Brewing Lambic

← An Overview of Lambic

Brewing

Seasons

Lambic brewing primarily occurs in the winter (October through May, although the exact dates are determined by the brewer based on outside temperature). The cold temperatures help cool the beer and begin the fermentation process. Additionally, there are many undesirable bacteria in the air during the summer that can infect the wort and negatively influence the fermentation. This can introduce acedic and other off flavors.

Raw Ingredients / Preparation

The Royal Decrees of May 20, 1965 and March 31, 1993 required that lambic brewers use at least 30% wheat. Today's modern lambic is brewed using a grain bill of roughly 30-40% raw (ungerminated) wheat and 60-70% malted barley (2-row or a combination of 2-row and 6-row). In most cases, both the wheat and the barley are coming from Belgian or German farms. The goal is to create wort that is rich in protein, amino acids and dextrins in order to provide nourishment to the microorganisms for months and years of fermentation. Aged hops also play an important role in lambic. Traditionally, hops containing low amounts of alpha acids are aged for anywhere between a year and three years; although some bales of hops wind up aging much longer. The hops are typically stored in an environment where they are susceptible to drastic temperature changes, such as an attic.

Turbid Mashing

In order to mash, the grain must be crushed to expose the inside of the kernel. This is achieved by a grain mill which will pulverize the grain to a powder while leaving the husk in tact which will aid with sparging and draining. The grains are sent to a vessel called a mash tun and mixed with water of varying degrees of temperature. The mash tun will serve as a place to convert the starches from the grain into sugars. The mash tun is a kettle shaped vessel usually containing multiple rakes made of metal that rotate around the tun and are powered mechanically. This aids in mixing of the mash as well as draining excess liquid after the mash is complete. Lambic undergoes what is known as a turbid mash. A turbid mash is a time-consuming method of conversion that involves removing the liquid portion of the mash, boiling it, and then reintroducing it into the whole mash. It is necessary to break down larger proteins, providing yeasts and bacterias with more food. This will result in a beer that is perceived to be drier in taste. Freeing the wheat of its amino acids will result in a higher dextrin content, giving the final product a fuller mouth feel. Different organisms will feed on different materials at different rates, providing another layer of complexity. This is opposed to a single-step mashing schedule where the grain rests at one temperature for an extended period of time. Single-step infusion results in less complex materials for organisms to break down.

An example of a turbid mash schedule is as follows:

• Mix water and grain to reach a rest temperature of 45C/113F for 10 minutes.
• Add water to reach a rest temperature of 58C/136F for 5 minutes.
• Extract a portion of "milky" liquid from the mash and transfer to a kettle for heating to 80C/176F.
• Add water to reach a rest temperature of 60C/149F for 30 minutes.
• Extract a portion of "milky" liquid from the mash and combine with the previous liquid.
• Add water to reach a rest temperature of 72C/162F for 20 minutes.
• Begin draining wort into a separate kettle for boiling.
• Transfer "milk" back to mash and stir.
• Begin sparging (rinsing) grain with water at 85C/185F.

Sparging

Sparging is a process of rinsing remaining sugar from the grain after the initial runnings of wort. This is done with near boiling water (165°F-190°F) which will halt the enzymatic conversion process. These second runnings are then combined with the first runnings into one batch. This helps extract dextrins and unconverted starches from the mash. These components are needed to support the long fermentation process and will ultimately be utilized by the yeast and bacteria. Without these usually undesirable products the lambic organisms will not thrive and produce an optimal product.

Boiling

Lambic boils can last upwards of five hours. Historically some boils have lasted days but modern practices run anywhere between 2 hours and 5 hours. Boiling serves a few purposes. These include:

• Sterilization of the wort
• Extraction of hop antibacterial compounds
• Reduction of hop aromatics
• Caramelization of the wort thanks to maillard reactions
• Extraction of the excess proteins from the wheat
• Reduction in liquid collected during extensive sparging to provide higher sugar content and thus increased alcohol content.

Hopping

Boiling is also when hops are added. The brewer will make a hop addition as the kettles are being filled, before the wort actually begins to boil. Other than being aged, the hops are usually Belgian, Czech, or German grown hops typically of the Hallertauer variety. It is important to use hops with low alpha acid content as brewers are not looking for bitterness or acid contents; only the antimicrobial properties contained within the hop. This will prevent undesired molds and bacterias such as acetobacter from inhabiting the wort.

Cooling/Inoculation

After boiling is complete, the wort is sent through a filter (often a simple metal screen) to clear the wort of major hop and trub debris. This slow process will eventually drain the wort into a vessel called a coolship (koelschip). Coolships often reside in the brewery's highest most point next to slatted windows so that the cool night air can deposit hosts of microorganisms that will ferment out the wort into lambic. This process can only happen during the cooler months of the year due to the fact that molds have a difficult time surviving the cold temperatures. It will take the wort a period of about 10 hours to cool to the desired temperature at which point it will be transferred to barrels.

Barrels

Barrel Selection

Lambic breweries do not like fresh barrels. Used red or white wine barrels are preferred. Most of the oak character has been stripped from the barrel, so not much will come through in the final lambic taste. Barrels vary widely in size, including sizes such as 267 liter Tonnes, 550-650 liter Pipes, and 3000 liter Foudres. Larger barrels or foudres are preferred over smaller barrels. These barrels are typically made from oak, chestnut, or cedar.

