Tag Archives: Ciphering

My Water – Application #1

In an earlier post, I began discussing my local water and now I am talking about practical examples of how I treat it, depending on the style.

To recap, here is the typical Pittsburgh area water:

Calcium 30 ppm
Magnesium 10 ppm
Sodium 25 ppm
Chloride 30 ppm
Sulfate 75 ppm
Alkalinity 70 ppm

I like this water profile – the levels of all ions are fairly low.  It is easier to add than to take away!  The only potential problem with this water is the calcium level.  The generally recommended level is 50 to 150 ppm, so I am usually adding calcium in one of the three common ways: calcium carbonate, calcium chloride or calcium sulfate.

Recently I brewed a Kolsch-Style Ale – the beer is mostly pilsener malt and just a touch of wheat malt.  Because this recipe has no dark or roasted malts, and my water has low levels of calcium it is quite likely that the mash pH would end up being too high.  Adding calcium should help a bit, and if I add calcium chloride it helps bring up the chloride to sulfate balance.  Why is that important?  Allegedly, beers with a high sulfate to chloride ratio tend to favor hop expression, whereas the reverse brings out the malt.  I have not confirmed this through experiment, but for now I will extend provisional acceptance.

The other thing I did was a about 3% acidulated malt to the mash.  This malt has been kilned in such a way as to encourage the production of lactic acid.  Chew some – it is sour stuff.  Besides helping to drop the pH, adding acid to food generally brightens the flavor.  I think it works well here.

If you are looking for help in figuring out all of the maths I recommend two sources:  John Palmer’s How to Brew website chapter 15-3 has a nice spreadsheet for entering your water data and looking at the effects of various mineral additions.  John’s spreadsheet calculates a target residual alkalinity value based on beer color.  I have read criticism of this method as being unreliable, but in fairness this is all a bit of a guess.  If you are running a production brewery then you are making the same few beers most of the time and you can nail down your water treatment.  As a homebrewer always trying something new you have to make your best estimations

A more advance calculator designed by Kai Troister can be found at the Brewer’s Friend website.  Kai has done a tremendous amount of investigation and experimentation.  His calculator takes into account you entire grain bill (including the types of malts you choose, not just mash color).  His calculator is a thing of beauty, and if you can soldier through the tedium required to enter all of the information, you will be rewarded!

My Water

Many words have been written about water in brewing.  Everything about water is pretty much known, how it behaves in the presence of malt, its impact of chemistry and flavor. Unfortunately water is one of those topics that many brewers struggle to understand. In this post I am going to talk about the local water (Southwest Pennsylvania) and how I approach its modification for brewing.

First I want to give credit to two sources that have taught me about 95% of what I know about water.  The first is John Palmer, whose website How to Brew is a fantastic resource and includes a free, simple, water chemistry spreadsheet.  The second in Kai Troester, whose even more detailed website and blog are full not just of information but experiments he has conducted.  My hats off to both, and thanks for the help.

The first thing about water is knowing what is in your brewing water.  When I became interested in the topic there were not many resources available to learn about the local water supply.  A few years back I called the local water company and found a very helpful person who sent me three or four years of local testing records.  While this was very useful, it was explained that some of the parameters were only tested once per year and for some measurement (sulfate, for example) there was some significant variation. But not having access to better information, I did my best with what I had.

Today, with the growing popularity of brewing, water test kits have become much more available.  A simple one that I use is made by API and is sold for use in keeping aquariums.  This kit is available for less than ten dollars and allows for quickly measuring two important parameters: water hardness and carbonate levels.  These two parameters are key to understanding and predicting your mash pH.  There are kits available which also measure sulfate, and places such as Ward Labs will test a sample of your water for a small fee. If you are a serious home brewer there is not much excuse for not knowing your water.

