Brewing Techniques

Mashing for All Grain Beer Brewing

Mashing can be a mystical process for first time all-grain or partial mash beer brewers.  At its heart, the mashing process uses hot water and natural enzymes to convert complex sugars from malt into simpler sugars that can be readily fermented.  We covered the basics of infusion mashing in an earlier article.

At its essence, mashing converts long chains of starches into much shorter sugar chains.  Several enzymes that naturally occur in barley malt play key roles in breaking down these sugars.  The process starts during malting when the barley grains are germinated and dried.  Beta-glucanese and proteolytic enzymes divide branches of complex sugars into shorter chains.

During the mash, the heavy lifting is done by diastatic enzymes that break down the protein and carbohydrate chains that lock up fermentable sugars.  Further, as these starches are heated they become more soluble in water, making it possible to extract the sugars and create the sweet wort extracted during lautering.  Crushing the grain before mashing increases solubility making it possible to extract a larger percentage of the sugars and starch.

Here’s a summary of the major enzyme groups found naturally in malted barley and their active range:

  • Phytase (86-126 F) – Lowers the pH of the mash.  Lowering the mash pH has a number of benefits, though a Phytase rest is rarely used by modern brewers.
  • Debranching (95-112 F) – Helps to increase the solubility of starches resulting in increased extraction for certain malts.
  • Beta Glucanese  (95-113F) – Breaks down the gummy heavy starches, which can help improve stability and extraction, particularly for mashes high in proteins and adjuncts such as wheat.
  • Pepidase (113-131F) – Produces free amino nitrogen, which can aid in fermentation.
  • Beta Amylase (131-150F) – Produces maltose, the main sugar fermented in beer.
  • Alpha Amylase (154-162F) – Produces a variety of sugars, including maltose and also some unfermentable sugars.  Mashing at the higher end of this range produces more unfermentables and therefore more body in the finished beer.

For single or multi-step mashes, the main step is called the conversion or saccrification step.  The bulk work of mashing is done by the alpha and beta amalyse enzymes, both of which are active to some degree in the normal 148-158F conversion step range.

Mashing at a lower temperature of 148-152F activated more beta amalyse, resulting in more maltose conversion.  Maltose is the primary sugar preferred by yeast, so a lower mash temperature results in a larger percentage of sugars being fermented resulting in a clean beer finish with higher attenuation, slightly higher alcohol content and less body overall.  It does generally take a bit longer for beta amalyse to do its work, so a longer conversion step at low temperature is needed.

Mashing at the high end of the range (154-158F) activates alpha amalyse, resulting in not only maltose but other unfermentable sugars.  Less of the sugars will ferment, leaving lower yeast attenuation and additional body in the finished beer.  Alpha amalyse completes its work more quickly than beta, so a slightly shorter step time can be used.

The other popular step used by modern brewers is the dough-in rest (protein rest).  Usually done at a temperature between 100-120 F, the dough in allows the grains to soak and saturate as well as allowing the key various lower temperature enzymes to begin chopping up longer chains of molecules.  This will generallylower your pH slightly, and improve your mash efficiency by a few percent.  I personally recommend a 20 minute dough in at a temperature between 100-112F for maximum impact.

Brad Smith Follow BeerSmith on Twitter and Facebook

Batch Sparge/Fly Sparge

Today we look at traditional fly sparging, batch sparging and no-sparge brewing techniques. Batch sparge techniques have become very popular with homebrewers recently, primarily because batch sparging requires less time and less equipment than traditional techniques at minimal added cost.

Sparging Techniques

Sparging (or lautering) is done at the end of the mash process, before the boil. The purpose is to extract the sugars created by the mashing process and dissolve them into hot water to form wort. We will then take the sugary wort, add some hops, boil it and ferment it to make our favorite beverage: Beer.

There are three techniques for sparging: the fly sparge, no sparge and batch sparge. Traditionally brewers use a fly sparge, where hot sparge water is continuously sprayed over the top of the mash tun to replace the hot wort as it is drained from the bottom of the mash tun. This gives a continuous flow, ideally with the flow in matching the flow out. Commercial brewers will monitor the specific gravity of the hot wort coming out of the mash tun and stop when it reaches approximately 1.010 to avoid off flavors and tannins associated with low wort concentration.

Duplicating a traditional fly sparge at home does create some challenges for the homebrewer. One must have not only a method for spreading water continuously over the grain bed, but also constantly monitor the flow of the water into the mash tun to make sure the grains do not run dry or overflow. Also fly sparging is a slow process – requiring as much as 60-90 minutes in some cases.

Batch Sparge and No Sparge

Two alternatives to fly sparging are the “no sparge” and “batch sparge” techniques. For these techniques a fixed amount of hot sparge water is added to the mash tun, the tun is gently stirred to assure even extraction for the batch, and then the entire mash tun is drained into the boiler, often at a fast rate (i.e. just open the spigot). The “no sparge” option uses a higher water to grain ratio when mashing and drains it all out in a single operation, while batch spargers use two or more sparge water additions, draining the mash tun empty each time.

The downside of batch sparging is reduced brewhouse efficiency – since a significant amount of sugar will be left undissolved and be discarded with the grains rather than make its way into the wort. For example a homebrewer fly sparging might achieve 73% brewhouse efficiency while a batch sparger might only get 66% brewhouse efficiency. Homebrewers compensate by adding more grain and just take the hit on efficiency.

For a commercial brewer the extra loss would be costly, but for the homebrewer making a 5 gallon batch of beer adding 1-2 pounds of extra grain (perhaps $2-4 in cost) is not significant. For most homebrewers, the extra few dollars of grain is a good trade off when compared to the extra time and equipment needed to do a proper fly sparge. Batch sparging also has the advantage of higher gravity for the runnings, which will rarely come even remotely close to the 1.010 limit mentioned earlier.

