Sour, Funky, and Fruited Beer Production 2
OVERVIEW
As discussed in Volume 2, Chapter 3, “The Brewhouse: Sweet Wort Production,” beer flavor can be described in four broad flavor-led groups: malt-led, hop-led, fermentation-led, and flavoring-led. Fermentation and flavoring-led groups derive their signature character(s) from the microbiota used to ferment and mature the beer and/or from added flavorings such as fruits, herbs, and spices or treatments such as wood aging. The use of phenolic off-flavor positive (POF+) yeast to make Belgian strong golden, dubbel, and tripel ales or Bavarian hefeweizen provides classic examples of a “clean” fermentation-led flavor platform. “Funky” beers, featuring a myriad of phenolic and fruity flavors, may rely on both souring by lactic acid bacteria as well as the action of the wild yeast strains of Brettanomyces (Brett). The classic sour-funky style is the Belgian lambic ale but can also include Flemish red and brown ales and traditional saison styles as well. Craft brewing has been influenced by these classic fermentation-led flavors and beer styles but has taken them in new directions with pure strain cultures, additional flavorings, exotic ingredients, and/or kettle-soured wort. These can be combined with barrel aging to give beers a complexity that occasionally defies description. This is craft brewing on the wild side, and an incredible wave of creative talent is on display at many breweries that make these very flavorful and unique types of beers.
It can be argued that sour and funky beers are at the root of traditional brewing. The science of brewing is relatively new, and the discovery of the significance of yeast in brewing as well as the use of single strains of yeast only began in the late 1800s. Prior to that time, various practices in brewing existed, and the products produced were, more than likely, exposed to non- Saccharomyces microbes from either a contaminated fermentation or the pitched leaven collected from the prior fermentation. Some remaining styles embrace the sour and funky and instead of fighting it, highlight the refreshing qualities a tart and complex beer can bring.
Clean, sour, and funky beers can be produced with or without any other flavoring additives such as fruits, spices, and so on, and they can be barrel aged or limited to stainless steel tanks. As in most of the craft brewing world, while tradition is a guide, there are no rules outside of good food safety manufacturing practices, and the brewer is free to use creativity, experience, and judgment to experiment with making interesting and exceptional beers. This is a broad subject, and this chapter will discuss general concepts.
For more detailed information, Michael Tonsmeire’s (2014) American Sour Beers is a good resource, along with the additional references listed. This chapter will explore the brewing practices in producing sour, funky, and flavored beers; the next chapter will delve more deeply into the barrel aging of these beers. Proceed with an open mind.
■ How are sour and funky beers made?
To make these beers, we can look to the traditional Belgian styles of sours, lambic, and saison and the brewing and fermentation techniques used in their production. These styles use particular fermentation, aging, and flavoring strategies to make an assortment of unique beers that differ from common lager and ale styles. In the craft brewing world, these types of beers tend to be super-specialty niche beers, made in low volumes, packaged distinctively, and commanding higher pricing. The three main styles of traditional sour and funky beers are as follows:
1. Lambic. These beers are brewed using a special process called turbid mashing and inoculated by an airborne microbiota, including various Saccharomyces and Brettanomyces yeast as well as lactic acid bacteria, to begin a “spontaneous” fermentation. The wort is fermented in wooden barrels or wooden tanks called foeders, where the beer is also aged for 1–3 years or sometimes longer. The beers can be sold unblended as straight lambic but are more commonly blended into a product called gueuze. The gueuze may be flavored with added fruits. They are rarely found on draft but are normally bottled conditioned for up to 12 months.
2. Flemish red and brown ales. The two main categories of these sour ale styles are as follows:
● West Flanders red ales are fermented first with POF+ Saccharomyces ale yeast and then aged in foeders containing resident lactic and acetic acid bacteria and Brett populations. The product is a blend of aged beer with younger nonaged beer.