Here is a breakdown of the typical minerals and ions found it Pittsburgh area water:

Calcium 30 ppm
Magnesium 10 ppm
Sodium 25 ppm
Chloride 30 ppm
Sulfate 75 ppm
Alkalinity 70 ppm

This is really nice brewing water, as most of theses levels are at or below the minimum required (and it is always easier to add the required minerals, versus having to dilute with distilled water in order to reduce concentrations).  The other not so obvious but equally import factor is this water’s low residual alkalinity (in the range of 35).  What the heck is residual alkalinity and why should you care?  Here is my quick and dirty explanation:

For a number of reasons, the ideal mash pH is 5.3 to 5.7.  When water and malt are mixed, chemical reactions occur with the calcium and magnesium in the water. These reactions tend to lower the mash pH (make it more acidic, which is a good thing).  Darker roasted and crystal malts tend to lower the pH more than lightly kilned malts. This tendency to a lower pH is offset by the alkalinity of the water.  The residual alkalinity is the measure of a water’s tendency to lower mash pH.  It is calculated from the water’s calcium, magnesium, and alkalinity levels.  Grain bills with high levels of roasted/crystal malts tend to require water with higher residual alkalinity (RA =100 and up) whereas very pale beers needs a lower residual alkalinity to allow the pH to drop low enough (RA less than 0).

One can see that a RA of 35 is a very happy medium, very suitable for pale ales and other medium colored beers.  Only the most pale beers may require acid malt or an acid addition to bring their pH in line.  Compare this to two other extremes in brewing water: Dublin, the home of stout, has a RA >250.  Pilsen, the Czech home of the pilsner beer has a RA of probably about 10.

If there is a downside to this it is the fact that the mineral levels, especially sulfate, are on the low side for hoppier beer styles.  Note this consideration is only about beer flavor and not about mash pH.  Extract brewers should have low concern about residual alkalinity but should pay attention to sulfate, chloride, and sodium levels. Note that besides pH, the calcium can impact the yeast performance.  At 30 ppm the calcium in my water is a little low, and an extract brewer might still benefit from small calcium additions.

In the next post about water I will provide specific examples of how I went about treating my brewing water.

So, How’s that Working for You?

Back to beer.

Over the course of a few posts, I described a method devised to accurately predict the brewhouse efficiency using a batch sparge process.  I guess you could call it my sparge hypothesis, and if it is then we must experiment to find out if it seems to explain reality.  Almost like real scientists.

The most recent batch I made was an English IPA. I targeted a batch size of 18.0 liters, with an OG of 13.6 °P (1.055 sg).  Between me and my recipe formulator I came up with the following grain bill:

Mash Grains / Adjuncts

% Yield

Weight

Marris Otter

82.0%

3.400

Crystal 10

75.0%

0.200

Crystal 60

75.0%

0.150

English Brown Malt

70.0%

0.100

Red Wheat Malt

81.0%

0.070

This is a total of 3.92 kg of malt with a predicted brewhouse yield of 78%, based on a mash conversion efficiency of 90% (note: I also added some golden syrup to this recipe, so the mash numbers do no reflect the total amount of fermentables in the final wort).  Therefore I was targeting 2.48 kg of fermentables solely from the wort itself.

Using my usual water to grain ration of 3, my mash in water volume was 11.8 liters, to be topped up with 4.4 liters prior to the first runoff.  The second runoff called for an addition of 10.3 liters.  My targeted boil kettle volume was 22.5 liters (at mash temperature) with an OG of 10.7 °P.

How did I do?

Well, excellent, thank you.  At the end of the mash and sparge I had 23 liters of wort at 10.7 °P.  Not bad.  My final brewhouse yield was 79%, and my mash conversion efficiency was 91%.  At the end of boil I had 18.9 liters at 13.3 °P (1.054), of which about 17 liters ended up in the fermenter.   All, in all, a pretty good job.

So, pat myself on the back and go on, right? Well, not quite so fast.  Upon digging deeper, there are some anomalies to be found. Look at the data results:

For the first runoff I was expecting 11.7 liters at 15 °P.  Calculations predicted 10.30 kg of water and 1.82 kg of fermentables.  I measured 13.0 liters of wort at 15.1°P, which consisted of was actually 11.5 kg of water and 2.05 kg of fermentables. The second runoff should have consisted of 10.3 kg of water and 0.66 kg of fermentables.  Instead I calculated it was 9.5 kg of water and 0.46 kg of fermentables.

So why did that happen?  I am not sure, but it motivates me to take a look through old data and continue to keep meticulous records on future batches.  Because, after all, it ain;t rocket science.

Go Figure – Putting it all Together (Finally!)

Introduction

OK, we have had a lot of background posts but we are finally getting to the crux of the biscuit ( ‘ ) !