An additional concern with batch sparging is that stirring the mash upsets the grain bed, allowing more tannins and grain bits to make it into the wort. To reduce this risk, some brewers use a hybrid batch sparge method where they add sparge water slowly to the top and avoid stirring or completely draining the mash tun. This hybrid method does require additional time for the water to flow through the grain bed – much like a traditional fly sparge.

Batch sparging is more popular than no-sparge because it lets you use a traditional water to grain ratio when mashing, a smaller mash tun (typically a 5 gallon mash tun for a 5 gallon batch), and achieves much higher efficiency than no sparge options.

Batch Sparge Calculations

The most popular is a two stage batch sparge with equal size batches (equal amount of wort drawn off, not equal amount of sparge water added). Two equal size runnings of wort (equal batches) also maximizes the extraction efficiency. Calculating the amount of water to add for each sparge is straightforward where boil_size_l is your target boil size in liters, mash_water_l is the number of liters of mash water added and grain_wt_kg is the grain weight:

Two stage batch sparge additions:

  • batch_1_sparge_liters = (boil_size_l/2 – mash_water_l + grain_wt_kg * 0.625)
  • batch_2_liters = boil_size_l / 2

If you have deadspace under the mash tun, you must also add that amount of extra water to the first batch. If you have the newest release of BeerSmith, you can get an optimal “equal runnings” batch sparge that duplicates the sparge water calculations described above by selecting any of the default batch sparge mash profiles. The batch sparge amounts needed are displayed using the brewsheet (Preview Brewsheet) for your recipe.

The next item to consider is how much extra grain is required to use your batch sparge method. Unfortunately it is difficult to know this in advance, since your mash efficiency will depend on the milling of your grain, efficiency of your lautering system and other factors. A good rule of thumb is to add about 10% to your grain bill (or alternately take about 7% off your starting overall brewhouse efficiency of the recipe) for the first try. Some people use this “rule of thumb” method to size their batch sparge grain bill.

If you use brewing software or a spreadsheet, you can calculate your overall brewhouse efficiency and use that number to properly size future batches. In BeerSmith, these calculations can be accessed from the “Brewhouse efficiency” button in the top section of any open recipe. This display your estimated overall efficiency and OG in the “Brewhouse Efficiency based on Target Volume” section. Enter your actual volume into the fermenter and measured OG into the dialog and the program will calculate your actual overall brewhouse efficiency which you can use for your next batch. After a few batch sparge trials you should have a good handle on what your brewhouse efficiency, and you can then use the “scale recipe” command to adjust web recipes to your personal brewhouse efficiency.


BeerSmith Home Brewing
Discussion Forum:
BeerSmith Support:
Blog Articles:

Decoction Mashing
Decoction Mashing for Beer Recipes

Decoction mashing is a great way to enhance the flavor and clarity of your all grain beer recipes, and requires only minimal additional equipment and time.  Few homebrewers use decoction mashing in their recipes, but it is a very powerful technique for enhancing many styles of beer.

Decoction mashing involves nothing more than extracting a fraction of your mash mixture and bringing that portion to a boil in a separate vessel.  Then the boiling wort is added back to the original wort to raise the temperature of the entire mixture for the next mash step.  All that is required is a separate smaller pot and heat source.

History of Decoction Mashing

Decoction mashing predates common use of the thermometer.  In those early days, it was difficult to achieve accurate infusion temperatures for today's infusion mash, and also malts were undermodified compared to the highly modified malt we have today.  Brewers instead discovered by trial and error that if they extracted a fixed fraction of the mash and boiled it they could achieve the accurate temperature steps needed to mash their malts.

Decoction was used extensitvely in continental European recipes, and is still heavily used in many German and Bohemian styles.  Many commercial brewers today use decoction mashing as well because it results in higher extraction rates and also maximum extraction of flavor from the malt.

Why use Decoction Mashing

The first thing most all grain brewers learn is that they should not overheat their mash or they will risk killing off the enzymes needed to convert sugars, effectively stopping conversion.   Yet in a strange paradox, decoction mashing actually results in higher conversion rates than infusion mashing.  In fact, decoction mashing has a number of benefits (Ref: FAQ):

  • Boiling extracts maximal flavor from the malt, which can be a real advantage for many malty styles of beer including most German beer styles.
  • Boiling the mash destroys the grain cell walls, releasing additional enzymes for conversion and resulting in a higher extract conversion rate than infusion mashing.
  • Boiling wort will carmelize a portion of it, again enhancing the malty flavor of the beer.
  • Proteins in the mash tend to coagulate during the boil and are filtered out during lauter resulting in better clarity.

At the same time, some care must be taken while using the decoction method.  Decoction does take longer than a single infusion mash.  When heating the decocted fraction, you need to monitor it to avoid scorching the mash.  Safety is a concern when handling large quantities of hot wort, and you must be careful not to splash the wort to avoid hot side aeration.

The Decoction Method

All decoction mashes start with a single infusion step where hot water is added to the mash to start the mashing process.  Typical temperatures for the first step vary.  Multiple step decoctions are often used.  Some examples of steps include:

  • 95F (35C) - Acid and Glucanese rest - to break down gummy solids (glucose) and lower pH of the mash for undermodified malts
  • 127F (52C) - Protein rest
  • 145F-153F (63-67C) - Beta Amalyse Rest
  • 158-167F (72-75C) - Alpha Amalyse Rest

Decoction mash profiles may have one, two or even three decoctions.  When selecting a decoction profile, keep in mind that many of the traditional multi-step decoction methods were designed for undermodified malts as opposed to modern modified malts.  However, multiple step decoction methods will add a unique character and flavor to your beer.

The amount of water used in a decoction can vary tremendously.  Traditional infusion mashes and many modern decoction methods use a relatively thick ratio of 1.25-1.5 quarts per pound of grain.  Older decoction mash profiles often used much higher water to grain ratios - as high as 2 or even 3 quarts per pound of grain.  Slightly higher conversion rates are possible at the lower ratios, but some purists still use the higher traditional ratios to reduce the chance of scorching.  You also need to consider what will fit in your mash tun and boil pot.

