Brewing a beer


Head Honcho
Staff member
Say I was going to brew a beer now for summer drinking (would have brewed the last beer in October but ignoring that for the sake of the argument) what would I brew?

A big roasty porter, a Russian Imperial Stout? Too high in alcohol, too much body etc, not enticing in summer.

So a pale ale it would be (a pale lager would have had to be brewed months ago so it could take 2 weeks to ferment and more weeks to lager, cold storage.)

Again, a big ale is out—too heavy for summer drinking and need weeks to age to lose the alcohol heat. Let us set the abv (alcohol by volume to under 5%.) Not wanting Love on a Beach (fucking close to water) we will set the abv to 4.5%. Now, how much malt will be needed?

We need to define some terms.

Wort—unfermented beer. Winemakers call the juice from pressing grapes must while brewers call the liquid running from the chiller into the fermenter wort.

OG, Original Gravity—the density of the wort before fermenting starts, a measure of the sugars, fermentable and unfermentable, plus other ingredients

FG, Final Gravity, the density of the finished beer. OG – FG is a measure of the amount of sugar fermented by the yeast.

Abv, alcohol by volume calculation is complicated by the fact that the FG measures not just the amount of sugars turnmed into alcohol but also the fact beer contains alcohol which is lighter than water.

Degrees of Extract—a laboratory figure for the amount of sugar gotten out of a weight of grain. Look it up for yourselves, e.g. look up Bairds or Weyermann websites is and see DE for pale malt 301. A brewer can get maybe 80% of the laboratory figure

Brewlength—the volume at the end of the brew. Here we tend to do 22L batches, in the US they make 5gal batches, ≈ 5 x 4 = 20L. But there are wastages, I allowed 2L of wort sopped up by the hops plus bits stuck in chiller, below the outlet of the kettle etc, so we work on 24L. Since we boil wort for an hour we start with 26L of wort. I use V (volume) to stand for brewlength.

We decided that abv is to be 4.5% so we have: (OG - FG) x ƒ = abv where ƒ is a correction factor that allows for the alcohol being lighter than water factor. We do not need to use that equation, however.

Let us think a bit more about our desired beer. It is a smallish beer so we need to pack it full of body and flavor. Malt flavor is what we are considering. To get some body into our beer we want to work the malt to get as much body and flavor as we can.

We could use more malt—but keeping to the 4.5%abv target we have set ourselves we have to keep the OG low enough to not have the beer over 4.5%abv. So we need to have more malt but not use all of it. Hmmmm there are two ways to do that. Remember abv = (OG - FG) x ƒ = 4.5. We see that is we keep FG high OG - FG is small and so abv is small. A beer made so it is dry, with little body, a very low FG will have most of the sugars fermented out so high alcohol. So we can use techniques to keep FG a bit high and end up with an ale with some body to it despite it being under 5% abv.

What about malt flavor? The answer here is pretty easy: we use the best ale malt there is, Maris Otter. There is some resurgence of interest in a very nice Australian malts, Schooner and Sloop. But a good malt. That has to be the basis. Anything else we can do? We want to keep the ale nice and pale, deep gold but no darker say. It has to look nice on a bloody hot day, color and a nice head of foam. We could add some slightly roasted malt to increase the maltiness of the ale: vienna malt say, lightest of the roasted malts. But we can make some nice “light amber malt” in our own kitchen stove! Will describe how we do that later, just note that we will make 2Kg of light amber malt from however much Maris Otter we decide to use.

For decent head we could have say 250g wheat malt as part of our grist: wheat has a lot of protein and it is protein that keeps a head on the beer. Or we could use wheat malt extract to prime the bottles. We do not want our beer too fizzy, we want to drain the first glass in one blissful go, so priming will be light.

OK, that is it for malt, beer also contains hops!

Next post—all about the hops we will use. We will set our target bitterness as 80% of our OG. This, in our little pale ale, is not up to IPA standards but is a noticeable pleasant, mouth cleansing bitterness. A chap called Daniels went through a vast number of beers and noted the relationship between bittering, BU, and gravity, OG units. An extra special bitter might be 6% abv and have more Bittering Units than Gravity units. Nice sipping beer, not what we look for in the middle of an Australian summer! We will keep BU:OG at 80% (personal preference, experience in brewing.)

Next post: talk about the process of brewing and how we will tweak it to get a smallish ale with a nice body to it. Then a post full of lovely brewmath!
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Head Honcho
Staff member
Brewing starts with water except we call that mash liquor as we may have added some gypsum to the water to get more value out of our hops and we heat that to a specific temperature. This mash liquor is run into a mash tun and then the crushed grains of malt are carefully sitrred in. Enzymes readied in the malting process are activated by the heat and pH of the mash and turn the starch that makes up most of the interior of the grains of malt into fermentable and unfermentable sugars.

