Brewer's Friend Home Brewing Software

Stir Plates and Growing Brewing Yeast Quickly

Creating a simple yeast starter as outlined here at brewersfriend.com will greatly increase your yeast cell count, but there is a way to easily supercharge this process. By using a stir plate you will be able to grow nearly 100% more yeast cells using the same volume of starter in the same amount of time. Basically, for the same investment in yeast, time and starter liquid, you will be able to double your yeast production with a stir plate.

A stir plate is a simple machine consisting of a base which houses a motor with variable speed control. Fig 1. This motor is used to spin two precisely spaced magnets, which in turn will spin a magnetic stir bar inside your flask. The intent here is to use this stirring motion to:

1. Keep the yeast in suspension
2. Release CO2 from the starter solution
3. Continuously aerate the starter liquid

Fig 1.

There are several important guidelines to follow when utilizing a stir plate to create a starter:

1. Ideally, boil the starter wort in the flask that you will be using to create the starter, this will help to sanitize the flask.
2. DO NOT use an airlock on a stir plate starter as it will impede the ability of the stir plate to exchange CO2 from the fermentation for O2, which will help grow yeast.
3. DO use foil to cover the top of the flask instead of an airlock.
4. Ferment the starter at 75F – 80F. While not optimal for flavor production, you are trying to grow yeast, and warmer temperatures will accelerate this process.

By doing the above, you are creating the perfect growing environment for your yeast cells, allowing them to grow at a much greater rate than they would with the use of a simple starter with no stir plate. After the starter has fermented out completely (approx 24 hours), remove the starter from the stir plate and chill so that the yeast may settle. After a short period of time (several hours), the yeast will form a nice thick slurry in the bottom of the flask, allowing you decant the starter wort prior to pitching. Decanting is required since the wort has been oxidized and fermented at a higher temperature than is optimal for most yeasts (75F-80F recommended). Though this temperature is excellent for yeast growth, it does not leave a very favorable flavor in the starter liquid.

Our yeast pitching calculator makes choosing and hitting your desired pitch rate very simple.

Our calculator will allow you to enter all of the vital statistics about your wort so that it can properly calculate the number of yeast cells you will require, the required volume of your starter wort and the volume of yeast slurry that you must pitch to meet your ideal pitching rate.

Below is a side by side comparison of the number of yeast cells created in a 1.5L simple starter (no stir plate) and a 1.5L stir plate starter. The results may surprise you!

Starter volume: 1.5L
Amount of Yeast used in starter: (1) Liquid Smack Pack / Vial – 100B cells
Fermentation Time: 24 hours
Temperature: 75F (recommended to quickly grow yeast)

Using the above criteria, a simple starter will produce approximately:

182 billion yeast cells, pitch rate of 0.71 M cells / mL / °Plato (just below the pro recommended pitch rate)

Using the above criteria, a stir plate starter will produce approximately:

282 billion yeast cells, pitch rate of 1.09 M cells / mL / °Plato (a very healthy pitch rate)

As you can see from the above comparison, utilizing a stir plate you are able to increase by 100% the yeast growth with the same amount of starter wort while using the same amount of yeast pitched into said starter. Conversely, you can also create the same amount of yeast in a stir plate starter as you are able to with a simple starter, with nearly half the starter volume. The latter is of great interest to lager brewers who will routinely need to create very large starters to reach the proper pitching rate for their lager beers. Lagers will routinely require a 3L-4L stir plate starter. If you utilized a simple starter (no stir plate), you would be in the neighborhood of 6L to reach the proper pitching rate.

Posted in Beer Styles, Yeast Cultures | 24 Comments »

Recipe OktoberFEAST Ale AG (5.5 US gal.)

With fall just around the corner, cooler temperatures and shorter days are on there way. This calls for a maltier, less hoppy, less zingy beer to satisfy us on those cool evenings around the fire. As the temperatures go down, the ABV of seasonal beers goes up. To speed up the process, this Oktoberfest beer is not a classic Maerzen lager, but an ale.

The following recipe is based on 75% brew house efficiency, see an explanation of brew house efficiency here at Brewers Friend.