The initial strike water is calculated as if it was a normal infusion, and can be done using the BeerSmith strike temperature tool or an online calculator.  Typically the first infusion targets either 95F (an acid rest) or 127F (a protein rest).

After the infusion step, a fraction of the mash is decocted (drawn) and put in a separate pot to be slowly heated to a boil.  Some people argue whether the thin part of the mash or thick part should be drawn.  I generally try to get a representative sample of the mash, including both grains and wort.

Calculating the fraction of the mash to decoct can be easily done.  A program like BeerSmith has both a separate tool for calculating decoctions and an integrated mash profile system that lets you simply select a decoction mash profile and automatically calculates the fractions and provides step by step mashing instructions.

Alternately, a quick google search will provide you with online decoction calculators.  If you prefer doing it by hand, this article recommends the following fraction:

F = (TS - TI) / (TB - TI - X)

Where f is the fraction, TS is the target step temperature, TI is the initial (current) temperature, TB is the temperature of the boiling mash and X is an equipment dependent parameter (typically 18F or 10C).

Care must be taken when boiling the mash to avoid scorching.  Mix the mash continuously and heat it gently.  Once the decoction starts to boil you can add it back to the original mash and mix thoroughly to achieve the next step.  Hold each step for the recommended time, much as you would with any infusion mash and continue with additional decoctions or sparging.

Finally, if you are using a decoction to achieve mash out temperature (usually around 178F target temperature), you need to draw only the liquid portion of the mash as mashing out with a large portion of grains can result in undesirable flavors.

Thank you again for your continued support!

Brad Smith

Follow BeerSmith on Twitter and Facebook

Making Full Bodied Beer

For many beer styles such as traditional ales, browns, porters and stouts, a full body beer style is very desirable. Full body beers have complex character, better head retention and enhanced mouthfeel. Higher body is achieved by raising the final gravity (FG) of a beer without producing an incomplete fermentation. Body can be enhanced by adding unfermentable (complex) sugars, and also by increasing the amount of protein in the brew. Making full body beer at home can easily be done if you use the following four tips:

Use more Carmelized and Roasted Malts

Malts that have been carmelized like caramel or crystal malts have long chains of sugars that are called dextrins. Even lighter caramel malts such as Carapils have dextrins in them. Dextrin sugars are carbohydrates that are almost tasteless, do not ferment, and subsequently remain in the finished beer enhancing the mouthfeel and perceived body to the brew. A pound of Carapils or caramel malt will significantly enhance the body of an average 5 gallon batch of beer. Malto-dextrin powder is another adjunct that can be added to enhance the amount of dextrin and therefore body of the beer. Roasted malt, chocolate, and special malts have a high proportion of other unfermentable sugars, and similarly increase the finished body while adding sweetness, raising FG, and enhancing flavor. This method works well for malt extract brewers as well as all grain brewers.

Add Unmalted Grains

Unmalted grains and many non-barley grains contain a large percentage of proteins. Examples include Wheat, Oatmeal, Flaked Barley, unmalted barley and undermodified malts. Proteins do not ferment and can have a profound effect on enhancing mouthfeel. Unfortunately proteins also reduce clarity of the finished beer, so large amounts of protein enhancing ingredients are best used in darker beers (Oatmeal Stout) or beers that are characteristically cloudy (many wheat beers). Note that many unmalted grains such as wheat, flaked grains and unmodified grains require mashing, and are not suitable for steeping in a malt extract beer.

Use a Higher Mash Temperature

A third method for enhacing beer body is to increase the temperature when mashing. A higher temperature during the saccrification step (convert at around 156-157F) will reduce the effect of the beta amylase enzyme leaving larger sugar chains in the beer. These long unfermentable sugar chains will remain in the beer resulting in a higher final gravity and enhanced body. If you are using BeerSmith, simply select any of the "Full Body" mash profiles to convert your mash at a higher temperature.

Use a Low Attenuation Yeast Strain

Select a brewing yeast strain with low average attenuation. Low attenuating yeasts will consume fewer complex sugars leaving a higher final gravity and ultimately a beer with more body. Select a yeast with average attenuation below 70% if possible. Examples of low attenuation yeast include many English, European and traditional ale yeasts, Alt and many of the English and British ale yeast variants.

Combine all four of these methods for your next complex English Ale, Porter or Stout to make a full bodied beer! Have a great week and happy brewing!


Brad Smith

Follow BeerSmith on Twitter and Facebook

Apparent and Real Attenuation

What is Attenuation?

Attenuation is a term often thrown around by home brewers at parties to impress non-brewers, but understanding the different forms of real and apparent extract and attenuation can help beginning and advanced home brewers alike.  So in this two part series on the BeerSmith blog we take a look at beer attenuation in all of its various forms, and how you can use it in recipe design.

So you are at a party looking to impress the non-brewing muggles, but instead a brewing geek comes up and starts talking about original extracts, apparent extracts, and ABVs.  Here's how to tell if he really knows what he's talking about:

Attenuation is nothing more than the percentage of the original extract that has been converted via fermentation to CO2 and alcohol (and a few lesser compounds like esters in small quantities).  Recall that the basic brewing process for all grain starts with the mashing process, which converts your barley grain into sugary wort.  If you are an extract brewer, then you just start with sugary wort syrup.

You boil the sugary wort, cool it, add some yeast, and fermentation starts.  During fermentation a portion of the sugary wort is converted to alcohol (primarily ethanol).  That portion of the sugar, expressed as a percentage, is the attenuation of the beer.   Apparent attenuation is very easy to calculate as follows:

Apparent_Attenuation_in_% = 100 * (OG - FG)/(OG - 1.0)

where OG is your original gravity and FG is your final gravity.  So if you have a beer with an original gravity of 1.050 and it finishes with a gravity of 1.010, the math works out to be  100*(1.050-1.010)/(1.050 - 1.000) which is exactly 80%.  So for this example, 80% of the available extract in the wort fermented to become alcohol and CO2.