There are two of these amylase enzymes, alpha and beta (don’t nobody tell horseboy!) Alpha amylase is comfortable at higher temperatures and converts the long chains of glucose molecules into shorter chains, typically less than 12 linked glucose molecules. These are called dextrines and are not fermentable by yeast.

Beta amylase prefers cooler temperatures and takes the small chains created by alpha amylase and turns them into individual glucose molecules. Yeast can ferment single glucose molecules, maltose, two glucose molecules linked together and maltotriose, three glucose moloecules linked together, but not longer chains.

Enzyme kinetics. The hotter the mash the faster the amylase enzymes work—and the quicker beta amylase denatures, dies if you like. So, to get the body we want we will create a hot mash, mash liquor at 82°C. Normally I would use 3L mash liquor to each kilogram of malt but a thicker mash is supposed to give more body so we will use 2.5L/Kg.

Normally mixing the grain into the mash liquor results in a mash temperature 10°C lower than the mash liquor temperature, and I generally aim at a mash temperature of 68°C. Since we are creating a stiff (ooh err missus) mash, less mash liquor per kilo of grain we will make the mash liquor a bit hotter than normal. Once mash liquor and crushed grains are well mixed we cover the mash tun so the mash doesn’t lose too much heat. We leave this for an hour, traditionally tho half an hour is likely enough in fact.

So our small pale ale is off to a good start, good malt flavor, a bit more body than we normally find in a beer of this lowish abv. We can enhance malt flavor and body a bit more—we need to rinse out the sugars etc that we have created by letting the amylase enzymes do their thing. This is called sparging and we can tweak the process. As we start pouring sparge liquor over the top and collecting the wort from the outlet of our mash tun the runnings we collect get thinner and thinner runnings of little flavor and then we get off flavors, silicon and husky tastes from the errr, husks. So when we calculate the amount of malt to go into the mash tun we can add a kilo more malt then stop sparging rather earlier.

So you see while we do have brewmath and can calculate recipes exceptional beers require knowledge, experience—artistry!

What if we find out we have 18L of wort of too high a gravity for our 4.5%abv target? We can dilute it with water.

V1 x G1 = V2 x G2 since we do not lose gravity, just dilute it. So the new volume (V2) we want of the right OG we can calculate

V2 = V1 x G1/G2 and the dilution amount is V2 - V1.

What if we find we have too much wort of too low a gravity? All we can do is boil the wort down to the desired volume. This will darken the beer, however and we are looking at a light amber ale. BIG problem for a commercial brewer who needs to brew beers exactly the same every batch. A shoulder shrug for a home brewer who wants great beer each batch!

Gravity units = SG - 1000 so an FG of 1012 = 12 gravity units

OK, to calculate our malt bill we have an equation derived from experience:

abv = (OG-FG)/7.6 (Coopers Brewery website) OG - FG is a measure of the sugars used up in the ferment

We want an FG of 1012-3, a bit more than the usual FG - 1010 for a beer of the abv we want.

4.5 = (OG - 12)/7.36, rearranging:>

OG = (4.5 x 7.36) + 12 = 45.12 gravity units

The formula for calculating OG =

G = W x (DE x Efficiency)/V


G is the number of gravity units, 45 in this case
W is the weight of malt in Kg
V is volume in litres
DE is the total, lab derived, sugars that can be extracted from a weight of malt = 301 as we saw above.
Efficiency is the percentage of the laboratory extract a brewer actually gets. We want a fairly low efficiency, arranging mash and sparge to ensure that. Instead of 80% efficiency we aim for 70%

70% of 301 = W x (.7 x 301)

So we can now put some values into our equation:

45 = W x 211/24, rearranging

W = 45 * 24 / 211 = 5.12Kg

I would have just guess OG needed to be 1050, FG 1012 and played with the formulas a bit. There is a rule of thumb

FG = OG / 4 that would have given us OG = 12 x 4 = 48 but since we want more body we want FG a bit higher.

I have shown how we can ensure the higher FG by decreasing efficiency of the mash by using high temperature mash liquor, low mash liquor:weight grain and sparging a bit less than I would usually do.

Plenty of malt, low mash efficiency = more malt = more body and more malt flavor no off flavors, no using lactic acid to get the final, thin runnings from our mash.

Malt is half the story. Hops are the other half and we are going to pack our ale with hop flavor and aroma while hitting our goal of tons of hop flavor and aroma. Next post.
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Head Honcho
Staff member
For bought English Ale we would use English hops tho when the hop harvest failed English brewers turned readily enough to German hops. If brewing for a competition Beer Judge Certification Guidelines are used. I never used them, consider them a straightjacket and a nonsense but for an English ale English hops seem the thing to use. If making an American Pale Ale I would use American hops but since we started with English Maris Otter malt we will use traditional English hops, especially the mainstays Goldings and Fuggles.

I say traditional—nineteenth century hops were different, e.g. Long Square Garlic! The mind boggles!

