Lesson 5 - Hop Chemistry SAQ
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This lesson allows you to test yourself on the material covered in Lesson 4 on ‘Hop Chemistry’ and determine the level to which you have attained the outcomes.
Suggested Response - Q3
**“The α-acid content of the hops is the only hop component which contributes to final beer bitterness.” Do you agree with this statement? Explain why.
Response:
We can
strongly disagree with this statement.
α-Acids provide little bitterness due to their low solubility; they need to be isomerised into iso-α-acids before they can provide bitterness.
Oxidised forms of α-acids, known as humulinones, are soluble in beer and are 66% as bitter as iso-α-acids. Again, although they are derived from α-acids they are not α-acids.
A small amount of α-acids can be dissolved during dry-hopping but they are not very bitter (0.1 times the bitterness contribution of iso-α-acids).
The β-acids can oxidised to form hulupones that also provide bitterness.
Hard resins can positively influence bitterness, but more as an additive effect on the iso-α-acids, as opposed to directly.
The polyphenols in hops also provide bitterness and astringency and increase the perceived bitterness of the iso-α-acids.