Brewing pH

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The pH value is of major importance for the brewer since it has a great impact on many processes during brewing. For example, the pH can have a significant impact on the performance of enzymes during mashing and therefore the quality of the final product.

The pH of the brewing water does not matter. Rather, it's the minerals dissolved in the water that are significant because of their influence on pH of the mash, the boil, the fermentation, and ultimately the packaged beer. Controlling pH at those points in the process is what matters.

The pH changes based on the temperature. However, pH measurements should always be taken at room temperature and expressed as such. This is easier on the measurement device, and it is the standard in technical documents.

There are broadly two schools of thought when it comes to salts. UK brewers tend to think that adding principally calcium salts to achieve a spectrum of ions in the water and hence beer is the best way to control water, mash, wort and beer pH and affect the palate of the beer. European brewers tend to control mash pH through acidification either through acidulated malt or biological/mineral acidification.

It is claimed that at lower pHs there is a slight stimulation of limit dextrinase activity. Conversely, the activity of lipoxygenase is less at lower pHs and this may be to the advantage of flavor stability and foam stability of the finished beer. Furthermore, the pH value also influences the solubility of hop components and the color of mash and wort. If the pH value during wort boiling is too high, break formation will be insufficient, resulting in a decreased colloidal stability.

The influences of the concentration of H+ ions on beer flavor are usually considered as the impact of pH on the production of flavor components, which can, of course, be considerable,21,22 and the effect of various ions on pH control is discussed later in the Section 4.5.5.5. However, H+ ions can also exert direct flavor effects.21

• At pH values below 4.0 (or 0.1 mg/L H+ ions), beers tend to taste sharper and acidic, with an increased drying after-palate and a tendency for perceived bitterness to be enhanced.
• At lower pH (3.7 and below, or 0.2 mg/L H+ and above), these effects rapidly increase in intensity, with markedly enhanced metallic after-palates.
• Above pH 4.0, the palate effects relate to increased mouth-coating, with enhanced scores for biscuit and toasted characters.
• At pH 4.4 and above (or 0.04 mg/L or 40 µg/L H+ ions and below), the mouth-coating effects become increasingly more accentuated, with soapy, and even caustic, characters developing.

It should be noted that in the case of organic acids, their flavor contributions are not restricted merely to acting as suppliers of H+ ions in order to produce the characteristic sourness, but the structural features of these molecules also determine their flavor threshold.22 For example, organic acids such as acetic, lactic, and citric have very different flavor characteristics, but all contribute to perceived acidic and sour flavors. These effects can be very important in classical acidic beers, such as "Gueuze" and "Lambic" beers.

in many ways, pH control throughout the brewing process (from mashing-in to final packaging) is fundamental to achieving end product consistency. The maintenance of control of pH during wort production, fermentation, and conditioning is of great importance to beer quality by ensuring reproducible conditions for the numerous enzymic and chemical reactions occurring during these key beer production stages. In addition, finished beer pH impacts beer flavor as well as physical and microbiological stability.21,22

During mashing, the pH decreases due to malt enzymes activity, which releases phosphates from nucleic acids. In the process of wort boiling, the wort acidity is increased by precipitation of phosphates in the presence of calcium and magnesium ions. Hop bitter acids and Maillard reaction products further contribute to pH reduction. When fermenting, the pH declines by the activity of yeasts that consume amino acids and produce organic acids. The pH also changes because of presence of the carbon dioxide, which dissolves in the solution (Basařová et al., 2010).

A residual alkalinity of zero means that there is no pH influence. A positive residual alkalinity will lead to an increased pH, and a negative residual alkalinity will decrease the pH.

pH Meters

Modern pH meters usually have a feature called Automatic Temperature Correction (ATC). This feature helps maintain calibration of the probe away from the calibration temperature. However, it does not correct for the chemical pH change that occurs with fluctuating temperature.

See pH testing

Mash pH

The key point for control of pH throughout the brewing process is during mashing.

most authors agree that there is considerable merit in maintaining mash pH in the range 5.0 to 5.5. This is especially the case with regard to the pH optima of the malt enzymes involved (i.e., 5.3 to 5.6 for α-amylase; 5.4 to 5.7 for β-amylase; 4.2 to 5.0 for proteolytic enzymes). In addition, many authors suggest that this pH control is best achieved by maintaining a low alkalinity (bicarbonate content) in brewing liquor (at least less than 50 mg/L; ideally less than 20 mg/L), plus sufficient Ca2+ to achieve the desired pH level (not less than 100 mg/L).

