirable aromas: strongly acidic, nail polish, rotten eggs, mold
   • Taste small amount if smell is acceptable (should be tart, possibly fruity or funky, but not unpleasant)

Brewery consultant Will Meyers suggests, “Don’t rush this process. Each step allows the most competitive and beneficial microorganisms to dominate, creating a more stable and effective culture.”

Long-Term Storage and Maintenance

To preserve your wild culture for future use:

Refrigeration Method

1. Feed culture with fresh wort or sugar solution
2. Allow to become active for 24 hours
3. Refrigerate in sealed (but not airtight) container
4. Feed monthly with fresh sugar solution or wort
5. Viable for 3-6 months with proper maintenance

Freezing Method

1. Mix equal parts active starter and 50% glycerin solution
2. Divide into small sealed vials
3. Freeze at -4°F (-20°C) or colder
4. Viable for 1-2 years
5. Thaw and step up with fresh wort when needed

Dried Culture Preservation

1. Spread active starter thinly on sterilized parchment paper
2. Dry at low temperature (below 95°F/35°C)
3. Scrape dried flakes into sterilized container
4. Store in cool, dark place
5. Rehydrate and step up when needed

“I maintain my wild culture like a sourdough starter,” explains <a href=”https://brewmybeer.online/fermented-drinks-alternative-brews/how-to-make-kombucha-at-home/” target=”_blank”>kombucha and wild fermentation specialist</a> Marie Lavender. “Regular feedings keep the culture vibrant, and the microbes actually evolve to better process your specific brewing environment and ingredients over time.”

Brewing with Wild Yeasts

Recipe Adaptation for Wild Fermentation

Converting conventional recipes for wild fermentation requires several adjustments:

1. Malt Bill Considerations:
   • Increase fermentable sugars by 5-10% to account for potentially lower attenuation
   • Consider adding 5-10% of easily fermentable sugars (honey, table sugar) to ensure complete fermentation
   • For sour styles, increase wheat or unmalted grains to provide food for lactic acid bacteria
2. Hop Adjustments:
   • Reduce hop rates by 20-30% for wild fermentations, as many wild yeasts are more sensitive to hop compounds
   • Focus on late hop additions if hop character is desired
   • Consider dry hopping after primary fermentation has slowed to maintain hop aroma
3. Water Chemistry:
   • Start with slightly higher mineral content to provide buffering capacity
   • Calcium levels of 100-150 ppm support yeast health and fermentation
   • Avoid excessive sulfate, which can enhance perceived bitterness
4. Timeline Expectations:
   • Plan for primary fermentation of 2-4 weeks (versus 1-2 weeks with commercial yeast)
   • Secondary aging often requires 3-12 months for flavor development
   • Taste periodically to track development

According to wild fermentation expert Sandor Katz, “The most important adaptation is patience. Wild fermentations simply cannot be rushed if you want to achieve depth and complexity.”

Three Beginner-Friendly Wild Fermentation Recipes

Wild Flower Mead

This simple mead recipe is perfect for first-time wild fermenters:

Ingredients:

• 2 lbs (0.9 kg) raw, unfiltered honey
• 1 gallon (3.8 L) spring water
• 2 cups organic flower blossoms (dandelion, elderflower, or apple blossom)
• 1 organic lemon, zest and juice
• Small handful of organic raisins

Process:

1. Combine water and honey, stir thoroughly but don’t boil
2. Add flowers, lemon zest/juice, and raisins
3. Cover with cloth and secure
4. Stir vigorously twice daily to incorporate oxygen
5. After 3-7 days, visible fermentation should begin
6. Continue stirring daily for 2 weeks
7. Strain into secondary fermenter with airlock
8. Age 3-6 months before bottling

Wild Fermented Cider

Capturing the terroir of your local apples:

Ingredients:

• 1 gallon (3.8 L) fresh-pressed, unpasteurized apple juice (no preservatives)
• 1 organic apple, roughly chopped with skin
• 1 tablespoon raw honey

Process:

1. Pour juice into sanitized fermenter
2. Add chopped apple and honey
3. Cover with cloth secured with rubber band
4. Stir twice daily until vigorous fermentation begins (typically 3-7 days)
5. Remove apple pieces and install airlock
6. Ferment until activity slows (3-6 weeks)
7. Rack to secondary container
8. Age 2-6 months at cool temperatures
9. Bottle still or with priming sugar for carbonation

Wild Kvass

A traditional Eastern European fermented beverage:

Ingredients:

• 1 lb (450 g) organic rye bread, preferably dense sourdough
• 2 gallons (7.6 L) filtered water
• ½ cup raw honey or maple syrup
• ¼ cup organic raisins
• 1 organic lemon, sliced
• Optional: fresh mint or berries for flavor

Process:

1. Toast bread until dark brown but not burned
2. Place bread in large pot with 1 gallon water
3. Bring to simmer, then remove from heat
4. Add remaining water, honey, raisins, and lemon
5. Cover with cloth and ferment 2-5 days, stirring occasionally
6. Strain and bottle
7. Refrigerate and consume within 2 weeks

These recipes serve as excellent introductions to wild fermentation with relatively quick turnaround times and approachable flavor profiles.

