Balancing Your Draft System

https://byo.com/article/balancing-your-draft-system-patience-is-a-draft-serving-virtue/

If there’s one comforting thing about the internet, it’s the warm familiarity of what are often endlessly repeated discussions on the same topics! One of the most common, at least in homebrewing circles, is this: “What pressure should I use to carbonate my finished and kegged beer?” The ensuing fusillade of recommendations tend to run towards some combination of “set it to X pressure for 48 hours, then reduce it to Y and serve it.” I have to say, that advice always irks me. Not because it’s wrong, per se — I’m sure you’ll get carbonated beer — but because it’s unnecessarily complicated. Instead, I tend to jump in and recommend a method that’s both simpler, requires no tinkering with the CO2 tank or regulator, and has the added benefit of ensuring smooth, easy pours: Just balance your draft system, once and forever. The steps are simple.

1. Decide on a carbonation level and serving temperature, and identify the appropriate pressure to set your regulator to deliver (for reference, I recommend the Brewers Association Draught Beer Quality Manual, but you can find plenty of temperature-PSI tables online).
2. Set your regulator and temperature controller to the appropriate pressure/temperature.
3. Create enough corresponding resistance so that your beer is pouring at a manageable rate.

It’s Step 3 that most people need a little guidance on, and we’ll come back to it, but before we get there let me make the pitch for this overall simplistic approach. The trouble with the “adjust the regulator” route, where you’re amping up pressure for a couple of days and then dropping it to “service” pressure, is that you’re inviting trouble into your life. Yes, you can shorten up your conditioning time, but you’re likely going to give back a lot of that time in the tinkering, irritating, nonstop “Dance of the Tweaked Regulator.” You’re coming down from your “pressurizing” PSI, and you either bleed the keg of gas or get a pitcher and let it blow out that first over-pressured gush of beer. Then you wait a couple of days to see if it’s at the right carbonation level. It’s too light, so you bump up the PSI. Now it’s pouring too fast. You cut it back. Now it’s pouring too slow. On and on it goes as you try to match your pressure to your desired carbonation level to your pour rate, and maybe you start playing with the temperature, too, and all the while you’re guessing at whether you need to make one more adjustment . . . Instead, I prefer to just set it and forget it. Do the math on this once, and you’ll never need to do it again. When you have a new keg to put on, you just hook it up to the gas and wait. Simple.

Balancing The System 
Balance starts in the keg. Whatever your desired carbonation level, there’s an equilibrium point where the pressure on the head space is exactly what it needs to be to not only create your desired CO2 level, but also to hold it there. If the pressure is too high, you’ll keep gradually pushing more CO2 into solution, slowly overcarbonating the beer. If it’s too low, you’ll gradually lose CO2 into the headspace, flattening the beer. Temperature matters here, too, because CO2 absorbs (or comes out) of your beer at different rates at different temperatures. So, we consult our handy PSI-Temperature table and find the required PSI. Let’s say we want to serve our beer at 39 °F/4 °C (a little cool, maybe, but it’ll warm up in the glass and this way you’re extending your flavor stability/shelf life). If we want 2.5 volumes of CO2, we find that we need right around 12 PSI (83 kPa) to create it and hold it at that carbonation level. Simple enough. Set your regulator, set your temperature controller, and hook up your keg.

Determining Carbonation: 

Volumes of CO2

That’s just the first two steps, though. Now we’re on to step three — balancing the system so that it pours properly. To do that, we need to create the right amount of resistance between the keg and the faucet (and, ultimately, your glass). Now, you can work this from the regulator side, but as noted previously, doing that requires some trial and error, with no guarantees you’ll find the right settings before you kick that keg! It has the added detriment of putting your beer in a state of flux. If you carbonate at high pressure but drop to 2–3 PSI (14–21 kPa) to serve at a lower pressure, you don’t have that equilibrium in the headspace, so your beer is slowly decarbonating and trending towards flat (or, really, pétillant). Likewise, if you carbonate at one pressure but, because you have too much resistance, you need to increase the pressure to address a slow-trickle of a beer pour (less common, but not unheard of if you’re pushing up from a basement kegerator or across a longer distance), you’ll end up with beer that’s slowly gaining carbonation and becoming more spritzy.

Instead, let’s balance that equilibrium pressure so that our beer stays at a constant carbonation level and pours smoothly. We have two tools at our disposal: Gravity and the beer line we’re pouring through. We have 12 pounds (83 kPa) of pressure pushing on the beer as it comes through the line. We need to create about 12 pounds (82 kPa) of resistance. Do that, and you get stable carbonation and a soft pour every time.

Let’s start with gravity. It’s not likely that you’re deliberately adding height to your pours by lowering kegs or raising taps, so this is most likely something you’re factoring in based on your draft system design rather than adjusting. All the same, it’s still important to do so! If your kegs are one foot (30 cm) below your taps, you’ll get about 0.43 pounds (3 kPa) of resistance. We back that off of our target “balance point” of 12 PSI (83 kPa), and we’re down to 11.57 pounds (80 kPa). 

