Extraction and Isomerisation of Hop Compounds Flashcards
(16 cards)
What are hop α-acids not very soluble in?
Cold wort
Hop α-acids are also not very bitter in cold wort.
What process increases the solubility and bitterness of hop α-acids?
Boiling wort
The heat of the boil isomerises hop α-acids into iso-α-acids.
At what pH level can hop utilisation reach up to 90%?
pH 8-10
Standard wort pH of 5.2 results in around 35% utilisation.
What is the maximum boil time for optimal hop utilisation?
Around 4 hours
How does wort gravity affect hop utilisation?
Utilisation is greater in lower gravity worts
What effect does trub have on hop utilisation?
Hop acids can be adsorbed on trub, leading to greater loss
At what temperature does isomerisation drop significantly?
Below 80°C
What is the effect of boiling wort at higher pressure?
Increases the rate of hop utilisation
How does hop age affect α-acid levels?
α-Acid levels decrease as hops oxidise over time
Which has better utilisation: hop cones or hop pellets?
Hop pellets
Hop cones require more vigorous boiling for extraction.
What happens to hop utilisation as the quantity of hops added increases?
Utilisation decreases as wort becomes saturated
What aspect of the wort boiling system affects hop utilisation?
Vigour of the boil
Which hop varieties have higher utilisation rates?
Varieties with higher α-acid levels
What three factors affect hop utilisation in wort?
- Wort pH
- Concentration of dissolved material (gravity)
- Level of trub formation
What is the effect of foaming during the boil on hop utilisation?
α-Acids and iso-α-acids are lost on foam formation
What is essential for consistent fermentations and beer colloidal stability?
Formation and precipitation of complexes between polyphenols and proteins
