How To Brew – The Brewing Process

Table of Contents

Overview

Now that you know all the basic ingredients that go into the brewing process, its time to look into the brewing process itself. We will discuss milling, mashing, sparging, boiling, and knockout. The final two steps of the brewing process, fermentation and conditioning, are discussed on the next page. The brewing equipment required can be found in a separate post here. I mentioned it in the brewing ingredients page, but the first thing I do is design my recipe using the BeerSmith application. It gives you key measurements like strike water volume and temperature, sparge water volume, and mashing time and temperature. It can accommodate all-grain and extract recipes. This guide will cover all-grain recipes, but you can apply most of these techniques to an extract recipe as well.

Pre-Brew Notes

Before diving into the brewing process, I cannot stress enough how important it is to make sure everything is cleaned and everything that touches the wort after the boil is sanitized. When brewing, I clean all the cold side components in three separate buckets. The first is a scrub in powdered brewery wash (pbw), the second is a hot water rinse, and third is sanitizer (star-san). I let all the components rest in the sanitizer for 10 minutes before handling them. If it has not been washed recently, scrub the inside of your fermenter with pbw and rinse it well.

Once all the parts are sanitized, begin assembling the clean fermenter. Before putting any attachments on, fill a spray bottle with star-san diluted according to the directions and spray the attachment point. Once the fermenter is fully assembled, fill it with star-san solution diluted according to the directions and let it sit until you need it. I usually do all of this during the mash.

Milling

The mill I use with a 0.040 inch gap.
Mill setup with roller gap displayed

Before you can add the malted barley into your brewing system, you must mill it. Before being milled, the starch reserves in the malted barley are tightly packed in protein carbohydrate matrix’s that prevent enzymes from being able to access the starches. The milling process cracks open the husk and exposes the starch to the brewing water during mashing, which leads to gelatinization. The starches must be gelatinized and liquefied before they can be converted to sugars. When determining the width of the mill, keep in mind that the finer the crush, the greater the extract, but too fine of a crush can cause issues during wort separation by creating an unstable mash bed. Try to keep the husk intact during milling, as an intact husk promotes bed stability and helps reduce the extraction of tannins and other undesirable components.

Operating the Mill

Most homebrewers and craft breweries use a two roll mill, which is two rollers lined up horizontally with a small gap between. The gap I am currently using is 0.040 inches. One roller is fixed in place and connected to a drill or a motor, and the other spins freely. The roller that spins freely can be moved to adjust the gap. The rollers have coarse grooves on them to assist in cracking. The mill comes with a hopper, so once you measure out your grains, just pour them into the hopper and start the mill. Be precise with your measuring, especially with your specialty malts. Heavily roasted malts like roasted barley are very intense, so adding just half a pound extra to your 5 or 10 gallon batch would cause major flavor, color, and bitterness changes from your pre-designed recipe.

Things to Remember

Do not forget to place a bucket below the mill. I have made that mistake more than once and have had the pleasure of scooping up the crushed grains and cleaning up all the dust that comes with them. If you are using a drill to operate your mill, try to keep the roller speed consistent throughout the milling process for an even crush. If you run your grains through the mill and they are not crushed as much as you would like, feel free to adjust the gap and run them through again.

Rice Hulls

If you are milling rye or wheat, I highly recommend mixing them well with your base malt. Rye is very hard, and putting too much at once will cause your mill to make loud and unpleasant noises. Wheat can clog up your mill if all put it all in at once. When done milling, I recommend putting a healthy amount of rice hulls into your grain bin. I would use anywhere between 3% and 5% of the total grain bill’s weight in rice hulls. Rice hulls do not add any flavor, color, or sugar, but they help tremendously with mash bed stability. If using rye or wheat, use double the amount of rice hulls that you usually do. As mentioned in the ingredients page, wheat and rye do not retain their husk, so there is greater instability. They also have greater protein and beta-glucan levels, increasing wort viscosity.