Most resistance will come from your tubing. The wider the tube and the smoother the surface, the less resistance you get. So, if we’re talking commercial “barrier” tubing, there’s very, very little resistance because it’s commonly used in long-draw systems where the beer is traveling as much as a couple of dozen feet before it reaches the kegs. Most of us, though, will use 3⁄16-inch ID vinyl tubing (common in home kegging applications), which creates roughly three pounds (21 kPa) of resistance per linear foot (0.3 m) [Note: this resistance number is not a hard rule, numbers vary depending on the tubing manufacturer. Be sure to check their numbers if available.] If we need 11.57 pounds (80 kPa) of resistance, we need 3.86 feet (or three feet, ten inches, or 1.18 m) of tubing between the keg’s out post and the faucet shank. Cut it, install it, and you’re done. You should, at the pressure and temperature we’ve selected (in this example), have perfectly smooth pours, at just the right carbonation.

Hook up your kegs, and leave them be. In 5-8 days, you’re pouring perfect beer! 

Rush Jobs 

What if you don’t have the time to give, though? It’s the night before the graduation party, and you have three kegs that you’ve just filled because (like most of us) you lost track of it and didn’t keg them last week when you should have.

This is where those high-pressure tricks come in handy. If you need carbonated beer in a hurry, start with leveraging pressure and temperature in your favor. If you have a temperature-controlled fermentation fridge, set your controller to 34 °F/1 °C and get that keg in there. Then, put your backup CO2 cylinder (you have one, right? If not, you can use your primary if it’s not too difficult to detach from your kegerator) in there with it, with the pressure turned up to 35 PSI (240 kPa). A couple of hours later, you should have cold, at-least-partially-carbonated beer – hook it up to your system, and let it take it the rest of the way up over time. This is also the method I use when I don’t have room in my kegerator for a finished keg, but might want it on hand as a backup for a party or event. Use this method to “pre-condition” a keg that you might need to put on at short notice. It’s a bigger pain to bring carbonation down than it is to tolerate it being a little low while it comes up, and even a short period of high-pressure/low-temperature carbonation will yield a reasonable amount of CO2 in solution, and you can still enjoy your homebrewed beer even if it’s not at its perfect carbonation level in the meantime.

Another time-honored method is agitation. If you’ve ever had a CO2 tank hooked up to your keg, you’ll notice that you hear the gas running into the keg — but only for a few seconds. At that point, it’ll go quiet. If you move the keg, though, you’ll hear the gas start to “run” again. Why the change? Because agitating the beer breaks the surface tension, you’re both increasing the surface area of the beer and the motion also “gulps” some of the gas in the headspace down into the beer. The result is quicker absorption of CO2 into the beer. Some homebrewers will set the keg on its side and rock the keg to get it to quickly “gulp” CO2.

Both of these methods come with a major caveat, though: They’re easy to screw up. I’m unaware of any particular formula or calculator that has reliably shown just how long to leave your beer on high pressure at low temperature to get a specific outcome — my approach to this is very much based on trial-and-error (about an hour at near-freezing and 35 PSI (240 kPa) of pressure, then onto my normal, balanced system). No one can tell you how, or how many times, or how long to shake your beer to get the “right” amount of carbonation. Far and away, the best method here is to plan ahead as best you can, and connect your kegs to a balanced system with at least a few days of time to let your beer get properly carbed.

Safe, Boring, Smart?

There’s one last element of this to touch on, and it’s this: Using this method, all of your beers will be served at the same carbonation level and temperature, regardless of style. Saison at the same pressure as usually-more-still Scottish ale. German Pilsner at cellar-temperature English pale ale. It’s true, you’re giving up some control over an important contributor to beer flavor. I still think it’s worth it, though.

First, most of your beers are going to be about the same pressure anyway. Yes, Berliner weisse should be jamming at three-point-something volumes, but it’s still pretty solid at 2.5. Yes, that ESB should be hand-pump sparkling, but it’s still fine at 2.2.

Second, you have other options. If you have a beer that’s spritzy and highly-carbonated, consider bottle-conditioning it instead of putting it on keg. If it’s meant to be only lightly-carbonated you can do the same, or put it on your draft system and bottle it all up right off of the faucet when it hits the just-right barely-there carbonation level.

Last, consider making a “high” and “low” settings chart for yourself, and adjust by temperature. If you want a more-carbonated set of beers, drop the temperature down to increase absorption. You’ll need to be careful about overcarbonation and the service problems it presents (since you’re forcing more CO2 into your beer than your system was designed to pour), but it’ll take time to get to that point. If you want it less-carbonated, increase the temperature. It’s not perfect, but it’ll work in a pinch, especially if it’s just for a few days to a couple of weeks.

And, of course, you can always use more than one regulator! Multi-body regulators allow homebrewers to hold kegs at varying pressure levels. Splitters and manifolds can be added along with a secondary regulator for more flexibility.

The relative advantages, though, of the safe, boring, set-and-forget method will usually be worth it. Make a good catch-all choice on carbonation levels, do the math (once) on pressure, temperature, and resistance, and enjoy your stress-free draft system and the freedom of not having to make constant adjustments or cleaning up after your Uncle Steve dumps head all over the place because your system is pouring a little too hard. Just hook up your kegs and enjoy. Written by
Josh Weikert

Going for Gose

http://www.beerhunter.com/documents/19133-001353.html

 I was in Leipzig on a Wednesday evening, not typically the best for the pub and restaurant business anywhere, and the Bayrischer Bahnhof was packed. By far the most popular beer was the Gose. This is made principally from grains grown locally and malted in nearby Krostitz.

