How Do Temperature and pH Affect Mashing and Lautering?

Brewers carefully manage temperature and pH throughout the brewing process to control enzyme performance during mashing, reduce tannin extraction during lautering, enhance yeast activity during fermentation, and improve the overall quality of the beer (Buttrick, 2012). Let’s explore how these two key factors—temperature and pH—affect mashing and lautering, and their impact on the final product.

The Role of Temperature in Mashing

Temperature has a significant impact on enzyme activity during mashing, directly affecting the efficiency of starch conversion and the overall quality of the wort. Enzymes are biological catalysts that operate best within specific temperature ranges, and each enzyme has its own optimal range (Kunze, 2014).

As the mash temperature rises, the rate of enzyme-catalyzed reactions increases, promoting protein unfolding, starch gelatinization, and diffusion of nutrients from the grain into the wort (Briggs, 2004). This process also helps to break down the cellular structure of the grain’s endosperm, particularly in unmodified malts, allowing enzymes better access to starches.

Here are the key enzymes involved in mashing and their optimal temperature ranges:

• Proteases: Work best between 35-45°C and help break down proteins that surround starch granules.
• Glucanases: Operate at 45-55°C and break down hemicellulose gums, which can cause filtration problems.
• Amylases: These enzymes, responsible for converting starch into fermentable sugars, perform best between 61-67°C. The two main types, α-amylase and β-amylase, each work at slightly different ranges, contributing to wort fermentability (Buttrick, 2012).

If the mash temperature is set too low, enzyme activity decreases, resulting in poor conversion of starches to sugars. This can lead to a lower extract yield and longer lautering times (Agu, 2011). On the other hand, excessively high temperatures can cause enzyme denaturation, where the enzyme loses its functional shape, significantly reducing its ability to catalyze reactions (Kunze, 2014).

The Role of pH in Mashing

While temperature plays a dominant role in enzyme activity, pH is another important factor in optimizing the mash process. Each enzyme has an ideal pH range, and deviations outside this range can slow down the enzymatic activity. For example, proteolytic enzymes that break down proteins work best in a pH range of 5.0-5.2, while amylases operate optimally between 5.4-5.8 (Buttrick, 2012).

The pH of the mash influences not only enzyme efficiency but also the solubility of proteins and other wort components. Maintaining a mash pH between 5.2 and 5.4 is considered ideal for achieving good enzymatic activity, efficient starch conversion, and minimizing the extraction of undesirable tannins and polyphenols (Briggs, 2004). Lowering the pH too much can lead to greater solubility of nitrogenous materials, but this can extend saccharification time and reduce extract yield.

The Influence of Water Chemistry on pH and Mashing

Water chemistry plays a significant role in determining mash and wort pH. Calcium and magnesium ions are key players, reacting with wort components such as phosphates and proteins. Calcium, for instance, binds to phosphates and proteins, releasing free hydrogen ions, which lower the mash pH (Briggs, 2004).

Figure 1. The reaction of Bicarbonate in an Acidic Solution to Increase Alkalinity (Briggs, 2004)

Conversely, bicarbonate ions in the brewing water act as a buffer, neutralizing acidity and raising the pH (Figure 1). For this reason, brewing liquor (water used for brewing) must be carefully managed to balance these reactions. For example, calcium phosphate becomes less soluble at higher temperatures, leading to a drop in pH during mashing and boiling (Briggs, 2004).

Figure 2. The reaction of Calcium Ions when Phosphoric Acid is used to Increase Acidity (Briggs, 2004)

It’s important to note that mash and wort pH changes with temperature. For instance, at 65°C, the pH of the wort is about 0.35pH lower than at ambient temperature, and at 78°C, it is approximately 0.45pH lower. This phenomenon occurs because weak acids dissociate more as the temperature increases, which means brewers must account for these pH shifts when making adjustments during mashing and boiling (Briggs, 2004).

pH Control During Mashing and Lautering

Mashing lightly kilned malts with distilled water typically results in wort with a pH between 5.8 and 6.0, stabilized by the natural buffering capacity of phosphates and proteins in the grain (Briggs, 2004). Single-stage infusion mashes, however, are run at a lower pH range of 5.2-5.4, which ensures efficient enzyme activity. At ambient temperatures, this results in wort with a pH around 5.5-5.8.

