Revision as of 05:07, 19 February 2011

This is the 3rd and last article in a series of articles intended to educate the interested brewer about pH in brewing. Part 1, An Overview of pH, showed the basic principles behind pH and how it can be measured, part 2, How pH affects brewing, illustrated the effects pH has on various brewing processes and which pH ranges are considered optimal. This article will be the most practical. It shows how malt and water settle at a pH and how this pH can be affected through changes in water composition, malt bill and mash additions. For the interested brewer, it also goes behind the scenes and explains the chemical processes that are at work. A number of water treatment and brewing water building options are explained; starting with the basic and ending with more sophisticated ones.

Water, malt and mash pH

Water and malt are both pH buffers, that means they have their own pH and a desire to resist pH changes. When they are brought together at dough-in, they will settle at a pH which will be the mash pH. Which pH they'll settle at depends on how strong either of the components (water and malt) pull the pH to their respective sides. In this "tug of war" malt is the acidic one, it wants to lower the pH, and water tends to be the alkaline component, it wants to raise the pH.

As we have seen in Enzymatic Activity the mash pH range that works for brewing is fairly wide. 5.0 – 6.0 will work with most enzymatically strong malts and 5.3-5.5 is considered optimal. This wide range of possible mash pH values is the reason why most brewers don't have to worry about mash pH and water chemistry at the beginning of their home brewing career. As we will see later, average water and grist compositions generally found in (home) brewing are likely to result in a mash pH in that range. Only at the extremes will brewers experience problems in mash conversion and off flavors that arise from incorrect mash pH levels and spark the brewer's interest in that rather technical topic.

But even if you don't experience off flavors or mash problems from incorrect mash pH, there is likely a point in your brewing career where the beers are good and very enjoyable but you want to take them to excellent. Controlling your mash pH and moving it into a more optimal range has the potential to do that for you. The effects that pH has in brewing were elaborated in How pH affects brewing and they start with a proper mash pH.

Figure 1 - balancing malt and water in its simplest form is like balancing a scale

A correct mash pH is all about matching the right water with the right grist and possibly the addition of some acid. Since we brewers generally start with a style of beer or recipe in mind, the grist composition is known and we want to know what kind of water modifications are need to get the desired mash pH. In a way this is like balancing a scale (Figure 1). On the left is the malt and on the right is the water. But we are not interested in their actual weight. Instead we want to know how acidic is the malt is and how alkaline is the water.

To determine how acidic malt is, I ran a few experiments were I tested the distilled water mash pH of base malts and the acidity of various specialty malts. And what I found was that darker malts are generally more acidic that lighter colored malts. While there were a few exceptions to that rule, which we will examine later, we will work with that for now: The darker malts in the grain bill, the more acidic the grist is.

That acidity of the malt is counteracted by the alkalinity of the water. Water alkalinity measures the waters ability to neutralize acids and thus resist a change in pH. In fact, it is measured by adding a strong acid to a sample of water until it reaches a pH of 4.3 [deLange]. The amount of acid needed determines how alkaline the water is. The more acid that is needed, the more alkaline the water is.

When grist and water are mixed the alkalinity of the water will neutralize some of the malt’s acidity. Neutralization happens when an acid and a base are brought together. The result is a salt and water and a pH that lies between the pH of the acid and the pH of the base. The acidity of the grist is best thought of as its mash pH with distilled water. Alkalinity present in the water or from the addition of alkaline salts pulls that pH higher (more alkaline) while the addition of acid, calcium or magnesium lowers that pH (more acidic).

If, for example, the grist has low acidity because it contains only lightly colored malts and the water has a lot of alkalinity, the mash pH will be higher than desired. If the opposite is true, lots of malt acidity from dark grains and low alkalinity water, the mash pH will be lower than desired. If malt acidity and water alkalinity are balanced, the pH will be in the desired range.

Mash as a pH buffer

Grist, water, acid and salt interactions within the mash are best thought of as the addition of acids or bases to a strong buffer which is largely formed by phosphates, proteins and amino acids present in the malt. Dealing with a buffered system means that the amount of acid or base needed to change the pH depends on the amount of buffer (in this case weight of the grist) and the desired pH change. The amount of acid it takes to lower or raise the mash pH of 1 kg of grist by 0.1 pH units is about 3-5 mEq. A simple Model for pH Buffers shows how we can model pH buffers as differently shaped vertical tubes.

