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A breWorld Technical Article.Ray Alton (01/03/99)

T I T L E : Water Water Everywhere.....

Beer contains approximately 90% water, and the importance of the liquor to final beer qualitycannot be over-estimated.

Historically a correlation was observed between the liquor composition of an area and the type ofbeer that the region could best brew. The Pale Ales of Burton-on-Trent and Edinburgh, Porters ofLondon, Stouts of Dublin and Lagers of Pilsen are classic examples.

Water falling as rain, hail, sleet or snow is pure, but dissolves gasses such as oxygen and carbondioxide from the atmosphere. On reaching the ground the water runs off into rivers, streams andlakes and on in some cases to reservoirs. The composition of the water in the reservoirs isdependent upon the nature of the catchment area. In areas where the rocks are hard, the water willnot penetrate deeply, and will be 'soft' - that is low in dissolved salts. In areas where the rocks aremore permeable - gypsum or limestone for example - water will penetrate readily and dissolvemany minerals on its way to the reservoirs to become 'hard'.

Figure 1

Soft

Hard

Calcium 10 240

Magnesium 2 50

Bicarbonate 15 250

Sulphate 5 500

Nitrate 5

40

Chloride 5 50

The water supplied by local Water Authorities is required to be potable - that is fit to drink and freefrom pathogenic organisms. In order to reduce microbiological counts chlorine will usually beadded, but the water is not sterile. Fortunately however the micro organisms found in water are not

beer spoilage organisms, being unable to survive the conditions of high ethanol and hop resinlevels and low pH found in beers.

So the objective of liquor treatment is to convert the water sent to us by the Water Authorities intoacceptable brewing liquor. This we achieve by the removal of unwanted ions and addition ofrequired levels of desirable ions.

CalciumOf the ions required for brewing, calcium is by far the most important. This is because of theacidifying effect that calcium has on the wort.

3Ca2+ + 2HPO42- (r) Ca3(PO4)2 ¯ + 2H+

Wort contains large amounts of phosphates derived from the malt, and these have a bufferingeffect - that is they tend to mop up hydrogen ions and keep the pH higher than desired. Calciumions precipitate phosphates as insoluble calcium phosphate and release hydrogen ions into thewort. It is worth mentioning at this point that whilst the pH of the wort is critical, that of the water inthe HLT is not. The pH of water may vary from about pH 5 to pH 8 dependent upon the levels ofdissolved carbon dioxide - even de-ionised water can have pH levels as low as 5 after exposure tothe air. However the carbon dioxide is driven off by heat in the HLT and the pH of the water will



rise.

A combination of the presence of calcium ions and the decrease in pH has a number of effects onthe brewing process:

* The low er pH imp roves ß-amylase activi ty and t hus wor t ferm entabi l i ty and extract.

The optimum pH for ß-amylase activity is about 4·7. Wort produced from liquor containing nocalcium has a pH in the order of 5·8 - 6·0, compared to values in the range of 5·3 - 5·5 for wortsproduced from treated brewing liquor. The activity of the ß-amylase then is greatly enhanced by theaddition of calcium, this enzyme increasing the production of maltose from Amylose, and thusmaking worts more fermentable.

* Calc ium has a benef ic ia l effect on the precip i ta t ion o f wo rt prote ins, both dur ing mashingand dur ing the boi l .

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

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

Proteins are also degraded, that is converted to simpler substances by proteolytic enzymes calledproteases. 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, furtherreducing 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 andencouraging formation of hazes, in particular chill hazes. Product shelf life can also be adverselyaffected.

* Calc ium ions p rotect the enzyme a-amylase from inhib i t ion by heat.

a-amylase is an endo enzyme, cleaving the internal 1,4 glucosidic links of amylopectin resulting in arapid 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 encou raged by Calc ium ions in the mash and cop per helps afford the wortand subs equent beer produced a greater resistance to m icrobio logical infect ion.

* The reduced pH of the sp arge l iquor reduces extractio n of un desirable si l icates, tanninsand 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 pr ecipi tates oxalates as insolu ble calcium o xalate.

This again occurs in both the mash tun and the copper. If oxalates are not removed they can causehazes 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 aproblem to the micro brewer.

* The presence of calc ium reduces co lour form at ion in the copper.