The grist comprises between 50 and 60 per cent malted wheat. The other malts are a Pilsener and a small proportion of Munich. The hops are Northern Brewer (for bitterness) and Perle, from the nearby Elbe-Saale growing area. Like most wheat beers, Gose has a low hop bitterness. In this particular style, the balancing dryness is provided by the ground coriander seeds and salt, which are added in the whirlpool.

 When I tasted a prototype Gose, four years ago, I felt that its refreshing acidity was too overtly citric, and that a lactobacillus should be used. This was a passing comment - I am not a technical consultant - and I was gratified to be told by proprietor Schneider that he had taken up my suggestion.

The main fermentation is with a Weihenstephan wheat beer yeast, but both this and the secondary are in cylindro-conical tanks. These are used as unitanks, with a cold lagering. Again, the wheat should provide crispness but the typically estery flavours from the yeast must not overpower the spicing. The beer has a starting gravity of 11.0-11.25 (1044-45), and emerges with an alcohol content of 4.6 per cent by volume (3.7w).

 All the beers at Bayrischer Bahnhof are unfiltered. The Gose has a full haze; a yellowish color; a fine, sustained, bead; a hint of apple-skin aroma on the nose; a light but smooth, textured, body; restrained ripe-plum fruitiness in the palate; and a dry, herbal, coriander finish. The tangy, refreshing, sharpness of the salt is quite subtle. The use of coriander and salt in this beer is contrary to the the German Beer Purity Law, the Reinheitsgebot, and this posed a difficulty when the style was revived.

Now that the beer is on a firm footing, the state of Saxony has been persuaded to grant an exemption. After all, Gose existed before Northern Germany had accepted the Beer Purity Law, which was originally a Bavarian measure. Fruit versions Gose laced with various syrups Like the lactic wheat beers of Berlin, this traditional Leipzig speciality is offered plain (the most popular version), or with a lacing of raspberry syrup or green essence of woodruff (Waldmeister).

These summery quenchers are known as "sunshade" (Sonnenschirm) drinks. A version with an alcoholic cherry liqueur is much more rounded, with a more genuinely fruity flavor. I could enjoy it as an after-dinner beer, but it is identified on the menu as being more suitable for women (Frauenfreundliche). Such a proclamation might be deemed a trifle sexist in London or New York. I particularly like the combination of Gose with Allasch, the local, sweet, almond-flavoured version of the caraway liqueur Kümmel. More than one might be sickly, but the combination of the sour-ish, salty, beer with a spicy, sweet, liqueur is very lively. This is seen as a more wintry drink, and called an umbrella (Regenschirm). The Gose is also available to go, in the traditional "brandy flask". In this instance longneck means a good eight inches. The brewery had some difficulty in finding a company to make these bottles. They are being made by a company in the glass-producing area near Venice, and they have been rigorously tested at the brewing faculties in both Berlin and Weihenstephan (near Munich) to ensure that the long neck and shoulder can stand the pressure of carbonation. The Bayrischer Bahnhof bottles are fitted with a swing-top, but the original Gose vessels had no stopper. The idea was that the yeasty head formed a natural bung in the long neck, just as it seems to have done in the terra-cotta amphorae of ancient times. Thus the beer would carbonate naturally. The brewery also produces a wheat beer, using the same yeast but in the type of open fermenter typically used for that style: with a lip for the excess foam. This brew is called Kuppler Weissbier, the first word referring to the man who couples the carriages on a train. It has a full amber to tan color, reminiscent of the famous Weissbier made in Bavaria by the Schneider brewery. (There is no connection between that brewery and Thomas Schneider of the Bayrischer Bahnhof. Schneider is a very common name in Germany). Brewmaster Brewmaster Bertram Rostock enjoys the beer garden Kuppler has a good, toffeeish, malt character and an aniseedy spiciness, but I could have taken more clovey, fruity, notes. Although Thomas Schneider is a brewer himself, he has employed Bertram Rostock to man the kettles. Bertram, who studied in Berlin, is a young veteran of a start-up brewery in nearby Landsberg. He told me that he was not yet satisfied with Kuppler. He felt it needed more throughput before the yeast habituated itself. There is also a Schwarz ("black") lager. Black suggested coal, in the railroad context, so this is called Heizer (stoker, or fireman). This beer has a lightish, but very smooth, body; a full mouth-feel; and very good chocolate-toffee flavors. A Pils called Schaffner (conductor) is perfumy and very dry, though I felt slightly yeasty. Brewer Bertram told me that he was working to reduce the yeast in suspension without losing it altogether. The pub also offers spirits, wines, cocktails, simple pastas and typical German dishes, though nothing very specific to Leipzig. The Bayrischer Bahnhof is also supplying its Gose to half a dozen local pubs, notably including Ohne Bedenken, which pioneered the revival of the style. This is a less elaborate, more basic, pub, offering the Gose variations with hearty snacks of bread and cheese (typically a local counterpart to Camembert, made into fritters). Thomas Schneider had previously used another brewery to produce a Gose for a Ohne Bedenken. It was the beer that gave the pub its name. When Gose was first reintroduced there, a customer, shocked by the taste, asked proprietor Hartmut Hennebach: "Is this stuff drinkable?" To which Dr Hennebach replied: Ohne Bedenken ("Without doubt"). Dr Hennebach had originally worked in the pub as a bartender after being fired from his job as micro-biologist for political dissent during the Communist period in East Germany. The pub had been a Communist political club in those days, but a "Gose House" until perhaps the 1930s. Around 1900s, Leipzig is said to have boasted 80 Gose houses, many of them student cafes offering inexpensive beer and food. Gose is said to have been consumed in Leipzig since the 1700s, but to have taken its name from the smaller town of Goslar, its original home. The whole story sounds remarkably similar to that of Gueuze-Lambic, once typically served with bread and cheese in scrubbed-table bars in Brussels, but perhaps taking its name from the smaller town of Lembeek. Both are wheat beers, distinctly acidic, and traditionally gaining their carbonation by bottle-conditioning. By European standards, Leipzig and Brussels are quite distant from one another, and culturally quite different, but far longer connections have been established in the world of food and drink. Published: AUG 31, 2000 In: Beer Hunter Online