Table 1 - Examples for 1 mEq worth of acid and base. A pH of ~5.5 is assumed

mEq (milliequivelent) or Eq (1 mEq = 0.001 Eq) is a unit commonly used to express the amount of acid or bases. Rather than giving the specific amount of acid or base needed it specifies the number of hydrogen ions that are added (acid) or absorbed (base). To convert Eq to actual amount of acid its molar weight, number of hydrogen ions donates/aborbed and concentration needed to be known. Lactic acid for example has a molar weight of 90 g/mol. Above a pH of 5 almost all its molecules donate 1 hydrogen ion. This means 90g pure lactic acid contribute about 1 Eq acid. The lactic acid we commonly use has a concentration of 88% by weight and 1 Eq of that weighs 102 g. Most commonly we work with mEq which is 1/1000 of that.

Calcium carbonate (chalk), on the other hand, has a molar weight of 100 g/mol but can absorb 2 hydrogen ions. To get 1 Eq worth of acid neutralizing power 50g chalk are needed. In brewing that neutralizing power will be lower due to the acidifying effect of the calcium when it reacts with the malt’s phosphates. But more about this later.

Table 1 on the right shows the amounts of a few acids and bases that provide 1 mEq of neutralizing power.

The buffer capacity of the malt, which affects the amount of acid or base needed to change the mash pH, does to some extend depend on the malting process as well as the mashing process. This may lead to differences how the mash responds to pH correction efforts and makes exact mash pH predictions difficult.

Factors that affect mash pH

The following is a more detailed discussion of what affects mash pH in brewing.

Grist

Figure 2 - the mash pH of mashes with various base when mashed with mineral free (i.e. distilled water)

Figure 3 - The titratable acidity of various specialty malts plotted over their color. The sample mashed made from these malts were titrated to a pH of 5.7

Very lightly kilned malts have a natural pH between 5.7 and 5.8. This tends to be even higher for wheat malts. Once malts are kilned more strongly to produce darker base malts the distilled water pH drops because of the formation of acidic melanoidens. This is shown in Figure 2 which plots the color and distilled water mash pH for a number of different base malt samples. There is a loose correlation between malt color and mash pH: "The darker the malt the lower the mash pH".

Specialty malts like crystal and roasted malts are kilned to even darker colors than base malts. While they may constitute a much smaller portion of the grist they can contribute a large portion of the grist’s color and with it acidity. The latter lowers the grist pH beyond the pH of its base malts.

The acidity of various specialty malts is plotted over their color in Figure 3. While crystal type malts fairly strongly adhere to the "the darker the more acidic" rule the tested roasted malts showed a constant acidity regardless of their color. This is s result of differences in the production process between crystal and roasted malts. The color of crystal malts is created while the malt is still wet which allows for the creation of more acidic compounds while the color of roasted malts is created after they have already been dried. Though that creates a stronger color it creates less acidity. (Troester 2010)

For us brewers this means that grist containing large amounts of roasted malts are likely less acidic than grists containing large amounts of dark crystal malts even though the resulting beers might be darker in color.

Water minerals

The minerals listed here may either come from your base water, from salts added to your water before dough-in or salts added to the mash. Experiments have shown that there is no significant difference between these sources of minerals.

What makes a difference though, is the amount of minerals that are brought into the mash. This amount depends on both mash thickness (how much water per unit of grain) and the mineral concentration in the water. In other words, water in a thin mash will be able to have a more effect that water in a thick mash since in the latter case there will be less water, and with it less minerals, per grain compared to thin mashes.

This being said, brewers should not think that thick mashes provide a piratical means of dealing with high alkalinity water, for example, since the alkalinity won’t be able to move the mash pH as much. Any water that is not used in the mash is used during the sparge where it is able to adversely affect the pH in both the grain bed and boil kettle.

Alkalinity

Alkalinity is the water’s ability to neutralize acids. This the ions involved with that neutralization are the bicarbonate and carbonate ions. When brought in contact with the more acidc malt these ions absorb hydrogen ions which raises the pH. The extent to which the pH rises depends on the amount of malt, amount of water and the bicarbonate and carbonate concentration in that water. The latter is also expressed as the water’s alkalinity. The more bicarbonate and carbonate ions there are per unit of malt the more the pH will rise. When bicarbonate or carbonate neutralized an acid it forms carbon dioxide. While bicarbonate is able to neutralize one acid molecule carbonate can neutralize two:

H⁺ + HCO₃^- -> H₂O + CO₂ 2 H⁺ + CO_{3<.sub>^2- -> H2O + CO2}

Due to the poor solubility of calcium carbonate and the presence of atmospheric CO2, appreciable amounts of carbonate are rarely found in brewing water.