Managing Risk and Ensuring Safety

While wild fermentation is generally safe due to the selective pressures of alcohol and acidity, some precautions are important:

1. Sanitation Practices:
   • Clean all equipment thoroughly, even though you’re working with wild microbes
   • This prevents unwanted contaminants like mold from gaining a foothold
   • Use food-grade sanitizers on any equipment that contacts your brew after the initial fermentation begins
2. pH Monitoring:
   • Invest in an inexpensive pH meter or pH strips
   • pH below 4.5 prevents most harmful bacteria from growing
   • Check pH early in fermentation and periodically thereafter
   • If pH remains above 4.5 after several days, consider adding a small amount of food-grade lactic acid
3. Visual and Aroma Assessment:
   • Learn to identify normal versus abnormal fermentation patterns
   • White to light tan foam is normal; green, black, or orange growths indicate mold
   • Pleasant sour, fruity, or funky aromas are good; putrid, fecal, or garbage-like smells indicate spoilage
4. When to Discard:
   • Visible mold growth (fuzzy or powdery patches, especially green or black)
   • Strong chemical aromas (acetone, solvent-like)
   • Rotten egg smell that doesn’t dissipate after a few days
   • Slimy texture or unusual film (unless it’s a known pellicle from Brettanomyces)

According to food scientist Dr. Benjamin Chapman from North Carolina State University, “The ecology of fermentation creates an environment hostile to most harmful microorganisms. The combination of alcohol, acidity, and carbon dioxide provides multiple hurdles to pathogen growth.”

Advanced Wild Fermentation Techniques

Mixed Fermentation Strategies

Mixed fermentation involves intentionally combining wild cultures with commercial yeasts:

Sequential Inoculation

1. Begin fermentation with commercial yeast (often a neutral strain)
2. Allow to ferment until 75% complete (typically 3-7 days)
3. Add wild culture for complexity and finishing

Split Batch Method

1. Ferment main batch with commercial yeast
2. Ferment smaller portion with wild culture
3. Blend to desired flavor profile after fermentation

Three-Stage Microbe Addition

1. Primary: Commercial Saccharomyces yeast for 1 week
2. Secondary: Brettanomyces addition for several months
3. Tertiary: Lactic acid bacteria for souring in final stage

These approaches allow brewers to balance predictability with the complexity of wild fermentation.

Spontaneous Fermentation (Coolship Method)

The most traditional approach to wild fermentation, used in lambic production:

1. Wort Production:
   • Create wort with high percentage of wheat or unmalted grains
   • Extended boil (2-4 hours) concentrates sugars and reduces proteins
   • Aged hops provide preservative qualities without excessive bitterness
2. Overnight Cooling:
   • Transfer hot wort to shallow, open vessel (coolship)
   • Allow to cool naturally overnight, exposing to environmental microbes
   • Traditionally done during cooler months (40-50°F/4-10°C) to select for beneficial microbes
3. Transfer and Extended Fermentation:
   • Move to oak barrels or neutral fermenters
   • Allow to ferment spontaneously with captured microbes
   • Typically requires 1-3 years for complete development

As noted by Jean Van Roy of Cantillon Brewery, one of the world’s most respected spontaneous fermentation producers, “We don’t make beer, we make wort. Nature makes our beer through the mysterious process of spontaneous fermentation.”

Creating Sense of Place: Developing Local Brewing Terroir

Embracing Regional Differences

Wild fermentation offers something commercial yeasts cannot—a direct connection to place:

1. Local Ingredient Sourcing:
   • Use fruits, flowers, and herbs from your immediate environment
   • Work with local farmers for grain and honey sources
   • Consider foraged ingredients for truly local expression
2. Seasonal Brewing Cycles:
   • Align brewing schedule with natural agricultural cycles
   • Spring captures offer different microbes than autumn captures
   • Develop a calendar based on local conditions
3. Environmental Factors:
   • Altitude, humidity, and local flora all influence available microbes
   • Coastal areas often have different wild yeast profiles than inland areas
   • Urban versus rural environments capture different microbes

According to Dr. Matthew Farber, Director of Brewing Science at University of the Sciences, “The microbiome of a brewery is unique to its location, creating fermentation characteristics that cannot be replicated elsewhere—this is the true meaning of terroir in brewing.”

Building a House Culture

Many successful wild brewers eventually develop a house culture—a stable mixed culture that produces consistent yet complex results:

1. Selection Through Successive Brewing:
   • Use your favorite wild batch to inoculate subsequent batches
   • After several generations, the culture stabilizes with dominant strains
   • Continue to feed and maintain between brews
2. Blending for Consistency:
   • Maintain several vintages of wild fermentations
   • Blend older and younger batches to achieve desired profile
   • Document the character of each batch for future reference
3. Culture Evolution:
   • Expect your house culture to change subtly over time
   • Seasonal variations will occur naturally
   • Periodically capture fresh cultures to introduce to your house blend

Trevor Rogers, co-founder of de Garde Brewing, explains their approach: “We’ve never pitched commercial yeast. Our house culture has evolved over years of spontaneous fermentation in our location, and it produces a character unique to our brewery and our coastal environment.”