We are now going to calculate how figure out how much water and grain will be needed to execute a recipe, using a batch sparge approach.  One thing to know about batch sparging is that the highest efficiency will be achieved if both the first and second runoffs are the same volume.  A tip of the hat to a home brewer by the name of Ken Schwartz, who not only figured this out a long time ago, but wrote down the explanation.  If you are interested in the math behind this assertion, please click here.

As a reminder, here are the “givens” that will be used in this example:

Target Original Gravity for Wort 15° P  / 1.061
Final Wort Volume 20 liters
Water Boil Off Rate 4 liters per hour
Boil Time 1 hour
Water Absorbed by Grain 1.5 liters per kilogram
Water to Grain Ratio for Mash 3.0 liters per kilogram
Expected FGDB Yield 78.9%
Target Wort Mass (pre-boil) 25.22 kilogram
Sugar in Wort 3.18 kilogram
Water Required (in wort, pre-boil) 22.04 kilogram

The Algorithm

Here is the steps that will be followed:

  1. Estimate grain weight
  2. Calculate water requirements
  3. Calculate how much sugar will be extracted in first runoff
  4. Calculate how much sugar will be extracted in second runoff
  5. Add the results of steps 3 and 4
  6. Does the total from step 5 equal the amount of sugar called for in the recipe?
  7. If the answer to 6 is no, then go back to step 1, otherwise you are finished!

Water Requirements

In my approach to this you need to start with a guess as to how much grain will be needed. Since we need 3.18 kg of sugar and since the grain is supposed to yield 78.9% of its weight as sugar let’s guess:

3.18 kg / 78.9% = 4.03 kg of grain

The recipe requires 22.04 kilograms of water in the boil kettle, so we will need that plus how much water is absorbed into the grain. The amount absorbed by the grain is estimated to be 4.03 (grain weight) times 1.5 (estimated waster absorbed by grain) or 6.04 kg.

Since we want to runoff approximately one half of the water in each of the two runoffs, we will need to initially add one half of the water required in the kettle before boil plus the water absorbed by the grain, or 22.04/2 + 6.04 = 17.06 liters.  After we finish the first runoff we will add the second half of the water requirement (22.04/2) or 11.02 kg water to the lauter tun before conducting the second runoff.

Note: If you mash in with 17.06 kg of water you will have a water to grain ration of about 4.2, which is probably about 2 quarts per pound.  This might be higher than you want, if so, just mash in at the ration you want and add additional water just prior to runoff.

Sugar Calculations

Assuming you actually convert 78.9% of the grain to sugar (which you probably won’t but we will discuss that in a moment) then before the first runoff there will be 3.18 kg of sugar dissolved in 17.06 liters of water.  The gravity is then:

(100 x 3.18) / (3.18 + 17.06) = 15.7 °P

Once the first runoff is drained into the boil kettle there will be a wort with 11.02 kg of water and a gravity of 15.7 °P.  The sugar mass is therefore

Ms (1st runoff) = -(ºP x Mw) / ( ºP – 100 ) = – (15.7 x 11.02) / (15.7 – 100) = 2.05 kg

The sugar remaining in the grain is now:

Ms (grain) = 3.18 kg – 2.05 kg = 1.13 kg

When the second addition of water is made to the lauter tun, there will again be 17.06 kg of water but only 1.13 kg of sugar. The new gravity is

(100 x 1.13) / (1.13 + 17.06) = 6.2 °P

When this is runoff, the mass of the sugar that will be collected is:

Ms (2nd runoff) = -( ºP x Mw ) / ( ºP – 100 ) = – (6.2 x 11.02) / (6.2 – 100) = 0.73 kg

So the total sugar collected is

Ms (total) = Ms (1st runoff) + Ms (2nd runoff) = 2.05 kg +0.73 kg = 2.78 kg

While this represents a brewhouse efficiency of 87% (2.78 kg actual sugar / 3.18 kg targeted sugar) we have not achieved our required 3.18 kg of sugar in the boil kettle. What to do?

Recalculate

We needed 3.18 kg.  We got 2.78 kg.  So why not increase the grain by the ration of 3.18/2.78 (or 114.4%) ?

114.4% x 4.03 kg = 4.61 kg of grain.

What changes?  Well since we have more grain we will lose more water to the grain.  The new water loss is 4.61 x 1.5 = 6.91 kg.  So the first water addition is:

11.02 + 6.91 = 17.93 kg water.