Style: Maerzen (ale)
BJCP Guidelines:
OG: 1.050-1.056
FG: 1.012-1.016
ABV: 4.8-5.7
IBU: 20-28
SRM: 7.0-14.0

Recipe Targets:
OG: 1.056
FG: 1.014-1.016
ABV: 5.3%-5.5%
IBU: 24.1
SRM: 13.5.
Volume: 5.5 gallons

Malt Bill:
Belgian Pilsner 4.25 lbs
Vienna 2.25 lbs
Munich 20L 2.00 lbs
Aromatic 1.00 lbs
Crystal 20L 1.00 lbs
Crystal 40L 1.00 lbs

Water Profile: Munich water profile to accentuate malt flavor.

Ca: 88 SO4: 11 Mg: 3 Na: 10 Cl: 2 HCO3: 156 Alky: 240

Mash in with 23.0 quarts (2qt/lb) of water at 167F to rest at 158F for 60 minutes. This water was also treated with Five Star Buffer 5.2.

Mash out at 168F utilizing additional infusions or direct heat.

Collect 8.0 gallons (adjust to compensate for your own boil rate) at a SG of 1.039

Boil for 100 minutes with the following hop schedule. (Adjust your qty. to adjust for any difference in AA value)

Hops:
Tettnanger 3.3AA 1.00oz 100 minutes
Tettnanger 3.3AA 0.50oz 45 minutes
Tettnanger 3.3AA 0.50oz 30 minutes

Chill wort to pitching temperature, see an explanation of “no chill” brewing here at brewersfriend.com.

Yeast: SafAle S-04 11g packet.

Fermentation Temperature: 65F

Time in Primary: 14 days

Carbonation: 2.5 volumes

Posted in Recipes | 4 Comments »

Identifying Hops Techniques

It’s the season to harvest, and if you’ve been diligent and foresighted, you have a nice crop of well-labeled hop plants, and have no need for this article.

However, if the labels you planted next to the vines have faded & run since you planted them, or if your hop harvest didn’t come from a garden, but from a fortunate find of a hop plant at the state park or growing over the fence from a neighbor, identifying what you’ve got is a bit more important to you.

Visually, one species of hop cone looks much like another, so just looking won’t help. Aroma can be a huge indicator of the hop type, so you should start with that. If your hops are dried (which they should be, after harvest!), they won’t have a lot of aroma initially. Take the cone between your palms of your hands, rub your hands together, and then cup them near your nose and inhale. The hop aroma should be strong enough to identify any significant aromatic markers, such as the citrus aroma of Cascade or Centennial hop.

Some folks claim that the only way to really identify a hop is to brew with it. While that might work, there’s an easier way to identify the flavors & bitterness of a hop without risking a batch of beer. Once you’ve crushed the hop between your hands and smelled the aroma, throw your teakettle on the stove & heat some water to boiling. Making hop tea is the next-best thing to brewing with it, so toss your crushed cone in a cup and add boiling water. Let it steep for about five minutes to fifteen minutes, and then smell the aroma again. It should be fainter, but still the same notes as you smelled before. Strain the hops out of your tea, and then take a sip of the tea, checking for both flavor and bitterness. Because it’s a small amount of hop, steeped for a short amount of time, bitterness will be minimal (relative to your beer), but a highly bitter hop will be noticeable.

One word of caution: do not chew on the hop directly. It’s tempting and a fun prank to play on novice brewers, but the intensity of the bitterness will drown out other flavors in the hop, making identification harder, not easier. You get better flavors and a better balance from making the ‘tea’, and your palate isn’t smothered afterward.

Posted in Hops Growing, Ingredients | No Comments »

Fall Hop Harvest Guidelines

Now that you have spent the entire growing season diligently caring for your vines, it is time to harvest what can turn out to be copious amounts of hops on healthy, mature plants. The following will cover some guidelines for you to follow in order to assure that you are harvesting your hops at their peak of potency and freshness. A little study in this area will allow you to accurately time your harvest so that you can maximize your return on your annual investment in water and time.