Reducing the pH during mashing can improve enzyme activity and accelerate starch degradation, leading to increased soluble nitrogen and free amino nitrogen, which are vital for yeast nutrition. However, excessively low pH can extend saccharification times and lower extract yields. Lowering the pH too much can also affect wort color and reduce hop utilization (Briggs, 2004).

In some cases, brewers may use lactic acid (either from chemical or biological sources) to lower mash pH, which has been shown to enhance beer quality, especially when using high percentages of unmalted barley in the grist (Lowe, 2005; Lowe, 2004).

Effect of pH and Temperature on Lautering

During lautering, it’s crucial to maintain both temperature and pH at optimal levels to ensure good filtration and prevent the extraction of undesirable compounds from the grain bed. If the pH rises too high, particularly due to bicarbonates in the sparge liquor, polyphenols and tannins can be extracted, leading to astringency in the final beer (Briggs, 2004).

Properly controlling sparge water pH by reducing bicarbonate levels and using appropriate amounts of calcium can help prevent these issues. Additionally, keeping the grain bed temperature consistent during lautering reduces the viscosity of the wort, improving filtration efficiency and speeding up the lautering process (Bühler, 1996).

pH Changes During Boiling and Fermentation

As the wort is boiled, its pH typically decreases by 0.2-0.3 due to the precipitation of calcium salts. By the end of the boil, the wort pH usually sits around 5.0, which is ideal for yeast health and fermentation (Buttrick, 2012).

Fermentation further lowers the pH by 0.5-0.7, depending on the yeast strain and brewing conditions. Most barley-based beers finish fermentation with a pH between 4.1-4.5, while wheat beers tend to be slightly more acidic. In styles like lambics or other sour beers, acid-producing bacteria can drive the pH even lower, contributing to the beer’s distinctive tartness (Buttrick, 2012).

References

Agu, R. (2011) Effect of Mashing Temperature on the Processability of Malted Barley. Tech. Q. Master Brew. Assoc. Am. 48(1), 4-8.

Bamforth, C. (2001) pH in Brewing: An Overview. Tech. Q. Master Brew. Assoc. Am. 38(1), 1-9.

Briggs, D., Boulton, C., Brookes, P., and Stevens, R. (2004) Brewing Science and Practice. Woodhead Publishing Limited, Cambridge, UK, 104-122.

Bühler, T., McKechnie, M., and Wakeman, R. (1996) Temperature Induced Particle Aggregation in Mashing and its Effect on Filtration Performance. Food and Bioproducts Processing, 74 (4), 207–211.

Buttrick, P. (2012) Mashing, in The Oxford Companion To Beer; Oliver, G. Ed.; Oxford University Press, New York, 576-578.

Kunze, W., Manger, H., and Pratt, J. (2014) Technology Brewing & Malting, 5th ed; Handel, O. Ed.; VLB, Berlin, 220-225.

Lowe, D. P., Ulmer, H. M., Barta, R. C., Goode, D. L., and Arendt, E. K. (2005) Biological Acidification of a Mash Containing 20% Barley Using Lactobacillus Amylovorus FST 1.1: Its Effects on Wort and Beer Quality. Journal of the American Society of Brewing Chemists. 63 (3), 96–106.

Lowe, D. P., Ulmer, H. M., Sinderen, D., and Arendt, E. K. (2004) Application of Biological Acidification to Improve the Quality and Processability of Wort Produced from 50% Raw Barley. Journal of the Institute of Brewing, 110 (2), 133–140.

Muller, R. (1991) The Effects of Mashing Temperature and Mash Thickness on Wort Carbohydrate Composition. J. Inst. Brew. 97, 85-92.

Schwarz, K., Boitz, L., and Methner, F. (2012) Release of Phenolic Acids and Amino Acids During Mashing Dependent on Temperature, pH, Time, and Raw Materials. J. Am. Soc. Brew. Chem. 70(4), 290-295.

Taylor, D. (1990) The Importance of pH Control During Brewing. Tech. Q. Master Brew. Assoc. Am. 27, 131-136.