The sugar that should be converted in the mash is now

78.9% x 4.61 = 3.64 kg

Initial gravity is

(100 x 3.64) / (3.64 + 17.93) = 16.9 °P

And

Ms (1st runoff) = -( ºP * Mw ) / ( ºP – 100 ) = – (16.9*11.02) / (16.9-100) = 2.24 kg

Ms (grain) = 3.64 kg – 2.24 kg = 1.40 kg

New Gravity = 1.40 / (1.40 + 17.93) = 7.2 °P

Ms (2nd runoff) = -( ºP x Mw ) / ( ºP – 100 ) = – (7.2 x 11.02) / (7.2 – 100) = 0.86 kg

Ms (total) = Ms (1st runoff) + Ms (2nd runoff) = 2.24 kg + 0.86 kg = 3.10 kg

Closer, but not quite there.  What if we scale up by the factor of 3.18/3.10?  That is 4.73 kg of grain.  If you run through the calculations a third time, the sugar in the kettle will be 3.16 kg.  One more iteration results in the the target of 3.18 kg in the boil kettle, starting with 4.76 kg of grain.  Since 4.76 kg of grain can be expected to yield up to 3.76 kg of sugar, the brewhouse efficiency is 85%.

That is not really the whole story.  At the beginning of this example a conversion efficiency equal to the FGDB yield of the grain, and that is unlikely. Around 4-5% of the grain weight is water, and achieving perfect conversion may not be practical.  I assume a mash conversion efficiency of 90%, typically, which means that instead of 4.76 kg of grain I would need perhaps 5.29 kg.  But even that represents a brewhouse efficiency of 76%.

Summary

Obviously an iterative calculation such as this are well suited to an Excel spreadsheet.  I plan to create one and use it to illustrate factors which can impact efficiency.

Stay tuned!

Go Figure – No Grain, No Gain

I want you to know that we are working our way toward a cohesive theory of how to calculate and execute a recipe to hit the target volumes and gravities.  This post should be a quickie, but it is still an important step on the path.

We discussed grain and extract potential, the old FGDB (fine grind dry basis) value which tells you how much sugar you can expect to extract from your grain.  As we have mentioned, it should be a top end number, the best you can get.  You can find the FGDB yield in a variety of places.  For instance ProMash brewing software lists it for a variety of grains.  You can also look up a particular malting companies web site to see if they offer the information.  The sidebar links on this blog will send you to some of the relevant sites.

The point of this post is to make it clear how to calculate the overall expected efficiency you should get from your particular grain bill.  It is simple, for each grain multiply its expected yield by its percent weight in the recipe.  Add these up.  The total is the expected overall grain bill efficiency.  Here is an example:

Example Calculation - Overall Grain Bill Efficiency

Done!

 

Go Figure – The Wort (pre-boil)

I have spent a little time discussing efficiency, what it means, and how to calculate it.  Which is all good stuff, but probably dreadfully boring for many, many brewers.  The goal of this series of ‘Go Figure’ posts is to explain how to consistently predict brewhouse efficiency and subsequently hit target gravities so that the brewer can makes the beer that was designed.  If you are the type of brewer who never measures the wort gravity or really bothers to check the volume in the fermenter, you may want to move on before you head begins to hurt.  However if you are frustrated because you never seem to it the gravity you are looking for, read on.

The first step in targeted your gravity and volume is… determining the target gravity and volume,  because you cannot hit a target if you do not know what it is. If you are working from a recipe from a book or online, the original gravity and a target volume are usually given.  The original gravity is most important; we can scale the recipe to almost any volume that is required.

As far as the required volume is concerned first decide how much wort you want in the fermenter.  Add to that the amount of wort you expect to leave behind in the boil kettle with the hop residue and trub.   The ‘boil kettle loss’ will vary depending on the recipe.  A very hoppy pale ale with lots of hops will likely result in more kettle loss.  Whole hop cones can absorb a fair amount of wort, and the loss associated with those will likely be different than a brew with just pellets.  I don’t have a hard and fast rule, but 1 to 2 liters of wort over and above the targeted fermenter volume is probably a good place to start.