What is Apparent Extract and Real Extract?

The gravity of beer is most often measured using hydrometers.  However, hydrometers are calibrated to measure the sugar content of a solution of water.  Finished beer, however, contains alcohol (ethanol) which skews the hydrometer reading because alcohol is less dense than water.  Therefore, a hydrometer reading taken on finished beer will show lower (less extract content) than the beer actually contains.

Apparent extract (often written as AE) is the measured hydrometer reading for the finished beer, usually expressed in degrees plato by professional brewers.  For a homebrewer, this is the same as your final gravity (FG), but convert it from a specific gravity to degrees plato if you want to sound like the pros.  To  do a rough Plato calculation in your head, one degree plato is approximately 4 points of specific gravity, so a finished beer with a specific gravity of 1.012 (1.012 is "12" points) is approximately 3 degrees plato.  If you want an exact calculation you can use a tool like BeerSmith or an online converter.

Real extract (often written as RE) is the real extract content of the finished beer, accounting for the actual alcohol content and imperfect nature of hydrometers.  Real extract can be calculated from the starting gravity and apparent extract (final gravity) as follows:

Real_extract = 0.188 * Original_extract + 0.8192 * Apparent_extract

where Real_extract, Original_extract (which is just your OG) and Apparent_extract (your FG) are all in degrees plato.

Now you know enough to be dangerous at dinner parties.  

Apparent vs Real Attenuation

Now that we understand real-extract, what is the difference between real and apparent attenuation?  Well real attenuation is nothing more than the attenuation calculated using the real extract instead of the apparent extract.  Real attenuation is the actual attenuation of the beer during fermentation, accounting for the fact that the hydrometer reading was skewed when measuring the apparent attenuation (FG).

So which is right?  Well obviously the real attenuation gives the accurate number for the percentage of extract in the wort that actually fermented.  However, by convention, if you hear a brewer talking about the attenuation of their beer they are almost always talking about the apparent attenuation of their beer.  Why?  Because it is easier to measure the apparent extract (FG) of your beer, and its easier to calculate the apparent attenuation.  Brewers like to brew more than they like to use calculators so they will quote apparent attenuation first.

Using Attenuation in Recipe Design

Yeast suppliers provide apparent attenuation ranges for their beer in their data sheets, so you can look up apparent attenuation ranges for your favorite yeast.  Generally yeasts with higher attenuation will produce a drier, cleaner, less malty finish.

However you may also notice that high attenuation yeasts almost always have lower flocculation (flocculation refers to how quickly the yeast falls out of the beer).  There is a reason for this - high flocculation yeasts will start to drop to the bottom of the fermenter before they have had a chance to consume all of the fermentable sugars, leaving a sweeter, more full bodied beer.  So looking at both attenuation and flocculation is important depending on the style you are brewing and how much time you have to age it.

High attenuation yeasts (with low flocculation) will give you that dry, clean, fully fermented finish, but they may take a long time to clear completely unless you use fining agents.  Low attenuation yeasts (high flocculation) will result in a fuller bodied, more complex beer as they may not fully ferment complex sugars, but they will clear more quickly.

If you survey yeast data sheets, you will also notice that lagers almost always have a higher average attenuation than ales.  This is a fundamental difference between the ale and lager yeasts - ale yeasts can not fully ferment some forms of maltose sugar (specifically maltotriose), while lager yeasts can.  This is why many lager yeasts product a higher attenuation beer with few esters and a cleaner finish.

Selecting the right yeast with appropriate attenuation to match you beer style is important.  Don't use a high attenuation yeast if you are brewing a complex English ale.  Similarly a low attenuation yeast would be a poor choice for a clean style like a Bavarian Pilsner.


I find that occasionally I have low attenuation for a batch - even lower than I would expect from a given yeast - indicating incomplete fermentation.  The causes for this can be varied.  Low attenuation is a common problem with many extract beers.  Often it is an indication of using old or partially oxidized malts or poor quality yeast - try to get the freshest malt extract you can buy.

For all grain brewers, low attenuation can sometimes be caused by incomplete conversion during the mash.  Other common causes include not pitching sufficient yeast (i.e. not using a starter), not maintaining proper temperature during fermentation, and poor aeration of the wort before fermentation.  When I find a finished batch with low attenuation, I like to go back and look at my brewing process to try to determine where I went wrong.

Brad Smith
Follow BeerSmith on Twitter and Facebook

Visit For More About Home Brewing!

Copyright 2012 BeerSmith LLC

Dimethyl Sulfides (DMS) 

Dimethyl Sulfide (DMS) is a sulfur compound produced during fermentation of beer that has the aroma of cooked or creamed corn.  

DMS (Dimethyl Sulfide) is a byproduct of mashing and fermentation, so it is present to some degree in all beers.   It has the aroma of cooked or creamed corn.  Because people can perceive DMS even at very low flavor thresholds (of 10-150 parts per billion) it can have a significant impact on the flavor of finished beer.

DMS is primarily found in lagers for a variety of reasons we will discuss shortly.  DMS is actually desirable at low levels in many lagers, but excessive levels of DMS will create a strong cooked corn aroma and flavor.  German lagers contain the highest DMS concentrations (50-175 parts per billion).  American lagers generally contain less than 100 ppb, and British ales contain the lowest concentrations at 10-20 ppb. (Ref: Wikipedia).

Where DMS comes from:

All malt has in it a chemical called S-Methyl Methionine (SMM) which is responsible for DMS. SMM is an amino acid formed during germination and kilning of barley as part of the malting process.  The maltster can reduce SMM by slightly under-modifying the malt, and adjusting the kilning temperatures, but this is largely outside the control of homebrewers.  However, two row pale malts have significantly lower SMM levels than six row pale malts, so you can reduce your DMS levels by choosing a two row pale malt base.  Also very pale lager malts (such as pilsner malt) tend to have slightly higher SMM levels due to the very low temperatures used in kilning.

