Malted barley is contained inside a waterproof husk. In order to get at the starches inside, the malt must be milled. The goal of milling is to break open the husk and crack inside of the malt without destroying the husk.
The Mash is the process that allows conversion of the starches in the malt into fermentable sugars.
The milled malt is mixed with hot water (liquor) in the mash tun. It is important that the malt becomes saturated with the hot liquor to allow the enzymes to get to work. The mash is held for approximately an hour at a temperature between 146F to 160F, depending on the style of beer.
The main goal of the mash is to convert the starches in the malt into fermentable sugars for the yeast to eat. Starches in malt are a complex carbohydrate made of long strings of many glucose molecules linked together. Yeast can only ferment sugars up to three glucose molecules long. In order for fermentation to happen these starches need to be covered or broken down.
There are two types of enzymes in malted barley: Alpha-Amylase and Beta-Amylase. Each of the two enzymes work a little different. Alpha-Amylase tends to create more dextrins (short chain carbohydrates), while Beta-amylase produces more fermentable sugars. Dextrins give the beer body and simple sugars are used for fermentation. The two enzymes work together to break the links in the starches. The enzymes have specific temperature ranges that they work best at. This is why the temperature of the mash is important, as it has an impact on both the alcohol content and body of the beer.
Lautering is the separating of the sugar-y liquid that is now called “Wort” from the grain. The bottom of the mash tun has a false bottom (giant sieve). This holds the solids back and allows the wort to flow through, either to recirculate or “runoff” (transfer) to the kettle.
While the wort is running off into the kettle, the mash is being sparged with hot liquor to rinse all the sugar from the malt. Once Runoff into the kettle, we are now ready to boil the kettle for our next step.
The wort is now brought up to a boil. The boil usually lasts between 60-90 minutes. This accomplishes two goals:
1. Extracting hop bitterness and 2. Sanitization of the wort.
Boiling is necessary to extract bitterness from the hops. Early in the start of the boil hops are added. Their job is to add bitterness to the beer. The alpha-acids (AA%) that produce bitterness in the beer are not soluble in water (or wort). Boiling converts the alpha-acids to a soluble state through a process called isomerization. The oils that produce the hop flavor and aroma are very volatile and evaporate quickly, so the bittering hops only contribute bitterness to the beer, while the flavor and aroma are boiled away.
Depending on what type of beer is being brewed more hops may be added near the end of the boil. Generally, hops that are added about 15-30 minutes before the end of the boil contribute flavor to the beer. Hops added just a few minutes before the end contribute aroma to the beer. These hops still contribute some bitterness, but are mainly used for their flavor and aromatic properties.
The second main reason for the boil is to sanitize the wort. In the end, we need clean wort for the yeast to thrive in so we make great tasting beer.
Once the boil is over the wort is spun to create a “whirlpool”. This causes centrifugal forces that move all the solids (hops and rub) to the center in a fairly compacted cone. We want to leave as much of this matter behind for easier handling and control of your product.
Knockout is the process of chilling the boiling wort to fermentation temperature (55F to 75F) as fast as possible, depending on beer and yeast style. This is important because the sooner the yeast can be added to the wort, the less time there is for a chance of contamination or spoilage. This is commonly achieved through the use of a plated heat exchanger. Cold liquor is counter flowed through alternating plates and the wort is flowing the opposite direction through the other plates. This transfers the heat to the water. As the cooled wort exits the heat exchanger, we inject oxygen (O2), which is vital for the early stages of fermentation. The wort is then run into a fermenter where the yeast is pitched. The byproduct of this is hot water, which we reuse for the next batch.
Fermentation is the process by which yeast converts the sugars in the wort into alcohol and carbon dioxide gas (CO2).
To begin the fermentation process the cooled wort is transferred into a fermentation vessel and yeast is pitched. If the yeast is an ale strain, the wort will be maintained at a constant temperature of approx. 68F, for around two-weeks. If the yeast is a lager stain the temperature will be maintained at approx. 55F for about six-weeks. Since fermentation produces a substantial amount of heat the tanks must be cooled constantly to maintain the proper temperature.
Before the yeast is pitched into the wort the specific gravity is measured. Specific gravity tells us the sugar content of the wort. This initial measurement is referred to as the original gravity (OG). After fermentation the specific gravity will be measured again to determine how much sugar is left. This is referred to as the final gravity (FG). Plugging these two readings into a formula tells us the alcohol content.
The fermenter is sealed except for a vent for the CO2. An airlock, which commonly consists of a hose with its end in a bucket of sanitizer, is used to allow CO2 to escape and prevent outside contaminants from entering. Sometimes the fermenter is opened to add flavor ingredients such as hops. Adding hops to the fermenter is known as dry-hopping. This gives the beer a bright hop flavor without adding any bitterness.
When fermentation is nearly complete, most of the yeast will settle to the bottom of the fermenter. The bottom of the fermenter is cone shaped which makes it easy to capture and remove the yeast. The yeast is saved and used in the next batch of beer. The yeast can be reused a number of times before it needs to be replaced. Some breweries have been using the same yeast for decades although common practice is 8-12 batches per fresh pitch of yeast.
When fermentation has finished the beer is called to approx. 32F. This helps the remaining yeast settle to the bottom of the fermenter along with other haze causing solids. This is often aided through the use of a fining or clarification agent. Once the beer is clear, it is racked (transferred) to a “bright” tank. Bright is a term used to say the beer is clear. Beers will vary widely in clarity, but finished beer is still magnitudes clearer then fermenting beer.
The bright beer tank is where the beer is carbonated then, either, served or begged. Most breweries force carbonate their beer with a pours stainless steal stone that inject CO2 in the form of tiny bubbles.