Since 5 gallons is a common homebrew batch size, and 5 gallons is about 19 liters, targeting 20 or 21 liters at the end of boil is a reasonable number. For the example I am about to give, I will use 20 liters because it is a nice round number.  For this example I will assume a  target original gravity of 15 ºP or 1.061 specific gravity.

Calculate the amount of fermentable sugar and water required.  That means converting volume to mass.  20 liters of wort at a specific gravity of 1.061 should weigh 21.22 kg (yes, I am using mass and weight interchangeably.  I am not that pedantic.).  Next, we know 15 ºP means that 15% of that mass is sugar, so:

( 21.22 kg wort * 0.15 % sugar by weight ) = 3.18 kg of sugar.

And of course the water mass is just the difference:

( 21.22 total kg of wort – 3.18 kg sugar )  = 18.04 kg water

We are almost done with our work here.  We know  how much water and sugar need to be in the kettle at the end of boil, it is time to account for the water that will be boiled off.  Again this will vary with your particular setup. I generally boil off 3.5 to 5.0 liters of water per hour depending on the batch size and how vigorous I set the boil.  For this example we will assume a one hour boil and a 4 liter per hour boil off rate.

So, our pre-boil wort should be:

( 20 liters wort + 4 liters water ) = 24 liters

It should weigh:

21.22 kg final mass + 4 kg water = 25.22 kg pre-boil mass

And finally the gravity should be:

 25.22 kg / 24.0 liters = 1.051 specific gravity, about 12.6 ºP.

So, armed with this information we can begin to calculate the amount of grain and water that will be required for the batch.  The next post in this series will discuss grain bill calculations.

Go Figure – Lautering Efficiency

The last post on this topic discussed mash efficiency, which was defined as how effectively the brewer converts the grains into wort sugars.  With that step completed, the brewer now needs to extract those sugars from the mash and get them to the boil kettle.  And the effectiveness of this process is what will be called lautering efficiency.

I believe these topics are best illustrated via example, so let us continue with the example presented in the mash efficiency post.   Five  kilograms of malt with a FGDB yield of 80% was mashed at 3 kilograms of water per kilogram of grain or 15 kilograms of water (Note: I giver water measurement by mass, not volume. A beauty of the metric system is that at room temperature one liter of water weighs 0.998 kilograms. (I just round that to 1.000.  There is more to come about water density in another post).  In this example the gravity of the liquid in the wort was measured at 19.0 °P, which corresponded to 3.5 kilograms of sugar and a 87.5% mash efficiency.

So now, just open the spigot on the mash tun and drain the liquor into the brew pot.  The first obvious fact is that  no matter what happens  the wort in the brew pot will be 19.0 °P (we already measured it, remember?).  So, assuming no further rinsing of the grains, our lautering efficiency will be a function of how well the mash/lauter tun drains.  How well will it drain?  It depends on the equipment.  In my brewery I find that I lose about 1.50 liters of water per kilogram of grain.  So back to the example above:

Water Loss = 5.0 kg malt x 1.5 kg water loss/kg malt = 7.5 kg

After starting with 15 kg of water, 7.5 kg are absorbed into the grain and 7.5 kg are now in the boil kettle.  How much sugar is in the boil kettle?  Remember:

Ms = -( ºP * Mw ) / ( ºP – 100 ) = -(19*7.5) / (19 -100) = 1.76 kg sugar

Since the sugar in the mash tun was calculated to be 3.5 kg, we have extracted exactly 50%, which is our lauter efficiency (so far).  The overall brewhouse efficiency is:

Mass of Sugar in Brew Kettle / (FGDB Yield * Mass of the Grain) =

1.76 / (0.80 * 5.0) = 44%

which is of course pathetic but this is just an example.  Plus, the grains have not been rinsed or sparged in any way.  For arguments sake, assume 7.5 kg of water is now added to mash/lauter tun.  What happens?

Well, first remember that there is again 15.0 kg of water in the mash tun (the 7.5 kg absorbed by the grains plus the 7.5 kg we just added).  There is 1.74 kg of sugar in the mash tun (we started with 3.50 and there is now 1.76 in the boil kettle).  Therefore:

ºP = ( 100 * Ms ) / ( Ms + Mw ) = (100 * 1.74) / (1.74 = 15.0) = 10.4 ºP

If the mash/lauter tun is drained again then again 7.5 kg of water will be lost and 7.5 kg of water will go into the boil kettle.  How much sugar will be carried with this rinse?