Heating the SMM present in pale malt will always produce some DMS. During the mashing process (and even the boil), some SMM is broken down into both DMS and a variant of DMS called Dimethyl Sulfoxide (DMSO) which is basically DMS with an oxygen atom attached.  So after the mashing process we have wort that contains both DMS and DMSO (as well as some residual SMM).

The good news is that DMS itself is very volatile and a lot of it will boil off rapidly when we boil or wort during the brewing process.  However DMSO is more stable, and some of it can be converted to DMS during fermenation.  Vigorous ale fermentations generally produce less DMS.

Finally, infection can produce a DMS like flavor and aroma, though it will generally be an aroma closer to cabbage than corn.  If you have a strong cabbage aroma or flavor you may have an infection in your finished beer.

DMS in the Beer Brewing Process

DMS is created whenever wort is heated, so some DMS is present in any beer.  DMS is created in the mash, however most DMS is evaporated during the boil, so the boil is the primary place to focus if you have a DMS problem.

The half-life for DMS is 40 minutes, so half of the DMS will be boiled off in a 40 minute vigorous boil.   So if we do the math, a 60 minute boil gets rid of 64.7% of the DMS and a 90 minute boil rids us of 79% of the DMS.  That is why most experienced brewers recommend a 90 minute or longer vigorous boil.

Since DMS needs to evaporate off during the boil, it is important not to cover your pot.  Covering a brew kettle during the boil will prevent the DMS from evaporating and create a beer with much higher levels of DMS.

Rapidly cooling your wort after boiling is also important.  The SMM to DMS conversion continues at temperatures well below boiling, so DMS is produced even while the wort is cooling after the boil.  However, unlike the mash, DMS produced while cooling cannot be boiled off.  This conversion continues even if the hot wort is vented.  For every hour you have hot wort sitting around, you will produce approximately a 30% increase in DMS.

During fermentation, CO2 bubbles actually help remove from DMS from the beer.  More vigorous ale yeasts tend to produce lower DMS levels.  Also different strains of yeast do tend to produce DMS during fermentation primarily by converting DMSO (which does not boil off) to DMS.  Lager yeasts and yeasts fermented at lower temperatures tend to have higher DMS production.  Certain wild yeasts and bacteria can create high levels of DMS as well.

DMS aromas (including some sulfur or rotten-egg aroma) during fermentation (particularly lagers) are not unusual, so you don't need to toss your beer out just because you have a DMS aroma during fermentation.  Some of this will fade naturally during the lagering process.

Finally, beers with robust flavor profiles (dark beers, strong ales, etc) tend to mask the DMS cooked corn flavor with other flavors such as roast, chocolate or caramel malts.  Because of this, high DMS levels are most perceivable in lightly flavored beers such as low-adjunct pilsners, many German lagers, continental lagers and extremely light ales.  DMS is rarely a problem in beers that are Amber colored or darker, and also rarely an issue with most robust beer styles.

Controlling DMS - Summary

  • High DMS levels are most often perceived as a problem in light lagers such as Pilsner and many German lagers
  • Choose a 2 row pale malt (over 6 row) as a base malt to minimize SMM (a DMS precursor)
  • Very pale base malts (such as pilsner malt) tend to have higher SMM levels which drives higher DMS production
  • Avoid using corn as an adjunct with these beers, as it can enhance the creamed corn perception
  • Boil your wort for 90 minutes or longer with a vigorous rolling boil
  • Don't cover your boil pot - leave it open so the DMS can evaporate during the boil
  • Minimize hot wort standing time by rapidly cooling your wort after the boil
  • Select a yeast and correct fermentation temperature to minimize DMS production
  • For many lagers, DMS aroma is normal during fermentation, but it should fade with time as you lager and age the beer

If you brew a beer with high DMS levels (creamed corn aroma) take a close look at the suggestions above, and focus on your boil, as that is where DMS can be most easily controlled.

Thank you again for your continued support!


Brad Smith

Follow BeerSmith on Twitter and Facebook

Fining Your Beer: Techniques

Author:  BYO StaffIssue: December 2000

Hazed and confused about cloudy beer?  Read on...

Clear Your Beer: Cut through the haze and fine your way to maximum clarity

Historically speaking, clear beer is a recent invention. For most of its history, beer was a dark, cloudy beverage. In British pubs in the 1100s, patrons would pass around an earthenware bowl with lines marked on the inside. Each patron would “take it down a peg” for a penny and pass the bowl on. In those dark, smoky pubs the appearance of beer was basically irrelevant.   

Attitudes towards the appearance of beer began to change with the widespread use of clear glass. Once beer drinkers could see their beer, they began favoring clearer beer. Today, bar patrons want crystal clear beer for their pennies.   

For the homebrewer, clearing is both an aesthetic concern and a stability issue. Clear beer not only looks better, but it is more stable than cloudy beer. A beer with
elevated levels of haze will have the tendency to deteriorate rapidly.

Types of Haze   

There are different kinds of haze that form in beer. These include permanent haze, yeast haze and chill haze. Permanent haze is, as the name suggests, a haze that does not go away. The presence of permanent haze is evidence of a serious problem in the brewing process. Once formed, it cannot be eliminated without further damaging your beer.    

Permanent haze can be due to biological contamination or an excess of starch in your wort. If the haze is biological, you need to pay closer attention to your cleaning and sanitizing procedures. If you have starch haze, you need to ensure you are getting complete conversion in your mash. Don’t run your wort off until the iodine test gives a negative result. If you use good ingredients and your brewing procedures are fundamentally sound, it’s not very likely that you will encounter this type of haze.     

Yeast haze affects all beers unless something is done to counteract it. After fermentation, yeast can remain in suspension indefinitely. If you use flocculant yeast and store your beer cold, the amount of yeast haze in your beer will probably be minimal. However, if you want a beer that sparkles you will need to get rid of it.    

Chill haze is a haze that forms when beer is cooled and disappears when the beer warms up. Repeated heating and cooling cycles can cause chill haze to turn permanent. Chill haze is formed when proteins in the beer bond weakly with polyphenols (also called tannins).    