Because of its influence on the structure of the catalyst molecules, the hydrogen ion concentration is almost as important as the temperature. It is affected by the quality of the brewing liquor, additions of acid and the mash concentration.

Mash pH outside the normal range will result is full, one-dimesional malt flavors, and may reduce fermentability. Increased tannins and silicates may be extracted at high pH.

Today in many cases artificial acidification by addition of lactic acid or mineral acid (mostly phosphoric acid) is used to adjust the pH. The calcium content during mashing and sparging can be influenced by dosing with calcium chloride and/or calcium sulphate.

It is advantageous to control the pH value to within 5.4-5.5 when mashing.

keeping the pH low, e.g., to 5.5, improves beer flavour and stability.

In order for the mash enzymes to work properly, a pH of 5.2-5.4 is optimal.

The mash pH value is essential for enzymatic activity and thus for maximum extract recovery. Lowering the mash pH to 5.4 to 5.6 leads to higher attenuation limits, reduction of viscosity, rapid lautering, and less increase in wort color during boiling.

Mashing-in above gelatinization temperature and at a lowered pH of 5.2 (measured at mash temperature) not only allows for a shortened mashing program, but also has an important, positive impact on final beer flavor stability.

pH control favors proper enzyme activity, especially preventing it from being overly basic. For example pH 5.8 at 60°C reduces amylase activity to 85%, and too 65% at pH 6.2 at 60°C. High pH also results in dull and poorly defined malt flavors.

Mash acidification can be very advantageous, one benefit being that it renders softer, more satisfyingly full-bodied beers with a pleasingly rounded character.

Lower-modified malts benefit from lower mash pH to optimize proteolysis, and therefore improve total extract and FAN.

The pH of 150°F wort is known to be about 0.3 lower than the same wort measured at room temperature.

Time is an important factor for pH change in the mash.

"The target mash pH range should probably be 5.2-5.6".

Not only should a fresh beer have a pleasant taste, it should also keep its original flavour and freshness in spite of the treatment with stabilising agents. According to Aerts et al [3] a combination of pH 5.2 and a temperature of 63 °C at mashing-in results in a prolonged flavour stability and physical stability of the beer.

Base malt is generally alkaline, and speciality malt is generally acidic.

Mash pH can be lowered by any of the following methods, or a combination thereof:

• Adding non-alkaline calcium or magnesium salts to the water (e.g. calcium chloride, calcium sulfate, or magnesium sulfate)
• Adding a pure food-grade lactic acid or phosphoric acid product
• Adding acidulated malt to the grist
• Biological acidification. Biological acidification is the use of a small quantity of wort fermented with lactic acid bacteria (which produce natural lactic acid); this method produces the best sensory characteristics. (See below.)

There are times when the mash pH needs to be increased in order to mash a dark, more acidic grist. However, alkalinity is never added to sparge water. Mash pH can be raised by adding sodium bicarbonate.

Controlling mash pH has the following benefits:

• The range of enzymes is considerably improved because all the important enzymes, with the exception of beta amylase are activated
• More growth promoting substances go into solution at low pH values, improving the supply of zinc for example
• The extract yield is increased
• Protein excretion improves (better break formation)
• The redox potential improves, making the work and beer less susceptible to oxidation.
• Flavor stability is improved because fewer aging components are formed by reducing the pH of the mash to 5.2
• Lautering proceeds more quickly
• Color formation during the boil is suppressed
• The activity of the phosphatases is promoted and they strengthen the buffering capacity through the release of phosphates
• Fermentation is faster due to better trub sedimentation, a faster drop in the pH, and higher degree of attenuation in the cellar
• Filtration is improved by lower viscosity values
• The flavor is mellower, fuller, and softer
• The hot bitterness is more pleasant and does not linger
• The beer is fresh, and has a fresher, stronger, and more characteristic taste
• The foam has finer bubbles and is more stable
• The color of the beer is lighter
• better flavor stability can be expected, particularly as the lipoxygenase is sensitive to pH values below 5.2 and is then no longer effective
• chemical-physical stability is improved, with a reduced protein haze tendency

Mash acidification should only be used at temperatures above 60°C or only moderately with well modified malts because proteolysis is promoted by lowering the pH value.