Take note, the following guidelines are on a cone by cone basis, rarely, if ever, will all of your cones be ready for harvest simply because some of them are presenting the signs that they are ready to harvest. Harvests can many times take days, or weeks to complete in separate stages for the home brewer. Hops farmers will often harvest everything at once, but at home you can take more care.

1. Hop cones appear less “tight”, the leaves of the cone are visibly “opening” (Fig 1)

2. The bases of the hop leaves are showing ample amounts of bright yellow lupulin (Fig 2)

3. When squeezed, the cones emit the fragrant scent that you would come to expect from fresh hops (pungent, fragrant)

4. When the cone is squeezed between your fingers and released, it feels papery, resilient, not green and hard

5. The small bract leaves at the base of the hop stem are beginning to dry and the tips are browning (Fig 3)

(Fig 1)

(Fig 2)

(Fig 3)

Typically when you observe a hop cone presenting all of the above traits, there will be an ample number just like it, enough to justify harvesting all of those that have peaked. Those cones that do not exhibit the signs listed above are best to be left alone until they do. It can take days or even weeks for them to mature.

Once you have harvested the ripe cones, it is time to prepare them for preservation. Hops have several enemies when it comes to maintaining their characteristics.

1. Temperature

2. Oxygen

3. Time

Hops must be stored cool, or better yet frozen. The oils that exist in the lupulin glands are volatile and do not store well at room temperature. These oils are also easily oxidized, which means that long term storage planning must include some sort of vacuum packaging. Lastly, even if you have frozen and vacuum packaged your hops, time is one enemy that you cannot avoid, that is, unless you actively brew and use your hops!

To prepare your hops for storage as discussed above, they are typically dried. You can freeze them wet, or use them wet in a specialty beer if you like! There is a school of thought, however, that believes that freezing WET hops will actually serve to preserve the hops longer, though drying them is the norm. (Source Charlie Papazian, Homebrewers Companion)

To dry the hops you can use many methods, but stay away from cookie sheets and ovens if you can. Hops are fragile, their oils and thusly their characteristics are extremely susceptible to degradation from high temperatures, best to dry them slowly and naturally. Food dehydrators have been used with success, or another method that is used with great success is the box fan and window screen method.

(Fig 4)

If you have a home, you most certainly have windows, and you most certainly have some window screens to go along with them. You can use some chairs, 5 gallon buckets, really anything you can think of to support the window screen horizontally above the floor. Now, you must do the same with a cheap box fan from any retail store… supported above the floor (to allow it circulate air), but below your window screen, facing upward.

You can then spread your freshly harvested hops across the screen in a singular layer and turn the fan on low. You don’t want the hops flying all over your garage, but you do want to promote drying and air circulation. Agitate the hops periodically to ensure even drying of all of the hops. Allow this process to carry on until your leaf hops are papery and sufficiently dry to store. Once this is accomplished, vacuum seal and freeze any hops that you do not intend to use right away to preserve them.

When you are picking, make sure to keep the different varieties you grow in separate containers and drying screens as not to mix them up.

Posted in Hops Growing | 1 Comment »

White Labs WLP300 Yeast Review

White Labs has always been a favorite of mine, no matter the yeast variety, they produce excellent beer and are very reliable yeasts. Aside from the fact that you get a great product, you get a really cool test tube looking vial that is already labeled, which you can use to store harvested yeast after your primary fermentation is complete.

One yeast that I can give nothing but rave reviews to is the WLP300 German Hefeweizen yeast. From the quick start, the raging fermentation and excellent final flavor profile, this yeast is a show stopper in your summer Hefeweizen. Below are some stats on this yeast and how I have effectively used it in my beers. Mrmalty lists this as the strain as Wyeast 3068 Weihenstephan Weizen Yeast.

