Mashematics is a Canberra Brew Supply business whose origins date back to early 2003.

If you are looking for our on-line shop click here

You will find our pricing reasonable compared to what is out there and excellent in the context of what is available in Canberra.

But if you are a financial member of Canberra Brewers you can take advantage of excellent discounts, bulk buys and one time offers.


Oxygen Part 1…grain, crack, mash.

Oxygen its what we breath, our most basic sustenance, yeast feels the same way. The best brewers oxygenate their cooled worts as a matter of course

However it can be and is not good for our beer in other processes everything your grain should as fresh as possible but by by fresh thats up to at least two years old and 4 years or longer if stored cool and dry. For this we can thank Acsorbic Acid Oxydase which not only keeps our grain fresh along with other compounds but slows the oxidation of polyphenols and thiols in the mash.

However as soon as your grain is cracked oxygen starts it’s nasty work and gets to the AAO. A window of 15 minutes from crack to mash is considered safe.

The water that we pour is about 8ppm and at mash temperatures about 4ppm which is a significant amount of oxygen. We need to deaerate our mash water, the easiest way is boil and quickly cool to strike temperature (water absorbs oxygen from the atmoshere at 1-2 ppm per hour).

The grain should be added dry and the strike water under-let for least possible oxygen uptake, but it will happen during the course of the mash so to the mash sparge water add 30ppm potassium metabisulphite, this should be about right as we want to knock out any oxygen that finds, usually through agitation, its way in. It is also helpfull to add Brew Tan B at 1.5g per 20 litres of mash sparge water.  The gallotannins in BrewTan B react with wort proteins and is highly effective at coagulating proline and thiol containing proteins which are involved in lipid and protein oxidation.

If you are recirculating then keep the outlet well under the top of the mash and also be very scared of how you sparge, and if you do use the drain out of the pipe method keep the bottom of the pipe just under the drained wort level by using a pulley attachment.

These products are readily available from Mashematics

Mill gap size

Much is written about mill gap, some from highly reliable sources and others, well its the internet !

From a small scale brewing point the most importants factors are minimal flour , maximum whole husk and lots of grits, so it is always a god idea to to have a look at the crack after the few first few hundred grams.

We sell mainly Gladfield New Zealand malts. These grains are very plump and very friable. If you are used to using less friable and slimmer grains you almost certainly have your mill gap too small for the best efficiency with Gladfields.

Here is what Gladfields have to say:

Mill gap. In this blog, I would like to draw your attention to your grain mill.

Your mill is the most important equipment you have in your brewery, without it, you could not start your brewing day.

How many of you spare a thought of your mill dying on you on a brew day? Pretty serious aye! Your mill doesn’t need to be fancy, flash or very powerful. To be honest, the most important thing about your mill is the roller gap size.

If the gap is too wide, you will under crush your malts resulting in poor yield per kilo of malt to litres of beer. If you have it too tight you will have issues with off flavours because you have trashed the husk and the most painful part of having your mill gap too tight is that you will have higher chance to have a stuck mash.

No one wants to spend longer then it is needed to brew a beer, so you all have to agree the mill gap is quite important.

Gladfield Malts are consistent in size. We screen our malts on a 2.5 mm screens which not many maltings around the world do. Most maltings de-culm the malts but not screen it. Hence our malts are free of dust, sticks and small grains.

New Zeland is famous for its plumpness which helps. If you brew with Gladfield Malts you will see consistency in grain size, if you lock your mill to the ultimum gap size you don’t need to alter from brew to brew, your welcome!

I measured our pilot brewery’s 2 roller mill now you have a size to go by.

The measured gap is 1.45 mm. We have set our mill to reflect our malts plumpness and never had any issues with runoffs or stuck mashes.

Below is our blurb about malt crush:

Our malts are both plumper and more friable. If the malt mill roller is too tight, Gladfield’s malt will be more likely to shatter and create too much flour. Consequently, brewers could experience stuck mashes. We recommend checking the malt crush before brewing with our malts for the first time. For the ideal malt crush look for the following:

• Husk – 20%
• Coarse Grits – 35%
• Fine Grits – 35%
• Flour – 10%

The average size of our malt grain is >2.8mm for barley and wheat.