The level of chill haze in beer increases over time. There are three ways to minimize or reduce chill haze: reduce the amount of haze-forming proteins, reduce the amount of polyphenols and remove the protein-polyphenol complexes after they have formed. We’ll go into this in further detail a bit later in the article.

Assessing Haze in Your Beer   

To see how hazy your beer is with your current brewing procedures, try this test. Take two of your homebrews and one commercially brewed beer of the same style. Leave the beers at room temperature until the day before the test. The night before, put one bottle of homebrew in the fridge. Leave the other out at room temperature. You can chill the commercial beer or not, it doesn’t matter.   

Take three identical glasses and pour out the three beers. Be careful not to pour out any of the yeast sediment from the homebrews. Compare the commercial beer to the room temperature beer by holding both up to a window or light. Any difference in clarity will be due to yeast haze. The commercial beer should not have yeast haze and chill haze will not have formed in the room-temperature homebrew. Unfiltered homebrew will probably be clear, but it will have a slight
dullness when compared to the commercial beer.   

To assess the amount of chill haze in your beer, you will need to compare the room temperature homebrew to the chilled one. Any additional haziness in the cold beer will be due to chill haze. As you will see, it’s chill haze that usually contributes more to the overall haze of your beer.    

Finally, compare your cold homebrew to the commercial beer. After seeing your beer next to a crystal clear beer, do you want yours to look better? If you do, then you’ll have to keep reading to get the lowdown on fining techniques.

Techniques for Clearing Your Beer   

A well-made and properly-stored beer will naturally be somewhat clear. The techniques listed in this column can help polish such a beer to make it much clearer. They are not designed to “rescue” poorly made beers.

Removing yeast haze from beer at the peak of fermentation, the concentration of yeast is about 50 million cells per milliliter. Most of the clearing happens without any interference from the brewer. Allowing the yeast to completely settle in secondary goes a long way towards eliminating yeast haze. Proper beer storage also helps minimize yeast haze. Ideally, beer should be stored at 40° F after it has bottle conditioned at room temperature. Once it’s ready, you should move it to a fridge or somewhere cold, and keep it there until you drink it.    

Fining with Isinglass   

Beer can be fined with isinglass to remove yeast cells. Isinglass is an extract from the swim bladders of sturgeon. Isinglass is rich in collagen, which binds to yeast cells in solution. The collagen-coated yeast drop out of solution.    

Isinglass usually comes in powder form. New developments in isinglass powders allow for a simpler process. You can buy treated isinglass powders that simply dissolve in water. If you can’t find the powder, here is the traditional way. It works well at clearing yeast, but it does take some preparation time to use properly.    

The isinglass solution must be made in advance and the pH must be adjusted. Finally, it needs to be stored cold to equilibrate. You should wait until the beer has settled as much as possible before adding isinglass. To fine your beer with isinglass, use the following procedure:

Step 1. Dissolve 30 to 60 mg/L in a volume of water equal to 1% of your batch size. For a 5-gallon batch, add 0.5 to 1.0 grams of isinglass to 200 mL of water. Use distilled water. For best results, gradually add water to the powder.
Step 2. Lower the pH to 2.5 to 3.0 with phosphoric acid. Add the phosphoric acid gradually and check the pH as you go. Be sure to stir thoroughly after each addition and wait a minute after stirring before you take a pH reading.
Step 3. Store the isinglass solution in the refrigerator for two to three days before use.
Step 4. Add to your beer. If you use a bucket, you may want to stir quietly with a sterilized spoon. If you ferment in a carboy, give it a little swirl to distribute the isinglass. In either case, try not to disturb the wort too much.
Step 5. Allow the isinglass to settle overnight.
Step 6. Bottle or keg your beer.

Removing haze-causing proteins from beer

Limiting the amount of haze-causing protein in your beer starts before you start brewing — before you even buy your ingredients, actually. Brewing strains of barley have been selected to be low in protein compared to feed strains. The choice of brewing ingredients can also affect beer clarity. Beers made with dark malts are usually clearer than paler beers.   

Throughout the brewing process, there are opportunities to remove protein from your beer. For all-grain brewers, certain malts may require a protein rest. (Most modern malts are well-modified and don’t require a protein rest.) When the wort is boiled, a “hot break” is formed. This break material, which is partially composed of proteins, should be left behind in the kettle when the beer is moved to the fermenter. Likewise, the cold break is left behind when a homebrewer moves his beer to the secondary. And finally, proper storage reduces the amount of chill haze in beer.    

If stored cold, chill haze will form and settle out of your bottles in about a week. You can prove this to yourself by comparing a beer that has been in the refrigerator for a week with a beer that has been stored at room temperature and cooled overnight. (Whenever my wife complains that all the space in the fridge is taken up by beer, I immediately launch into a lecture on “protein/polyphenol precipitation.” It never helps, but I sure get a kick out of saying protein/polyphenol precipitation.)

Fining with Irish moss   

Irish moss is a fining agent used during the boil. Irish moss is not a type of moss; it’s really a kind of seaweed. At the pH of wort (typically 5.0 to 5.5), Irish moss carries a negative charge. At the same pH, haze forming proteins carry a positive charge. Adding Irish moss to your wort attracts haze-forming proteins to it. The “moss” settles out after the boil, taking the proteins with it. To use Irish moss, follow this procedure:

Step 1. Wet 0.04 to 0.125 g/L Irish moss with just enough water to cover it. For a 5-gallon batch, use approximately 1.0 to 2.5 grams of Irish moss. A gram of Irish moss is approximately one teaspoon.
Step 2. When there is 15 minutes left in your boil, add the Irish moss.
Step 3. Whirlpool your wort before siphoning to a fermenter. The trub should settle into the middle of
the brew kettle.
Step 4. Siphon your wort to your fermenter. Minimize the amount of trub carried over from the kettle.