The pH shift is partly compensated since the phosphatases release a considerable proportion of the phosphates during mashing which plays substantial role in buffering. It is therefore worthwhile to acidify the wort as well. An optimum pH value of 5.1 to 5.2 is desirable during wort production. (at the end of the boil??)

The mash pH should be controlled as early as possible in order to optimize the engine activity and inhibit LOX.

The method of mash pH reduction send to be a significant factor. Calcium additions seen to have a more synergistic affect on mash performance as a whole versus mineral or organic acid additions.

The best a brewer can to to achieve consistent pH control is to find a consistent, high-quality source for malt and focus of brewing water composition, salt and/or acid additions, and consistency of sampling and measurement methods.

The degree of grist crush can affect pH. The buffering capacity decreases with a more coarse crush. For example, mash pH may be significantly higher in a mash with a coarse crush. However, it is speculated that this effect should diminish with longer mashing time, as the grist becomes fully hydrated and more initiates are available for reaction.

High pH can negatively affect hop bitterness, making it "biting and crude".

A rest at 35–40°C was once called the "acid rest" since phosphatases and other acid forming enzymes are active in this temperature range. However, practical experience has shown that the mash pH is quickly established and then is held in check from that point forward by strong buffering agents in the mash. Thus, other methods are required for controlling mash pH.

Sparge liquors may resemble mashing liquors, but it is desirable that the bicarbonate levels are very low, otherwise there is an undesirable rise in the pH of the last runnings as the buffering substances are leached from the mash.

Usually the mash pH is adjusted only once at the onset of mashing.

pH control during sparging can be of importance in limiting the excessive extraction of polyphenols and silica compounds (principally derived from malt husk), both of which increase as the pH increases.16,18 As extract gravity reduces during wort runoff, the pH of the wort tends to increase (thus favoring increased extraction of tannins and silica), unless the sparging liquor contains a relatively high level of Ca2+ ions (up to 200 mg/L), in order to ensure a consistent wort pH value throughout runoff21,30.

Lloyd Hind (as long ago as 1938!) recommended that sparging water should contain sufficient Ca2+ ions to achieve a wort pH of 5.2, after boiling.

Silicate can be extracted from malt by sparging at a high pH.30 It is associated with Ca2+ and Mg2+ and may cause haze in the beer and scaling of vessels and mains.

Except in countries that produce beer according to the Reinheitsgebot (the German Purity Law), acid can be added to the mash and wort. A variety of mineral acids can be used, but most commonly, phosphoric acid is employed because it leads to the formation of phosphates, which are positive for a vigorous fermentation.

Lower pHs at every stage of brewing favor better processing and superior palate. I say low pH but perhaps absence of higher pH is a better way to put it so you are not tempted to add IBCs of mineral acid to every brew. Lower pH in the mash gives a better conversion of starch and proteins to fermentable material and FAN, in boiling while it does reduce hop utilization a lower pH favors a more effective removal of haze forming substances, lower color pick-up and it is believed the production of a less astringent (drying mouthfeel) palate. A lower pH in the finished beer helps yeast flocculation, makes finings work more effectively in the cask or tank, gives an improved shelf-life and cleaner palate. Low water alkalinity and the correct concentration of calcium in the brewing water are instrumental in giving these lower pH conditions.

A higher degree of final fermentation, better protein breakdown, faster lautering, more favorable protein excretion when wort boiling, higher yields and more extensive fermentation as well as lighter colors of the beers and milder hop bitterness are the results of a lower pH during mashing and wort boiling. It may be necessary to increase the amount of hops. It is noticeable, however, that the beer pH does not change in the same way. Due to the improved effect of the phosphatases during mashing in connection with a reduced precipitation of phosphates, the wort has an increased buffer capacity, which offers increased resistance to the pH drop during fermentation. In order to limit the buffering of the wort a little and thus achieve more favorable pH values in the beer, it is advisable to add gypsum or calcium chloride up to the aforementioned ratio of carbonate to non-carbonate hardness such as 1: 2−2.5.