Hop Storage, age and degradation

Hops are only harvested once a year per hemisphere. This requires that hops are packed and stored in conditions that optimise that just pelleted quality. The Northern harvest happens about now but we do not start receiving hops here to typically late March (apart from some urgent airfreight varieties). Clearly the suppliers want to move move most the previous years first and the simple fact is that well stored they as perfectly fresh as the incoming.

What is well packed and what is well stored and how long will hops last before they start to noticeably degrade, well clearly that depends on the packing and storage. Hops are not unusual in that the big killer is air, and specifically oxygen.

Most importantly then the hops need to avoid air, ideally this is vacuum packing, they need to be kept cold (freezing is not required but may not hurt) and away from light. The worst possible storage is in clear plastic bags, which have a high oxygen permeability, outside the fridge and in the light. Clear bags (such as oxygen barrier bags that have been vac sealed and kept in the dark) are fine, this very handy if you are repacking on household vac-sealer.

There is a measure, that goes back to the 70’s called Hop Storage Index (HSI). This the amount of alpha acid acid loss after 6 months at 25C. Not much use us really !!

Here is a link to a Czech paper on hop storage, they conclude “Each component of hops has its specific value in beer brewing. These experiments have shown that the only safe way to preserve bitter acids is to store the hop pellets in a chilled space without air access.”

Correctly packed and stored your expensive dried hops will have no problem maintaining their quality over three years and probably more. Badly packed and after 6 months things start going cheesey.


Bio Transformation

There have been some great discussions and education in Canberra Brewers on Bio Transformation

Here is a nice simple one pager:

LAL-bestpractices-Biotransformation-print+bleed (1)


Calcium…O Calcium

It is often said that Calcium is good for your bones and good for your beer. Canberra’s water @ 13 is fine Ca wise for Pils but a bit low for many styles (O Vienna @ 200 or Burton @270)

Here is a bit from (you will get a 404, mine is an old copy)

<<Of the ions required for brewing, calcium is by far the most important. This is because of the acidifying effect that calcium has on the wort. […] A combination of the presence of calcium ions and the decrease in pH has a number of effects on the brewing process:

  • The lower pH improves ß-amylase activity and thus wort fermentability and extract. The optimum pH for ß-amylase activity is about 4·7. Wort produced from liquor containing no calcium has a pH in the order of 5·8 – 6·0, compared to values in the range of 5·3 – 5·5 for worts produced from treated brewing liquor. The activity of the ß-amylase then is greatly enhanced by the addition of calcium, this enzyme increasing the production of maltose from Amylose, and thus making worts more fermentable.
  • Calcium has a beneficial effect on the precipitation of wort proteins, both during mashing and during the boil.

Protein-H + Ca2+ (r) Protein-Ca ¯ + 2H+

The hydrogen ions released further reduce the pH which encourages further precipitation of proteins.

Proteins are also degraded, that is converted to simpler substances by proteolytic enzymes called proteases. These are found in the malt, and have optimum activity at pH values of about 4·5 – 5·0. The reduction in pH then caused by the presence of calcium encourages proteolysis, further reducing protein levels and increasing wort Free Amino Nitrogen levels (FAN).

FAN compounds are utilised by the yeast during fermentation for the manufacture of amino acids, and an increase in FAN levels in the wort improves the health and vigour of the yeast.

High protein levels in beers also have negative effects, making beer more difficult to fine and encouraging formation of hazes, in particular chill hazes. Product shelf life can also be adversely affected.

  • Calcium ions protect the enzyme a-amylase from inhibition by heat.

a-amylase is an endo enzyme, cleaving the internal 1,4 glucosidic links of amylopectin resulting in a rapid reduction in wort viscosity. The optimum temperature range for

a-amylase activity is 65°C – 68°C, but the enzyme is rapidly destroyed at these temperatures. Calcium stabilises a-amylase to 70 – 75°C.

It can be seen then that the presence of calcium has positive effects on the activity of a-amylase, ß-amylase and Proteases, some of the most important enzymes in the brewing process.