Fining with silica gel   

Silica gel can be used to fine beer prior to packaging. Silica gel particles bind to proteins before dropping out of solution. To clarify your homebrew with silica gel, use the following procedure:

Step 1. Dissolve 0.3 to 0.5g/L silica gel in sterile water. For a 5-gallon batch, use approximately 6 to 10 grams of silica gel. Add just enough water to completely dissolve the solids, less than a cup. Add water
to the powder or gel, not the solid
to the liquid.
Step 2. Add gel to beer and stir or swirl lightly.
Step 3. Allow to settle overnight.

Removing all the proteins from your wort or beer is not advisable.  A beer without any proteins would be bland and lack a head. Just as there are haze-forming proteins, there are essential head-forming proteins. Even though Irish moss and silica gel preferentially remove haze forming proteins, they can also remove foam-active proteins. Any fining procedure needs to strike a balance between removing enough protein to reduce haze, without removing so much protein that foam stability and mouthfeel
is affected.   

The typical dosage for Irish moss quoted in most homebrew books is on the low side of the range listed above. If your beer has chill haze, but still has a decent head on it, increase the amount.

Removing polyphenols (tannins) from your beer   

Since “good” proteins can be removed along with “bad” proteins by protein fining agents, many brewers attack chill haze by reducing the amount of polyphenols.

Fining with Polyclar AT   

The most popular polyphenol fining agent is “polyvinylpolypyrrolidine,” or PVPP. PVPP goes by the name Polyclar AT and is widely available to homebrewers through local supply shops and mail-order outlets. For fining with Polyclar, just use the following procedure:

Step 1. Dissolve 0.3 to 0.5 grams of Polyclar per liter of beer in sterile water. For a 5-gallon batch you will need 6 to 10 grams (approximately 2 to 4 teaspoons) of Polyclar. This will completely dissolve in a few ounces of water. Slowly add water to powder and stir.  
Step 2. Add mixture to beer and stir.
Step 3. Allow to settle six hours.

Just as with protein fining agents, overfining with Polyclar can lead to problems. At high doses (higher than the quoted range), Polyclar can reduce the color and hop bitterness of beer.


Another method to use in place of or in conjunction with fining is filtration. Almost all commercial breweries filter their beer for appearance and stability. Filtration strains out particles of haze, yeast and sometimes bacteria to give a level of clarity that is far superior to fining methods alone.    

Beer to be filtered is often fined first. Too much yeast, for example, can clog a filter. Alternately, beer can be rough filtered first, followed by a polishing filtration. Filtered beer can potentially suffer from some of the same problems of overly-fined beers. Filters can remove desirable substances in your beer along with the yeast and chill-haze. The details of filtration vary depending on the filtration set up, but these are the basics:

The beer is chilled overnight in a keg so that chill haze is formed. The filtration system is set up so that pressure is applied to head of the unfiltered beer keg. The unfiltered beer keg is connected to the filter, which in turn is connected to the dipstick of the receiving keg. The beer will flow out of that keg, through the filter, and into the receiving keg. The receiving keg is not completely sealed so CO2 can escape as the keg fills.   

When deciding on how much effort to put into clarifying your beer, you should consider two things: How important the look of your beer is to you and how long you are going to store your beer. If you are giving some of your beer away or entering it in a contest, looks might be more important. If your beer is not going to be consumed quickly, clarifying it will keep it in good shape so you can enjoy it longer. The full treatment for clarifying a beer would include a yeast fining agent, a protein fining agent, and a polyphenol fining agent. Alternately, you could filter the beer for maximum clarity.    If your beer is going to be consumed rapidly and you don’t mind a little haze, you might want to consider taking an easier route. Adding Irish moss to the kettle and Polyclar to the secondary fermenter before packaging takes almost no time. These two easy steps will significantly reduce the amount of chill haze in your beer.

Chris Colby is a science editor living in Bastrop, Texas.

Fining Agents - Improving Beer Clarity

A fining agent is a compound added to beer to aid in precipitating  and binding with compounds that reduce clarity.

Fining agents generally have large molecules that are positively charged.  These charged molecules attach themselves to negatively charged contaminants and then precipitate them out of the finished beer - helping these contaminants rapidly settle to the bottom of the fermenter.

The three haze producing contaminants affected by finings are: suspended yeast, proteins from the malt, and polyphenols which can come from both hops and malt. A fourth cause of haze is microbiological contamination from infection, but finings will do little to help mitigate infection - so cleanliness at every stage is still important.

Finings may be added either at the end of the boil or in the fermenter.  Irish moss and whirlfloc tablets are used at the end of the boil, primarily to precipitate proteins during the cold break.  Finings for the fermenter are added a few days before bottling or racking to precipitate yeast, proteins and polyphenols.  These include chillguard, gelatin, isinglass and polyclar.

For boiled finings, often called "copper finings", these should be added in the last 10-15 minutes of the boil, as boiling them longer often reduces their effectiveness.  Finings added in the fermenter are usually added 4-5 days before bottling or racking the beer to give the fining time to precipitate yeasts and proteins and keep these out of the finished bottle or keg.  Care must be taken when adding these finings as the large molecules can create an effect called "nucleation" which releases carbon dioxide stored in the beer, and can lead to a gush of rapid foaming.

Irish Moss

Irish moss is a dried additive derived from seaweed.  It is added in the last 10-15 minutes of the boil to aid in coagulation and precipitation of proteins during the cold break.   Approximately 1 tsp is needed per 5 gallons of wort.  Irish moss does a great job reducing protein haze in the finished beer, and you can actually see clumps of protein form and drop out at the end of the boil when it is used.

Whirlfloc Tablets

Whirlfloc tablets, like Irish moss, is derived from seaweed, but also includes additional purified carrageenan, which is the active ingredient in Irish Moss.  One tablet is added per 5 gallons of wort during the last 10 minutes of the boil.  Since it shares the same active ingredients as Irish moss, whirlfloc does a great job precipitating proteins at the end of the boil.