The improved enzyme action during mashing (from hitting the correct pH target) increases the breakdown processes of the individual groups of substances. The protein solution increases, as does the breakdown of β-glucan (but to a significantly lesser extent). Due to the better action of the β-amylase, the final degree of fermentation increases, but only to the extent that the activity of the α-amylase is not impaired, which is expressed in a somewhat longer saccharification time at mash pH values below 5.45. However, oxidation processes are also restricted by the subdued action of polyphenol-, peroxy- and lipoxygenases. The mashing process can be accelerated by shortening the rest periods or by using higher mashing temperatures. A low pH value when boiling the wort promotes protein excretion, reduces the increase in color and promotes brisk fermentation.

Due to the action of phosphatases, The lowest pH values and also the lowest buffer capacity mean mashing temperatures of 62 to 65 ° C. A decrease in the mash pH leads to increased buffering, which can then weaken the pH drop during fermentation. High calcium contents in the brewing water (due to gypsum or calcium chloride) precipitate phosphates and in turn reduce the buffering of mash and wort.

Lower mash pH can help reduce the formation of gel-protein (particularly in a mash exposed to oxygen).

Mash pH has a minimal effect on the oxidation that occurs during mashing, as measured by free thiol groups.

However, the pH of the mashes strongly affected their extract percentages. Mashes at pH 6.0 yielded the highest extract values, there was slightly less extract in the pH 8.0 mashes, and the pH 3.8 values were very low.

Keeping mash pH below 5.6 helps avoid negative impact from LOX.

Brewers usually aim for mash pH of 5.2–5.6 and a wort pH of 5.1–5.5. Increasing pH during lautering can lead to extraction of materials from the grain bed such as silicate and polyphenol.

Lower mash pH improves flavor stability (reduced LOX activity), increases fermentability (increased LD activity), and increases protein degradation (increased protease activity).

Mash pH is lower by about 0.34 when measured at 65°C vs 18°C. cites Bamforth 2001 MBAA TQ 38

Wort filtration was slower at lower pH values (P < 0.001). At a lower pH, wort viscosity was lower, but the wort turbidity was much higher (22). The higher turbidity at lower pH values was hypothesized to be responsible for the increased filtration index observed in this study. The higher turbidity in the β-glucan-free worts was formed by non-β-glucan components, presumably wort proteins.

Mashing at pH 5.0 gave a slightly higher extract (16.6°P) compared to mashing at pH 6.0 (16.3°P), which is in accordance with the report of Taylor and MacWilliam (33, 34). This is likely to be due to the more efficient availability or activation of limit dextrinase (35, 36). This higher extract does not always indicate higher fermentability. The mash pH for maximised fermentability is around 5.5-5.6 (37-39), since this is the pH optima at mashing temperatures (60-70°C) of α- and β-amylase, measured in wort at room temperature. During the mashing process, the pH of the adjusted mash drifted towards a more natural wort pH: the pH 5.0 mash had an average pH of 5.07, while the pH 6.0 mashes had an average pH of 5.92. This is due to the release of various wort substances during mashing, such as amino nitrogen compounds and organic acids, which have buffering capability. The first and second wort sparges had average gravities of 10.5 ± 0.7°P and 5.7 ± 0.4°P. But here, the opposite effect could be seen with mash pH and extract: the first and second sparges of the spent grain mashed at pH 5.0 had lower extracts on average (10.3°P and 5.4°P) than the ones mashed at pH 6.0 (10.7°P and 5.9°P). This effect was particularly noticeable in the tannic acid sparges (Δ°P of 0.7 between different pHs).