Now, this is a little ale, bitterness will be small: rememe ber OG = 1045, 80% of that is 36. We could devise a complex hop schedule with Goldings, Fuggles and Bramling Cross hops. Not going to. Will use East Kent Goldings (so called, hops are grown in other parts of England) alone. This is how you build a deep hop flavor.

Now, hop brewmath.

Bittering units achieved obviously depend on the bittering capacity of the hops used and the amount of hops used. The more hops used, the bitterer the hops are the bitterer the beer will be.

EKG typically have a bittering capacity, or alpha acid component of 5.7%. Fuggles which are used more for their flavor and aroma might have 4% AA.

It should not be hard to understand that the longer hops are boiled the more of the bitterness can be extracted from them.

We boil our wort for an hour. Hops added at the start of the boil are boiled for the full 60 minutes and have the highest utilisation.

Hops added 15 minutes before the end of the boil have the lowest utilisation rate—hops added after 15 minutes, say five minutes before the end of boil have such a low utilisation rate we don’t bother calculating the bitterness they add: our palates cannot tell the difference between 20 and 25 bittering units!

OK, some definitions and then lovely brewmath!

For our purposes hops have alpha acids and flavor and aroma compounds. The longer the hops boil the more bitterness is added to the wort but the more the aroma and flavor are boiled out “brewing for the neighbors” as we say. Hops that boil for the full hour provide only bitterness, little to no hop flavor and no aroma at all.

Hops boiled for 30 minutes provide less bitterness than the 60 minute addition (lower utilisation, remember?) but provide some flavor. Hops boiled for 15 minutes provide little bitterness but plenty flavor and some aroma. Hops added 5 minuted from the boil provide no detectable bitterness but plenty flavor and aroma and hops added at the end of the boil provide only aroma.

We tried our best to pack our ale with malt flavor, using more malt than we really needed, so we will pack our ale full of hop flavor and aroma! Yes sir!

So we will split the bittering addition between a sixty minute addition, a thirty minute addition, a 15 minute addition and a 5 minute and end of boil addition.

The last two additions are easy: we will add 15g Goldings at 5 minutes and end of boil. Nothing to calculate, experience shows those additions add enough flavor and aroma.

What about the 15 minute addition, the 30 minute and 60 minute additions?

We have an OG of 45 units, 80% of that will be our target bitterness. BU = 80% of GU is a nice level of bitterness for our little ale, a higher ratio of BU to GU means we will sip the beer, we want one that goes down quick on a hot summers day!

We will add 15g of Goldings 5 minutes before the end of boil and another 15g at end of boil, packing our ale with hop flavor and aroma. This is based on experience, brewing lots of 24litre batches of beer.

What about the 15 minute addition? A 30 minute addition, the 60 minute addition? These all add detectable bitterness but the 15 minute addition is made for hop flavor and aroma.

So the 15 minute addition we decide to add 20g of hops, usually I would add 15g but we are packing our ale with flavor and aroma.

How to calculate bitterness?

BU = w x AA x U/(10 x V)

U is the Utilisation rate, w = weight of hops in grams, AA, alpha acid content is noted on the label of your packet of hops and utilisation has been measured for all sorts of lengths of boils. For 15 minutes of OG 1050 wort U = 11.4%

So we can calculate the IBUs from the 15 minute hop addition:

BU = 20 x 5.7 x 11.4/240 = 5.14 ≈ 5IBU

We wanted total IBUS to be 80% of 45 = 36IBU. We now have 5 leaving 31BUs to be gotten from the early additions. Most beers I would add one bittering addition but sometimes used two, a 60 minute and a 30 minute and we will do this for our ale that we want to pack chockfull of flavor and aroma.

So how do we decide how much to add at each addition? To increase the 30 minute addition which adds flavor but has a lower utilisation rate we decide to add the same number of IBUs from each addition, 15.5IBUs, call that 16 IBUs

Utilisation for a 60 minute addition in a 50GU wort is 23.1% so we now need to solve for weight of hops:

16 = w x 5.7 x 23.1/240, rearranging:

w = 16 x 240 / (5.7 x 23.1) = 29g

Doing the same for the 30 minute addition, U = 17.7

w = 16 x 240 /(5.7 x 17.7) = 38g
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Head Honcho
Staff member
So, we wanted a small pale ale packed with flavor, we chose Maris Otter malt. We toasted 2Kg of our 5.12Kg of malt to light amber in our kitchen oven. Flavor, yup!

We wanted the ale to have some body to it. The 5.12Kg of malt is more than we would usually use but by using a hot, stiff mash we got the extra body we wanted and the sparging finishing earlier also helped make the beer pure in flavor.

A beer needs hops to bitter it else it drinks like treacle. Hops also add flavor and aroma so we devised a hop schedule that packed our little ale with tons of hop flavor and aroma. A light fizz so the first glass can be drunk in one gorgeous swallow, the second glass can be drunk slowly, savoring everything we have packed into the ale.

So we have a nice little light golden ale that makes ideal drinking in a hot summer yet has a flavor punch well above its weight.