Mashing

A picture of the mash with a sparge ring on top.
Picture of the mash with a sparge ring on top of the mash bed

The first step in the brewing process is mashing. Mashing is the mixing of your milled malt, or grist, with your brewing water. During the mashing process, the starches gelatinize, soluble materials dissolve, and the grist releases its enzymes, which convert the starches into fermentable sugars. The mashing process has come a long way since beer’s beginning thousands of years ago, so I will briefly discuss the stages that are no longer as popular and spend more time on what is more commonplace.

Stages of the Mash

Today’s malts are very heavily modified, as described on the brewing ingredients page, so many of the early steps are not as necessary as they were before the 1900s. All of these stages are still used in mashing styles like decoction and step mashes, but they are becoming less and less common. The stages of mashing are below.

  • Acid Rest
  • Protein Rest
  • Starch Conversion

Acid Rest

The main purpose of the acid rest is to reduce the initial mash pH. Before modified malts and an understanding of water chemistry, this step was necessary to reduce the pH to a level that would successfully convert the starches to fermentable sugars. Acidification is done by the enzyme phytase, which is most active between 86 and 127 degrees Fahrenheit. It breaks down phytin into phosphates, which react with calcium and magnesium to form phytic acid. This acid is what lowers the pH. Today, if the mash pH needs to be adjusted, we just add an acid to it, like phosphoric acid or lactic acid.

For beers that have a high percentage of under-modified malts such as wheat, rye, oats, or unmalted barley, you may want to consider using a rest right around 100 degrees Fahrenheit. These under-modified malts have higher amounts of beta-glucans, which are soluble in hot wort but insoluble in cold beer. This means they can cause beer haze. Resting at 100 degrees Fahrenheit allows the beta-glucans to be hydrolyzed by beta-glucanases. Maltsters usually indicate when beta-glucan content is high.

Protein Rest

Protein rest, or protein degradation, is another step that has become less common in recent years. Most of the protein degradation occurs during the malting process, and the proteins that do dissolve are not significant. This rest is usually around 122 degrees Fahrenheit for 15 to 30 minutes. The enzymes proteinase and peptidase are the two enzymes active during this stage. This stage used to be utilized to free up more starch from the barley, and to provide free amino nitrogen to the wort. Some brewers use this step for head retention, but it is a very minor enhancement and for the most part not necessary with the modified malts of today.

Starch Conversion

This is the step that is essential, and the main aspect of any mash. This is when the starch reserves are converted into sugars through a process known as saccharification. The two main enzymes in this step are alpha-amylase and beta-amylase. These two enzymes convert approximately 60% to 80% of the starches to fermentable sugars. Alpha-amylase rapidly reduces insoluble and soluble starch into maltose, glucose, and limit dextrins. This enzyme is active between 140 and 167 degrees Fahrenheit, and is optimal between 140 and 158 degrees Fahrenheit. Alpha-amylase can attack the bonds between glucose units anywhere along the chains, so it breaks up large chains of molecules into smaller chains that can be used by beta-amylase.

Beta-amylase removes one maltose sugar at a time, so it works efficiently and sequentially down starch chains. Beta-amylase’s optimal temperature range is between 131 and 149 degrees Fahrenheit. Since these two optimal temperatures are different from each other, a lot of brewers have a couple rests to hit both of the enzymes. As the temperature increases, both of these enzymes will work faster and begin to denature. Denaturing means the shape of the enzyme changes, and it will no longer convert the starches to sugars. Because beta-amylase will temporarily work above its temperature range, many brewers will mash at a single temperature, usually at 152 or 156 degrees Fahrenheit.

Factors That Affect Mashing

Temperature, time, and mash thickness are the biggest factors that will impact your mash. Mashes that are held at higher temperatures (154 to 158 degrees Fahrenheit) tend to mash quicker, produce higher yields, but have less fermentable sugars. This is because at higher temperatures, the alpha-amylase is more active. Alpha-amylase produces more maltotriose and dextrins, which makes a sweeter beer. Irish reds and sweet stouts use this mashing technique. Mashes held at lower temperatures (144 to 149 degrees Fahrenheit) on the other hand produce lower extract but have higher amounts of fermentable sugars. Beta-amylase is more active in these mashes and produces more maltose, the main fermentable sugar. Pilsners and dry stouts use this mash technique to have a dry finish.

