Acidification of the Wort Flashcards
(12 cards)
What is the typical drop in wort pH during wort boiling?
0.3 to 0.5 pH units
This drop is influenced by various factors including the formation of melanoidins and the concentration of hop acids.
What are the main contributors to the drop in wort pH during boiling?
- Formation of melanoidins
- Increased concentration of hop acids
- Liberation of H+ ions when calcium and magnesium react with amino acids and peptides
- Liberation of H+ ions when calcium and magnesium react with phosphates
The liberation of H+ ions from calcium and magnesium reacting with phosphates is typically the most significant contributor.
What is the ideal starting pH for wort before boiling?
5.5-5.8
The starting pH can be affected by ions in or added to the water and the mashing and wort separation process used.
What is the desired pH range for wort at the end of boiling?
5.0-5.3
This pH range is considered a good compromise for the requirements of wort boiling.
What reaction occurs when calcium ions react with phosphates during boiling?
Calcium phosphate is precipitated
This reaction displaces H+ ions, leading to a reduction in pH.
What happens to the concentration of calcium in wort by the end of the boil?
It may drop from 100 mg/L to 40 mg/L
At least half the calcium present in wort can be precipitated by the end of the boil.
What compounds are sometimes added to encourage a reduction in pH during boiling?
- Calcium sulphate
- Calcium chloride
These compounds help to achieve the desired pH levels in the wort.
What is calcium oxalate and why is it significant in brewing?
It is a compound formed when calcium reacts with oxalic acid released from malt
If not removed during boiling, it can form scale known as beer stone and cause beer gushing.
What are the effects of calcium oxalate crystals in beer?
- They can form nucleation sites for CO2 bubbles
- They lead to over foaming when the package is opened
This phenomenon is referred to as beer gushing.
How can the pH be reduced directly during brewing?
By adding acids such as phosphoric or lactic acid
Phosphoric acid may be used in high gravity or high adjunct worts, while lactic acid is believed to produce smoother tasting beer.
What is sour wort and how is it produced?
It is produced by fermenting unhopped wort using specific strains of Lactobacillus
Sour wort is thought to produce a smoother tasting beer than those acidified with mineral acids.
Why is achieving the right pH throughout the boil important?
- Improves protein coagulation
- Improves diacetyl reduction during fermentation
- Encourages yeast growth
- Helps increase fermentation rate
- Inhibits the growth of spoilage microorganisms
- Reduces colour formation
- Helps achieve the correct beer pH
Each of these factors contributes to the overall quality and stability of the final beer product.