Salty Gose

I am quite intrigued by ancient beer styles, one of them is the Gose beer from Leipzig, Germany. The Gose (pronounced gose-uh) is an ancient German Ale that is both sour and salty. Unlike any other beer Gose is brewed with slightly salty water.

While researching the beer style I found the Salty Gose the Margarita recipe from Billy Broas from the HomeBrew Academy. (http://homebrewacademy.com/gose-homebrew-recipe)

I used a slightly adapted recipe for the Southyeaster 2015 Summer festival.

Salty Gose

Stats
Original Gravity: 1.058
Final Gravity: 1.015
ABV: 5.58%
IBU: 4.5
Efficiency: 65%
Batch Size: 25 liters
Boil length: 90 minutes

Malt
3 kg Pilsner Malt (42.9%)
3.kg Wheat Malt (42.9%)
1 kg Acidulated Malt (14.3%)

Hops
10 grams Tettnang (4.5% AA) – 60 min

Yeast
US-05 Safale dry yeast (any clean yeast will do)

Other
10 grams freshly crushed coriander seeds
15 grams Lime zest
40 grams Sea salt (iodine free)

Mash at 65°C for 90 minutes. Add the coriander, lime zest, and salt with 10 minutes left in the boil.

Naturally carbonate with 750ml of Triple Sec

The beer turned out really well with a slight sour spiciness and hints of bitter sweet citrus from the Triple Sec.

Carbohydrate conversion

Digestion of carbohydrate by gycosidase - an SN1 reaction

A very important example of a nucleophilic substitution reaction that is thought to occur though a two-step, dissociative (SN1) mechanism is the hydrolytic breakdown of carbohydrates. In chapter 11 we will focus on these reactions and learn that the terms ’hemiacetal’, ’acetal’, ’hemiketal’, and ’ketal’ are used to describe the different patterns of bonding that we are seeing here - but for now, we will just look at the reaction from the standpoint of the SN1 mechanism that we learned about in chapter 8.

You probably know that carbohydrates, (also called oligosaccharides), are sugar polymers. Cellulose, the tough, fibrous material in plants, is one of the most abundant organic compounds found in nature. It is basically a long chain of glucose molecules linked together:

Comment

The bonds connecting individual sugar units in carbohydrate chains are called glycosidic bonds, and enzymes that break them are called glycosidases. Humans do not have glycosidases capable of breaking the glycosidic bonds in cellulose - and thus we cannot use cellulose a source of energy - but cellulose is nonetheless necessary to us as dietary fiber. Cows and other ruminants are able to derive energy from cellulose because they maintain bacteria in their digestive tract which possess the proper glycosidase enzymes.

Starch, the carbohydrate that we eat in bread and pasta, is also a long chain of glucose molecules. However, the glycosidic bonds linking the individual glucose units in starch have a different stereochemical configuration from those in cellulose, and humans do have the proper glycosidase enzymes to digest starch. We will discuss carbohydrates again in chapter 11, and you will learn many more details if you take a course in biochemistry.

We focus now on the chemistry by which glycosidic bonds are broken and formed. Enzymes called glycosidases catalyze these reactions. Consider for example the following reaction, catalyzed by a bacterial enzyme, in which the glycosidic bond between two glucose molecules in cellulose is cleaved.

Comment

This is a hydrolysis reaction – recall that this term is used to describe any reaction where a bond is being broken by water. If you look carefully, you will recognize that this reaction is simply a nucleophilic substitution at the carbon indicated by the arrow: water is the nucleophile, and the leaving group is an alcohol, specifically the glucose molecule on the right side. In the next few figures, the leaving group will be referred to as ’HO-R’ for simplicity.

(A quick note on hydrolysis reactions: we will see many more examples of hydrolysis reactions throughout our study of organic chemistry. In eukaryotic cells, many hydrolysis reactions occur in the acidic (pH  4.5) environment of the lysosome, an organelle that specializes in breaking large molecules down into small ones.)

Evidence suggests that glycosidase reactions probably occur through an SN1 mechanism, implying the formation of a short-lived cationic intermediate. Here is the first, rate-determining step:

Comment

Notice that the positively charged carbon on the intermediate is adjacent to an oxygen. Recall from previous discussions (section 8.4B) that oxygen can act as a powerful electron donating group because of the resonance effect of its lone pairs. This is best illustrated by drawing a second resonance contributor, in which the positive charge is placed on the oxygen. This intermediate is generally referred to as an oxonium ion.

