Spontaneous & Mixed‑Fermentation Beers

These beers derive character from non‑Saccharomyces yeasts and bacteria (e.g., Brettanomyces, Lactobacillus, Pediococcus) and/or ambient wild microflora. Processes often include long aging, wood maturation, and blending to achieve balance and complexity.

Belgian Spontaneous Fermentation

Lambic

• ABV: ~5–7% | Acidity: medium to high | Color: Pale to gold
• Process: Turbid mash; extended boil with aged hops; cooled in coolships; spontaneous inoculation; barrel aging.
• Profile: Earthy funk, citrus, hay, barnyard; firm yet balanced acidity.

Gueuze

• ABV: ~5–7% | Acidity: medium to high | Blend: young and old lambics
• Process: Bottle‑conditioned blend of 1‑, 2‑, and 3‑year lambics; highly carbonated.
• Profile: Bright, sparkling acidity; layered Brett complexity; long, bone‑dry finish.

Fruit Lambic (Kriek, Framboise, etc.)

• ABV: ~5–7% | Acidity: medium to high
• Process: Whole fruit refermentation; traditional versions unsweetened; intense fruit expression with lambic complexity.

Faro

• ABV: ~3–5% | Acidity: lower; often sweetened
• Profile: Gentle sourness; approachable lambic variant with residual sweetness.

Mixed‑Culture & Wood‑Aged Ales

Flanders Red Ale

• ABV: ~4.6–6.5% | Acidity: medium‑high | Color: Reddish amber to deep red
• Process: Mixed cultures; extended oak aging; blending for balance.
• Profile: Tart cherry, red currant, balsamic; vanillin/oak; tannic structure.

Oud Bruin (Flanders Brown)

• ABV: ~4.5–8% | Acidity: medium | Color: Brown to deep brown
• Process: Mixed fermentation; dark malt; conditioning and blending typical.
• Profile: Plum, dried fruit, caramel; mellow acidity and oxidative notes.

Mixed‑Fermentation Saison / Farmhouse

• ABV: ~5–8.5% | Acidity: low to moderate | Color: Pale to copper
• Process: Primary Saccharomyces with Brett secondary; sometimes Lactobacillus; bottle conditioning common.
• Profile: Peppery, citrusy, dry; layered funk over time; refreshing acidity possible.

American Wild Ale (umbrella term)

• ABV: varies | Acidity: varies
• Process: Either mixed culture primary or secondary; often barrel‑aged and blended.
• Profile: Spectrum from lightly tart and fruity to deeply sour and funky.

Traditional Sour Wheat Ales

Berliner Weisse (traditional)

• ABV: ~2.8–3.8% | Acidity: medium | Color: Very pale; highly carbonated
• Process: Historical mixed cultures with Brett and Lactobacillus; modern quick sours use kettle souring (distinct profile).
• Profile: Bright lemony acidity; light body; sometimes served with flavored syrups.

Gose (Leipzig tradition)

• ABV: ~4–5% | Acidity: low to medium | Salt and coriander additions traditional
• Profile: Gentle tartness; saline/mineral note; citrus and herbal spice; refreshing.

Process Considerations

• Microbial Ecology: Balance among Saccharomyces, Brett, and lactic acid bacteria shapes acidity, funk, and attenuation.
• Wood and Oxygen: Barrels provide micro‑oxygenation and house microflora; blending mitigates batch variability.
• Time Horizons: Months to years; young beer supplies sugars and freshness, old beer contributes complexity and dryness.
• Stability & Packaging: Bottle conditioning common; refermentation risk requires robust process control and glass selection.