Preparation

A beechwood twig brush called a ramon is used to scrub out the sediments, and, as needed, the barrel can be scraped clean by spinning sharpened chains inside it. The barrels washed with hot water and steam to sanitize and prepare them for use. If they are to be stored empty, sulfur is burned in them to preserve their sanitation. Because wooden barrels tend to carry microbiological agents, the extent to which the barrel is cleaned significantly impact the beer that it produces. Sanatiation of barrels is extremely important as the process used lead to substantial variation in the beer produced.

Initial Fermentation

The wort is transferred via hose into the barrels through the top bung hole. Barrels are completely filled and loosely capped with a silicon or wooden cork. In some cases a tubing system will serve as an overflow into buckets for when initial fermentation begins; making it easier to clean up after the barrels. Fermentation will typically occur within a few days, but can take up to a couple of weeks to begin. Factors that can affect when fermentation begins include the temperatures during inoculation or the temperatures during those first few days in the barrel. Organisms work more quickly at higher temperatures.

Resting

Lambic will develop and rest in the barrels for between a year and three years in most cases. Some experiments have led to lambic resting for upwards of five years though. As lambic ages in the barrel, it matures. It takes on a more complex profile as different yeasts and bacterias interact, die off, rearrange esters and fermentation byproducts, etc. The lambic's sugar content is decreased over time and it becomes drier. It will also take on more of the barrels character due to longer exposure time and will oxidize.

Topping Up/Maintenance

Most barrels are topped up only once after initial fermentation has completed and there is a significant airspace between the lambic and the bung. After most CO2 production has been completed, the barrels are hard-bunged and left to rest indefinitely.

Fruiting

Fruit Selection/Preparation

The most commonly used fruits in lambic production are cherries (Kriek) and raspberry (Framboise, Frambozen). Many other fruits have been experimented with in the beers discussed on this site. Examples include plums, blueberries, gooseberries, apricots, currant, strawberries,, apple, banana, and a variety of wine grapes. Traditionally whole fresh fruit was steeped in lambic of minimum one year but modern practices include using frozen fruit or fruit extracts/juices.

Duration

Traditionally, fruit and lambic was racked into barrels. Today however, fruit is mostly placed in a stainless tank and lambic is transferred on top to rest until secondary fermentation has ceased. This may be as quickly as four weeks or as long as eight weeks. Most fruits are added whole without being crushed or pitted. Once fermentation is completed, the now fruited lambic is transferred to a bottling tank through a filter. The filter could be cellulose or any other type of filtering material. Fruit ratios vary but generally run between 200 and 300 grams of fruit per liter of beer.

Blending

Fruit Lambics

Fruit lambics are typically not blended with other fruit beers. In some events, if the lambic shows too much sign of fruit (over-fruiting), the brewer will blend in some unfruited lambic to mellow the flavor.

Gueuze

Gueuze is loosely defined as a blend of 1, 2, and 3 year old lambics. This ratio is very dependent on the blender's intentions, what barrels are available to choose from, and what those barrels provide in terms of flavor profile. Recently, more blenders have been experimenting with adding 4+ year old lambic to blends.

Generally speaking (and never a steadfast rule): 3 year lambic will be softer and more mellow, providing a nice base. This is used in lower proportions. A 2 year lambic will provide the most character and interesting nuances in a blend. This is used in slightly higher amounts. A 1 year lambic will provide fresh, active yeasts to further develop the blend once it is bottled, along with more fermentable sugars for bottle fermentation. This is used in the highest proportion. Again, this is not always the case. Sometimes a brewer may choose to use any age lambic in a much higher proportion than outlined here. The process is guided by tasting and smelling barrels.

The specific gravity of the final blend must be high enough to ensure that bottle refermentation occurs.

Pasteurization

According to Wikipedia, "in 1864 Pasteur discovered that heating beer and wine just enough to kill most of the bacteria that caused spoilage prevented these beverages from turning sour. This was achieved by eliminating pathogenic microbes and lowering microbial numbers to prolong the quality of the beverage."

Some lambic brewers choose to pasteurize their product prior to the completion of secondary fermentation. This allows for a sweeter product, retaining a lambic or gueuzes residual sugars and, in the case of a fruited lambic, the sweet fruit flavors. It also eliminates refermentation in the bottle and minimizes other changes to the beer, allowing industrial lambic producers to ensure a more consistent product that does not continue to develop.

Bottling

Depending on the sugar content (gravity) of the final blend/lambic, sucrose sugar may be added in small amounts to provide food for yeasts to feed upon in order to aid in the creation of carbon dioxide within the bottle. This is adjusted according to the level of desired carbonation.

During the bottling process, lambic is sent from the stainless steel bottling tank, typically fed by gravity. Bottling machines, technologies, and techniques vary widely from brewery to brewery. Unlike when other beer styles are bottled, lambic bottles are often not flushed with CO2 prior to bottling.

Lambic bottles are thick walled, reinforced, Champagne styled. Green or dark brown in color. The bottles are filled to the arch of the neck and topped with either a wine or 'mushroom' styled cork. In the case of a wine cork, a metal crown cap is applied to help maintain the carbonation and to prevent the cork from popping out during the production of CO2 within the bottle.

Bottles are left unlabeled until time for sale. Bottles are left for a minimum of three months, though most blenders prefer to age their bottles for minimum six months before sale, especially in the case of gueuze. This will allow bottle conditioning to occur, and allow the beer to work through phases of viscosity that may occur (Pediococcus byproducts known as 'ropiness').

References

← An Overview of Lambic