Time is similar to the temperature, where shorter mash times at higher temperatures produce less fermentable wort and longer mash times at higher temperatures produce more fermentable wort. Short mash times at low temperatures will also create less fermentable wort, while long mash times at low temperatures create more fermentable wort. Make sure to consider what characteristics you want in your beer before choosing your mash time and temperature.

Finally, thin mashes, or mashes that have more water compared to grist (>2.0 qt/lb), tend to produce more fermentable sugars. This happens because the concentration of the enzymes in the thin mash is low, which slows conversion, but the enzymes are not inhibited by high concentrations of sugars. Thin mashes produce more sucrose and maltose and tend to do best with light lager beer styles. Thick mashes (<1.25 qt/lb) produce more glucose and maltotriose, therefore decreasing fermentability and creating a sweeter, maltier beer. The thick mashes have greater temperature stability and protect the enzymes. Ales and heavier lagers like bocks do best with thicker mashes.

Mashing Styles

The three mashing techniques discussed below are infusion mashing, step mashing, and decoction mashing. Infusion and step mashing are more popular, and what I use almost exclusively when brewing. Decoction mashing is traditionally used for brewing German lagers, but is very time intensive and requires extra equipment.

Single Infusion Mashing

Single infusion mashing is very simple and does not require numerous temperature increases and rests. It only requires one rest, one vessel (the mash tun), and works best with well-modified malts. This is the technique I use in most of my recipes on the recipe page. You will want to have good temperature control with this technique, because as discussed above, a mashing temperature difference of just a few degrees can make a huge difference in the final product.

Single Infusion Mash Process

Strike water is the brewing water you fill up your mash tun with, and it needs to be at a pre-determined volume and temperature. BeerSmith calculates these values if you use that program. The calculations need to account for the grain temperature and weight, because adding the room temperature grains will lower the water temperature. The volume needs to account for the mash thickness you want.

Stir in the grains with a mash paddle as you dump them in. If you do not, the grist can clump together and form doughballs, which reduces efficiency. If the temperature is too high after you add your grains, just continue to stir until the temperature reaches your goal. Insulate your mash tun so it maintains its temperature throughout the mashing process. Your mash tun also needs a filter on the bottom that will allow the wort to flow through but keep the grains out.

If you are able to, place the mash tun on a burner so you can intermittently add some heat if you need to. If you have a pump, recirculate the wort from the bottom of the kettle through to the top of the grain bed through a sparge ring to set up your mash bed and increase wort clarity. When not using a pump, use a clean bucket to draw off half a gallon or wort or so and gently pour it back on top of the grain bed the last 10 minutes of the mash. These are the recommended times for given mash temperatures:

  • 40 minutes @ 156 degrees Fahrenheit
  • 60 minutes @ 152 degrees Fahrenheit
  • 75 minutes @ 148 degrees Fahrenheit

Once mashing is done, increase the temperature to 168 degrees Fahrenheit. This will turn the enzymes off and set your fermentable sugar profile. Begin sparging once the mash reaches 168 degrees.

Step Mashing

The step mashing is very similar to single infusion mashing, but instead of just one rest, there are multiple. The beer style, recipe, and your personal preference determine whether it is two or three rests. The mash temperature is increased by either direct heat or infusion. Multi-step mashing is an easier alternative to decoction mashing, but it does not exactly match the flavor profile. You can choose the specific steps you want, but we show a common three step mash below.

Step Mash Process

The list below has a common step mash schedule. This schedule assumes the temperature raised by direct heat.