the mash pH has a major effect on the levels of metal ions that leach into the lautered wort. For iron, manganese and zinc, a strong negative correlation exists with a lower mash pH leading to a higher amount of Fe, Mn and Zn leaching out into the wort (see Supplementary Figure S6). A similar observation was reported by Holzmann and Piendl in 1977 (21). This is likely to be due to most metal ions having an increased solubility in more acidic environments, as a higher pH promotes the hydroxide precipitation of metals. Additionally, the higher level of protons in an acidic mash compete with the metal cations for any binding sites within the wort matrix (such as endogenous polyphenols), thus increasing the number of free metal ions. Furthermore, the activity of antioxidants (e.g. chelators) is also often linked to their pH dependent solubility, as was seen in previous studies (19, 40). Polyphenols, among other chelators, are more soluble and active at alkaline pH (41). Again, copper is the exception. A lower pH leads to a slightly - but statistically significant - lower level of Cu (20-30 μg/L) which is independent of other factors (see Supplementary Figure S6). This could be attributed to the enhanced protein coagulation during mashing at pH 5 (as opposed to pH 6), as the isoelectric point of most wort proteins is around pH 5.2 or below (37, 42-44). Copper binds with the coagulating proteins, precipitates and is removed with the hot break during lautering (45, 46).

Calcium ions tend to limit extraction of polyphenols and silica during mashing and inhibit color formation during the boil (by lowering pH?).

5.29 mash temp (140f) = 5.44 room, 5.31 mash temp (161) = 5.40 room

pH affects the flavour of beer, its flavour stability and resistance to spoilage craft-organisms. Substances such as phosphates and products of protein breakdown in wort act as salts of weak acids at wort pH. Wort pH is often adjusted by addition of lactic acid but the pH change is relatively small because of the buffering effect. A salt of a strong acid and a strong base (like NaCl, the salt of hydrochloric acid) on the other hand provides no buffering action and adding the acid or the base changes the pH immediately. Buffering capacity is very important in brewing since it controls wort and beer pH. Overall, the optimum pH for enzymes that is active during mashing is pH 5.3 – 5.4. If the pH is higher than this, breakdown of proteins, starch and large dextrins is less efficient. This results in slower wort separation at the end of mashing, lower extract, lower soluble nitrogen and FAN concentrations and often lower fermentability. At higher pH values more polyphenolic material is extracted from the cereal husks with resulting astringency and unwanted increased colour. It is therefore good brewing practice to reduce water hardness by reducing the bicarbonate concentration of brewing liquor to less than 20mg /L (20ppm). One method is by adding phosphoric acid to the hot liquor tank and overnight heating to above 90°C. The mashtun pH is then further reduced to 5.3 – 5.4 by adding calcium sulphate and or lactic acid to the mash. The pH at the end of boiling also to a large extent determines the pH of the final beer. In general the pH decreases by about 1 pH unit during fermentation. 5.2 pH pitching wort thus usually gives a beer with a pH of about 4.2.

Avoid pH above 5.5 when lautering.

The maintenance of a consistently low pH reduces the extraction of polyphenolic compounds and silica that may affect beer quality.

Boiling the water can remove some carbonate (to help remove alkalinity), but this is not a preferred method due to its moderate effectiveness, lack of consistency, and high energy consumption.

Good pH control (lowering mash pH) has a positive effect on the activity of beta-amylase and thus of wort fermentability and extract because the optimum pH for beta-amylase activity is about 5.2–5.6. Furthermore, it has a beneficial effect on the precipitation of wort proteins, during both mashing and boiling.

Lower mash pH improves the extraction of calcium, magnesium, iron, manganese, and zinc. Sodium and copper extraction peak within 5.5-5.7. Potassium extraction is relatively unaffected by mash pH.

Boil pH

For the boil, acid is usually added shortly before the end. This allows better hop utilization and better DMS removal.

Low kettle pH can reduce hop utilization (reducing hop bitterness and expression). High kettle pH can cause harsh hop bitterness.

The pH of wort decreases by about 0.3 units during boiling31 due to the precipitation of phosphates and proteins/polypeptides complexed with calcium. Moreover, wort gravity will have a significant influence on wort pH, with lower values achieved as the gravity increases. The recovery of hop bittering compounds is increased at higher pH values since α-acids are more soluble at higher pH. Some brewers adjust wort pH by acidification but only toward the end of boiling to ensure minimum impact on hop utilization. Lower pH values during boiling will restrict the solution of tannins (this time from hops) and therefore reduce the risk of beer astringency. In addition, color formation may also be reduced by lower pH or increased Ca2+ concentration.