  • The drop in pH encouraged by Calcium ions in the mash and copper helps afford the wort and subsequent beer produced a greater resistance to microbiological infection.
  • The reduced pH of the sparge liquor reduces extraction of undesirable silicates, tannins and polyphenols from the mash bed. The extraction of such materials is encouraged by alkaline sparge liquor. These materials are very undesirable, contributing to harsh flavours, hazes in the finished beer and decreased beer stability.
  • Calcium precipitates oxalates as insoluble calcium oxalate.

This again occurs in both the mash tun and the copper. If oxalates are not removed they can cause hazes in finished beers and also contribute to the formation of beerstone in FV’s, CT’s and casks. Oxalates are also thought to promote gushing in certain beers, although this is not generally a problem to the micro brewer.>>

Generally speaking you will use Calcium Chloride for maltier beers and Calcium Sulphate for hoppier beers or ideally a combination of the two.

More to come


Brut too

Brut IPA seems to be the current Wunderkid and I thinks makes a nice balance with the slightly older kid on the block NEIPA. I have only tasted one commercial example and no home brewed though I intend to make “Trotskys End” in a few weeks.

The use of enzymes in beer is nothing new, were it not for enzymes we would not have beer. Large commercial operations use added enzymes to make..shudder at the thought..Lo-carb beers…

So if you want to try to replicate here is a fact sheet

Brut too 1

Mashematics will be stocking Glucoamylase. Keep an eye out.


High Gravity and ABV

Alcohol does strange things.

One of those means that the ABV calculated by good old simple OG-FG * x is pretty good up to about 6% ABV when the results start to drift. This is not new and was observed by Daniels in his classic Brewing Great Beers. Having brewed a RIS with some pretty stupid gravities I found calculating using this method was the better path.

So here it is (the first of a number of online calculators)


How to measure pH (AJ deLange)

I would like to thank AJ deLange for permission to re-post his pages.

pH Meter Calibration Procedure

I frequently get asked about how to use and calibrate a pH meter. Let’s start with use and then move on to calibration.

Measurement of mash pH is the use to which meters are most often put by brewers. Assuming the meter is calibrated (see below) here is how that is done.

1. Stir the mash thoroughly. This is especially important if the measurement is to check on the effects of an acid or alkali addition. Withdraw a small sample of the liquid. It doesn’t matter if some grain is included.
2. Cool the sample to room temperature, ideally the same temperature as the buffers you used for calibration. This prolongs electrode life and reduces the burden on ATC. If you use a small metal saucepan you can achieve the cooling quickly by immersing it in cool/cold water.
3. Rinse the electrode with DI water, shake off and blot (see calibration below) and insert the electrode into the sample. Move the electrode around for a few seconds (sample rinses any water off bulb and junction) then stop and wait until the reading is stable. Some meters will decide when the reading is stable for you and beep to signal this. Record both the reading and the temperature.
4. Repeat the process every 5 minutes or so until the readings stop changing. This usually 15 – 30 minutes after strike.
5. Rinse the electrode with DI water and return to storage solution or just tap water for short term (i.e. between readings) storage.

For calibration the overall instructions are simple: follow the manufacturer’s instructions. For those who don’t have a meter in hand and want to have an idea as to what is involved or for whom the supplied instructions are less than adequate the following is offered.

Buffers and samples should be at room temperature.