Chillguard is a silica gel that is used in the fermenter a few days before racking or bottling.  To use chillguard, dissolve ½ tsp into ½ cup of hot, but not boiling water and gently mix it into 5 gallons of beer.  Chilguard is primarily effective in precipitating proteins.


Common unflavored clear gelatin can be purchased from the local grocery store and is effective in reducing both proteins and polyphenols.  Gelatin is a collagen based agent derived from hooved animals.  Add 1 tsp of unflavored gelatin to a cup of hot, but not boiling water and gently mix it into your fermenter.  Again, wait a few days before bottling or racking to allow the gelatin to clear the beer.


Isinglass is also a collagen based additive derived from fish bladders.  Used primarily by commercial brewers, isinglass is effective against all three major barriers to clarity: yeast, proteins and polyphenols.  Isinglass in its pure form must be mixed with an organic acid before use, but many types of isinglass sold for homebrewer use are so called "instant" variants that come premixed with the acid needed for preparation.  Be sure to follow the directions that came with your isinglass.  Typical application rates are ½ tsp mixed with 1 cup of hot water per 5 gallons of beer, and allow 4-5 days before racking or bottling.


Polyclar is an additive that consists of powdered PVPP plastic.  The plastic is positively charged and very effective at removing polyphenols from finished beer.  Polyclar is added in the fermenter at the rate of 2 tablespoons per 5 gallons.  Again, the polyclar is usually mixed in a cup of warm water first and then gently mixed into the fermenter. Allow 4-5 days for the polyclar to work before bottling or racking.

The fining agents above are the ones most commonly used by homebrewers.  Note that often it is best to use a combination of techniques if you want to attack cloudiness caused by proteins, yeasts, and polyphenols all at once.

I personally use Irish Moss on any beer style where clarity is important, and then use some judgement as to whether to add additional finings at bottling based on the state of the beer at that point.  Naturally you don't want to discount other methods such as rapidly chilling wort, choosing high flocculation yeast and cold storing your finished beer.

Thank you again for your continued support!


Brad Smith

Copyright 2012 BeerSmith LLC

Mash Efficiency Experiments

The following is a very good set of experiments and results that focus on various mash techniques.
Well worth the read.


No Sparge Beer Brewing for All Grain Brewers

No sparge brewing offers an attractive alternative for those who don't want to deal with the hassle of fly sparging or batch sparging by using a full volume mash in an single step - just mash and drain.

All grain beer brewers are always looking for shortcuts when brewing beer.  Its not that we're lazy, it is just that we want to make the most of our limited brewing time.  No sparge saves time by including the full boil volume in the mash and skipping the extra steps of having to heat sparge water, and sparging.  It also has the advantage of creating a pH stable mash with no risk of oversparging the grains.

What is No Sparge?

Before we jump into the no-sparge method, we need to briefly review fly sparging.  A traditional fly sparge requires you to heat sparge water in a separate vessel to around 168F (75.6 C).  Then this sparge water is sprinkled over the grain bed in the mash tun, often by a "fly arm" which distrubutes the water evenly.  Simultaneously wort is drawn from the bottom of the grain bed through a screen of some kind and into the boiler.  The flow of water must be managed to keep the grain bed flowing, and also the brewer must be careful not to "oversparge" by running too much water through the grain bed, which can lower the pH of the wort unacceptably and add an astringent tannin flavor to the finished beer.

In the no sparge, we skip adding sparge water entirely.  Instead the total volume of water needed for mashing and boiling is added to the mash tun at the start of the mash, and simply drained from the mash tun into your boil pot once the mash is complete.  It does require a larger mash tun (about double the size), since you need to be able to hold all of the grains, the water they absorb, plus the full volume needed for boiling.  However you entirely eliminate the need for a hot liquor tun to heat sparge water.  You simply mash with a lot more water, and then drain the wort out.

The Advantages of No Sparge Methods

No sparge has some advantages over a traditional fly sparge.  First, you avoid having to separately heat sparge water up and also the need for a fly arm, since all of the water is already in the mash.  Second, mashing at a high water to grain ratio can result in a more complete conversion and good attenuation - which is desirable for many beer styles.  Third, since all of the water is in the mash tun already at a stable pH level due to buffering from the grains, you don't run the risk of "oversparging" your mash and extracting excessive tannins.  Finally, no sparge is simple - you just drain the wort into your boiler, taking care to do the usual "vourlof" step of recirculating the first few quarts of runoff.

No Sparge Water Volumes

No sparge temperature calculations can be done with any standard infusion calculator (software or online) - the only question being how much water you need to add up front?  You should start with your required pre-boil volume which is how much water you need before boiling your wort.  Then you need to add more water to compensate for grain absorption.  Grain absorbs about 1 liter/kg (or 0.12 gallons/lb) of grain, so if you take your total grain bill in pounds or kg you can quickly estimate the extra water needed.  Finally you need to account for any losses in the mash tun, such as wort trapped below the drain for your mash tun.  Putting it all together in gallons we have:

  • Grain_absorption_gals = Total_Grain_Lbs * 0.12
  • Mash_water_needed_gals = Pre_boil_volume_gals + Grain_absorption_gals + Mash_tun_deadspace_gals

For metric, just substitute 1 liter/kg for the 0.12 value, and do the math in kilograms and liters.

Once we know the total mash water needed, we can use any infusion calculator (Tools->Infusion in BeerSmith) to get the strike water temperature needed.

No Sparge in BeerSmith

You can use any of the BIAB (Brew in a bag) mash profiles on a recipe to force BeerSmith into a full boil mash volume.  Just select any BIAB mash profile as your all grain mash profile in BeerSmith 2.  The only other caution is that you might want to go to Options->Advanced and change the BIAB Grain Absorption to be the same as the normal grain absorption (0.96).  Normal BIAB brewing retains a bit less water in the grain, and making this adjustment will make the BIAB mash profiles match the no sparge method exactly.


Brad Smith

Follow BeerSmith on Twitter and Facebook

Visit For More About Home Brewing!

Copyright 2014 BeerSmith LLC