● East Flanders brown ales are made with dark specialty malts and are also fermented with POF+ ale yeast. Originally, they were fermented and kept in wood barrels where they would be exposed to Brett, but in more modern practice, the beer is kept in stainless steel tanks, with no wooden vessel aging, to which pure strains of lactic acid bacteria are added. These beers are less likely to have been exposed to Brett and acetic acid bacteria. In both styles the beers are tart and may be sweetened with sugars or added fruits before pasteurization and packaging.
3. Saison. The name translates to season, and the beers were traditionally farmhouse Bière de Garde or keeping beer, made in the cold months for consumption by farmworkers in the summer. Traditional saisons were meant to slake the thirst of farmworkers, as they were low in alcohol, 2.5–3.5% alcohol by volume (ABV), and made from mixed cultures of ale yeast, lactic acid bacteria, and Brett, which finished out dry, tart, and refreshing, with a clear Brett character. Modern saison beers are in the 6% ABV range and often fermented completely with STA1+ (superattenuating) diastaticus yeast to dryness, finishing clean, bitter, and less tart.
Tradition provides ideas and some guidance, but as in the rest of craft brewing, innovation and experimentation, as well as a lot of patience, are required to make sour and funky beers. Beyond that an endless combination of yeasts, bacteria, fruits and spices, vessels, temperatures, and so on can be used to produce the myriad of flavor possibilities that compose these exotic and wild beers.
■ What is coupage?
Coupage is a French word more commonly used in winemaking and can be described as a structure of many parts blended into a functioning whole. Beers that are aged or treated in separate processes, including individual barrels, will have their own definitive characteristics. When ready, an aged sour or lambic beer is blended with other beers of the same condition and with younger and fresher beers to produce something different and more complex than either is individually. This is called the coupage.
The coupage produces the following:
● A wine-like flavor including some tartness in the beer
● An increase in acidity that protects the beer from unwanted bacterial contamination
● A more complex flavor profile
● Different beers obtained by different blends
The coupage is the blending process that the brewer of these specialty beers manages in order to achieve a certain flavor profile, either through tasting, analytical measurements, or both.
Lambic Beers
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What is spontaneous fermentation?
Belgian lambic beer is the essential sour and funky beer style. Lambic beers are traditionally made from malted barley and unmalted wheat using a unique mash system called turbid mashing, described next, and then allowed to cool in a shallow open pan-shaped tank called a cool ship. This exposes the wort to a large surface area, where it can be inoculated by the wide variety of microbes present in the air. The natural inoculum can include various bacteria and wild yeast, including Saccharomyces and Brettanomyces strains, that are particular to the geography and location of the brewery, which could be amid orchards in the countryside or in the middle of a busy major city. The inoculated wort is then mixed prior to being pumped into wooden barrels or foeders, where it begins fermentation. This is referred to as spontaneous fermentation because a cultured and/or harvested yeast pitch is not used; instead the fermentation is a result of natural inoculation of the wort from the immediate environment and appears to happen spontaneously on its own.
■ What is turbid mashing?
The wort used to produce lambic is traditionally made using the turbid mashing process and is particular to the lambic beer style. The goal of turbid mashing is to produce what would normally be considered a poor-quality wort for almost any other beer style but that ideally fits the needs of spontaneous fermentation and extended aging. In lambic brewing a quick and vigorous fermentation that would explode out of the barrel and finish quickly is not desired; rather, initial moderate activity followed by a long, slow fermentation is preferred. The grist for a turbid mash must include a large amount of unmalted grain, and traditionally, about 35–40% unmalted wheat is used, with pale malted barley providing the balance. The lambic wort should have a supply of sugars fermentable by the Saccharomyces yeast(s) that are present, significant amounts of large dextrin sugars for the Brett to work on after the main fermentation concludes, and a low free amino acid (FAN) concentration, which slows down the Saccharomyces and limits the growth of wort spoilers such as Enterobacteriaceae, which
2.1. A traditional unheated mash-lauter tun in a lambic brewery. Mixing of the mash with the various hot liquor and turbid wort infusions is carried out with a mechanical stirring mechanism that rotates around the tun while facilitating both horizontal and vertical blending. (Courtesy Brasserie Cantillon. Photo by K. Ockert—© MBAA.)