The active site of the enzyme has two aspartate residues, one positioned above the substrate (Asp1) and one below (Asp2). The leaving group is protonated by Asp1: protonation, as you recall, creates a better leaving group.

Here is the second step of the glycosidase mechanism:

Comment

This is because the leaving group remains bound in the active site after the formation of the oxonium ion intermediate, and blocks the bottom side of the electrophilic carbon from attack. The water nucleophile, as it attacks from the bottom side, is deprotonated by Asp2.

Because the reaction results in inversion of configuration, the enzyme is called an inverting glycosidase.

Researchers have also identified retaining glycosidases, which catalyze similar hydrolysis reactions except with retention of configuration:

Comment

The active site architectures of the inverting and retaining glycosidases are actually very similar: both have two aspartate residues positioned above and below the electrophilic carbon. The first step in the retaining mechanism is the same as in the inverting mechanism: formation of the oxonium intermediate.

Comment

In the retaining reaction, however, the bottom side aspartate (Asp2) acts as a nucleophile instead of as a base (step 2 below) , attacking the electrophilic carbon directly and forming what is referred to as acovalent intermediate (the enzyme is covalently attached to the terminal glucose molecule via the aspartate residue).

Comment

In the meantime, ROH (the other section of the celluose chain) diffuses away from the active site. The substrate-enzyme linkage then breaks (step 3), resulting in formation of the same oxonium ion intermediate as before. A nucleophilic water molecule then attacks from the top side, as Asp1 serves as a catalytic base (step 4).

Comment

What has occurred here is known as a double displacement mechanism: in order to achieve substitution with retention of configuration, two nucleophilic substitutions have occurred in a row, each with inversion of stereochemistry. The overall result of two successive inversions at the same stereocenter is, of course, retention.

It is important to remember that the stereospecificity observed in the two examples of SN1 reactions above is due to the exquisite control that enzymes have over the reactionsthey catalyze. Nucleophiles and electrophiles are bound in precise locations so that nucleophilic attack can occur from one side and one side only. While concerted SN2 displacements take place specifically with inversion of configuration in both enzymatic and non-enzymatic situations, remember (section 8.2B) that nonenzymatic SN1 reactions generally result in racemization. Recall also the reasoning behind this: with no enzymatic control, the nucleophile can attack the planar, sp2-hybridized carbocation intermediate from either side with equal probability, resulting an a racemic mixture of both the R and S product.

Attribution

ChemWiki

Licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License

Mashing and Lautering

Mashing

Interior view of a mash tun in a Scotch whisky distillery, showing the stirring mechanism.

In brewing and distilling, mashing is the process of combining a mix of milled grain (typically maltedbarley with supplementary grains), known as the "grain bill", and water, known as "liquor", and heating this mixture. Mashing allows the enzymes in the malt to break down the starch in the grain into sugars, typically maltose to create a malty liquid called wort.¹ There are two main methods—infusion mashing, in which the grains are heated in one vessel; and decoction mashing, in which a proportion of the grains are boiled and then returned to the mash, raising the temperature.²Mashing involves pauses at certain temperatures (notably 45 °C, 62 °C and 73 °C) [113°F, 144°F, and 163°F], and takes place in a "mash tun"—an insulated brewing vessel with a false bottom.^3 4 5 The end product of mashing is called a "mash".

Infusion mashing

Most breweries use infusion mashing, in which the mash is heated directly to go from rest temperature to rest temperature. Some infusion mashes achieve temperature changes by adding hot water, and there are also breweries that do single-step infusion, performing only one rest beforelautering.

Decoction mashing

Decoction mashing is where a proportion of the grains are boiled and then returned to the mash, raising the temperature. The boiling extracts more starch from the grain by breaking down the cell walls of the grain. It can be classified into one-, two-, and three-step decoctions, depending on how many times part of the mash is drawn off to be boiled.⁶ It is a traditional method, and is common in German and Central European breweries.^7 8 It was used out of necessity before the invention ofthermometers allowed simpler step mashing. But the practice continues for many traditional beersbecause of the unique malty flavor it lends to the beer; boiling part of the grain results in Maillard reactions, which create melanoidins that lead to rich, malty flavors.⁹

Mash tun

An empty mash tun showing the integrated mash rake.

In large breweries, in which optimal utilization of the brewery equipment is economically necessary, there is at least one dedicated vessel for mashing. In decoction processes, there must be at least two. The vessel has a good stirring mechanism, a mash rake, to keep the temperature of the mash uniform, and a heating device that is efficient, but will not scorch the malt (often steam), and should be insulated to maintain rest temperatures for up to one hour. A spray ball for clean-in-place (CIP) operation should also be included for periodic deep cleaning. Sanitation is not a major concern before wort boiling, so a rinse-down should be all that is necessary between batches. Smaller breweries will often use a boil kettle for mashing.

Mash Ingredients

Each particular ingredient has its own flavor that contributes to the final character of the beverage. In addition, different ingredients carry other characteristics, not directly relating to the flavor, which may dictate some of the choices made in brewing: nitrogen content, diastatic power, color, modification, and conversion.