Calcium and Magnesium

Brewing water also contains calcium and magnesium ions. These ions are able to react with phosphates from the malt to form insoluble phosphate salts which precipitate. At mash pH values between 5 and 6 most of the phosphate is available as ?? HPO₄^2-. The reaction with calcium liberates hydrogen ions which react acidic and lower the pH of the mash [Narziss&Back]:

3Ca²⁺ + 2 HPO₄^2- -> 3 Ca₃(PO₄)₂ /down + 2 H⁺

Magnesium shows a similar reaction with phosphates. Malt contains about 1 % of phosphate by weight [deLange]. About 80% of than end up in the wort. This amount is far greater than the calcium or magnesium that is brought in with the brewing liquor which makes these ions the limiting factor.

As early as 1914 did the German brewing scientist Windish show that water ions have an effect on the mash pH. Kolbach, another German brewing scientist, later showed that it takes about 1.75 calcium ions and twice as many magnesium ions to produce one hydrogen ion. (1.75 calcium ions equal 3.5 calcium equivalents)

My own research on this subject reported slightly lower numbers: 1.3-1.5 Calcium ions and 2.4-2.8 magnesium ions [Troester]. It should be noted that Kolbachs work was primarily targeted at the final wort pH and not so much the mash pH. There is however a close correlation between the two.

Residual Alkalinity

The acidic reaction of calcium and magnesium counteracts the alkaline reaction of the water’s alkalinity, which prompted Kolbach to define the residual alkalinity as the alkalinity that remains after the calcium and magnesium reactions have been considered. Based on his work the following formula for residual alkalinity RA has been established in the brewing world:

Where:

• RA: residual alkalinity given as an equivalent measure (mEq/l, ppm as CaCO₃, dH)
• A: alkalinity given in the same equivalent measure
• CH: calcium hardness of the water, which is the calcium ion concentration given in an equivalent measure
• MH: magnesium hardness of the water

The residual alkalinity of the water allows brewers to estimate a water’s effect on the mash pH. If only alkalinity and general hardness (GH) are given the residual alkalinity can be estimated as:

This makes the assumption that about 30% of the water hardness comes from magnesium and the remaining 70% come from calcium, which is the average split between calcium and magnesium hardness (see Estimating Residual Alkalinity

Water with a residual alkalinity of 0 gives about the same mash pH as distilled water while water with a RA greater than 0 yields a higher mash pH. If the water’s alkalinity is low but its calcium and magnesium levels are high the residual alkalinity can also be less than 0. In this case the use of that water will yield a lower mash pH

Acids

Other factors

Malt color and grist acidity

Strategies for affecting mash pH

When the expected or tested mash pH is outside the desired range of 5.3-5.5 the brewer may choose to change that pH. This can be done by:

• changing the grist
• changing the water
• designing water from scratch
• addition of acids or salts to the mash

Changing the grist

There was a time when brewers didn't know about water chemistry. They used the local water that was available and noticed that some beers turned out better than others. This led to the development of local beer styles. But these days we brewers don't want our water to dictate what beer styles we should brew. As a result changing the grist is rarely seen as a viable option.

The only case where a grist change is appropriate is the use of acidulated malt or Sauermalz. Acidulated malt is Pilsner malt that has been sprayed with lactic acid before it is dried again. The final lactic acid content of this malt is about 3% by weight. Each % of acidulated malt in the grist lowers the mash pH by ~0.1 pH units. More than 4-5% should not be used in order to prevent excessive lactic acid amounts that may be noticeable in the final beer taste.

The use of Sauermalz is an elegant way of complying with the German purity law (Reinheitsgebot) since this lactic acid has been produced by lactic acid bacteria that are naturally occurring on the surface of the malt.

More info about the use of lactic acid can be found later in Adding acids

Changing the water

Before the water can be changed we need to know more about the mineral content of the water. How to read a water report explains in detail the various minerals that can be found in drinking water. It also explains what to look for in a water report.

When the water is changed to correct the mash pH it’s residual alkalinity is changed to match the needs of the grist composition used in the recipe. The desired residual alkalinity range can be estimated from the beer’s color. The darker the beer the more residual alkalinity will be needed to counteract the acidity of the grist.