  • Have strike water ready to mash in @ 100 degrees Fahrenheit and rest for 30 minutes
  • Raise temperature to 121 degrees Fahrenheit over 10 minutes
    • For highly modified malts – hold for 10 to 15 minutes
    • For under-modified malts – hold for 30 to 45 minutes
  • Raise temperature to:
    • 148 degrees over 15 minutes when brewing drier beers @ hold for 60 minutes
    • 156 degrees over 15 minutes when brewing sweeter beers @ hold for 60 minutes
  • Raise temperature to 168 degrees Fahrenheit over 15 minutes for mash out
Multiple Infusion

As you can see, this process takes significantly longer than the single infusion mash, but it hits a wide range of temperatures. There is a lot of waiting between rests, but it allows you to hit all of the enzymes’ optimal zones. In infusion mashing, you add a set amount of boiling water to your mash to raise the temperature. It takes away the waiting between rests, but you do not hit all the intermittent temperature ranges. John Palmer, author of How To Brew, gives this equation for calculating the amount of boiling water to add.

WB = (M – T)*(0.2G + WM)/(W – M)

Where:

  • WB is the amount of boiling water
  • M is the target temperature of the mash
  • T is the initial temperature of the mash
  • G is the amount of grain in the mash in pounds
  • WM is the amount of water in the mash in quarts
  • W is the temperature of the infusion water

So, if we have 10 pounds of grain in the mash with 10 quarts of water, and we want to raise the mash from 121 degrees Fahrenheit to 148 degrees Fahrenheit with near boiling water (estimate 205 degrees Fahrenheit), we would use this equation.

WB = (148 – 121)*(0.2(10) + 10)/(205 – 148) would give us 5.7 quarts. For this technique, you will need to adjust for the new water added after each infusion. Keep in mind the water to grist ratio to keep the mash thickness at what you would like. Stir the boiling water into the mash to make sure the temperature is evenly spread throughout the entire mash bed. After the last infusion, make sure to recirculate your wort to clarify and set up the mash bed for sparging.

Decoction Mashing

Decoction mashing is the traditional method used when brewing northern European lagers to get the most out of the original under-modified malts. To perform a decoction mash, you remove portions of the mash (decoctions), bring it to the starch conversion temperatures, boil the decoction, and then add it back into the mash. Traditionally, brewers did triple decoction mashes at the temperature ranges described above in the infusion mash section. Decoction mashing takes up significantly more time and energy than the other mashing techniques, so be prepared for a long brew day. Well-modified malts no longer require decoction mashing, but this technique adds unique flavors to beer styles such as oktoberfests, bocks, and and dunkels.

Decoction Mash Process

The guide below describes how you would perform a triple decoction mash. When I was brewing a triple decoction mash, I pulled off approximately a third of the mash each time. These decoctions should be thick, at about 1 qt/lb water to grist ratio. It is the thick portions of the mash that have the inaccessible starches and proteins, not the thin parts that already have the enzymes. There should be just enough liquid to prevent scorching. During these steps, stir the mash that you pull aside the whole time you are boiling it to prevent any burn spots.

Triple Decoction Schedule
  • Have strike water ready to mash in @ 100 degrees Fahrenheit and rest for 15 to 20 minutes
  • Pull off approximately 30% of thick mash and move it to a separate kettle, heat to 152 degrees and hold for 10 minutes
    • After 10 minutes @ 152 degrees, heat it up to a boil and hold it there for 15 minutes for light beers, 25 minutes for dark beers
    • Slowly add the boiling mash back into the mash tun while watching the mash temperature
      • If you reach your target temperature of 120 – 130 degrees before adding all the decoction back to the main mash, wait until the decoction cools to target temperature before adding back in
  • Hold the mash temperature at 128 degrees Fahrenheit for 15 to 20 minutes
  • Repeat the decoction process and pull off approximately 30% of the thick mash, heat it to 152 degrees, and boil it the exact same as before. Once the boil is done, add it back to the main mash the same as the first time
    • The temperature should raise to 148 to 156 degrees Fahrenheit after this decoction
  • Hold the mash temperature at 148 to 156 degrees depending on your style for 45 to 60 minutes
  • For the last decoction, pull off approximately 40% of the mash and do the exact same as the first two decoctions
  • This should bring your mash to mash out at 168 degrees Fahrenheit. Hold for a few minutes, and begin sparging

The triple decoction lasts about 6 hours, so it is not for the faint of heart. You can alter it to be a double decoction by mashing in at 128 degrees Fahrenheit, or even a single decoction by mashing in at 148 to 156 degrees Fahrenheit. Whatever you decide to do, have fun! It is hard work, but the mash will smell amazing and the beer will turn out great.

