Lesson 4 - Brewing Water Composition and Impact
This lesson deals with the influences of water composition on brewing equipment, the brewing process and beer quality. It will cover the positive and negative impacts that the various compounds found in water have on beer. We will explore the recommended water specifications for brewing key beer styles. We will also examine how to correct levels of some of the key salts within water.
Minerals in Water
Many minerals occur naturally in water, but the final mineral composition of any water source may differ from another. Therefore, brewers must analyse the product water to understand how it will affect the brewing process and the final product.
The minerals found in the final beer come from the following sources:
- The minerals already dissolved in the source water.
- Minerals that have been added (or removed) to the product water by the brewer.
- Minerals that have been added to the mash or wort by the brewer during the brewing process.
- Minerals that dissolve into the mash or wort from the brewing raw materials (such as malt).
We will ignore the impact of raw material addition for the purposes of this lesson, as there are so many different raw materials available. However, raw materials can have an impact on the final mineral levels.
The same source water will be coming into the brewery and used for various brewing recipes, so it is a good starting point to measure the mineral composition in the source water. We can then, by various water treatment methods, remove or add minerals to deliver a product water that is suitable for brewing.
When developing recipes or changing a water treatment regime, it is important to understand that other raw materials can affect the mineral levels in the final wort and beer. For example, malt can provide as much as 150 mg/L of chloride, so it's very easy to have excess levels in the finished beer. There is little point adjusting the levels of minerals in the water if you can't accurately measure the minerals in the beer or their effect on its flavour.
Let us look at the suggested levels of mineral composition to produce water that is ready for brewing all beer styles.
Later in this lesson, we will explore how to tweak these levels to make them more suitable for specific beer styles.
Table: Mineral parameters (not required for potability, but suggested for brewing product water)
|
Constituent |
Suggested levels in source water (mg/L) |
Positive attributes |
Negative attributes |
|
Alkalinity (as CaCO3) |
0-100 |
|
High alkalinity can raise the mash pH. Promotes carbonate scale. |
|
Calcium |
50-150 |
Decreases mash pH by precipitating calcium phosphates and releasing hydrogen ions. Stabilises malt enzymes during mashing. Precipitates oxalate ions (improved clarity and reduced gushing). Improves ‘hot break’ formation. Restricts colour formation during wort boiling. Works as a co factor for amylolytic and proteolytic enzyme activity improving brewhouse extract. Aids yeast flocculation. |
Low pH decreases extraction of hop bittering compounds. Too much gives beer a dry and harsh mineral-like character. |
|
Chloride |
0-100 |
Is thought by some to help to give beer body and fullness to the palate, as well as sweetness (up to 300 mg/L) Improves beer clarification and colloidal stability. |
Can contribute to stress corrosion of certain grades of stainless steel. Levels above 300 mg/L can give an overly full mouthfeel. Above 400 mg/L gives salty and harsh flavour. Excess (> 500 mg/L) levels can inhibit both yeast fermentation and flocculation and become toxic to yeast. |
|
Magnesium |
0-40 |
Effects similar to calcium, but not as pronounced. Co factor in yeast metabolic pathways. |
High levels can cause a sour/bitter taste (> 15 mg/L). Very high levels can have a laxative effect. |
|
Potassium |
< 10 |
Yeast co factor. |
Can make water taste salty at levels > 500 mg/L. |
|
Silicate |
< 25 |
|
Can form scale, damaging boiler systems and membranes. Can cause haze when bound with calcium. High levels can cause slow run-off during lautering, and haze in beer. |
|
Sulphate |
0-250 |
Thought to emphasise hop character and dryness. Increases activity of carboxypeptidase and aminopeptidase. |
Can act as a precursor to the formation of H2S and SO2 during fermentation. > 400 mg/L can cause astringent and unpleasant bitterness. |
|
Zinc |
0.1-0.5 |
Vital yeast nutrient at levels less than <0.5 mg/L. Helps limit H2S formation. |
High levels of zinc (> 5 mg/L) cause an astringent flavour. Levels > 0.5 mg/L can cause off-flavours and inhibit yeast growth. |
The table above highlights how some of the various minerals directly affect the brewing process or beer quality. There are some indirect effects to consider too, although some refer to effects beyond the brewhouse. We will still mention them, as the brewer usually ensures that the mineral content is set during the brewhouse stage.