The residual alkalinity’s effect on pH also depends on mash thickness. The thinner the mash the more pronounced the effect of the water’s alkalinity will be. At a mash thickness of 2 l/kg (0.95 qt/lb) it takes a residual alkalinity change of about 130 ppm as CaCO₃ (2.6 mEq/l) to change the mash pH by 0.1 pH units while it takes a RA change of just 75 ppm as CaCO₃ (1.5 mEq/l) to achieve the same pH change at a mash thickness of 4 l/kg (1.9 qt/lb).

Raising the residual alkalinity (raises mash pH)

If the water’s residual alkalinity is too low the addition of alkaline salts like calcium carbonate (chalk, CaCO₃) or sodium bicarbonate (baking soda, NaHCO₃) or even strong bases like calcium hydroxide (Ca(OH)₂) raises its residual alkalinity. If calcium carbonate is used it will not dissolve in the water unless CO₂ is added. Though there are ways to dissolve CO2 many brewers simply add it to the brewing water without dissolving it. In experiments I found that dissolved chalk is not only twice as effective in raising the water’s residual alkalinity, undissolved chalk is also not able to raise the mash pH by more than 0.2 pH units. In other words the addition of more than 500 mg/l undissolved calcium carbonate, which is equivalent to a residual alkalinity of about 200 ppm as CaCO₃, has little or no effect on mash pH [Troester, 2010]. As shown in grist color and pH water with a residual alkalinity of more than 200 ppm as CaCO₃ is rarely needed, even for the darkest beers. In contrast, baking soda does not show this behavior. It also doesn’t add calcium ions which counteract part of the acid neutralizing power of the added carbonate. The drawbacks of adding baking soda is the increase of the water’s sodium content and the lack of calcium which has a number of positive effects on beer quality.

Another substance that can be used to increase the alkalinity of the brewing water and thus raise the mash pH is calcium hydroxide (pickling lime, slaked lime, CaOH). It dissolves in water and doesn't show the limits that undissolved chalk has while it also adds calcium to the mash. The only drawback is that it is a caustic substance and needs to be handled with care.

Lowering the residual alkalinity (lowers mash pH)

In most cases the residual alkalinity of the water is too high for the desired beer color which causes the mash pH to be too high. In this case the water’s residual alkalinity needs to be reduced. For that we brewers have a number of options:

• dilution
• addition of calcium
• addition of acids to neutralize all or part of the bicarbonates
• alkalinity removal through boiling or slaked lime additions.

Dilution

The idea of dilution is simple: reduce the bicarbonate concentration, and with it the alkalinity, by mixing the water with water that contains only little bicarbonate. The water generally used for dilution is distilled or very low mineral water like reverse osmosis water. When using such water for dilution the residual alkalinity of the diluted water is

RA_{diluted water} = RA_{undiluted water} * r / 100

Where:

• RA_{diluted water}: the resulting residual alkalinity
• RA_{undiluted water}: the starting residual alkalinity
• r : the percentage of undiluted water used.

Since dilution with low mineral water lowers the concentration of all minerals it may be necessary to supplement the resulting water with calcium ions to get their concentration back into the desired range of 50-100 ppm. This should be done with calcium chloride or calcium sulfate (gypsum) in order to avoid adding bicarbonate which would negate the alkalinity lowering effect of dilution. The added benefit of supplementing calcium is an additional residual alkalinity reduction through the acidic reaction between calcium and malt phosphates.

Adding Calcium

As already discussed in #Calcium and Magnesium calcium and Magnesium are able to lower the mash pH trough a reaction with phosphates brought in by the malt. This is of particular interest for beet styles that benefit from water with high permanent hardness. In permanently hard water the anions balancing the calcium and magnesium ??cations?? are chloride and sulfate which have no effect on the mash pH. This is not true for temporary hard waters where the balancing anion is bicarbonate.

Examples for these styles of beer are English Ales and Dortmunder Export. A mash water content of 150 mg/l can yield a mash pH drop of 0.1 – 0.2 pH units depending on the mash thickness.

Due to its lower effectiveness with respect to changing the mash pH and its lower desired concentration in brewing water, magnesium salts are generally not uses to affect mash pH in any meaningful way.

====Adding acids====

The water’s bicarbonate content, and with it the alkalinity and residual alkalinity, can also be lowered or completely removed through the addition of organic or inorganic acids. The hydrogen ions released from these acids react with the bicarbonate to form carbon dioxide and water:

H⁺ + HCO₃^- -> H₂O + CO₂

When acids are used to reduce the alkalinity bicarbonate is replaced with the anion provided by the acid. As a result, excessive use of acids, which may seem necessary with very alkaline waters, can lead to an excess of these ions and affect the taste adversely. To prevent this water alkalinity may first need to be reduced with means that lower the water’s mineral contents like dilution and alkalinity precipitation, for example.