Reducing alkalinity by adding acid is simple and widely practiced (as opposed to using heat or slaked lime). The acid used can be mineral, such as phosphoric, or organic, such as lactic acid. Some brewers extend acid addition beyond water treatment and acidify during mashing (to achieve a desired pH value) or during wort boiling. It should be noted that, if lactic acid is used, wort buffering capacity may increase, and this risks an increase in beer pH.

The phosphatases in the mash increase the buffering capacity by releasing phosphate ions. Consequently, the pH decrease during fermentation is lower and the effect of acidification is reduced. For these reasons, wort acidification (in the kettle) to a pH of 5.1 to 5.2 is advisable. Combined mash and wort acidification leads to higher brewhouse yields, rapid lautering, a softer beer taste, better foam stability, and less color formation in the wort boiling stage. A disadvantage of acidification is the lower bitterness yield due to slower isomerization of α-acids at low pH values.

Higher pH values during the wort boiling result in lower protein excretion, the wort lacks breakage and shine. The higher content of malt and hop tannins in these worts gives them a darker wort or flavor. Beer color. The higher pH also favors an increased dissolution of the hop bitter substances. These are then in a more intensely bitter, more molecular solution or in the form of humulates and can sometimes cause a rough and scratchy bitterness. For these reasons, the hop doses of beers brewed from carbonate water must be kept lower than that of beers made from soft water, without fully compensating for the disadvantages.

Wort pH ≤5.0 is detrimental to the integrity of the whirlpool trub pile, leading to high losses or increased trub carryover to the fermenter.

The pH is a critical factor in obtaining maximum protein precipitation. To improve hot break removal after wort boiling, the pH of the wort should be between 5.0 and 5.2. Lermusieau [13] showed that clear worts were obtained in the whirlpool for pH 5.0 and 5.2. For pH higher than these values the clarity was not acceptable.

Fermentation pH

The pH falls during fermentation as a result of the consumption of buffering materials—principally FAN, the release of organic acids, and possibly the direct excretion of H+ ions by yeast.21,22,32 The nature and content of buffering materials present in wort collected in the fermenter will be a direct consequence of pH control during wort production. The rate and extent of the pH decrease during fermentation are a balance between buffering capacity and the factors stimulating yeast growth. Increased yeast growth reduces pH.

pH during fermentation can make a sizeable impact on the production of flavor components by yeast.

High pH manifests itself during fermentation: slower fermentation, smearing of the yeast cells, reduction in the degree of fermentation and insufficient excretion of protein, tannins and hop resins lead to an unsatisfactory composition of the beer.

Higher the pH on the scale 4–4.5, the lower the level of the most damaging oxygen species in beer.

Yeast growth occurs over the pH range from 2.8-8.0 (19). However, cultures do not function equally well throughout this wide range. Biomass is produced best above pH 4.0 and slows as pH goes down. Low pH reduces the tolerance of Saccharomyces sp. to ethanol. Kudo, et al. (22) demonstrated a relationship between the concentrations of K+ and H+ and the completion of alcoholic fermentation. They suggested that a minimum K+ / H+ of 25:1 is required. As pH drops below 3.2, the increase in H+ raises the risk of premature arrest of fermentation. Added stress is placed on yeast at low pHs and is compounded by low nutrient concentrations, temperature extremes, high sugar and/or high alcohol. Additionally, highly chaptalized juice has a limited buffering capacity. As a result, the organic acid and CO2 production during the initial stage of fermentation can drop the pH (Cone, personal communication, 1995). Juice/musts with pH <3.1 should receive an increased yeast inoculum.

See also

• Water
• pH testing

Biological acidification

Biological acidification can be used both in the mash and in the boil.

Malt contains massive amounts of lactic acid bacteria on its surface. These naturally occurring bacteria can be cultivated and produce up to 2% lactic acid at 48°C. A calculated amount of the acidified wort is added to the mash or boil in order to lower the pH to a specific value.

The biological acidification takes place with the help of the lactic acid rods found on the malt, from which specific species such as Lactobacillus amylovorus and L. amylolyticus prevail.

The acid is produced in the following way: An approximately 10% light, unhopped wort is inoculated with a culture of these bacteria. After about 24 hours at 47–48 °C, the lactic acid content is 0.7–0.8%; after a further 8–12 hours, the limit value of 1%. With regard to the ability of the lactic acid sticks to multiply, it is beneficial to achieve an acid concentration of less than 0.4% after the amount required to acidify the wort has been removed. Over a longer period, the lactic acid concentration will increase to around 1.3-2%.

