Polyphenols Flashcards
(16 cards)
What is the origin of most polyphenols found in beer?
Derived from malt, extracted during mashing and wort separation
What does the name ‘polyphenol’ mean?
‘Polus’ meaning ‘many’ combined with ‘phenol’, which is a molecule with a hydroxyl group attached to a phenyl ring
How are polyphenols structured?
Made up of two or more phenol rings, ranging from small molecules to large polymers
What is tannic acid?
A type of polyphenol used as a beer stabilising agent
Name the four classes of phenolic material in beer and wort
- Simple phenol-based molecules
- Flavanols
- Proanthocyanidins
- Complex flavanols
What are proanthocyanidins?
Dimer and trimer forms of flavanols, also known as anthocyanogens and polymeric flavanols
How do polyphenols affect beer during wort boiling?
Combine with proteins to form trub and haze in beer
What percentage of beer polyphenols are involved in haze formation?
Around 10%
What is the significance of proanthocyanidins in beer?
They are the most significant polyphenols in haze formation
What are the two schools of thought regarding the oxidation of polyphenols in brewing?
- Good: They remove oxygen that could damage beer flavor
- Bad: They store oxygen and contribute to stale off flavors
How can polyphenols affect flavor stability in beer?
They can form complexes with metal ions that catalyse flavor staling reactions
What effect do polyphenols have on the palate of beer?
They can impart an astringent palate or increase palate fullness
Where in malt are polyphenols concentrated?
In the husk, pericarp, and testa
How do higher kilning temperatures affect polyphenol extraction?
They make polyphenols easier to extract
What mashing practices increase polyphenol extraction?
Milling and mashing practices that increase the dissolution of the husk fraction
What effect do higher temperatures have on polyphenol extraction during mashing?
They increase the extraction of polyphenols