2.2. A steam-fired traditional “bright wort” brew kettle for strong wort in a lambic brewery. (Courtesy Brasserie Cantillon. Photo by K. Ockert— © MBAA.)
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can produce unwanted biogenic amines and sulfury, vegetal off-flavors. The turbid mashing process is somewhat similar to the decoction mashing process and includes separation and boiling steps, except that extracted starch-rich, turbid, and milk-like wort is not subjected to complete starch conversion. The traditional brewhouse for turbid wort production contains a single mash-lauter tun with a mixer (Fig. 2.1), a “bright” wort kettle (Fig. 2.2), and a “turbid” wort kettle (Fig. 2.3). A modernized version for 10 hl production is shown in Figure 2.4. The process varies slightly from brewer to brewer, but essentially, a turbid mashing program includes the following:
1. Hot liquor at about 65° C (149° F) is blended with the grist at a liquor-to-grist ratio (L:G) of about 0.6–0.8 to produce a thick mash at about 48° C (118° F) and left to rest for 15–20 minutes.
2. A second infusion of 85–100° C (185–212° F) hot liquor is used to raise the mash temperature to about 56° C (133° F) and left to rest again for 15–20 minutes.
FIG. 2.3. A steam-fired traditional “turbid wort” kettle used to boil turbid and weak wort in a lambic brewery. (Courtesy Brasserie Cantillon. Photo by K. Ockert— © MBAA.)
FIG. 2.4. A modern stainless steel brewhouse built for the turbid wort mashing process with a mash-lauter tun (on the brew deck), bright wort kettle (left), and turbid wort kettle (right). (Courtesy Gueuzerie Tilquin.
Photo by K. Ockert—© MBAA.)
3. The mash is vorlaufed briefly, and milky wort is run to the turbid wort kettle, where it is heated to 96–100° C (205–212° F). The heating gelatinizes the starches in the wort but also denatures the diastatic enzymes present as the temperature increases. The rate of heating affects the starch degradation into fermentable sugars and dextrins and consequently varies from recipe to recipe.
4. A third infusion of 85–100° C (185–212° F) hot liquor is added to the mash, bringing the temperature to about 66° C (151° F) for saccharification, and held for 15–20 minutes; the mash is vorlaufed, and the strong unsparged wort is run directly to the bright kettle.
5. The hot milky wort from the turbid kettle is returned and mixed into the main mash, raising the temperature to about 78–80° C (172–176° F), and held for 15–20 minutes, where further saccharification occurs. This process helps to partially convert the solubilized starches in the turbid wort into fermentable sugars but leaves a large concentration of unfermentable dextrins.
6. After vorlaufing the unsparged strong wort is also run to the bright kettle.
7. The mash is then sparged using 85° C (185° F) hot liquor, and the weaker runnings are sent to top up the bright kettle and then refill the turbid kettle. The high-temperature sparge helps to further gelatinize and solubilize the remaining starches from the unmalted wheat component.
8. The worts in both kettles are boiled with an addition of aged whole-cone hops. The minimum boil time is 2 hours, but often the wort is boiled for up to 4 hours. The long boil time assists with further gelatinization and breakdown of the starches, concentration of the wort, precipitation of proteins, development of color and malt flavor, and some volatilization of undesirable flavor effects (cheesiness) of the aged hops.
The recipes used by different lambic brewers are unique to their process, tradition, brewing philosophy, and desired outcomes. Each step along the way may include different temperatures and rest times; however, the basic outcome is the same: produce a wort that contains fermentable sugars for primary fermentation by Saccharomyces yeast and lactic acid bacteria that occurs in the first weeks and months and dextrins to ensure a slow secondary fermentation by Brettanomyces yeast that proceeds over a period of a year or more.
