Self-Assessment Questions

1. ** A brewer has complained to you that the hop utilisation at the brewery is much lower than expected. What questions would you ask the brewer, to help them trouble shoot their hop utilisation problems? Provide recommendations of what they should do.

2. ** “The IBU value of beer can mislead the consumer as what to expect with regards to bitterness”. Do you agree or disagree? Support your answer with relevant facts.

3. *** You are brewing your flagship lager. Your recipe states that there are three hop additions in the wort kettle, with the following requirements:

  • Hop addition 1 – start of boil – utilisation is 35% and the α-acid is 13%.
  • Hop addition 2 – halfway through boil – utilisation is 25% and the α-acid is 13%
  • Hop addition 3 – 16.7 kg of hops to be added 10 minutes before end of boil. The hop has an α-acid of 5% and a utilisation of 15%

The brew length is 250 hL and the target wort IBU is 30. The total IBU contribution from the first addition is 15 IBU.

a)    If 4 kg of hops were added at the second hop addition, what IBU contribution will this give (show all calculations)?

b)   How much iso-extract, with a concentration of 30% iso-α-acid and a utilisation of 90%, will be required to meet the target of 30 IBU?

c)     Where and how in the process would you add the iso-extract?

 

*** You have been given two hop varieties to trial in your brewhouse. They have the following properties:

 

Variety A

Variety B

α-acid %

5

10

Cohumulone

23

23

β-acid %

4

4

Total oil %

1

2.8

Myrcene

25

60

Caryophyllene

7

7

Farnesene

20

0

 

The beer brewed in the trial must have a noticeable woody/floral hop aroma.

You have 10kg of T90 pellets of Variety A and 5 kg of T90 pellets of variety B. You must use up all of the T90s in the trial. To make up any shortfall in bitterness, you have  pre-isomerised kettle extract (PIKE) which is 34% iso-α-acids with an extraction rate of 70%.

The brew length is 100 hL and the hop utilisation at the start of boil is 35%; at the end of boil it is 15%. The target IBU for the beer is 30.

a)    When in the boil will you add each of the hop varieties and product?

b)    How much PIKE will you need?

c)    Describe two ways in which the hops and PIKE could be dosed into the wort kettle.

 

5. ** Hops provide bitterness and aroma to beer, but they can also enhance packaged beer foam. How would you use hops, and the various hop products available, to improve the foam in a beer?

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