Nitrogen content

The nitrogen content of a grain refers to the mass fraction of the grain that is made up of protein, and is usually expressed as a percentage; this fraction is further refined by distinguishing what fraction of the protein is water-soluble, also usually expressed as a percentage; 40% is typical for most beermaking grains. Generally, brewers favor lower-nitrogen grains, while distillers favor high-nitrogen grains.

In most beermaking, an average nitrogen content in the grains of at most 10% is sought; higher protein content, especially the presence of high-mass proteins, causes "chill haze", a cloudy visual quality to the beer. However, this is mostly a cosmetic desire dating from the mass production ofglassware for presenting serving beverages; traditional styles such as sahti, saison, and bière de garde, as well as several Belgian styles, make no special effort to create a clear product. The quantity of high-mass proteins can be reduced during the mash by making use of a protease rest.

In Britain, preferred brewers’ grains are often obtained from winter harvests and grown in low-nitrogen soil; in central Europe, no special changes are made for the grain-growing conditions and multi-step decoction mashing is favored instead.

Diastatic power

The diastatic power (DP), also called the "diastatic activity" or "enzymatic power", of a grain in general refers only to malts, grains that have begun to germinate; the act of germination includes the production of a number of enzymes such as amylase that convert starch into sugar; thereby, sugars can be extracted from the barley’s own starches simply by soaking the grain in water at a controlled temperature: this is mashing. Other enzymes break long proteins into short ones and accomplish other important tasks.

In general, the hotter a grain is kilned, the less its diastatic activity; as a consequence, only lightly colored grains can be used as base malts, with Munich malt being the darkest base malt generally available.

Diastatic activity can also be provided by diastatic malt extract or by inclusion of separately-prepared brewing enzymes.

Diastatic power for a grain is measured in degrees Lintner (°Lintner or °L, although the latter can conflict with the symbol °L for Lovibond color); or in Europe by Windisch-Kolbach units (°WK). A malt with enough power to self-convert has a diastatic power near 35 °Lintner (94 °WK). Until recently the most active, so-called "hottest" malts currently available, American six-row pale barley malts, have a diastatic power of up to 160 °Lintner (544 °WK). Wheat malts have begun to appear on the market with diastatic power of up to 200 °Lintner. Although with the huskless wheat being somewhat difficult to work with, this is usually used in conjunction with barley, or as an addition to add high diastatic power to a mash.

Color

In brewing, the color of a grain or product is evaluated by the Standard Reference Method (SRM),Lovibond (°L), American Society of Brewing Chemists (ASBC) or European Brewery Convention (EBC) standards. While SRM and ASBC originate in North America and EBC in Europe, all three systems can be found in use throughout the world; degrees Lovibond has fallen out of industry use but has remained in use in homebrewing circles as the easiest to implement without a spectrophotometer. The darkness of grains range from as light as 3 SRM/5 EBC for Pilsener malt to as dark as 700 SRM/1600 EBC for black malt and roasted barley.

Modification

The quality of starches in a grain is variable with the strain of grain used and its growing conditions. "Modification" refers specifically to the extent to which starch molecules in the grain consist of simple chains of starch molecules versus branched chains; a fully modified grain contains only simple-chain starch molecules. A grain that is not fully modified requires mashing in multiple steps rather than at simply one temperature as the starches must be de-branched before amylase can work on them. One indicator of the degree of modification of a grain is that grain’s Nitrogen ratio; that is, the amount of soluble Nitrogen (or protein) in a grain vs. the total amount of Nitrogen(or protein). This number is also referred to as the "Kolbach Index" and a malt with a Kolbach index between 36% and 42% is considered a malt that is highly modified and suitable for single infusion mashing. Maltsters use the length of the acrospire vs. the length of the grain to determine when the appropriate degree of modification has been reached before drying or kilning.

Conversion

Conversion is the extent to which starches in the grain have been enzymatically broken down into sugars. A caramel or crystal malt is fully converted before it goes into the mash; most malted grains have little conversion; unmalted grains, meanwhile, have little or no conversion. Unconverted starch becomes sugar during the last steps of mashing, through the action of alpha and beta amylases.

Grain milling

The grain used for making beer must first be milled. Milling increases the surface area of the grain, making the starch more accessible, and separates the seed from the husk. Care must be taken when milling to ensure that the starch reserves are sufficiently milled without damaging the husk and providing coarse enough grits that a good filter bed can be formed during lautering.

Grains are typically dry-milled. Dry mills come in four varieties: two-, four-, five-, and six-roller mills. Hammer mills, which produce a very fine mash, are often used when mash filters are going to be employed in the Lautering process because the grain does not have to form its own filterbed. In modern plants, the grain is often conditioned with water before it is milled to make the husk more pliable, thus reducing breakage and improving lauter speed.

Mashing-in

Mixing of the strike water, water used for mashing in, and milled grist must be done in a such a way as to minimize clumping and oxygen uptake. This was traditionally done by first adding water to the mash vessel, and then introducing the grist from the top of the vessel in a thin stream. This has led to a lot of oxygen absorption, and loss of flour dust to the surrounding air. A premasher, which mixes the grist with mash-in temperature water while it is still in the delivery tube, reduces oxygen uptake and prevents dust from being lost.