This is due to the reduction of extraction of colour forming compounds such as anthocyanogensand pro-anthocyanidins during the sparge. The reaction

Reducing Sugar + Heat (r) Melanoidins

is also inhibited.

* Calc ium ions improve beer f in ing performance.

Calcium ions encourage yeast flocculation, each divalent positively charged calcium ion attractingnegatively charged yeast cells to form small aggregations.

With all the above advantages of the presence of calcium and reduction in pH there is one minordisadvantage.

* The reduction in p H causes a decrease in hop u ti l isation, giving less bitter beers.

This increases hopping costs, since more hops will be required to achieve a desired level ofbitterness. However the optimum pH for hop isomerisation as used in the commercial production of

isomerised hop extracts is about pH 10, so a reduction from pH 5·8 in a mash with untreated liquorto pH 5·1 out of copper for a treated brew is not too critical.

You will see that much of the calcium added to the mash is lost - precipitated out as phosphate,proteinate or oxalate. Since calcium is specifically required in the copper for further precipitation ofthese materials it is common to add calcium to the grist or Hot Liquor Tank and to then make asecond addition to the copper. Where this is not practical it is quite acceptable to make a largeraddition to the grist or to the H.L.T.

Bicarbonate (Alkalinity)This ion needs to be very closely controlled in order to achieve good beer. High levels of

bicarbonate cause high pH values throughout the brewing process according to the equation:

HCO3- + H+ « H2CO3 (r) CO2 + H2O

HEATIt should be noted that bicarbonate ions are rather more effective at raising wort pH than calcium



ions are at reducing it.

The conversion of bicarbonate to carbonic acid is reversible until heat is applied, which drives offthe carbon dioxide. This effectively removes the acidic hydrogen ion from the system by using it toform a stable water molecule. The wort pH therefore remains high and all the advantages derivedfrom the presence of adequate calcium levels and reduced pH are lost. We therefore see the

following:

* Harsh after-tastes in the fin ished beer

* Extract wil l be red uc ed d ue to low er ß-amyl ase activ ity

* Poor er fermentation due to reduc ed FAN levels.

* Reduced prote in precip i ta t ion due to high pH

* Worts and beer more pron e to infect ion

* Increased extract of un desirable materials in the sparge, notably s i l icates, poly pheno ls andtannins

The net result of this is then to decrease beer stability and shelf life and to increase the likelihood oftroublesome hazes. Colour will be darker, and flavour will be detrimentally affected.

* Hop uti l is ation wil l be increased, giving mo re bitter beers

It is then essential to ensure removal of excess bicarbonate. You will recall from Figure 1 that ahard water may contain 250 mgs/l of bicarbonate. The maximum level that can be tolerated withoutadverse effect for the production of pale ales is 50 mgs/l, and the preferred level would be about 25mgs/l. It should also be noted that whilst additions of calcium may be made to HLT, grist andcopper, the removal of bicarbonate must be achieved in the Hot Liquor Tank. This may be done ina number of ways:

Deionsiation: Very effective, but high capital and revenue costs.

Lime treatment: Addition of carefully controlled amounts of lime (calcium hydroxide) to the HLT willprecipitate the bicarbonate as calcium carbonate. There are 2 major drawbacks:

1. The amount added needs to be exactly calculated and over addition may result in an overallincrease in alkalinity.2. The precipitated calcium carbonate can form a sludge on the bottom of the HLT that will needperiodic cleaning.

Boi l ing: This again is a traditional method of removal of bicarbonate (Temporary Hardness) butagain has 2 drawbacks:

1. Very expensive.2. Only effective where the alkalinity is present as bicarbonate. If the levels of sodium, potassium ormagnesium carbonates or hydroxides present are significant boiling will not be effective.

Acid Treatment : Now the most widely used method, for a number of reasons:



1. Relatively inexpensive.2. Easy to use and does not produce sludge in the HLT3. May add desirable anions - sulphate or chloride.4. Can use phosphoric or lactic acids if no anions are wanted - eg for lagers

It is essential to rouse the liquor when acid treating in order to encourage the removal of the carbon

dioxide. This can have corrosive effects on the materials of construction of HLT's if left in solution.