■ Why are aged hops used?
Lambic brewers are not looking for hop aromatics or bitterness in their wort. Bitterness competes with sourness and is actually considered undesirable in the flavor platform for lambic beers. However, lambic brewers do want the bacteriostatic effect of oxidized beta acids and the hop tannins, which will oxidize slowly during wood aging and develop mouthfeel. The beta acids help suppress certain bacterial growth
in the initial spontaneous fermentation. The aging process oxidizes the alpha acids, which greatly reduces their bittering effect. The beta acids are also oxidized during aging, making them more soluble in the wort and enhancing their bacteriostatic properties.
As mentioned in the last chapter, the fatty acids from oxidized alpha and beta acids that give aged hops their cheesy aromas may be biotransformed by yeast esterase enzymes into flavorful fruity esters. In any event, typical lambic beers do not retain any cheesy flavor components.
Aroma hops tend to have equivalent concentrations of alpha and beta acids. Traditional European aroma hop varieties that normally contain a low alpha acid content of less than 3%—for instance, Strisselspalt, Saaz, and Styrian Goldings—are typically kept in whole-cone form and aged for 3 or more years prior to use at rates of 0.4–0.6 kg/hl (1–1.6 lbs./bbl [beer barrel]). The single hop charge is added at the start of the long kettle boil.
■ How is the wort inoculated and aerated?
The boiled wort is passed through a hop strainer to remove the spent hop cones as it is pumped to a shallow cool ship. The cool ship is traditionally made of copper (Fig. 2.5) but can also be made of stainless steel (Fig. 2.6). A stainless steel cool ship in a cool ship house is shown in Figure 2.7. The main features are its shallow depth, about 30 cm (12 inches), and large surface area. The cool ship may or may not contain the entire brew. The inoculation can occur on a partial amount of the wort in the cool ship, which can then be blended to inoculate other cooled wort. The cool ship has four functions that include the following:
1. Cooling. The wort sits in the cool ship overnight and cools from boiling temperature to about 18–22° C (65–72° F) (Fig. 2.8). For this reason lambics are brewed only in the cold months, usually between October and March or April. Brewing does not usually occur in severe subfreezing weather because the inoculum in the air is diminished with very cold temperatures.
2. Trub separation. The trub in the wort settles out in the shallow vessel and clarifies the wort.
3. Aeration. The cool wort will have about the same dissolved oxygen content as water at the cooled temperature, approximately 7–8 parts per million (ppm).
FIG. 2.5. A copper cool ship in a lambic brewery. Note the louvered windows (far left) that help with air flow for the cooling wort and the wooden ceiling that will help cultivate microbes over time. Condensed vapor will drip back from the ceiling timbers into the cooling wort and help enable a relatively predictable microbiota for the inoculum of the wort. (Courtesy Brasserie Cantillon. Photo by K. Ockert—© MBAA.)
FIG. 2.6. A stainless steel cool ship in a lambic brewery. Air is brought into the cool ship room both for cooling and inoculation of the wort. (Courtesy Brouwerij Boon. Photo by K. Ockert— © MBAA.)
FIG. 2.7. A stainless steel cool ship installed in a small outdoor cool ship house. Outside air is brought into the cool ship house with mechanical blowers to help inoculate the brew. (Courtesy Gueuzerie Tilquin. Photo by K. Ockert—© MBAA.)
FIG. 2.8. Hot wort in a cool ship. The vapor given off is partially ventilated out and partially allowed to condense and drip back into the open vessel that is also exposed to outside air to help facilitate microbial inoculation. (Courtesy New Glarus Brewing Co. Photo by New Glarus Brewing Co.—© MBAA.)