For idle times, e.g. from the end of one brewing week to the beginning of the next, the culture must be lowered again to approx. 0.3% lactic acid concentration and cooled to below 30°C when it reaches 0.6–0.7%. In order to avoid contamination with Candida species and other wort pests, CO2 gassing is important during the entire biological souring process, also to protect against oxidation.

In order not to drive the protein coagulation too far and to avoid a delay in the degradation of the dimethyl sulfide precursor, the sour wort is added completely or partially to the boil in the last 10 minutes. In general, biological acidification produces very light, soft and mild-tasting beers with good foam and improved taste stability.

Malt contains a large population of lactic acid bacteria on its surface, which can be used to produce “natural” lactic acid by acidification of unhopped wort. Lactic acid produced in this way can be used in accordance with the Reinheitsgebot for mash or wort acidification and is often referred to as “biological acidification.”

Kunze suggests using a pure culture of Lactobacillus amylovorus or Lactobacillus amylolyticus because they are fast growing, produce lots of acid (up to 2%), are homofermentative, amylolytic, produce L-lactate, are hop sensitive, and do not grow below 30°C. They also do not produce off-flavors. Temperature of 48°C is maintained during acid production with these cultures.

The acid wort culture is maintained by periodically mixing fresh wort with acidified wort, ideally at a ratio of 1:1. Therefore the process should ideally be regulated so that about half the acid wort is needed for a batch, and then it can be immediately refilled with fresh unhopped wort. Oxygen should be excluded as much as possible.

The lactic acid content with the process described above is normally around 1-2%, and it will vary by culture and other factors. For example, higher gravity increases lactic acid yield. The amount of lactic acid in the acidified wort must be determined by titration. See Titratable acidity.

Lactic acid produced by means of natural fermentation using bacteria introduces reductones, providing protection against oxidation.

Biological acidification was originally proposed as a "natural" method for controlling mash pH. However the benefits extend beyond simply controlling the pH. It provides a cleaner aftertaste as better defined malt and hop flavors.

German brewers (e.g. Weihenstephaner) add saurergut at the end of the boil to ~5.3 so as not to interfere with hop alpha acid utilization. Low pH is needed for they lager yeast and a better taste from low pH in the final beer. Different bacteria strains produce different flavor. Bacteria from grain is used to comply with the Reinheitsgebot.

Cited by Fix

• Narziss L. Brauwelt. 1997;15(1).
• Oliver F, Dauman B. Brauwelt. 1988;6(3-4).
• Bach J, Fersing F. Brauwelt. 1997;15(3).
• Narziss L. Brauwelt. 1998;16(1).

Acidify unhopped first wort by incubating it with thermophilic lactic acid bacteria (Lactobacillus delbruÈckii, L. amylolyticus) at 45–47°C (113–116.6°F) for 8–71 h (Oliver-Daumen, 1988).

• https://www.researchgate.net/publication/337873372_Sour_wort_-_Biological_acidification_made_easy
• https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-63-0096

Science

There are three key buffering systems likely to be influencing wort and beer pH16,21,22:

• Carbonate/bicarbonate
• Phosphate; both inorganic and organic (especially phytates)
• Carboxylic acids (especially aspartate and glutamate side chains in proteins/polypeptides/peptides/free amino acids)