• Starter recommended?: YES
• Starter size (for 5 gallons): 1 quart
• Starter OG: 1.040 – 1.050
• Starter incubation time: 24 hours
• Blow off recommended?: YES
• Optimum fermentation temperature: 68F-72F
• Suggested ambient air temp during first 24 hours of fermentation: 65F
• Suggested ambient air temperature after 24 hours of fermentation: 70F
• Scent during fermentation: Bananas
• Flavor profile: Bananas and cloves
• Flocculation: LOW
• Attenuation: 72%-76%

Liquid yeasts yield a much lower cell count than the common 11g dry yeast packets. Dry yeast are also packed with nutrients and reserves so they are ready to ferment immediately after being re hydrated, liquid yeasts are not. This is why a starter is imperative. 24 hours is all that is really required to get this yeast really cranking and ready to pitch. See how to make a yeast starter at brewersfriend.com.

Typically with this yeast, my beer OG is low, 1.040 – 1.050 and the volume is 5.0 gallons. For the proper pitching rate for the above described conditions you will need about 158 BILLION yeast cells, requiring a 1qt starter. Quickly boiling up some DME OR using your actual wort from your brew and allowing the yeast to incubate for about 24 hours is all that you need to get this yeast ready to brew.

The ambient air temperature is important to note with this yeast as it ferments. Optimum fermentation temperatures are tight, between 68-72F, so temperature control is imperative for good consistent results. After pitching, this yeast will require approximately 8-10 hours to show real visible signs of fermentation. Fermentation is violent, heating up the wort to at least 5-7F greater than the ambient temperature. Therefore when fermentation begins, it is best to keep the ambient temperature at approximately 65F for the first 24 hours of violent fermentation, after this point you should safely be able to raise the ambient temperature to 70F to finish the remainder of the fermentation. Due to the violent fermentation associated with WLP300, a blow off tube is required, you can expect up to a quart of fluid to blow out of a typical 6 gallon fermenter.

Please note that on each vial of White Labs yeast it claims to be pitchable yeast, direct from the vial. While this may be true, in most cases you will be under pitching into your wort, experience a longer lag time and a less desirable fermentation.

See how to brew the CCB Hugh Hefeweizen with this yeast at brewersfriend.com.

Posted in Yeast Cultures | No Comments »

Hugh Hefe Hefeweizen AG (5.5 US gal)

Summer is the season for light and bright beers. A favorite that is light in body, low abv, but full of flavor and complexity is the hefeweizen. Perfect for a thirst quencher and suitable for a twist of citrus if you so choose.

The following recipe is based on 82% brew house efficiency see an explanation of brew house efficiency here at Brewers Friend.

Style: German Hefeweizen
BJCP Guidelines:
OG: 1.044-1.052
FG: 1.010-1.014
ABV: 4.3-5.6
IBU: 8-15
SRM: 2.0-8.0

Recipe Targets:
OG: 1.046
FG: 1.011-1.013
ABV: 4.3%-4.5%
IBU: 11.8
SRM: 2.9
Volume: 5.5 gallons

Malt Bill:
Belgian Wheat 5.0 lbs
Belgian Pilsner 2.25 lbs
Rahr Pale 6-Row 1.0 lbs

Water Profile:

Ca: 250
SO4: 244
Mg: 23
Na: 69
Cl: 106
(carb): 170

Mash in with 16.5 quarts (2qt/lb) of water at 160F to rest at 152F for 60 minutes. This water was also treated with Five Star Buffer 5.2.

Mash out at 168F utilizing additional infusions or direct heat.

Collect 8.0 gallons (adjust to compensate for your own boil rate) at a SG of 1.031

Boil for 100 minutes with the following hop schedule. (Adjust your qty. to adjust for any difference in AA value)

Hops:
Hallertau 5.1AA .6oz 100 minutes

Chill wort to pitching temperature, see an explanation of ‘no chill’ brewing here at brewersfriend.com.

Yeast: WLP300 German Hefeweizen liquid yeast. Click here for a review of this yeast.
NOTE: this liquid yeast benefits from making a 1qt yeast starter with an OG of approximately 1.040. See how to make a yeast starter at brewersfriend.com.