Sparging

The sparging setup with the hot liquor tank replenishing the mash tun with brewing water at the same rate the wort fills up the boil kettle.
Vessel setup from left to right is: Boil Kettle, Mash Tun, Hot Liquor Tank. Pumps move water from hot liquor tank to mash tun and wort from mash tun to boil kettle.

Now that we have finally made our wort, we need to transfer it over to our boil kettle. This is where the recirculation is going to come in handy. If you have been recirculating with a pump the whole time, your mash is already clear, your mash bed is set up, and you are ready to continue your brewing process and sparge. If you have not been able to recirculate up until mash out, now is the time to do it. Using your clean bucket, pull off a few quarts and slowly pour them back on top of the grain bed. The first bit will come out cloudy, but after a few buckets the wort will begin to run clear. Once your wort runs clear, as in there are no more chunks coming through, you are ready to sparge.

Continuous Sparging

I recommend using continuous sparging. Continuous sparging means that the sparge water is added to the mash tun on top of the grain bed at the same rate the wort is drained off into the boil kettle. You want to keep about 1 to 2 inches of liquid above the mash bed at all times. Below that can cause your mash tun to run dry. If the level gets too high, the weight of the water can cause your mash bed to collapse.

If you have two pumps to use, set them at the same speed, and caution on the slow side. Pulling too fast from the mash tun can create a suction effect that will pull all of the grains together and collapse your bed. This can only be fixed by pumping water from below the mash bed to refloat it. This is called underletting.

If you do not have pumps but have 3 kettles, a hot liquor tank (HLT), a mash tun, and a boil kettle, set them up vertically with the HLT highest and the boil kettle lowest. Through a valve on the bottom of the HLT, have gravity pull the water onto the top of the mash bed, and have gravity do the same with the wort from the bottom of the mash tun into the boil kettle. When filling from the top, make sure it fills slowly to not add additional oxygen to the wort.

If you only have a mash tun and boil kettle, use gravity to drain the mash tun into the boil kettle and continuously replenish the mash tun with sparge water with a clean pitcher or bucket. If pouring by hand or by gravity, consider placing a plate or plastic lid on top of the mash bed. This will take the impact of the water off of the bed and protect your delicate mash bed. Continue sparging until you either reach your desired pre-boil volume, or you start pulling wort that has a gravity below 1.008. This can be easily checked by a refractometer, which measures sugar content through Brix.

Boil

How a successful whirlpool will look
The whirlpool, which begins immediately after the boil

The next main part of the brewing process is the boil. The boil is key for sterilization, deactivating enzymes, color development, isomerization, increasing wort concentration, dissipation of volatile compounds, and protein precipitation. I always do a 90 minute boil, and I would caution against doing anything less than a 60 minute boil.

Sterilization, deactivating enzymes, color development, wort concentration, and protein precipitation are all important, but we don’t need to spend any more time on them besides a quick explanation of their importance, which is below.

