It’s a curious phenomenon that lambic beer, now a cult beer internationally¹, has been largely overlooked in its native Belgium since the 1960s. Yet, an international revival has emerged following the rise of natural wines that began in France during the 1990s. Lambic beers, known for their spontaneous fermentation process, are often perceived as purist or as employing minimal intervention, akin to the ethos of natural wines. This brewing method utilises wild yeasts, including bacteria like Brettanomyces and Pediococcus alongside the more common Saccharomyces cerevisiae, imbuing the beer with a distinctive acidity, sometimes funky aromas and a certain volatile acidity—qualities shared with some natural wines.

What is a lambic?

A lambic is a spontaneously fermented beer made from a mash of 60 to 70% pale two-row barley malt, 30% to 40% raw wheat and aged hops. Unlike conventional beers, lambics do not rely on manually added yeasts. Instead, they embrace the wild yeasts present in the environment, allowing these natural elements to inoculate the brew. The fermentation is done in oak foudres and is traditionally confined to the cooler months from October to May, allowing for natural temperature control of the process. While its production is theoretically² confined to the Pajottenland region and Brussels, no one will stop you from applying the principles of lambic brewing elsewhere to make your own beer.

How does lambic taste?

The result of this very particular brewing method is a clear pale yellow beer, with a very vertical acidity and alcohol levels around 6% ABV. Aromas tend to range from apples, citrus, white flowers and apple cider, vanilla from oak to apricots, candied lemon, hazelnut, yeast, biscuits and bread when aged over 10 years in the bottle. Even though Brettanomyces, Pediococcus and enteric bacteria are involved in the fermentation, most beers tend to be fairly clean. Nonetheless, funky aromas are also possible, with notes of animal, sweat or vinegar.

For more detailed tasting notes, see our table of tasting notes below.

Types of lambic

Finding pure, unblended lambic can be challenging; it’s often only available on tap directly at breweries. Instead, it is primarily sold as a derivative product:

• Faro: A young lambic, sweetened with brown sugar or molasses, generally featuring a healthy fizz, unless it has been pasteurized.
• Gueuze: A blend of young and old lambic, typically aged from one to three years in foudre. The younger lambic’s sugars promote refermentation in the bottle, resulting in a moderate effervescence when served.
• Fruit lambic: A lambic macerated or blended with fruit or fruit juice and allowed to referment in bottle to yield a moderate fizz when served. The most common fruit used is sour cherries (kriek).

History

The history of lambic beer is shrouded in uncertainty, with mixed accounts and no consensus on its origins. Part of this lack of clarity can be attributed to the decline in the popularity of lambic during the 1970s, which led to a loss in oral histories and accounts, further compounded by the absence of early records. The reliable information on lambic can be found through the HORAL collective of lambic brewers, writer Jef van den Steen³ and Raf Meert’s comprehensive treatise Lambic. The Untamed Brussels Beer: Origin, Evolution and Future. Although Meert’s work has not been peer-reviewed, it remains the most comprehensive analysis available, providing substantial documentation for its hypotheses. We have drawn primarily from his book for our summary below.

Contrary to popular belief supported by HORAL that lambic dates back to the 13th century, the earliest documented mentions of lambic are found only in the late 18th century. Meert reveals several references to lambic during this period, all within the city of Brussels. The story of gueuze is equally veiled in mystery. Meert, however, pinpoints the first mention of ‘gueuze lambic’ in barrels, dating back to an 1831 property inventory near Brussels.

The current form of gueuze, a blend of various aged lambics bottled together, did not emerge until the late 1800s. This period saw increased demand for effervescent beers. In response, lambic blenders experimented with carbonation methods, culminating in the practice of blending young and old lambics for bottle refermentation, established around 1900. This technique, similar to the méthode champenoise used in Champagne production, now stands as a hallmark of gueuze production.

By the First World War, there were hundreds of lambic producers, including brewers and blenders. However, the war led to a significant decrease in production, as many closed or had their copper brewing equipment seized. The Second World War further exacerbated this decline and in the subsequent post-war era, consumer preferences shifted towards heavier beers like Trappist dubbels⁴ and tripels. By the 1970s, lambic had fallen out of favour, perceived as outdated. This prompted producers to adapt by introducing sweet fruit lambics to appeal to tastes influenced by the sweetness of American soft drinks. Recently, however, the rising popularity of natural wines in Paris has sparked renewed interest in these spontaneously fermented beers. Over the past 20 years, the industry has seen a modest revival, growing from twelve to seventeen producers, comprising twelve brewers and five blenders.

How is lambic made?