Fermentation Temperature: 70F
(NOTE: WLP300 ferments very violently, raising the wort temperature by 5-7F above ambient temperature, adjust ambient temperature accordingly)

Time in Primary: 10 days
(NOTE: WLP300 is a very violent fermenting yeast, use a blow off for at least the first 24 hours of the fermentation)

Carbonation: 3.8 volumes

Posted in Recipes | No Comments »

What is SMaSH brewing

Beers are complex. They typically consist of several types of malt, some base, some specialty, and this lends to the complexity of the beer. In the same sense, many beers use more than one hop type, again adding to the complexity and dimension of the beer. Beer is the sum of all of its parts, but to create it you must understand each singular part.

SMaSH stands for single malt and single hop. The acronym was coined by a group of dedicated brewers at the popular home brewing forum HBT (https://www.homebrewtalk.com). A SMaSH brew is a way for any brewer to really get a feel (taste) for any base malt and any hop variety. It is also a very economical way to brew as it minimizes the cost of the batch.

SMaSH brewing is an excellent way to learn about the flavors various malts and hops impart on a beer. By focusing on just one grain and one type of hops in a recipe, you can truly get a feel for the flavor of the malt and hops used. This being said, unless you are experimenting with the properties of different yeasts, you will want to keep to a clean fermenting yeast like S-05, WLP001, Nottingham etc. Otherwise, the flavors contributed by the yeast will begin to overshadow those from the malt and hops.

A typical SMaSH recipe would resemble the following:

Malt:

• 8 lbs Maris Otter
• Mash for 60 minutes at 153F

Hops:

• 1 oz Centennial @ 60 min.
• .5oz Centennial @ 10 min.
• 1 oz Centennial Dry Hop

Yeast:

• SafAle S-05

Though not complex, a SMaSH brew will not only showcase the properties of the single malt and single hop being used. It can and will create a clean and easy drinking beer that will remind you with each glass of the properties of these individual ingredients. When formulating recipes, you will know if Maris Otter will suit your recipe better than Rahr 2-row pale malt. You will also have a better idea of whether or not you would prefer Centennial or Cascade in a certain recipe as well.

In order to formulate a recipe and enjoy the sum of all the parts, you need to understand the properties of each individual part. Do some experimenting, use your hop of choice for bittering, flavor and aroma. Explore the ability of the hop to create a favorable outcome in each of these roles. You may enjoy the bitterness of Centennial, but not the flavor or the aroma…. so be sure to use it in each of these capacities in your SMaSH.

One variation on this method is to split the batch into several parts. Brew a SMaSH brew and then split the 5 gallon batch into (5) separate 1 gallon batches. Pitch a clean fermenting yeast into one batch (WLP001, Nottingham, S-05) and then use any other yeasts that you are interested in testing into the other fermentors.

At this point you will have a simple beer where the yeasts properties can shine through. The clean fermenting yeast will provide a control, a flavor profile that all of the other yeast varieties can be judged against. With one 5 gallon brew you will be able to experiment with (5) yeasts and explore the properties of the malt and hops chosen for the SMaSH.

Update 9/23/2009:  Modified post to clarify origins of SMaSH acronym.

Posted in Brewing, Recipes | 8 Comments »

Keg Care and Cleaning PBW vs Oxiclean

Soda kegs, commonly used in home brewing draft systems, require regular cleaning and maintenance. Following is a brief description of keg care and cleaning requirements to assure optimum performance from these pressurized vessels. For an explanation of the keg components referenced below, see our article on keg anatomy.

Believe it or not, soda kegs do not always require cleaning between fillings. If a soda keg is emptied and is capable of being refilled with a similar beer prior to to the remnants of the previous brew going “sour” in the keg, cleaning is generally only required once every 2-3 batches.

1. Leave the emptied keg in the kegerator until ready to refill.
2. Lubricate all accessible seals with keg lube (a food grade lubricant) Fig. 1
3. Rack your new brew into the uncleaned keg.
4. Replace lid and pressurize.

Fig. 1

Normal keg cleaning will be necessary when simply racking into an uncleaned keg is not possible.