1. Store the electrode in a storage solution recommended by the manufacturer. This will often be a saturated or nearly saturated solution of potassium chloride.
2. Prepare fresh 4 and 7 buffer solutions using deionized water. Several manufacturers sell capsules of powder which contain the buffers’ chemical components. These are simply added to a specified amount of DI water (50 or 100 mL) just before use. Premixed buffers are also sold in sealed packages (similar to the ketchup packages from fast food restaurants). These work as well as the buffers one mixes on the spot and are obviously more convenient but tend to be, because of the packaging, more expensive. Premixed buffers are also sold in bulk i.e. 1 L bottles or 4 L jugs or cubitainers. If buffers in this form are being used check that they are not beyond their expiration dates and pour small amounts of each into a clean beaker or preferably, sealed container, at the beginning of each brew day. Do not return used buffer to the bulk storage.
3. Remove the storage cap from the electrode. If the electrode is the refillable type, insure that it contains adequate fill solution, top up if neecessary and, whether you top up or not, open the fill hole so air can enter the electrode body allowing fill solution to freely flow out through the reference junction.
4. Rinse the electrode with a stream of DI water from a wash bottle. Blot dry with clean tissue or paper towel. Don’t touch the actual electrode bulb when you do this. You don’t need to get all the adhering water, just the bulk of it. Wicking of water into the paper is adequate.
5. Turn the meter on, allow it to stabilize for a few minutes, and then lower the electrode into the first buffer solution. With most modern meters it does not matter which one you go into first as these meters have automatic buffer recognition. Following the manufacturer’s instructions put the meter in calibration mode and initiate calibration if necessary (e.g. press the ‘read’ or ‘Cal’ button).
6. Move the electrode around in the buffer a little to rinse any adhering DI water off the bulb and away from the reference junction.
7. Wait until the reading stabilizes. Modern instruments tend to have stability indicators which beep or otherwise alert the operator when the reading is stable (hasn’t changed by more than a threshold amount in a given period of time). These often also instruct the operator ro move on to the next buffer when stability is detected. In others you may have to determine when the reading is stable yourself and indicate this to the meter by pressing a button. Follow the manufacturers instructions and/or prompts on the meter’s display.
8. When instructed to move to the second buffer, remove the electrode from the first buffer, shake adhering buffer off and rinse with a stream DI water. Blot away as above and insert the electrode in the second buffer. Move electrode around in second buffer.
9. When the second reading is stable, take whatever action is necessary to complete the measurement as above. In some meters there will be an option for a third buffer. In those meters you will have to do something (e.g. press an ‘exit’ button) to indicate to the meter that calibration is complete if you are doing a 2 buffer calibration.
10. The instrument will now calculate the calibration parameters (slope and offset) and, in some cases, display these to you in the case of slope either as a percentage (should be near 100) or a number like 57.3 which is the number of millivolts change per unit change in pH at some reference temperature. The offset will be a millivolt number which should be small i.e. a few millivolts (it can be negative). If the meter presents those numbers, write them in your log book. They represent a record of the rate at which your electrode is aging. Fancy meters will automatically store the calibration data, tagged with time and date, in the meter’s memory.
11. Take whatever action is necessary to indicate that the calibration is to be accepted (e.g. press a ‘store’ or ‘exit’ or other button as directed by the manual).
12. Remove the electrode from the second buffer. Shake, rinse and blot as before. Place in sample.
13. Press ‘read’ button if necessary. Otherwise monitor display. Move electrode around in sample.
14. When reading is stable (as determined by you or meter electronics) record pH and temperature. Fancy meters will automatically store these in memory and some will even transmit them to an external computer.
15. Remove from sample, rinse and blot dry as before. Move to next sample. If finished, rinse extra thoroughly. After shaking and blotting dry insure that cap contains sufficient storage solution to cover bulb and replace cap. Turn meter off if finished for the day. If not finished for the day the probe can be left in the last sample.

11b. As a check on the calibration you can measure the 4 and 7 buffers again at room temperature. You may wish to do this after some time has passed or even after you have finished measuring samples for the day. pH values are often printed on the buffer package. Sometimes they are not. If not and assuming you are using NIST traceable pH 4 and 7 technical buffers the pH values of the buffers are:

pH 7: 1911.4/K -5.5538 + 0.022635*K – 6.8146e-6*K*K

pH 4: 1617.3/K -9.2852 + 0.033311*K – 2.3211e-5*K*K

where K = °C + 273.15 (i.e. K is the temperature in Kelvins).
The values you read should be close to those given by the formulas or on the buffer package. If they are not then your meter is drifting.

Cool the 4 buffer to about 40 °F and measure its pH. Do this right after completing calibration. If your meter reads off by more than a few hundredths then its isolectric point is not equal to 7 and you must be careful to measure buffers and samples at close to the same temperature (ATC won’t work well).


pH a different perspective (AJ deLange)

I would like to thank AJ deLange for permission to re-post his pages.

