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Wort Chillers

A wort chiller is a device used to rapidly cool the wort after the boil has completed. Typically the wort is knocked down from boiling temperatures to less than 80° F as quickly as possible so that yeast can be pitched. Once the wort falls below boiling temperatures, it becomes susceptible to bacterial and wild yeast contamination. It is important to get the wort below 80° F without splashing or aerating it too much, as hot side aeration can oxidize your wort above that temperature.

There are three typical types of home brewing wort chillers. Immersion chillers are large coils constructed of copper or stainless steel. They are placed inside the brew kettle while cold water is pumped through the chiller, cooling the wort. Plate chillers are made of fused plates and have channels where the cold water is pumped in from one end, causing it to intersect with the plates being heated by the wort from the other end, which rapidly cools the wort. Lastly, counter flow convolution chillers have hot wort flowing through one tube as chilled water passes over it from the opposite direction in a surrounding tube. I personally prefer the counter flow convolution chillers because they permit me to cool my wort quickly while also being easy to clean, since hops and trub are less likely to get lodged in the tube than they are in a plate chiller.

 

 

 

Below is a photo of three examples of home brewing wort chillers: an immersion chiller, plate chiller and a counter flow convoluted chiller.

You can purchase the wort chillers here:

Home Brewing Wort Chiller

Home Brewing Wort Chiller

Turbidity

Turbidity is haziness or cloudiness in beer or wort. It is caused by the suspension of particulate matter in the fluid. In order to remove the turbidity of wort in the mash or lauter tun, it is recommended that you recirculate the wort over the grain bed, which will act as a particle filter. Recirculation is a great method of clearing the wort prior to sending it to the boil kettle.

Trub

Trub or hot trub is the excess material left in the boil kettle after the wort has been transferred. Boil kettle trub typically consists of hop matter, grain fiber, tannins, and the dense proteins known as the hot break that combine during the first 15 minutes of the boil, and ultimately drop to the bottom of the kettle. It is recommended that the trub not be transferred to the fermenter, as it may impart off flavors on the finished beer.

 

The trub that was left over in the boil kettle after the boil took place and the wort was transferred into fermenters.

Boil Kettle Trub

Boil Kettle Trub

Tannins

Tannins are organic compounds found in the husks’ grains. Excessive tannins are almost always considered to be a flaw in beers and are interpreted as a harsh astringent bitterness or a mouth drying sensation. Excessive tannins are typically caused by too high of a mash pH or excessive temperatures during mash out or sparging. Tannin extraction is dramatically increased when mashing or sparge water temperatures exceed 170° F. Please also note that as the lautering and sparge process comes to a finish, the pH of a mash is increasing, which compounds the potential for tannin extraction. In addition to the off flavors created by tannins, they can also be significant contributors to chill haze in a beer. Hops release tannins into beer, but the hop tannins are not considered to be significant contributors off flavors or chill haze.

 

Ways of removing excess tannins from beer including cold crashing, or cold conditioning the beer at approximately 34° F for two or more weeks. That should cause some of the excess tannins and proteins to precipitate out of the beer onto the bottom of the fermenter or conditioning vessel. You may also use a beer a beer fining agent such as gelatin or isinglass to help clear the tannins.

 

 

Session Beer

A session beer is defined as a beer with an alcohol by volume or ABV of less then 5%. The purpose of a session beer is to permit the drinker to enjoy multiple beers at a sitting without becoming overly intoxicated.

Secondary Fermentation

Secondary fermentation is the process of transferring your beer to a secondary fermentation vessel to allow the beer to complete its fermentation cycle and condition in a clean environment. The primary reason for a secondary fermentation is to improve the taste of a beer. Towards the end of the primary fermentation, much of the yeast, beer solids, and hop solids will fall out of the beer and form sediment on the bottom of the fermenter. If left in contact with the beer too long, the dead yeast and solids can impart off or undesirable flavors upon the beer. For this reason, many brewers choose to rack the beer off of the sediment into a secondary fermenter to allow the beer to finish out fermentation, clarify, and condition.

 

The need for secondary fermentation is somewhat dependent on the style and characteristics of the beer that you are creating. For instance, if I am brewing an American wheat hefeweizen, I probably will not go through the trouble of a secondary fermentation because it is a relatively low alcohol beer with a low flocculating strain of yeast. This means it will ferment quickly, so the beer is only in contact with the sediment for a short period of time, and much of the yeast will remain in suspension with this style of beer, so a yeasty taste and cloudy appearance is appropriate.

 

If I was brewing an IPA with a high starting gravity, and I wanted to highlight the hoppy flavor of the beer, I would certainly conduct a secondary fermentation to remove as much yeast and yeast flavor from the finished beer to help both with taste and clarity. Depending on the beer style, gravity, fermentation temperatures, yeast strain, and yeast health, a secondary fermentation can typically last anywhere from two weeks to several months.  When conducting a secondary fermentation on certain beers, such as sours, the secondary fermentation can in some cases last over a year.

 

An imperial chocolate stout being racked into a secondary fermentation carboy,

Beer being racked into a Secondary Fermenter

Beer being racked into a secondary fermenter.