1. Thoroughly rinse the keg with water to remove most of the remnants from the previous brew.
2. Fill with an OxiClean solution of (1) scoop OxiClean and 5 gallons water. Fig. 2
3. With the lid secure, attach keg to your draft system to push about 1 liter of solution through the keg to fill the beer out dip tube and soak the poppet.
4. Let keg sit for 24 hours, or for months, it is up to you.
5. Rinse keg with water and then again with a sanitizer like Star San prior to filling again.
6. Lubricate all accessible seals with keg lube.

Intense cleaning should take place once every 4-6 batches.

1. Dis-assemble keg components, soak all components and keg in an OxiClean solution for 24 hours.
2. During the dis-assembly inspect all components for wear and possible need for replacement. (poppets, seals, pressure relief valve)
3. Once clean, reassemble keg components, making sure to lubricate all rubber seals with keg lube during re-assembly.
4. Once assembled, rinse keg with water and then again with a sanitizer like Star San prior to filling again.

Fig. 2

Typical trouble spots in keg cleaning/maintenance will include:

Poppets: These consist of springs and intricate parts that can trap hop particles. The seals on the tip, if worn, will lead to leaks in the keg post when assembled. Be sure to clean them thoroughly and lubricate the small seals on the tip of the poppet.

Dip Tubes: The internal surfaces of the dip tubes can be a hiding place for all sorts of nasties. The use of an effective cleaner such as OxiClean or PBW (Powdered Brewery Wash) will rid these hidden areas of all organic matter, the use of a specialized dip tube cleaning brush can also put your mind at ease.

Dip Tube Seals: These seals are no more important than the other seals on your keg, but they are the most inconvenient to replace when the keg is full of beer and you realize a leak. Be sure that these areas are clean and that the seals do not show wear, of they do, replace them to save yourself a potential headache after the keg is filled.

The use of OxiClean (or its generic equivalent) has been referenced in this article. Following are some guidelines to keep in mind when using this, or any oxygen based cleaner in place of PBW. OxiClean is an attractive option as it costs anywhere from 50% as much as PBW, or 25% as much if using the generic equivalent. PBW is an excellent cleaner, but at $4 per pound there are other options that are much more wallet friendly for the home brewer, if you are so inclined.

Use OxiClean (or equivalent) if you answer yes to all of the statements below:

1. I have relatively soft water (hard water reduces the effectiveness of OxiClean).
2. I will not be cleaning aluminum (oxygen based cleaners will damage aluminum).
3. I like to save money.

Use PBW if you answer yes to any one of the statements below:

1. I have relatively hard water.
2. I will be cleaning aluminum.
3. Money is no object when it comes to brewing.

Posted in Equipment | 1 Comment »

How to bottle beer from the keg

Once a brewer begins kegging, he/she will never go back to bottling, or will they? There is something to be said for the convenience of bottled beer. It travels well, it can be given as a gift and it is the only way to get it to a competition. How do we get that sweet carbonated nectar into the bottles?

There are commercial CO2 bottling wands, guns, beer guns… but they are entirely too expensive and unnecessary to accomplish this simple task. There is no need to spend $50, $60, or $100 dollars to fill a bottle with beer effectively. Here is how:

1. You will need a 7’+ beer line with a picnic tap on the end Fig. 1
2. You will need a plastic bottling wand OR racking cane (this will fit into the picnic tap) Fig. 2
3. You will need a #2 drilled rubber stopper Fig. 3

Fig 1.

Fig 2.

Fig 3.

Assemble these components in this manner:

1. Cut a 45 degree angle on one end of the bottling wand/racking cane to allow the free flow of beer into the bottle
2. Slide the uncut end of the bottling wand/racking cane into the picnic tap
3. Slide the #2 stopper up onto the bottling wand/racking cane (this will seal the bottle while filling)
4. Attach the beer line to the keg itself.

See Fig 4.

Fig 4.

You are now ready to bottle beer, and there are some simple rules and procedures to follow to be successful.