A Different Perspective on pH

Advances in technology have resulted in pH meters with performance high enough and prices low enough that it is possible for a home brewer on almost any budget to afford one. Accordingly, a lot of questions about their use arise. Here we have two pages, the first dedicated to the practical aspects of calibration and measurement (here) and the second to the mathematical details of the calibration algorithm (here). The former was originally posted on the Homebrew Talk site and readers may wish to visit that site in order to avail themselves of related questions and answers on this subject which appear there from time to time. The result of all this that brewers are now striving to hit proper pH at several points in their brewing process without perhaps fully understanding what pH is or why it should be controlled to a particular value. We will argue here that this is perfectly proper on the basis that brewers have for years been controlling temperature throughout the brewing process without fully understanding what temperature is though they generally do know why it must be controlled. You are thinking “Of course I know what temperature is!” but I suspect that few of you actually do. The goal of this page is to draw comparisons between temperature and pH to get you to the point where you are as comfortable with pH as you are with temperature. We’ll do this by mystifying temperature a bit while simultaneously demystifying (we hope) pH.

Temperature – What is it?

The obvious answer is that it is a measure of how hot something is but what does that really mean? We usually don’t bother to ask or answer such questions because our interest in temperature is entirely practical. If it is 35 degrees out on a given day we dress very differently than if it is 5 without giving it a second thought beyond whether we are comfortable or not. In this regard temperature and pH are different. We are constantly aware of temperature not only with regard to our comfort at a particular moment but with regard to things like cooking where we know chicken should be done at 180 degrees and salmon at 230  and brewing where we know that sachharification at 63C will result in a more fermentable beer than saccharification at 69C But how often do we think about pH in our daily lives? Whenever we brew or poach an egg or make a Hollandaise sauce or add more sugar to lemonade we are making from fresh lemons or when we add pickling lime to a batch of dills we are responding to pH but most are probably not aware of that fact.

If we do think about temperature beyond what numbers imply comfort and what numbers produce good beer it is in terms of energy. We know that to increase the temperature of a system we need to apply heat and that heat is a form of energy (or so we think – heat is actually the transfer of energy by certain means). You can skip the next three paragraphs if you don’t care that much about what temperature actually is.

We can get an idea as to what temperature might be by looking at the ideal gas law: PV=nRT in which P is the pressure, V the volume, n the number of atoms of the gas in the volume, R a constant and T the temperature. Rearranging this to P=nRT/V we can then look at the pressure on the walls of the container in which this gas is held. We assume that the container is a perfect insulator. This means that no energy can escape it which implies that no heat can pass through it. This, in turn, implies that if an atom of the gas strikes one of the walls that none of its energy will be imparted to the atoms or molecules in the wall or, put another way, that the collision is perfectly elastic so that the energy of motion of the particle before and after the collision will be the same. This means that if a particle strikes the surface with velocity normal to it vn and vp parallel to it it must leave with normal velocity -vn and parallel velocity vp. For this to be the case the wall must impart an impulse (integral of force the time during which the force acts) = 2mvn where m is the mass of the particle. vn is a function of the magnitude of velocity, v, of the particle given by the magnitude of v times the cosine of the angle between the velocity and the normal. The impotant concept is that it is proportional to the speed of the particle.

The volume, V, of the container is proportional to the cube of some linear measurement made upon it such as the radius of a sphere or the height of a cylinder. The shape doesn’t change this cubed relationship: only the proportionality constant changes as the shape changes. Calling this linear dimension l it should be clear that when a particle strikes the wall of the container, and rebounds it will strike another wall some time later and that that time will be proportional to l and inversley proportional to the speed of the particle i.e. to l/v and that, therefore, the rate at which collisions occur must be proportional to nv/l and the total force exerted by the container walls must be proportional to the average impulse and the number of collisions per unit time i.e proportional to 2mv2/l. For every reaction there is an equal and opposite reaction so that there must be force on the walls equal to the force exerted by the walls. Pressure is the force per unit area and the area of the walls is proportional to l2 so the pressure on the walls of the container would be proportional to 2nmv2/l3 and, as volume is proportional to the cube of the linear dimension, also to 2nmv2/V. Comparing this to P=nRT/V we see thatT must be proportional to mv2.