Potential sources

• http://www.themodernbrewhouse.com/wp-content/uploads/2016/11/Weyermann_TKW_Mash-pH_2010.pdf pH in the Brewery: A Much Underestimated Brewing Variable (Weyermann Malting Company)
• http://www.themodernbrewhouse.com/wp-content/uploads/2017/04/reiter_1208.pdf Effects of Mash Acidification
• Biological Acidification of a Mash Containing 20% Barley Using Lactobacillus Amylovorus FST 1.1: Its Effects on Wort and Beer Quality
• Application of biological acidification to improve the quality and processability of wort produced from 50% raw barley
• https://www.researchgate.net/profile/Jean_Titze/publication/262013610_Sour_wort_concentrate_as_an_efficient_alternative_to_traditional_biological_acidification_or_the_use_of_acidified_malt/links/0f3175366991ec94a3000000/Sour-wort-concentrate-as-an-efficient-alternative-to-traditional-biological-acidification-or-the-use-of-acidified-malt.pdf
• https://onlinelibrary.wiley.com/doi/pdf/10.1002/jib.138
• http://www.themodernbrewhouse.com/wp-content/uploads/2017/04/reiter_1208.pdf
• https://www.sciencedirect.com/science/article/pii/S0723202098800453
• https://www.mdpi.com/2311-5637/4/3/51/pdf
• https://onlinelibrary.wiley.com/doi/abs/10.1002/jib.601
• https://onlinelibrary.wiley.com/doi/pdf/10.1002/jib.447
• https://link.springer.com/article/10.1007/s00217-017-2847-9
• https://www.asbcnet.org/community/Documents/WinningPaper_ASBCJ-2017-3861-01.pdf
• https://www.researchgate.net/profile/Birgit_Oconnor_geb_Schnitzenbaumer/publication/337873372_Sour_wort_-_Biological_acidification_made_easy/links/5defd13da6fdcc2837175640/Sour-wort-Biological-acidification-made-easy.pdf
• https://www.researchgate.net/profile/Hong_Li100/publication/282688106_Technological_Factors_Influencing_Buffering_Capacity_of_Wort/links/564bcd3408ae4ae893b80793.pdf
• http://www.themodernbrewhouse.com/ingredients/a-sauergut-reactor/
• https://onlinelibrary.wiley.com/doi/abs/10.1002/cite.201600038
• https://mediatum.ub.tum.de/doc/1251757/file.pdf

• https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.2005.tb00647.x

• https://www.brunwater.com/articles/post-fermentation-ph-adjustment
• https://www.brunwater.com/articles/dutching-beer
• https://www.brunwater.com/articles/ph-measurement-temperature
• http://www.themodernbrewhouse.com/ingredients/a-sauergut-reactor/
• Taylor DG, The Importance of pH Control During Brewing. MBAA Tech. Quart. 27:131-136, 1990. ..... Probably outdated
• "A new approach to limit dextrinase and its role in mashing."
• http://braukaiser.com/wiki/index.php/Mash_pH_control
• "The effect of brewing water and grist composition on the pH of the mash" Kai Troester
• https://byo.com/article/the-principles-of-ph/
• My wife “gets” sauergut now. Low Oxygen Brewing forum. 2020.
• pH in Brewing: An Overview
• http://www.themodernbrewhouse.com/wp-content/uploads/2016/11/hefebank-weihenstephan-biologicalacidification-englisch.pdf Biological Acidification
• http://www.themodernbrewhouse.com/wp-content/uploads/2016/11/DeLange-A-Different-Perspective-on-pH.pdf A Different Perspective on pH
• http://www.themodernbrewhouse.com/wp-content/uploads/2016/11/DeLange-Acidification-of-Water.pdf Acidification of Water
• http://www.themodernbrewhouse.com/wp-content/uploads/2016/11/DeLange-Estimating-Mash-pH.pdf Estimating Mash pH
• http://www.themodernbrewhouse.com/wp-content/uploads/2016/11/Final_galley.pdf Alkalinity, Hardness, Residual Alkalinity and Malt Phosphate: Factors in the Establishment of Mash pH
• http://www.themodernbrewhouse.com/wp-content/uploads/2016/11/MBAA_FREDERIC.pptx Some Observations on Mash pH Prediction and Control
• http://www.themodernbrewhouse.com/wp-content/uploads/2016/10/effect_of_water_and_grist_on_mash_pH.pdf The Effect of Brewing Water and Grist Composition on the pH of the Mash
• https://www.themodernbrewhouse.com//forum/viewtopic.php?f=3&t=2233
• http://www.themodernbrewhouse.com/wp-content/uploads/2020/07/27_131.pdf
• Palmer J. Putting brewing water adjustments in perspective. MBAA TQ. 2018;55:39–45.
• Bamforth pH in brewing: an overview MBAA TQ 2001;38
• The Role of Lactic Acid in Decreasing pH-Value in Wort and Its Impact on the Quality of Beer
• Influence of pH on flavour staling during beer storage