4. Inoculation. This is a primary function of the cool ship because lambic wort is not pitched with recovered yeast/bacteria leaven. The large surface area is exposed to the surrounding air and all its microbial flora and fauna. The exact nature of the microbiota varies with geography and location but includes a wide variety of different types and strains of yeasts and bacteria (Bokulich et al., 2012). This exposure can be encouraged with forced air circulation. Lambic breweries tend to naturally inoculate a similar makeup of microbes in each batch through this process and attain, over time, a certain level of consistency in fermentation and beer flavor.
■ What are the features of lambic fermentation?
The wort is decanted from the cool ship, leaving the settled trub behind, and in some breweries it is blended in a tank called a gyle to mix the inoculated wort with any uninoculated cooled wort. In others the entire brew is cooled in the cool ship. From there it is pumped into barrels (Fig. 2.9) or foeders (Fig. 2.10) and kept at an ambient cellar temperature of about 15–16° C (59–61° F) and at a moderate humidity. The barrels are filled by tubes or hoses that when withdrawn allow for a small amount of headspace.
2.10.
wooden tanks called foeders are also used to ferment and age lambic beer. (Courtesy Lambiek Fabriek Gueuzerie. Photo by K. Ockert— © MBAA.)
FIG. 2.9. Barrels filled with lambic wort will be fermented into beer and aged for up to 3 years. (Courtesy Brasserie Cantillon. Photo by K. Ockert— © MBAA.)
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FIG. 2.11. Blow-off tubing in a bung used to direct the foam from primary fermentation into a collection vessel or down a drain. The blow-off tube reduces pressure buildup in the barrel and keeps the area around the barrel clean. (Courtesy Gueuzerie Tilquin. Photo by K. Ockert—© MBAA.)
The primary fermentation can commence with an appearance of wort spoilers such as Enterobacteriaceae from the airborne inoculum in the cooling wort. However, their action is normally limited either by an addition of lactic acid in the brewhouse to acidify the wort to a pH of about 4.5 or when the naturally present Saccharomyces yeast begin fermentation, producing ethanol and dropping the pH below 4.6. The ensuing yeast fermentation produces a certain amount of foam that is normally diverted out with tubing set in the bung (Fig. 2.11). The initial “dirty” brown foam purges remaining trub particles as well as bitter hop resins (brandhefe). Removing fermentation foam and keeping the area clean discourages the presence of fruit flies and consequently the acetic acid bacteria (vinegar bacteria) they carry, but in some breweries the foam is left to dry on the sides of the bunghole in an effort to promote resident microbial populations.
The appearance of fermentation generally takes about 3 days, depending on the cellar temperature, and then carries on with mild intensity for another couple of weeks. After the foaming dissipates, the cask or foeder is topped up and sealed with a ventable bung to keep the barrel from pressurizing during its initial secondary fermentation.
The fermentable sugars in the wort are used by the Saccharomyces yeast and by lactic acid bacteria (e.g., Lactobacillus, Levilactobacillus, Pediococcus, etc.) from the inoculum. The fermentation produces alcohol and lactic acid tartness, which reduces the pH of the beer down below 3.8 and helps protect it from potential unwanted microorganisms. As these simpler sugars are depleted, the Saccharomyces yeasts and lactic acid bacteria will decrease activity, and the Brett yeast will begin to break down and assimilate the previously unfermentable dextrin sugars produced from the turbid mash in a slower fermentation lasting up to 3 years.
■ What is the difference between Brettanomyces and Dekkera yeast?
Yeast taxonomy has changed the scientific names of many yeasts over time. Lager yeast, Saccharomyces pastorianus, has undergone (at least) four reclassifications since it was initially called Saccharomyces carlsbergensis. Although at one time Brettanomyces and Dekkera were differentiated by their asexual (budding) versus sexual reproductive stages (Boulton and Quain, 2006), they are now regarded as the same yeast organism. The current taxonomy favors a one-fungus, one-name mentality, and yeast scientists