Mashing in (sometimes called "doughing-in") is typically done between 35 and 45 °C (95 and 113 °F), but, for single-step infusion mashes, mashing in must be done between 62-67 °C (144-153 °F) for amylases to break down the grain’s starch into sugars. The weight-to-weight ratio of strike water and grain varies from 1⁄2 for dark beers in single-step infusions to 1⁄4 or even 1⁄5, ratios more suitable for light-colored beers and decoction mashing, where much mash water is boiled off.

Enzymatic rests

Optimal rest temperatures for major mashing enzymes

Temp °C	Temp °F	Enzyme	Breaks down
40-45 °C	104.0-113.0 °F	β-Glucanase	β-Glucan
50-54 °C	122.0-129.2 °F	Protease	Protein
62-67 °C	143.6-152.6 °F	β-Amylase	Starch
71-72 °C	159.8-161.6 °F	α-Amylase	Starch

In step-infusion and decoction mashing, the mash is heated to different temperatures at which specific enzymes work optimally. The table at right shows the optimal temperature ranges for the enzymes brewers pay the most attention to and what material those enzymes break down. There is some contention in the brewing industry as to just what the optimal temperature is for these enzymes, as it is often very dependent on the pH of the mash, and its thickness. A thicker mash acts as a buffer for the enzymes. Once a step is passed, the enzymes active in that step are denatured by the increasing heat and become permanently inactive. The time spent transitioning between rests is preferably as short as possible; however, if the temperature is raised more than 1 °C per minute, enzymes may be prematurely denatured in the transition layer near heating elements.

β-Glucanase rest

β-glucan is a general term for polysaccharides, such as cellulose, made up of chains of glucosemolecules connected by beta glycosidic bonds, as opposed to alpha glycosidic bonds in starch. These are a major constituent of the cell wall of plants, and make up a large part of the bran in grains. A β-glucanase rest done at 40 °C (104 °F) is practiced in order to break down cell walls and make starches more available, thus raising the extraction efficiency. Should the brewer let this rest go on too long, it is possible that a large amount of β-glucan will dissolve into the mash, which can lead to a stuck mash on brew day, and cause filtration problems later in beer production.

Protease rest

Protein degradation via a proteolytic rest plays many roles: production of free-amino nitrogen (FAN) for yeast nutrition, freeing of small proteins from larger proteins for foam stability in the finished product, and reduction of haze-causing proteins for easier filtration and increased beer clarity. In all-malt beers, the malt already provides enough protein for good head retention, and the brewer needs to worry more about more FAN being produced than the yeast can metabolize, leading to off flavors. The haze causing proteins are also more prevalent in all-malt beers, and the brewer must strike a balance between breaking down these proteins, and limiting FAN production.

Amylase rests

The amylase rests are responsible for the production of free fermentable and nonfermentable sugar from starch in a mash.

Starch is an enormous molecule made up of branching chains of glucose molecules. β-amylase breaks down these chains from the end molecules forming links of two glucose molecules, i.e.maltose. β-amylase cannot break down the branch points, although some help is found here through low α-amylase activity and enzymes such as limit dextrinase. The maltose will be the yeast’s main food source during fermentation. During this rest starches also cluster together forming visible bodies in the mash. This clustering eases the lautering process.

The α-amylase rest is also known as the saccharification rest, because during this rest the α-amylase breaks down the starches from the inside, and starts cutting off links of glucose one to four glucose molecules in length. The longer glucose chains, sometimes called dextrins or maltodextrins, along with the remaining branched chains, give body and fullness to the beer.

Because of the closeness in temperatures of peak activity of α-amylase and β-amylase, the two rests are often performed at once, with the time and temperature of the rest determining the ratio of fermentable to nonfermentable sugars in the wort and hence the final sweetness of the fermented drink; a hotter rest gives a fuller-bodied, sweeter beer as α-amylase produces more unfermentable sugars. 66 °C (151 °F) is a typical rest temperature for a pale ale or German pilsener, while Bohemian pilsener and mild ale are rested more typically at 67-68 °C (153-154 °F).

Comment

Decoction "rests"

In decoction mashing, part of the mash is taken out of the mash tun and placed in a cooker, where it is boiled for a period of time. This caramelizes some of the sugars, giving the beer a deeper flavor and color, and frees more starches from the grain, making for a more efficient extraction from the grains. The portion drawn off for decoction is calculated so that the next rest temperature is reached by simply putting the boiled portion back into the mash tun. Before drawing off for decoction, the mash is allowed to settle a bit, and the thicker part is typically taken out for decoction, as the enzymes have dissolved in the liquid, and the starches to be freed are in the grains, not the liquid. This thick mash is then boiled for around 15 minutes, and returned to the mash tun.

The mash cooker used in decoction should not be allowed to scorch the mash, but maintaining a uniform temperature in the mash is not a priority. To prevent a scorching of the grains, the brewer must continuously stir the decoction and apply a slow heating.

A decoction mash brings out a higher malt profile from the grains and is typically used in Bocks orDoppelbock-style beers.

Mash-out

After the enzyme rests, the mash is raised to its mash-out temperature. This frees up about 2% more starch, and makes the mash less viscous, allowing the lauter to process faster. Although mash temperature and viscosity are roughly inversely proportional, the ability of brewers and distillers to use this relationship is constrained by the fact that α-Amylase quickly denatures above 78 °C (172.4 °F). Any starches extracted once the mash is brought above this temperature cannot be broken down, and will cause a starch haze in the finished product, or in larger quantities an unpleasantly harsh flavor can develop. Therefore, the mash-out temperature rarely exceeds 78 °C (172.4 °F).