MagnesiumMagnesium is an essential element of brewing liquor because it is required by yeast as a co-factorfor the production of certain enzymes required for the fermentation process. It is invariablyformulated into liquor treatments at relatively low levels. However caution must be exercised for 3reasons:

1. Excess magnesium can interfere with the reactions of calcium because its phosphates are moresoluble2. Above about 20 mgs/l magnesium can give beer a sour and bitter taste

3. In excess magnesium has a laxative effect

SodiumSodium is present in all beers. Excessive levels are undesirable as it imparts a sour and salty tasteat high concentrations. The flavour is more acceptable when the sodium is present as chloride thanas sulphate.

PotassiumPotassium is, like magnesium, a yeast co-factor and is required at trace levels for satisfactoryfermentations. It is more acceptable than sodium from a flavour point of view, giving a salty taste

without the sour notes. It is also gaining some favour as Doctors warn of the effects of high sodiumintake on blood pressure. However potassium salts are very much more expensive than the sodiumequivalents, and in excess potassium has laxative effects.

Sulphate and ChlorideIt is convenient to discuss the effect of these two ions together. Much is made in brewing literatureof the impact of these ions on beer flavour characteristics - sulphate gives beer a drier, more bitterflavour, whilst chloride imparts palate fullness and to an extent sweetness. However what must benoted is that it is the ratio of the concentrations of these two ions that is significant, rather thansimply the actual concentrations. A ratio of about 2:1 sulphate to chloride is about right for a bitterbeer, and it makes little difference if the actual values are 500:250 or 350:175 mgs/l. As will beseen in Figure 3 ratios of 1:2 sulphate:chloride are recommended for mild ales, whilst a ratio of 1:3may give best results for stouts or porters.

Sulphur is essential for the fermentation process, since the yeast needs to manufacture the twosulphur containing amino acids, cysteine and methionine. Some yeast strains will use sulphur fromsulphate ions for this purpose and will then excrete any excess as sulphite ions. These can then bereduced to form hydrogen sulphide or sulphur dioxide. Both of these materials have characteristicpungent odours and even at low levels can give unacceptable sulphury noses to the beer.



Bacteria also have the ability to produce a wide variety of sulphury off flavours, including rubber,garlic and cooked vegetable.

NitrateLevels of Nitrate are beginning to drop generally due to greater control of the use of nitrogenousfertilisers. Nitrates themselves are not a problem at levels below 50 mgs/l, however they can bereduced by yeast or bacteria to form Nitrites. These ions can then react with wort amines to formNitrosamines, which are carcinogenic.

Trace ionsMetals such as Iron, Manganese, Copper and Zinc may be found in small quantities in water andare all utilised by yeast at levels below 1 ppm. Higher levels can cause colloidal hazes and metallicoff flavours, particularly with higher levels of Iron. High levels of heavy metals can be toxic to theyeast.

Silica should also be at very low levels in brewing liquor because of the likelihood of colloidal hazes

being formed.

Ammonia should be absent in brewing liquors, being indicative of contamination by sewage.

Fluorine, present in most waters at about 1 ppm for dental purposes, has no detectable effect onthe brewing process. However Chlorine, used for sterilisation, may be at relatively high levels atcertain times of the year. This can cause problems since chlorine is a very reactive chemical andwill readily react with organics to form chlorophenols. These have a medicinal (T.C.P.) flavourwhich is in some cases detectable at levels below 1 ppb. Chlorine will be lost to some degree bythe heat in the Hot Liquor Tank, but not all water used within the brewery is from that source. Somebrewers may use untreated liquor to break down to gravity in fermenter, and rinsing followingcaustic or acid cleaning cycles will typically be with untreated mains liquor. One solution is to treatboth Hot and Cold Liquor Tanks with 10 ppm of Salicon Liquid 18% (20 mls in 10 brls liquor) androuse vigorously to remove the chlorine.

Cl2 + SO2 + 2H2O (r) H2SO4 + 2HCl (r) NaCl, KCl, CaCl2, Na2SO4,CaSO4, K2SO4

Typical Liquor Analyses for Beer Types:

BITTER MILD PORTER/ LAGER STOUT

Calcium 200 100 100 50

Magnesium 15 10 10 2



Bicarbonate 25 50 100 <25

Chloride 200 300 300 10

Sulphate 400 150 100 10

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