While many acids can be used to accomplish this task only a few have found practical use for water treatment in brewing. Those acids are:

• Lactic acid: This is an organic acid produced by lactic acid bacteria. To brewers it is available as a 88% by weight solution or acidulated malt. Acidulated malt is pilsner malt that has been sprayed with lactic acid and dried. It contains about 3% lactic acid by weight. Lactic acid may also come from a sour mash or sour fermentation. The latter or acidulated malt is the only acid that can be used for mash and wort pH adjustment in Germany. Narziss reports that the use of lactic acid yields in a smoother beer taste compared to the use of organic acids like hydrochloric acid [source ??]. The anions left behind by lactic acid are lactates which can give the beer a sour twang if used in excess. In my own beers I have used as much as 0.25 g lactic acid per liter of beer which amounts to about 4% acidulated malt without adverse taste effects.
• Hydrochloric acid (a.k.a muriatic acid): This strong inorganic acid replaces the bicarbonate with chloride and when used in excess can give the beer a salty taste. The muriatic acid found in hardware and pool supply stores is not necessarily food grade and should be avoided. If food grade hydrochloric acid is available it can be used for water treatment but great care should be taken when handling it. Unlike lactic acid, hydrochloric acid is a strongly caustic acid that readily reacts with almost anything it comes in contact with, including your skin and eyes.
• Sulfuric acid: This strong inorganic acid replaces bicarbonate with sulfate and would therefore be a good choice for hoppier beer styles. It is however even more aggressive and dangerous to handle than hydrochloric acid which is why it is rarely used by home brewers.
• Phosphoric acid is an inorganic weak acid that is much saver to handle and widely used in soft drinks. It replaces bicarbonate with phosphate and therefore increases the phosphate content of the mash. The amount of phosphate added, however, is small compared to the phosphate added by the malt and therefore the use of phosphoric acid should not lead to the precipitation of additional calcium and magnesium.

[Image:Acid_and_alkalinity.gif|frame|right|Table ? – The amount of acid it takes to lower the water’s alkalinity, and with it the residual alkalinity, by 100 ppm as CaCO₃]

In order to get the mash pH within the desired 5.3-5.6 range when brewing very pale beers, Pilsners for example, it is generally necessary to use an acid regardless how low the residual alkalinity of the brewing water is. This is because even calcium contents on the high end (150 ppm) and an alkalinity of 0 yields a residual alkalinity of only -70 ppm as CaCO₃. This residual alkalinity can only lower the mash pH by ~0.2 units when a 4 l/kg (2 qt/lb) mash thickness is used and even less for thicker mashes. With a distilled water mash pH for pilsner malt that tends to be between 5.7 and 5.8 the resulting mash pH would be in the 5.5 to 5.6 range.

Precipitation of calcium carbonate

Since the addition of acid does not change the total amount of minerals it may not be suited for the treatment of waters that contain too many minerals. One method that does this is the precipitation of calcium carbonate through either boiling or the addition of slaked lime. The calcium, and to some extent magnesium, and alkalinity removed through these methods is called temporary hardness. Temporary hardness is the calcium and magnesium ions that can be matched up with bicarbonate ions from the water. The remaining calcium and magnesium only has sulfate and chloride to pair up with and is called permanent hardness.

When water is boiled CO₂ escapes. This raises the water pH and leads to the creation of more carbonate from the existing bicarbonate. In the presence of calcium the carbonate forms calcium carbonate (a.k.a chalk, CaCO₃) which is poorly soluble and forms a white precipitate which settles out.

Ca²⁺ + 2HCO₃^- -> CaCO₃ /down + H₂O + CO₂ /up

<insert text about the limits that can be reached and how the drop in alkalinity can be estimated>

Since the process removes both alkalinity and calcium from the water it may be necessary to supplement the water with calcium salts like gypsum (calcium sulfate) or calcium chloride, which is best done before the water is boiled to increase the efficiency of the alkalinity precipitation. In addition to that the addition of a small amount of chalk facilitates this precipitation by providing nucleation sites for the precipitating chalk [deLange]. If you have water with a high temporary hardness (lots of bicarbonate calcium and magnesium) you may have already noticed this precipitation when you cook with your water.