  • Sterilization: There are microorganisms spread throughout the brewing process prior to boil. Boiling at 212 degrees Fahrenheit removes them and prevents any of them from causing an infection or off flavor.
  • Deactivating Enzymes: If the enzymes are not deactivated, they would continue to perform starch conversion. This would cause your wort to have a different sugar profile than you are expecting from your mash process
  • Color Development: The wort becomes darker during the boil. The boil causes the formation of melanoidins, the oxidation of polyphenols, and the caramelization of sugars – all of which darken the color.
  • Wort Concentration: The boil causes some of the wort to evaporate off. This causes the specific gravity to increase and the volume to decrease.
  • Dissipation of Volatile Compounds: The most important compound you want to get rid of is dimethyl sulfide, or DMS. This compound gives the beer a strong corn flavor.
  • Protein Precipitation: During the boil, the wort loses its turbidity and causes the proteins to fall out of suspension and precipitate as it coagulates. These proteins would cause problems with chill haze and fermentation if allowed to remain.

Your boil will most likely be powered by direct heat, but commercial breweries use other techniques like external heating jackets and internal heating systems.

Kettle Additions

Before I jump into the most well known part of the boil – the hops – I want to address the hot break. The hot break is the coagulation of proteins and polyphenols. They clump together and fall out of solution. This can happen anywhere between 5 and 20 minutes into a vigorous boil. During this time, foam will begin to rise. Watch the boil until the hot break is done, it can very quickly turn into a boil over. A boil over can be prevented by turning down the heat or lightly spraying the foam. If it is not caught in time, it will make a glorious mess that is fun to scrub off. I usually wait to add hops until this hot break is over to avoid excessive foaming.

And one last thing – do not leave a cover on during the boil. You can cover the wort while it is heating up to accelerate that process, but remove it just before the boil begins. Keeping the boil covered will quickly cause a boil over. The boil also releases sulfur compounds that need to be released. The sulfur compounds will fall back into the wort if the lid remains on, leading to the formation of dimethyl sulfide, which can add cabbage or corn flavor to your beer.

Hops

The brewing ingredients page has an in depth description on the hop plant itself and how bitterness and flavor is added to the boil, so I will keep this section limited to the hopping processes. Bittering hops are hops that are usually high in alpha acids and added early in the boil. Adding them early in the boil causes more iso-alpha acids to be added to the beer – making it more bitter. They are usually added around the 60 minute mark, but can be added as early as the beginning of the sparging process in what is known as first wort hops. Add flavor or aroma hops between the 15 and 30 minute mark. Add any aroma hops in the last 5 minutes of the boil.

Whirlpool Hops

When brewing certain beer styles such as New England IPA’s, whirlpool hop additions are key. For a successful whirlpool hop addition, first lower the temperature to 180 degrees Fahrenheit before adding them. When you add the hops at 180 degrees, utilization is decreased so the hops only impart minimal bitterness and you preserve the maximum amount of hop oils. Steep these hops for 20 to 30 minutes. Hopping rates for whirlpool hops can be anywhere from 1 to 3 ounces per gallon depending on your preference.

Dry Hopping

Dry hopping is the process of adding hops directly into the fermenter. Adding hops directly into the fermenter intensifies hop aroma and flavor. Boiling is the only way to isomerize the alpha acids, so adding the hops directly to the fermenter infuses new oils for fresh hop flavor and aroma. Try not to keep your hops in contact with the beer for more than 10 days, or you run the risk of developing grassy or vegetal flavors.

There is a new technique that has sprung up recently in regards to dry hopping New England IPA’s. Some brewers are adding dry hops towards the end of active fermentation. Many in the brewing community debate its impact, but some claim adding hops during fermentation causes something called biotransformation. Some brewers argue that biotransformation enhances the flavor and aroma of your dry hops through a reaction between the hop compounds and the yeast. More specifically, biotransformation occurs when certain terpenoids in the hops are in the presence of yeast in active fermentation. These terpenoids transform into other terpenoids. The transformation brewers look for specifically is the transforming of the floral geraniol into the citrusy citronellol. Again, the debate rages as to whether or not it creates a noticeable difference, but it is worth experimenting.

Miscellaneous Additions

I add two other ingredients to all my boils, yeast nutrient and whirlfloc tablets. You can use Irish moss instead of whirlfloc tablets, but they both aid in precipitating positively-charged proteins from the wort. Whirlfloc makes a huge difference in wort clarity, and I always add it in the last 10 minutes of the boil. Yeast nutrient is just an additional safety precaution to make sure all the required nutrients are present for the yeast to have a successful fermentation.

