Brewing Lambic

Brewing Process

Today’s modern lambic is brewed using a grain bill of roughly 30% raw (ungerminated) wheat and 70% malted barley. Different breweries use slightly different ratios for their own unique recipes.

The grains are sent through a mill, often located above the mash tun, resulting in a finely cracked grain; pulverized but not quite flour. This is then transferred to the mash tun where conversion of starches to sugars begins.

Lambic mash regiments are known as ‘turbid’ mashes. This is a very time-consuming method of conversion but is necessary to break down larger proteins, providing yeasts and bacterias 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.

Each brewery has its own turbid mash schedule but they all roughly follow the same guidelines.

The grain is added to the kettle alongside hot water. This will rest at 45C/113F for between 10 and 15 minutes. The next steps are to increase the temperature of the mash gradually either by:

• Adding boiling water in carefully measured amounts

• Removing a portion of the “milk” from the mash, transferring it to a secondary kettle for boiling, and returning it to the mash

Or some combination of the two

The rest temperatures following 45C/113F are loosely: 52C/126F to increase the breaking of larger protein chains, then a series of steps between 65C/149F and 75C/167F to begin the process of sugar conversion. Again, different breweries use different rest temperatures and different amount of steps. The wort is then sent to kettles to begin boiling while sparging occurs. Sparging is essentially rinsing the grain with water (85C/185F) to grab as much sugar from mash as possible.

Boiling:

As wort is filling up the kettles, aged hops are added to the kettle at a rate of up to 25 kg per 10,000 liters (pre-boil). Most breweries, as tradition goes, use dried, aged, Belgian or German hops. Some lambic breweries are now using fresh, pelletized hops.

The boil will last between 2 hours and upward of 7 hours. Historically, some boils would last days. The boil will eliminate hop aromas, release anti-bacterial compounds, and reduce the volume of liquid by approximately 25% which will effectively increase the gravity of the wort.

The wort is then sent through a simple screened hop filter and into the coolship. The coolship is what makes lambic, lambic. Coolships are long, shallow basins used for cooling the wort to an appropriate temperature for fermentation. They are commonly at the highest point in the brewery, near open slatted windows, allowing the cool breeze to deposit micro-fauna from the area onto the wort.

Once the wort is cooled it is transferred to wooden barrels or foudres (usually made of oak or chestnut). Barrels are filled to the top and left to begin fermentation. Fermentation will typically occur within days. Barrels are typically not topped up. In some cases, the wort is pumped to large stainless steel tanks with oak chips added to ferment there. (Lindemans) The wort, now becoming beer, will rest for between a year and in some cases up to 5 years.