While the aforementioned process is simple, the need to boil the water represents a great deal of wasted energy. The excess CO₂ can also be removed from the water through intensive aeration but that process takes a long time. In fact, surface water tends to have low temporary hardness because due to the lower CO₂ content in air the water’s CO₂ content is much lower than that possible in ground water and as a result this water cannot hold onto as much chalk as ground water.

A more practical approach that is used by many breweries is water treatment with slaked lime. The slaked lime is able to absorb both the water’s CO<sub<2 and raise the water pH to transform the bicarbonate into carbonate:

Ca²⁺ + Ca(OH)₂ + 2HCO₃^- -> 2CaCO₃ + H₂O

How to conduct this water treatment and calculate the amount of lime needed has been described in detail in Alkalinity precipitation with slaked lime and will not be discussed further.

Both boiling and slaked lime treatment will only remove bicarbonate and calcium (to some extend magnesium as well) but cannot remove sodium, chloride or sulfate. Those minerals do not affect pH but if a lower concentration is desired the only practical method the home brewer has for their removal is dilution with low mineral water or building brewing water from scratch.

Building brewing water from scratch

Using low mineral water like distilled or reverse osmosis water and adding back measured amounts of various salts is becoming increasingly popular among home brewers. One of the likely reasons is that reverse osmosis units have become reasonably affordable. Another is that this process provides ultimate control over the brewing water composition. However, it is not as economical for larger brewers since the production of 1 liter of reverse osmosis water may require as much as 6 liters raw water though the efficiency of these units largely depends on the mineral content of the raw water and the design of the unit.

When building water from scratch brewers should have the following salts on hand:

• gypsum (calcium sulfate)
• Epsom salts (magnesium sulfate)
• calcium chloride
• chalk (calcium carbonate)
• baking soda (sodium bicarbonate)

A digital scale for precisely measuring grams of salts is also very helpful. I have had very good success with jewelry scales (100-200g capacity, 0.01g resolution) that can be found on e-bay for ~$20.

One interesting aspect with respect to adding salts to build brewing water is the treatment of calcium carbonate. This salt is fairly insoluble when simply added to water, but it can be dissolved with the addition of CO₂. (Building water with dissolved chalk shows how. Interestingly enough it makes a difference if the chalk is simply suspended or actually dissolved. When dissolved only half the amount of chalk compared to suspended chalk is needed to achieve the same change in mash pH [Troester]. Despite the more predictable pH behavior of dissolved chalk most brewers do not dissolve the chalk in the brewing water.

Water modification spreadsheet

Calculating and predicting the results of water modification can be complicated due to the chemistry involved. To simplify these calculations a water calculation spread sheet has been developed. This spreadsheet supports:

• the use if simple GH&KH water analysis results
• mixing and dilution of water
• addition of salts for water treatment including dissolved chalk
• addition of slaked lime raising mash pH
• addition of lactic acid, acidulated malt and phosphoric acid
• slaked lime treatment
• beer color based mash pH prediction

Designing brewing water and mash additions

Salt and acid additions to the mash

The mash pH and later the wort pH can also be adjusted on the fly. This is done after the pH has been tested and found to be too high or too low by adding either salts or acids to bring the pH back into range.

Since the malt is the dominating pH buffer the calculation of the necessary acid or salts are best based on the grist weight while the mash thickness (i.e. the amount of mash water used) matters little.

The salts and acids that can be added to the water can also be added to the mash. If salts are added only to the mash their effective concentration in the beer will be lower since the additional water brought in during sparging will dilute the mineral concentrations in the kettle.

While it is practical to threat the water and the grist such that they achieve the desired mash pH, many brewers find it easier to measure the pH of a mash sample 5-10 min after dough-in and base the addition of salts and acids based on how far away this pH is from the target pH. This works particularly well for brewers who rarely repeat recuipes and thus have less historical data that could be used to estimate the necessary water and mash treatments.

While there doesn’t appear to be any difference between treating the water and treating the mash with respect to the pH that the mash will settle at, there can be a slight difference in expression of enzymatic activity. In particular in single infusion mashing the bulk of the fermentable sugars is created by beta-amylase early during the mash before large amounts of that enzyme fall victim to the mash temparture. This enzyme has a pH optimium between ??-?? and if the pH is sufficiently far off this optimium during the first 10-20 min the amount of fermentable sugars produced and with it the fermentablility of the created wort may suffer.