We have been very cursory here in using the same symbol, v, for velocity and speed and have glossed over the details of the averaging which is implied. In the final form, mv2, v2 is the average squared speed (magnitude of velocity) of the particles and is thus twice the average kinetic energy of the particles and this is the result we sought: the temperature of an ideal gas is a measure of the average kinetic energy of its particles. In a real gas or in a solid or liquid things become much more complicated and we must include the effects of particle/particle collisions as well as collisions with the walls and in diatomic or molecular gasses vibrational and rotational kinetic energy as well as translational but the result is the same: temperature is proportional to the average kinetic enrgy of the particles of the system. This definition is of little value to us when making beer. Another definition of temperature is that it is the first derivative of Gibbs energy with respect to entropy. I expect this definition is of even less use.

pH – What is it?

For the purposes of this discussion it is another parameter, like temperature, which you need to control to make good beer. We could stop right here but whereas readers are probably thoroughly comfortable with temperature, even though most probably don’t know what it really is, they are probably not so comfortable with pH as they don’t experience it in the same way as temperature i.e. they probably don’t have a ‘hands on’ feel for it the way they do with temperature. But let’s think about this for a minute. There is a physical sensation associated with pH and that is sour taste for low pH value and bitter taste for high. Something which is at high temperature feels hot. Something at low pH tastes sour. If you touch something that is at a very high temperature or at a very low temperature tissue damage will result. The same will happen if you expose yourself to excessively high or low pH. If you try to cook and egg at too high or low a temperaure range you will not get a properly cooked egg but, as many may know, there is a reason why cooks add vinegar to the water in which they poach eggs or to hollandaise sauces and that is to control the pH. You already know, or are learning, that it is not sufficient to control mash temperature for best results. pH must be controlled too.

Thus we see that there are parallels between pH and tempertaure in the sense that we can physically feel both, that we can hurt ourselves if exposed to materials outside a particular range of either and that we must control both in activities like cooking and brewing (and many others as well). At the completion of our discussion of pH we will see that for the brewer pH and temperature have one major thing in common: they are both things we can control and we do so because both effect the shape of protein molecules.

As we did above for temperature we will now discuss in more technical terms what pH is. In this case we’ll start with the most precise definition and work that back to more understandable terms. pH is a measure of the activity of hydrogen ions. The formal definition comes from the International Union of Pure and Applied Chemists (IUPAC), an international standards body concerned with matters chemical. The activity of a species is, as the name suggests, representative of its ability to participate in chemical reactions. The IUPAC definition of pH indicates that it is minus the logarithm to the base 10 of the molality scale concentration of hydrgen ions multiplied by an activity coefficient. When the hydrogen ion concentration is weak (pH between 4 and 10) and the solutions dilute the activity coefficient is close to 1 and the molality concentration (moles of ion per kilogram of solvent) and molar concentration (moles per liter of solution) will be very close to the same. Finally as the molecular weight of hydrogen ions is 1 gram per mole a concentration of 1 mole/kg corresponds to 1 gram/kg or approximately 1 gram/liter. Also as the hydrogen ion carries a unit of electronic charge 1 mole/kg corresponds to 1 eqivalent per kg or 1 equivalent per liter. The result of all this is that while pH is in fact precisely defined as the negative logarithm of the activity on the molal scale you can think of it in terms of the negative logarithm of the concentration expressed as grams/L. As an example,1 L of deionized water to which has been added 1 millimole (36.45 mg) of hydrochloric acid would have a hydrogen ion concentration close to 1 mmol/L (0.001mol/L) which is very close to 0.001 mol/kg water because the solution contains almost 100% water. As the solution is dilute (36 mg is only 0.004% of a kg) the activity coefficient is nearly 1 and the activity of hydrogen would be very close to 0.001 mol/kg (the activity coefficient is dimensionless) and the pH thus -log(.001) = 3. If we added 3.645 mg of hydrochlorc acid to 1L of water the concentration of hydrogen ions would be 0.0001 mol/kg and the pH 4. If we added 0.3645 mL of hydrochloric acid the hydogen ion concentration would be 0.0000101 mol/kg and the pH 4.9957 or, to two decimal places, 5.00. You are doubtless asking yourself ‘Where did that 0.0000001 mol/kg come from and why didn’t it appear in the pH 3 and 4 cases?’. The answer is that it comes from the water itself and that it does appear in the pH 3 and 4 cases but given that, even in the pH 5 case, it has no effect unless we try to measure pH to more than 2 decimal places, it has even less so at pH < 5 and we can ignore it.

