Lesson 8 - Water Final SAQ

***Brewing product water is composed of many different inorganic ions. The ions can all impact beer in various ways. Identify the key ions and discuss their relevance to the brewing process and final beer quality.

Response:

Carbonate/bicarbonate – main contributor to temporary water hardness and can raise the pH of the mash. An alkaline mash leads to:

• Poor saccharification
• Poor wort separation
• Dark worts
• Poor biological stability
• Poor protein precipitation
• Astringent beer (polyphenol extraction)

Carbonates can also form scale, which can affect the heat transfer efficiency of heated surfaces. This leads to poor wort boils, which can negatively affect colloidal stability, hop isomerisation, flavour formation and flavour removal.

Calcium – One of the key ions (together with magnesium) involved in water hardness – both temporary and permanent. Some of its impacts include:

• Low levels decrease water hardness and vice versa.
• Helps extract fine bitterness from hops, but high levels can drop wort pH, which decreases hop utilisation.
• Drops 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.
• Stimulates amylolytic and proteolytic enzyme activity improving brewhouse extract.
• Improves yeast flocculation

Magnesium – Similar impact to calcium, just to a lower extent. It is a co-factor in yeast metabolic pathways, but high levels cause sour/bitter flavours. Very high levels can have a laxative effect on the consumer.

Chloride – Helps to give the beer body and sweetness, but high levels give a salty taste and can contribute to stress corrosion of stainless steel.

Potassium – Acts as yeast co-enzyme; can make water taste salty at high levels.

Sulphate – Accentuates hop bitterness and dryness of the palate but acts as a precursor to H₂S and SO₂ formation. Very high levels lead to astringent and harsh bitterness.

Zinc – Vital yeast nutrient, especially with high gravity brewing, but high levels can be toxic to the yeast, which would lead to off-flavours and incomplete fermentations.

Sodium – Contributes to beer body and sweetness, but high levels can make the beer taste salty and sour.

Nitrate/Nitrite – Nitrate can be converted to nitrite which is toxic to yeast cells, leading to poor fermentations and off-flavours.

Iron /Manganese – Can cause incomplete saccharification of the wort, leading to poor fermentations and off-flavours. They are oxidation catalysts, which affect colloidal and flavour stability. Beer will gain a metallic flavour. They can also negatively affect yeast (leading to poor fermentations and off-flavours) as well as discolouring foam. They can also corrode stainless steel. Manganese can act as a co-factor to yeast enzymes.

Copper – Small amounts reduce sulphides, which are a precursor to H₂S. It is an essential nutrient for yeast, but high levels inhibit enzymes and can become toxic to yeast (poor fermentations and off-flavours). It acts as an oxidation catalyst, affecting beer flavour and colloidal stability.

Hydrogen/Hydroxide – Hydrogen ions drop the mash/wort pH. and hydroxyl ions increase the mash/wort pH.