If the lauter tun is a separate vessel from the mash tun, the mash is transferred to the lauter tun at this time. If the brewery has a combination mash-lauter tun, the agitator is stopped after mash-out temperature is reached and the mash has mixed enough to ensure a uniform temperature.

Lautering

Lautering is a process in brewing beer in which the mash is separated into the clear liquid wort and the residual grain. Lautering usually consists of 3 steps: mashout, recirculation, and sparging.

Recirculation

Recirculation consists of drawing off wort from the bottom of the mash, and adding it to the top. Lauter tuns typically have slotted bottoms to assist in the filtration process. The mash itself functions much as a sand filter to capture mash debris and proteins. This step is monitored by use of aturbidimeter to measure solids in the wort liquid by their opacity.

Sparging

Sparging is trickling water through the grain to extract sugars. This is a delicate step, as the wrong temperature or pH will extract tannins from the chaff (grain husks) as well, resulting in a bitter brew. Typically, 50% less water is used for sparging than was originally used for mashing. Sparging is typically conducted in a lauter tun.¹⁰

English sparging (or batch sparging) drains the wort completely from the mash, after which more water is added, held for a while at 76 °C and then drained again. The second draining can be used in making a lighter-bodied low-alcohol beer known as small beer, or can be added to the first draining.

Fly sparging (or German sparging), which is used by commercial breweries uses continuous process sparging. When the wort reaches a desired level (typically about an inch) above the grainbed, water is added at the same slow rate that wort is being drained. The wort gradually becomes weaker and weaker, and at a certain point, they stop adding water. This results in greater yields.

Lauter tun

A lauter tun is the traditional vessel used for separation of the extracted wort. While the basic principle of its operation has remained the same since its first use, technological advances have led to better designed lauter tuns capable of quicker and more complete extraction of the sugars from the grain.

The false bottom in a lauter tun has thin (0.7 to 1.1 mm) slits to hold back the solids and allow liquids to pass through. The solids, not the false bottom, form a filtration medium and hold back small solids, allowing the otherwise cloudy mash to run out of the lauter tun as a clear liquid. The false bottom of a lauter tun is today made of wedge wire, which can provide a free-flow surface of up to 12% of the bottom of the tun.

The run off tubes should be evenly distributed across the bottom, with one tube servicing about 1 m² of area. Typically, these tubes have a wide, shallow cone around them to prevent compaction of the grain directly above the outlet. In the past, the run-off tubes flowed through swan-neck valves into a wort collection grant. While visually appealing, this system led to a lot of oxygen uptake. Such a system has mostly been replaced either by a central wort-collection vessel or the arrangement of outlet ports into concentric zones, with each zone having a ring-shaped collection pipe.

A good quality lauter tun has rotating rake arms with a central drive unit. Depending on the size of the lauter tun, there can be between two and six rake arms. Cutting blades hang from these arms. The blade is usually wavy and has a plough-like foot. Each blade has its own path around the tun and the whole rake assembly can be raised and lowered. Attached to each of these arms is a flap which can be raised and lowered for pushing the spent grains out of the tun. The brewer, or better yet an automated system, can raise and lower the rake arms depending on the turbidity (cloudiness) of the run-off, and the tightness of the grain bed, as measured by the pressure difference between the top and bottom of the grain bed.

There must be a system for introducing sparge water into the lauter tun. Most systems have a ring of spray heads that ensure an even and gentle introduction of the sparge water. The watering system should not beat down on the grain bed and form a channel.

Large breweries have self-closing inlets on the bottom of the tun through which the mash is transferred to the lauter tun, and one outlet, also on the bottom of the tun, into which the spent grains fall after lautering is complete. Craft breweries often have manways on the side of the mash tun for spent grain removal, which then must be helped along to a large extent by the brewer.

Some small breweries use a combination mash/lauter tun, in which the rake system cannot be implemented because the mixing mechanism for mashing is of higher importance. The stirring blades can be used as an ersatz rake, but typically they cannot be moved up and down, and would disturb the bed too much were they used deep in the grain bed.

Footnotes

1. Audrey Ensminger, Foods & nutrition encyclopedia, Volume 1, page 188. CRC Press, 1994, ISBN 0849389801. Retrieved 2010-02-20. ↩
2. Dan Rabin, Carl Forget, The dictionary of beer and brewing, page 180. Taylor & Francis, 1998, ISBN 1579580785. Retrieved 2010-02-20. ↩
3. "Abdijbieren. Geestrijk erfgoed" by Jef Van den Steen ↩
4. Bier brouwen ↩
5. What is mashing? ↩
6. Malting and Brewing Science: Volume I Malt and Sweet Wort, D. E. Briggs, James Shanks Hough, R. Stevens, Tom W. Young, Springer (1981), ISBN 0-412-16580-5 ↩
7. Malts and malting - Google Books. books.google.co.uk. Retrieved 2010-07-09. ↩
8. Malting and Brewing Science: Malt ... - Google Books. books.google.co.uk. Retrieved 2010-07-09. ↩
9. Decoction Mashing brewery.org ↩
10. Palmer, John (2006). How to Brew. Boulder, CO: Brewers Publications. pp. Chapter 17. ISBN 0-937381-88-8.↩