Water is HOH or, if you prefer H20. A tiny fraction of the water molecues in any solution, separate into H+ and OH- ions. In pure water at 24.8°C that fraction is such that the concentration of hydrogen ions (equal to the concentration of hydroxyl ions) is 0.0000001 mol/kg = mol/L = gram/L. This lets us answer a second question: ‘What is the pH of pure water?’ and, as apparently, the hydrogen ion concentration is 0.0000001 in pure water, the answer is pH = 7. This is the case for pure water at 24.8°C. At room/laboratory temperature the fraction of dissociatin water molecules is a bit less and the pH thus rises to 7.085. Does this make sense in terms of our earlier discussion of temperature? At lower temperature the average water molecule has less kinnetic energy, is not moving as fast and is less likely to suffer a collision with another water molecule of sufficient violence to dislodge a proton. Does this work the other way too? Indeed it does. At saccharification temperature of 60 °C (140 °F) the pH of pure water is 6.51.

pH = – log(concentration) is the definition you will usually see in beginning level textbooks but it is rare that you will be interested in the number of mg of hydrogen ions in a liter of water or beer. What you will be interested in is what the implications of a particular concentration of hydrogen ions (i.e. a particular pH) are with respect to acids.

pH and Acids

The reason we must control pH is that by so doing we can regulate the degree to which acids are dissociated i.e. the extent to which they give up hydrogen ions (which are protons). As a protons are positively charged, each time an acid gives up a proton it becomes negatively charged by 1 electronic charge unit. The end result is that at higher pH acid residues are more negatively charged than at lower pH because they have lost more protons.

The following chemical equation shows electrically neutral carbonic acid at the left shedding one proton to become bicarbonate ion with unit negative charge and then the second to become carbonate ion with double negative charge.
pH a different perspective (AJ deLange) 2

We asserted above that high pH is required for this to happen but looking at the equation one sees more and more protons released as we move to the right and more protons present implies lower pH. There is no paradox here. To establish high pH and thus move this reaction to the right we need to absorb the protons. A consequence of Le Chatelier’s Principal is that if we remove something (protons) from the right hand side of a chemical equation (which we do by adding a base – a substance that absorbs protons) the reaction will proceed to the right releasing more to make up for the ones we have removed. The converse is also true. If we supply protons (which we do by adding acid – a substance which supplies protons) then the reaction will proceed to the left (notice that the arrows are double headed meaning that the reaction can proceed in either direction) thus absorbing protons and attempting to re establish an equilibrium. For any particular combination of carbonic acid and other acids or bases added to a given volume of water there is one extent to which the reaction moves forward which results in equilibrium. In adding these other acids and bases we are shifting the pH. The ultimate outcome depends on  the pH we set as illustrated in the following graph.

pH a different perspective (AJ deLange) 3

The term ‘carbo’ on the graph is my collective term for the sum of the molar amounts of carbonic acid, bicarbonate ion and carbonate ion. It is the total moles of carbon in those three species.Starting with a given amount of carbonic acid in water (CO2 bubbled through the water volume results in the production of carbonic acid and lowering of the the pH) the red curve shows the fraction of it that remains as carbonic acid as the pH raised by adding base. The blue curve shows the fraction that converts to bicarbonate ion and the green curve the fraction that converts to carbonate ion. Or we could interpret the curves as describing what happens as limestone (CaCO3) dissolves and acid is added moving the pH to the left. Or we could interpret it as telling us what happens if we add sodium bicarbonate to water (the pH goes to 8.3, about 1% of the bicarbonate become carbonic acid and about 1% becomes carbonate ion) as we add either acid or base to shift the pH away from 8.3.

