Lesson 5 - The Mashing Process SAQ

 **Explain the benefits of maintaining a mash pH of 5.2-5.4. What can we do to ensure that the pH of our mash is within this range?

Response:

The pH range of 5.2-5.4 is a compromise between providing the optimum temperature for the important mash enzymes and establishing the conditions that provide the following benefits.

• Enhanced protein coagulation, producing more hot and cold break (trub) hence improving colloidal and biological stability

• Improved foam stability

• Reduction in wort viscosity and hence improved wort separation

• Reduction in the extraction of polyphenols

• Lower colour forming potential (as long as pH is not raised before boiling)

• Increased flavour stability

The enzymes with optima matching this range most closely are carboxypeptidases aminopeptidases, limit dextrinase, β-amylase and ɑ-amylase. This means given the appropriate temperature conditions, proteins and starch can be broken down at the fastest rate possible. As these are the major components of extract, this range enables us to maximise extract recovery.

The first thing we need to do to ensure our pH is in this range is to measure it. Doing everything, it says in the textbook and hoping for the best will not guarantee your customers are happy! This measurement needs to be undertaken at the temperature of the mash, as temperature affects pH, and the figures quoted are for the pH at mash temperature. If the mash pH is not within the range, we have several options to either adjust the current mash pH or affect future mash pHs.

Water

The level of calcium, magnesium and bicarbonate in the water (or added to it in the form of salts) affect the pH of the mash and the mash’s resistance to pH change (buffering). If pH is too high and water has significant levels of bicarbonate, we need to take steps to remove it from the supply water using lime treatment, boiling, reverse osmosis, ion exchange or the addition of acids. We can also add calcium or magnesium to reduce the pH by interacting with phosphates. Calcium is a better option as it produces a greater pH reduction and provides a number of other benefits to the brewing process. Not least the stabilisation of ɑ-amylase at higher mash temperatures.

Grist

Malts with higher colours have more melanoidins which lower the pH. Using darker malts would therefore make the mash pH lower, but this would only be an option if the colour and flavour of beer were unimportant. So not really an option! Another option is the use of acid malts which carry lactic acid on their surface. These can be used to reduce mash pH. Thicker mashes tend to have lower pHs, so we could use a thicker mash to achieve a lower pH. However, the effects of mash thickness on the outcome of mashing are significant and will affect extract recovery and the nature of the wort produced, so this isn’t a sensible option for counteracting a high pH.

Acidification

None of the options so far will help us if we have already mashed in. If this is the case, we can add acid to the mash as it is mixed. Phosphoric and lactic acid are the most common acids used. We can also use sour wort, which is diluted first worts acidified by lactic acid bacteria. It is claimed that using sour wort can impart a softer flavour to the beer.

The most practical and effective way to manage mash pH is to:

• Control the ionic composition of the water

• Set the grist composition, mash temperature and water to grist ratio to that required for the brand being brewed

• Measure mash pH at the start of the process and use lactic acid or sour wort to adjust if necessary