Ms = -( ºP * Mw ) / ( ºP – 100 ) = -(10.4 * 7.5) / (10.4 – 100) = 0.87 kg sugar

So now there is 1.76 kg of sugar from the initial draining of the mash/lauter tun and 0.87 kg from the rinsing or 2.63 kg sugar in the boil kettle.  The lauter efficiency is now:

2.63 kg sugar (in boil kettle) / 3.5 kg sugar (in mash) = 75%

and the overall brewhouse efficiency:

Mass of Sugar in Brew Kettle / (FGDB Yield * Mass of the Grain) =

2.63 / (0.80 * 5.0) = 66%

a much more respectable figure!

I hope that we have now laid the basic groundwork for how I conduct calculations related to mashing and lautering.  It is fine stuff, but how can a brewer use this to plan his brew day and end up making the desired beer?  Well, first we need to establish the targets that need to be hit, then calculate how much water and grain will be needed.  That is where we are headed next.

Go Figure – Calculating Mash Efficiency

In the last post on this topic I discussed the concept of brewhouse efficiency and how to calculate it. Now I want to talk specifically about the mash, how to calculate mash  efficiency and what mash efficiency you can expect.

As mentioned in the last post, brewhouse efficiency is a combination of two separate efficiencies: mashing efficiency and lautering efficiency.  Mashing efficiency is a measure of how much of the starch in the grain is converted to sugar.  When the grains are mashed in, the enzymes in the grain begin the breakdown process.  In theory all of the starch can be converted, resulting in a mashing efficiency equal to the FGDB yield.  A number of brewing parameters will impact the mash yield: the moisture content of the grain, the crush quality, the mash temperature, the mashing time, and the mash pH (which is a function of the grain bill and the water characteristics).  But my goal is not to discuss these factors, but how to measure your mash efficiency so you can work on predicting it.

Measuring the mashing efficiency starts with rearranging the equation for degrees Plato:

ºP = ( 100 * Ms ) / ( Ms + Mw )

Where Ms is the mass of the sugar in the wort and Mw is the mass of the water. What never occurred to me, and I thank Kai for pointing this out, is that we can rearrange the equation to define Ms in terms of Mw:

Ms = -( ºP * Mw ) / ( ºP – 100 )

So if we know the degrees Plato and the amount of water in the mash, we can calculate the sugar and know the mash efficiency.  I like to use examples to illustrate the calculations,  so assume 5 kilograms of malt with a FGDB yield of 80% is mashed at 3 kilograms of water per kilogram of grain.  After one hour a sample of the mash has a gravity of 19 °P.  What is the mash efficiency?

The maximum theoretical yield is 80% x 5 = 4 kilograms of sugar.  To calculate mash efficiency use °P = 19 and  Mw = 5 kg grain x 3 kg water/kg grain = 15 kg water, so that:

 Ms = -( ºP  * Mw ) / ( ºP – 100 ) = -( 19 * 15 ) / ( 19 – 100 ) = 3.5 kilograms of sugar

and,

Mash Efficiency = 3.5 / 4.0 = 87.5%

So what mash efficiency should the home brewer expect? First of all remember that malt absorbs moisture in the range of 4% by weight, so you can probably start by assuming a maximum mash efficiency of 96%.  Beyond that the efficiency depends on a number of factors that have already been mentioned. I am still learning what system really does, but I have found that if I mash for one hour a mash efficiency of 90% works pretty well.

Next time, I will discuss lautering efficiency and how much of the wort sugar we can reasonably expect to extract from the wort.

Go Figure – What is Efficiency?

After ten years of brewing and ten years of guessing what my mashing and lauterng efficiency might be, I wasn’t so much frustrated as simply convinced there was no better way. I went about guessing what my efficiency might be. Then Kai Troester pointed me in the right direction.  But before we talk about that, let’s review what efficiency really means.

Efficiency is just of measure of how much fermentable and non-fermentable sugar the brewer extracts from the malt. All brewing grains are composed of a variety of materials, such as starches, sugars, proteins, tannins and the like.  Brewers want to extract the starches (and convert them to sugars) and the sugars (for converted malts such as crystal malts).