Primary Fermentation

Primary fermentation in beer brewing is the initial fermentation process where yeast will convert most or all of the wort sugars to alcohol and CO2 (carbon dioxide). After the yeast has been pitched into the wort, there is typically between 2 and 24 hour yeast lag time where the yeast acclimates to the fermentation environment and begins to replicate consuming sugars and the available oxygen in the wort; there is little alcohol conversion and CO2 generated during the lag phase.

Once the lag phase completes, a foamy head called a krausen begins to form in the fermentation vessel. The krausen is composed mostly of proteins, yeast, and the carbon dioxide that the yeast is rapidly producing. During primary fermentation the yeast is producing approximately equal parts of both alcohol and CO2. Depending on the style of beer, original gravity, quantity of yeast pitched, and fermentation temperature, the primary fermentation for an ale will last between 5-14 days, then it will then be transferred to a secondary fermentation vessel to allow the beer to condition and finish out its fermentation. In some cases only a primary fermentation is completed, and the beer may spending additional time in the primary fermenter or condition in the bottle, keg, or holding vessel.

 

Primary fermentation occurring two days after the yeast was pitched into an American Wheat style Hefeweizen. The krausen has formed and a great deal of alcohol and CO2 is being produced.

Primary Fermentation

Primary Fermentation

Racking

Racking is the process of transferring beer from one brewing vessel to another. Beer is typically racked utilizing a racking arm, racking cane, or racking tube. The beer is either pumped from one vessel to another, or a siphon or CO2 tank is used to create a positive or negative pressure and gravity is used to rack the beer.

 

 

A wide selection of home brewing beer racking accessories can be found here:

Home Brewing Beer Racking Equipment

 

Beer being racked from a primary fermenter to a secondary fermenter using a racking cane and tube:

Beer being racked from a primary fermenter to a secondary fermenter.

Beer being racked from a primary fermenter to a secondary fermenter.

Mouthfeel

Mouthfeel, or the mouth feel of a beer, is the mouth’s perception of the body of a beer and is typically described as light, medium, or full. A beer’s body is formed from the residual proteins, minerals, salts’ and unfermented sugars that remain in the finished beer. The body of a beer is perceived as viscosity or thickness by the mouth. Each style of beer has a coinciding expectation for mouthfeel, and beers are rated on that expectation. For instance, a lager or pilsner should have a light body, and an imperial stout should have a full body if brewed correctly.

Lag Phase

The lag phase is the period of time in which yeast adapts to the new fermentation environment and undergoes significant reproduction.  Depending on the state of the yeast (reactivated, chilled, or dried), health of the yeast cells, variety of yeast, amount of dissolved oxygen available in the wort, temperature of the wort, and amount of available fermentable sugars, the lag phase may last anywhere from 2 to 24 hours. The lag phase begins as soon as the yeast is introduced into the wort and very little CO2 or alcohol is produced while it is active.

 

The shorter the lag time, the better, so that the desired yeast has a chance to take control of the wort before unwanted bacteria or wild yeast strains do.There are several ways to decrease your lag time, including:

  • Creating a yeast starter
  • Rehydrating dried yeast
  • Keeping your yeast and wort at the correct temperature when pitching the yeast and continuing to monitor temperature until the lag phase has ended.
  • Well-aerating your wort so that the yeast will have enough oxygen available.
  • Pitching enough yeast for the gravity of your wort.

 

 

Original Gravity

Original gravity or OG is the specific gravity reading of a beer’s wort prior to having the yeast pitched for fermentation. The original gravity reading is important because it gives the brewer an idea of how much sugar is available for fermentation and what the approximate alcohol by volume will be once fermentation completes. The original gravity reading also permits a brewer to calculate his or her brew house efficiency to determine what percentage of starches and sugars were extracted from the grain bill used to make the beer. Typically either a hydrometer or refractometer are used to take the original gravity reading.

 

Below is the photo of a hydrometer which is used to take original gravity readings.

Beer Hydrometed, Final Gravity Reading

Oxidation

Oxidation is the degradation or modification of beer when it comes in contact with oxygen or an oxidizing agent. Oxidization in beer is inevitable and occurs in beer at all times regardless of how it is stored. That being said, there are ways to diminish the rate of beer oxidation.

A good rule of thumb is to prevent oxygen from coming in contact with your beer whenever possible. The only time that oxygen should intentionally be introduced to a beer is when aerating or oxygenating wort prior to pitching yeast, and, in rare cases, to facilitate a souring process. Great caution should be taken when transferring, racking, kegging, and bottling beer to avoid splashing it or exposing it to more oxygen then is necessary.

When possible, fermentation vessels, kegs and bottles should be purged with CO2 prior to and after having beer transferred into them. Heat is another factor that impacts oxidation, and, whenever possible, beer should be stored cold to reduce oxidation rates and to preserve its freshness. Another way to help slow the impact of oxidation is to keep bottles and fermenters shielded from sunlight.

 

Beer that has been oxidized typically has a stale or paper-like taste.  In darker beers, you may also smell or taste sherry notes.

 

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