Whirlpool

Technically the whirlpool is not part of the boil, but it immediately follows flame out. More advanced boil kettles have a tangential input used to whirlpool the wort. The wort is drawn from the center of the boil kettle through a pump and pushed into the tangential input, creating a whirlpool that draws any remaining hops and trub to the bottom the the kettle. The pump runs for 10 minutes and then rests for another 10 minutes. If you do not have a pump or the capabilities of running a whirlpool automatically, stir the wort in a circular motion to create a whirlpool for a couple minutes and then let everything settle. Once the whirlpool is finished, the wort is ready for transfer.

Knockout

Now that your wort is finished boiling and whirlpooling, you have to transfer it to the fermenter. Before you can transfer it, you first have to quickly drop the temperature of the wort to pitching temperature. For lagers, this temperature is between 45 and 52 degrees Fahrenheit. For ales, this temperature is between 60 and 64 degrees Fahrenheit. When you pitch the yeast slightly below fermentation temperature, initial fermentation does not produce as many unpleasant off-flavors. Cooling quickly is essential to the formation of cold break. Cold break consists of protein-polyphenol complexes that lose its solubility and precipitates out of solution. If you have a slow cooling process, the cold break loses its effectiveness because more protein is trapped in suspension. These proteins can cause chill haze and harsh, sulfur like flavors.

There are a few ways you can cool your wort. Breweries use either single stage or two stage cooling systems. These systems work great, but the heat exchangers are not cheap. In a single stage heat exchanger, pre-chilled water is run opposite the wort to cool it to pitching temperature. For a two stage cooling system, water removes the bulk of the heat in the first stage and the glycol system removes the rest in the second stage.

For homebrewers, wort chillers work great for cooling smaller batches of beer. The most common type of chiller is a copper coil immersion chiller. After whirlpooling, immerse the coil into the wort and run cool water through it. The water can be straight from a hose, or you can run your water through an additional coil that is in an ice water bucket beforehand to drop the temperature more rapidly. If you would rather cool outside of your boil kettle, you can pump your wort through a copper pipe with cool water run around the pipe, or use a plate chiller. Regardless of what you use, just make sure it cools your wort quickly to pitching temperature. Once you wort is transferred, take a hydrometer reading. This, along with post fermentation gravity, is required to calculate abv.

Aeration

Yeast needs a couple of things for a healthy fermentation, and one of those is oxygen. The wort must be oxygenated before fermentation, and fortunately there are a number of ways you can do it. Most commercial breweries inject pure oxygen into the wort during the knockout phase after the heat exchanger. Oxygenating hot wort increases the risk of oxidation and other unpleasant off-flavors. Oxygenation at cooler temperatures also allows you to benefit from increased solubility. If injecting pure oxygen, you can just use a diffuser. If you are injecting compressed air, you will need a filter to prevent any microorganisms from entering the wort. You can use a 0.23 micron sized HEPA filter, or an improvised cotton ball dipped in alcohol filter. If you are using air to oxygenate your wort, you will need to add more than if you are using pure oxygen.

For homebrewing, you can get by without having to install an in-line oxygenation system. Agitating your wort once it has been transferred to your fermentation vessel will add sufficient oxygen. To agitate in a closed fermenter, you can shake the vessel back and forth to splash it around a couple times. If using an open top fermenter, you can use a sanitized whisk or something similar to stir the wort around until there are a few inches of foam on top. Whatever method you use, just make sure you remember to do one. Most yeast strains need between 7 to 18 mg of Oxygen per liter, so make that yeast happy!

Closing

This is a complete description of the brewhouse portion of the brewing process. Following these steps will make you a delicious wort, and the perfect home for you yeast. The next page continues the brewing process with fermentation and conditioning, and discusses how to turn this wort into what you really want – beer. Sign up for our newsletter below to be notified when we release new brewing content!

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