Polyphenols Flashcards
What are polyphenols also referred to as?
Tannins
Tannins are a type of polyphenol.
What are polyphenols composed of?
Many phenol or phenol-like units
Approximately what percentage of polyphenols do hops contain?
4%
This percentage may fluctuate between 3-8% depending on the hop variety.
Where are polyphenols mainly found in hops?
In the bracts and bracteoles
What percentage of polyphenols in standard beer comes from hops?
20-30%
In heavily late and dry hopped beers, what can happen to the proportion of polyphenols derived from hops?
It can be as much as from the malt
What is the relationship between hard resins and polyphenols in hops?
Some substances are polyphenols but can also be classified as hard resins
List factors that affect the composition of polyphenols in hops.
- Hop variety
- Cultivation area
- Harvesting technique
- Degree of ageing
Name two polyphenols that have only been found in hops.
- Xanthohumol
- 6-prenylnaringenin
Which type of hops tends to contain a higher amount of polyphenols?
Aroma hops
What do polyphenols complex with to form trub?
Proteins and polypeptides
What role do polyphenols play in beer regarding antioxidants?
They act as free radical scavengers and chelate metal ions
How do high molecular weight polyphenols affect beer?
They affect haze and colour
What do low molecular weight polyphenols provide?
Antioxidant capacity
How do polyphenols affect beer mouthfeel?
They affect mouthfeel and astringency
What is the significance of essential oils in hops?
They contribute to hop aroma and flavour
