Lesson 5 - Hop Chemistry SAQ

1. *Name the three main hop constituents that are relevant to brewing, why they are relevant, and where they are found in the hop cone.

2. *Indicate whether the following statements are true or false. If false, provide a reason why you think this.

a) There is one type of α-acid and iso-α-acid.

b) The hop essential oils provide the aroma and flavour in hops.

c) Hard resins are oxygenated α-acids and β-acids; they are found in the bracts of the hop cone.

d) Since the polyphenols in beer come mainly from malt, those contributed by the hops have no brewing value.

e) The levels of β-myrcene increase during the hop ripening period and a-humulene levels decrease.

3. ** “The a-acid content of the hops is the only hop component which contributes to final beer bitterness.” Do you agree with this statement? Explain why.

4. ** You are the head brewer for a new start-up craft brewery. You have not been able to secure any hop contracts yet and thus only have access to small amounts of a selection of different standard hops. You need to source hops for your flagship beer, which has a perceived bitterness target of 25 IBU. The brewery is still being designed, so you can make changes to the process and equipment if required.

a) Detail what type of hop variety you would select (and why). What would you do to increase the hop utilisation to maximise the small amount of hops you have managed to source?

b) Consumer testing has shown that they would like the beer to have more hop aroma. What changes would you make to your hop choice and/or process, to achieve the desired hop aroma, as well as bitterness target?

5. ** Explain how the hop aroma in finished beer would change if the following three scenarios were adopted. Assume that all other parameters are the same, and ignore the impact on bitterness; detail what hop components would cause changes – if any:

a) Hops added at the start of boil only.

b) Hops added halfway through the boil only.

c) Hops added in the whirlpool only.