1. Be sure that your beer line and bottles are cold, this will reduce foaming during bottling.
2. Shut off the gas to your keg, use the pressure relief valve to relieve excess pressure.
3. Turn your regulator down to 3-5 PSI and turn the gas back on to the keg, this will give you a gentle flow rate to reduce foaming.
4. Open the tap and run a small amount of beer out as waste, this will prime the bottle filler.
5. Place the bottle filler in the bottle and seal the bottle with the rubber stopper. Fig. 5
6. Open the picnic tap to LOCKED position, and as the flow slows due to pressure, squeeze the side of the stopper to relieve the pressure and fill bottle until beer flows out the top, not just foam.
7. Move to next bottle and repeat.
8. When finished, give all bottles a quick shot of beer to top them off (place the tip of the bottling wand about 1” below the level of the beer in the bottle and secure the stopper when accomplishing this step)
9. Place caps on all bottles.
10. One at a time, tip each bottle on its side and upright again while holding the cap on. When the beer foams over, lock the cap on, repeat with all bottles (purging CO2). Fig. 6

Fig 5.

Fig 6.

Remember when you are finished bottling, to again increase your regulator pressure to maintain the proper level of carbonation in your keg. Happy bottling!

Posted in Kegging and CO2 | 5 Comments »

Beer Aeration Oxidation and Mitigation

Oxidation is not the same as aeration. Aeration is the process by which oxygen is introduced to your beer or your wort, oxidation is the outcome, it is what happens to your wort or beer when exposed to oxygen at the wrong point in the process. Aeration of COOL wort (<80F) prior to fermentation beginning, is the only safe type of aeration.

Aeration of HOT wort (>80F): Aeration of hot wort will cause oxygen to bind with various wort compounds. Over time, these compounds will break down, releasing oxygen into the beer and oxidize hop compounds and alcohol, leaving off flavors. These flavors taste like wet cardboard or Sherry.

Aeration during fermentation: Likewise, introducing aeration after fermentation has begun can cause yeast to create more diacetyl in your beer (buttery flavor or smell).

Aeration of finished beer: Aeration after fermentation is complete will cause more rapid staling of your beer, loss of long term stability.

Below we will discuss where in the process aeration and subsequent oxidation can occur and how to mitigate these dangers.

How can aeration/oxidation occur?

• Whipping up a froth while stirring your hot mash (>80F)

• Whipping up a froth while chilling your wort after the boil (>80F)

• Pouring hot wort from one vessel to another causing splashing (>80F)

• Transferring hot liquids through spigots without tubing to reduce splashing (>80F)

• Agitating the fermenter AFTER primary fermentation has begun (any temperature)

• Agitation after fermentation is COMPLETE (any temperature)

• Bottling, leaving too much head space and O2 in the bottle

• Not purging the head space in the keg when kegging beer

How to mitigate the danger of aeration/oxidation:

• Stir your mash gently

• Stir your cooling wort gently, create a whirlpool effect

• Do not pour hot wort from one vessel to another, it is dangerous AND can cause oxidation

• Use high temperature tubing to transfer hot wort from one vessel, to the bottom of another

• Do not agitate fermenting wort

• Do not agitate or splash fermented wort, use a siphon or a spigot and tubing to transfer beer

• Leave as little head space as possible when bottling (1” usually)

• Use O2 absorbing caps when bottling

• Purge kegs with CO2 prior to racking beer into them, and purge the head space with CO2 after the keg is sealed.

• Use spigots, siphons and hoses to allow gentle movement of hot or fermented fluids

Mentioned above is the issue of beer becoming oxidized through the bottling process. This can be caused by improper (turbulent) transfer of the finished beer from the fermenter to the bottle, or by leaving too much head space in the bottle. One way to mitigate the oxidation danger of head space in your bottles is by the use of O2 absorbing bottle caps (called Oxycaps).

These caps have a special liner in the underside of the cap which absorbs and sequesters O2 that is left in the bottle after capping. These caps are easy to come by and are only slightly more expensive than standard bottle caps ($1-$2 more per gross) Oxidation from bottling may not be an issue in bottled home brew if you consume your beer in a timely manner. However, for extended aging and storing these caps are cheap insurance to preserve your creation over time.

Posted in Brewing | 3 Comments »