At the Potosi Brewery, our brewing process combines old world traditional methods with state-of-the-art modern equipment, and utilizes only the finest raw materials obtainable. Mix all of that with our brewers’ passion for the craft and conscientious attention to detail and you get beer that is not only delicious, but consistently delicious.
The following steps not only honor the Potosi Brewing Company’s time-honored production process, but are in keeping with an eye towards the future – both in terms of sustainability and an ongoing pursuit of brewing the absolute pinnacle of quality beer.
Brewing Water Preparation
The deep aquifers surrounding Potosi’s hills and valleys provide natural spring water to the Potosi area and supply Potosi Brewery with excellent naturally sourced brewing water. That water is first stored in a repurposed dairy tank and when brewing, the water picks up energy as it passes through the brewhouse. The heated water is recaptured in a separate set of repurposed tanks and used in the following mashing step of the brewing process.
Whole malted barley is brought in from our malt silos, portioned, and then milled to the appropriate granular consistency. Specialty malts may be added for color and flavor, depending on the recipe. The malt mill discharges the milled malt (or malt grist) to a large hopper in preparation for mashing. The malted barley kernel is then cracked or split by the mill during the mashing process, giving the brewer access to the sugars and proteins within.
By targeting specific temperature ranges that activate natural enzymes within the malt during the mashing phase, our brewers convert complex sugars into smaller sugars that the yeast can later use during the fermenting process.
That malt grist is sent to the mash tun with hot water. There the malt is steeped to convert sugars and begin extracting other nutrients, protein and color. Conversion takes about an hour and then the temperature is raised to completely stop enzymatic activity.
After the mash is pumped to the lauter tun, we separate the grain from the liquid, or “wort.” The wort flows through a series of screens on the bottom of the lauter tun and then runs over to the boil kettle. All of the husk materials from the malted barley acts as a filter and begins clarifying the wort as it travels. Hot water is then sprayed over the grain bed to rinse out all the sugars from the grain, a process called sparging.
Once all of the wort is run off from the lauter tun into the boil kettle, it is heated to a boil using steam from our energy efficient on-demand boiler system. When a boil is reached, the brewer begins to add flavorful hops, and may add several hop additions throughout the boil depending on the recipe.
After the boil, the wort is sent to our whirlpool. As the heavy, sweet wort spins it separates the insoluble proteins from the hop material. The clarified wort is then sent through our wort chiller where it exchanges heat with cold water. The cooled wort is sent to the fermentation cellar and the heated water is stored and used for the next brew.
Taking into consideration each specific beer style, the appropriate strain of brewer’s yeast is added to the wort inside conical bottom fermentation tanks. The yeast then breaks down the malt sugars to produce alcohol and CO2, which gives the beer its distinct and familiar characteristics. Significant flavor development and maturation also take place during fermentation.
After yeast is harvested from the conical tanks for reuse, the beer is quite cloudy and we clear it up by running it through our centrifuge. The centrifuge speeds up the natural sedimentation process by removing excess yeast and protein. The centrifuge can be set to custom speeds to maintain just the right amount of haze or cloudiness for each individual beer style. The centrifuge has several advantages over alternative filtration processes including high yield and low waste. This means less beer waste and no process aids such as diatomaceous earth, which can be problematic to the environment and local water treatment.
Oak Barrel Aging
Some of our “bigger” beers spend several months aging in oak spirit barrels. These barrels are sourced in cooperation with both local and national distilleries, filled with strong beer and matured at temperatures between 50F and 60F. Barrels with unique characteristics (previously used to age bourbon, rye whiskey, brandy, etc) are selected for each particular style of beer. Over time the oak and spirit flavors are infused into the beer creating distinct complementary flavors. After 9-12 months the beer is racked out of the barrels and packaged for unique and tasty enjoyment.
Before packaging, the beer is carbonated and then sent to the bottling, canning or keg line. Our state of the art bottling line can produce up to 6000 12oz. bottles per hour or 250 cases per hour. We can also convert to package into 22oz. bomber bottles. Our can line can package about 2500 12oz cans per hour and can also be converted to package 16oz. cans. The keg line has can produce about 25-35 kegs per hour.
Warehousing & Distribution
Approximately 10,000 square feet of the brewery are used for warehousing, distributing and receiving of raw ingredients, packaging materials and both aging and packaged beers.