But how does the brewer know how much sugar to expect?  Maltsters test their brewing grains in special laboratory mashes.  One commonly reported result is the percent yield, fine grind dry basis (FGDB).  In short, the grain is ground fine and mashed in controlled conditions, and the amount of fermentable material is measured.  Most fully modified base malts available to home brewers have a FGDB yield in the range of 75% to 82%.  So one kilogram of malt should yield 0.75 to 0.82 kilograms of sugar.

But of course it is not that simple.  Notice that FGDB specifies dry basis, and brewing malts are not dry.  They absorb moisture, and while I have never personally measured the moisture content of my malt, the moisture level is often given to be 4%.  So that malt with an 80% FGDB yield will actually yield about 77% sugar by weight.

Next, and here where Kai’s insights are particularly valuable, the brewer must consider his mashing efficiency and his lautering efficiency.  If the mash is not conducted efficiently, then the yield will fall further.  Once the mash step is complete, the brewer must then extract the sugars by lautering the grains with water.  And this is another step where sugar can be lost and efficiency suffers.

At the completion of the mashing step, the mass of the sugar in the boil kettle will be less than the mass of the grain or even the amount of sugar predicted by the FGDB method.  I find that usually the brewhouse efficiency is defined as :

Mass of Sugar in Brew Kettle / (FGDB Yield * Mass of the Grain)

I have sometimes seen efficiency expressed as the mass of the sugar in the brew kettle divided by only the mass of the grains.  Obviously this will be a much lower value than the definition above, and there is nothing wrong with calculating in that manner.  However I believe the brewhouse efficiency formula that I have proposed is the most common one, and that it is slightly more indicative of the brewer’s true efficiency.

The last piece of the puzzle is determining how much sugar is in the brew kettle.  Most brewers are probably familiar with the formula for calculating degrees Plato:Where Ms is the mass of the sugar and Mw is the mass of water.

This formula simply expresses the amount of sugar in the wort on a weight percent basis.  As a practical example, consider 25 liters of 10 °P wort.  The first calculation that must be done is covert the volume measurement (25 liters) to a mass.  This is easily accomplished because we can convert the Plato measurement to specific gravity, specifically 10 °P is equivalent to a specific gravity of 1.040.  Therefore the wort has a mass of 25 x 1.040 = 26 kilograms.  And since 10 °P is equivalent to 10% mass by weight, we know the wort contains 2.6 kilograms of sugar.  If the brewer started with 5 kilograms of malt with a FGDB yield of 80%,then  the brewhouse efficiency would be 2.6 / (5 * 0.8) or 65%.

So now we know what efficiency is and how to calculate it.  But how can we control and predict it?  That is a subject for another post.

Go Figure

I have a degree in engineering.  Electrical engineering.  As an old colleague once said, “you can’t spell geek without an EE”.  I take that comment as a point of pride, actually.

Which brings us to the topic of coming up with brewing recipes, and more specifically deciding how  much grain and water and hops we need. I started brewing in 1997, when books, recipes, and resources were a lot more limited than they are today. This was the early days of the world wide web, and although homebrew geeks were early adopters, information was still limited. I had a homebrewing book by Dave Miller that was full of technical data, but still just a fraction of the information that can be found today with just a few clicks of the mouse.

Of course it wasn’t too long after that homebrewing software for the computer became available.  And it wasn’t long before I ran across ProMash, and boy was I hooked (see the first paragraph for clues as to why).  It was eminently customizable, and had enough bells and whistles to confuse all but the most dedicated home brewer.  You could create recipes, choose your IBU calculation method, edit water profiles, calculate water needs, deisgn multi step mashes, calculate efficiencies, carbonate your beer, and more. It was, and still can be, a useful brewing tool.

But one thing ProMash doesn’t do is help you calculate what your brewhouse efficiency will be.  Sure, you can enter a number for efficiency, but that never seemed to go too well.  I would enter 75% and actually get 68%.  Next time I would use 68% and get 74%.  Maybe I would try 72% and that was a workable average, but this whole thing seemed like too much guessing.

Then about a year or so ago I heard a discussion of brewhouse efficiency by Kai Troester of BrauKaiser on Basic Brewing Radio.  Lights went on in my head.  Brewhouse efficiency didn’t have to be a guessing game.  But it was time to do some cipherin’…

I will follow with a series of posts that I hope will clearly explain how I calculate my expected efficiency.  I hope you find them useful.