Troubleshooting Wild Fermentations

Common Issues and Solutions

Even experienced wild fermenters encounter challenges. Here are solutions to the most common problems:

Stalled Fermentation

Symptoms: Initial activity followed by premature stopping, excessive residual sweetness

Solutions:

1. Check fermentation temperature (raise to 70-75°F/21-24°C to encourage activity)
2. Add yeast nutrients (wild yeasts often need more nutrition than commercial strains)
3. Consider adding a small amount of commercial yeast as a finishing culture
4. Gently rouse the fermenter to resuspend yeast

Excessive Acidity

Symptoms: Overwhelmingly sour flavor that masks other characteristics

Solutions:

1. Blend with less acidic batches
2. For future batches, reduce fermentation temperature
3. Reduce oxygen exposure during initial fermentation
4. Add more unfermentable sugars to balance acidity

Off-Flavors

Symptoms: Medicinal, solvent-like, or plastic flavors

Solutions:

1. Extended aging often reduces these compounds
2. Ensure adequate headspace in fermenters
3. For future batches, be more selective in initial culture development
4. Consider blending with neutral commercial batches

Unwanted Film Growth

Symptoms: Thick, ropey pellicle or slick surface film

Solutions:

1. If accompanied by vinegar aroma, reduce oxygen exposure
2. Verify pH is below 4.5 to prevent harmful bacteria
3. For known good pellicles (often from Brettanomyces), this is normal and beneficial
4. When in doubt, taste a small sample; discard only if flavor is unpleasant

According to Professor Lucy Joseph, curator of the wine yeast collection at UC Davis, “Many ‘problems’ in wild fermentation are simply part of the process. What might be considered a flaw in conventional brewing can be a desired characteristic in wild fermentation.”

The Future of Wild Fermentation

Modern Applications and Innovations

While wild fermentation connects us to ancient traditions, modern brewers are innovating in exciting ways:

1. Lab-Verified Wild Cultures:
   • Some brewers now send successful wild captures to laboratories for analysis
   • Identifying specific strains helps understand flavor contributions
   • Creating banks of regional wild yeasts preserves biodiversity
2. Climate-Controlled Spontaneous Fermentation:
   • Modified coolship designs for varied climates
   • HVAC systems that mimic ideal seasonal conditions
   • Strategic brewery location and design to capture desired microbes
3. Cross-Fermentation Applications:
   • Using beer-captured cultures in winemaking
   • Incorporating cheese-making cultures into brewing
   • Exchanging cultures between different fermentation traditions
4. Microbe Banking:
   • Cryogenic preservation of successful wild cultures
   • Creating libraries of seasonally and regionally distinct captures
   • Protecting microbial diversity from climate change and habitat loss

According to Lance Shaner of Omega Yeast Labs, “We’re seeing increasing interest in isolating individual microbes from wild captures, allowing brewers to use specific components of a wild culture with more predictable results.”

Community and Collaboration

The wild fermentation community exemplifies the collaborative spirit of brewing:

1. Culture Sharing Networks:
   • Online forums for exchanging successful cultures
   • Local meetups and clubs for wild fermenters
   • International exchanges creating unique hybrids
2. Citizen Science Projects:
   • Mapping regional yeast biodiversity
   • Documenting climate effects on microbial terroir
   • Preserving traditional fermentation practices
3. Educational Initiatives:
   • Workshops and courses on wild fermentation techniques
   • University partnerships studying wild yeast genomes
   • Historical research into pre-industrial brewing methods

Embracing the Wild

Wild fermentation represents both a return to brewing’s roots and a frontier of flavor exploration. By capturing and working with the invisible microbial world around us, brewers create beverages with profound connections to time and place.

The unpredictability that often discourages conventional brewers becomes the very quality that wild fermentation enthusiasts embrace. Each batch tells a unique story—of season, location, ingredients, and the brewer’s patience and skill in guiding rather than controlling the fermentation process.

As you begin your wild fermentation journey, remember that you’re joining a tradition that stretches back to the very dawn of human civilization. The techniques have evolved, but the essential relationship remains the same: humans working in partnership with the natural world to transform simple ingredients into complex, nourishing, and delightful fermented creations.

Whether you’re capturing your first backyard culture or developing a sophisticated house blend of wild microbes, you’re participating in a living tradition that connects brewing to its wild origins—where every fermentation is unique, and every batch tells the story of its creation.

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Author: Lisa Fermenta
Email: lisa@brewmybeer.online
Fermented Drinks & Kombucha Specialist at Brew My Beer. Lisa is a fermentation expert who explores the health benefits of probiotics. From kombucha to mead, she loves experimenting with traditional and modern fermented drinks.