Lambic brewing begins with milling malted barley and unmalted wheat grains. The grains then undergo a turbid mashing process, which extracts both simple sugars and more complex starches. These starches are not digestible by the common yeast Saccharomyces cerevisiae, enabling prolonged fermentations lasting years, supported by other yeasts and bacteria.

After mashing, the wort is boiled to sterilize it. The process typically lasts a few hours. At this point, hops aged for one to two years are introduced. During this ageing process, the hops lose some bitterness while retaining their preservative properties. Because they add minimal flavour, it’s possible to use them in larger amounts.

The wort is then left to cool to room temperature overnight exposed to open air in large copper vats called coolships. The yeast and bacteria from the surrounding environment, developed symbiotically over years of lambic production in the brewery, naturally inoculate the wort. The next morning, the cooled liquid is transferred to oak barrels, where it ferments throughout the winter at approximately 10°C.

Normally, Saccharomyces species are preferred for brewing high-quality beer, while Brettanomyces, Pediococcus and enteric bacteria are typically viewed as contaminants, negatively impacting beer flavour. In lambic, Saccharomycescerevisiae and Saccharomyces bayanus dominate the alcoholic fermentation only for the first few months. Certain enteric bacteria produce some acetic acid in this phase. Following this, the Pediococcus species take over, producing lactic acid during the warmer months and reducing the beer’s pH to about 3. It is around eight months into the process that Brettanomyces strains start to dominate, consuming the remaining complex starches. This process not only increases the alcohol content but also significantly alters the beer’s flavour, adding savoury notes.

Brett and acetic acid are not as detrimental as in winemaking

In the context of winemaking, Brettanomyces and acetic acid are often considered undesirable, but in lambic brewing, these elements are not as harsh as long as they remain in moderate concentrations. On the other hand, improper barrel handling can lead to undesirably high levels of acetic acid. This is particularly true if there’s excessive oxygen exposure, either due to evaporation or a breach in the insulating yeast coating on the barrel walls.

Making gueuze and fruit lambic

Gueuze is made from a blend of lambics aged in oak barrels for different lengths of time. The best producers typically combine one-year-old, two-year-old, and three-year-old lambics in roughly equal measures, and some even include four-year-old lambic. The skill of the blender lies in selecting and combining barrels to achieve a desired structure and flavour profile, since each barrel will ferment differently and have a distinct taste. The older lambics in the blend contribute to a more complex, nuttier, and rounder flavour, while the younger lambics bring a freshness to the blend. Importantly, these younger lambics still contain complex starches, such as dextrins. These are essential for the Brettanomyces yeasts to trigger a secondary fermentation in the bottle, creating the carbonation that is characteristic of gueuze.

The second fermentation stage lasts for about eight months. Due to the lack of temperature control in the cellars, this period must include a summer season, as warmer temperatures are crucial for the optimal development of these yeasts. When nutrients are depleted, the yeast cells die and undergo autolysis, creating distinctive yeasty flavours. Although Belgians proudly compare this process to the méthode champenoise, it differs by omitting the disgorgement of the bottle, a technique used in Champagne to remove the dead lees from the bottle. Consequently, if the consumer chooses to age the bottle further, these yeasty characteristics continue to evolve. In fact, thanks to its acidity, gueuze can easily age for 20 years in bottle.

On the other hand, fruit lambics are made by macerating fruit in young lambic. The highest quality versions are made with whole, intact fruit, but some brewers opt for juice, concentrates, or syrups. As fruit is typically harvested in warmer months, this leads to a rapid secondary fermentation. Brewers then age the resulting mixture in oak barrels for several months, after which it is usually filtered and blended with a third of young lambic to allow for a final fermentation in bottle, similar to the process used in gueuze. To fully enjoy the fruit character, some recommend consuming these lambics within the first two years of their labelling. Among the most traditional fruit lambics is the kriek, made from sour cherries, with those made from the nearly extinct Schaarbeek cherry variety being particularly coveted.

Our collection of tasting notes

Below we provide a comprehensive table of our tasting notes of lambic and its derivatives. Similar to our wine tasting notes, tasting in a systematic manner has been instrumental to develop our palate and our understanding of these unique beers. Our notes are categorised into distinct sections: aromas detected by the nose, aromas discerned on the palate, and the overall structure of the beer.

Footnotes

1. Mainly France, Switzerland, Germany and the United States.
2. References to the Belgian Royal Decree from May 1965 tend to indicate this, but the document online makes no mention of Pajottenland nor Brussels.
3. Geuze & Kriek: the Secret of Lambic.
4. Also a relatively recent invention, dating back to 1921 in Westmalle.