By using the graph, or numbers derived from the same calculations used to prepare the graph, we can write balanced chemical equations covering the situation where, for example, we dissolve a unit of limestone with hydrochloric acid and adjust the pH, by controlling the total amount of hydrochloric acid we add, to a particular desired value. If that value is pH 8.71 the equation look like this

pH a different perspective (AJ deLange) 4

and, if it is pH 7.00 it looks like this:

pH a different perspective (AJ deLange) 5

It should be intuitively pleasing that it takes more acid to reach the lower pH. Readers should also take note that while the total charges on ions are 0 in both cases there is more negative charge on carbo species in the higher pH case than in the lower one (where the remaining charge required for balance is carried by chloride ion).

For brewers limestone dissolved in water is the source of alkalinity and alkalinity is a brewers major water related concern. In nature the dissolution of limestone is aided by carbonic acid which comes from respiring bacteria resident in the soil. The deatails of how this takes place are at the heart of brewing water chemistry but they are intricate if not complex and we have lost many brewers by the wayside in trying to explain them over the years. They are all set out in this paper which was published in Cerevesia in 2004.

The three pH values marked on the graph are, respectively from the left, two common pH values used for the end point titration in alkalinity determination and a typical mash pH. In measuring alkalinity we add acid to a sample of the water in question until the end point pH is reached i.e. until, per the graph, nearly all the carbonate and bicarbonate have been converted to CO2. In adjusting mash water for proper mash pH we do essentially the same thing but don’t go so low in pH.

pH and Protein

We have shown how we can control the charge on acid anions by varying pH. A protein is made up of a chain of amino acids some of which have charged side groups which behave like acids or bases. By varing the pH we can control the extent to which these side groups lose or retain their protons and thus whether they assume negative 0 or positive charge in accordance with the pricipal that higher pH always implies less positive (more negative) charge. pH, therefore, gives us control over the charge distribution over the length of the protein molecule. As like charges repel one another and opposite attract the shape of the molecule depends on the charge distribution and we can, thus, vary the shape of a protein molecule by varying pH. The enzymes upon which we depend for catalysis of the multiple reactions which take place in all phases of the brewing process are simply proteins. Their abilities to act depend on their shapes and thus on the pH of the environment in which they operate. This is why we must have suitable pH in the mash tun and in the fermenter.


pH and temperature are both sensible physical quantities which we can measure:

High pH substances taste bitter. High temperature substances feel warm
Low pH substances taste sour. Low temperatire substances feel cool

pH and temperature are both physical quantities that we can control:

To decrease pH add protons (acid). To increase temperature add energy
To increase pH remove protons (add base). To decrease temperature remove energy.

pH and temperature both have an influence over the conformation (physical shape) of protein molecules. For the enzymes which catalyze brewing reactions to do so most effecively they must be in a particular conformation. We can insure proper conformation by operating the enzyme in an appropriate band of temperature and pH. To make the best beer we must do exactly that.


We brushed over one aspect of pH and its measurement that while not important in day to day pH measurement as described in the page we have dedicated to that subject is significant and that is that we cannot measure the activity coefficient for the hydrogen ion (or any other single ion). This obviously has implications for how we define and measure pH and imposes limitations on its utility where the activity coefficient differs from 1. Thus pH is not, for example, the best measure of the acidity of strong acids where the activity coefficient can be much greater than 1. Nor, not knowing activity precisely, can we really define a scale for pH in terms of the formal definition. What we can do is define a pH scale in terms of the electrical response of standard electrodes to standard solutions and that is exactly what we do. The standard solutions are called ‘buffers’ and when we set up a pH meter we calibrate it so that it reads the pH value that the standard buffer has been declared to have. Thus a particular mix of two phosphate salts is declared to have pH 7.00 at a certain temperature even though, by the formal definition we cited earlier, it might actually have a slightly different value. We don’t care about this in practical application. We seek repeatability and consistency. If a meter is set to read 7.00 whenever its electode is dunked into this standard buffer then samples that read 7.00 all have the same pH. It’s probably worth mentioning that this ‘operational scale’ is thought to be within 0.02 pH of the activity scale over the region of pH with which we are concerned.