Lesson 9 - Brewing with Hops SAQ
This lesson allows you to test yourself on the material covered in the previous lesson, Brewing with Hops, and determine the level to which you have attained the outcomes.
Suggested Response - Q2
*Write short answers to the following questions:
a) Name four hop points of addition and say what the primary impact on hop flavour in the finished beer will be.
b) What is a hopback, and what is its purpose?
c) List five factors that can influence the efficiency of extracting the essential oils during dry hopping.
d) What temperatures should hop extracts and pellets be kept at during automatic dosing?
e) What is the LCV and provide a description of the method, including a diagram to show how the LCV value is read.
Response:
a) Four hop addition points and their primary impact on hop flavour in finished beer are:
i. Kettle Hop – Bittering.
ii. Late Hop – Bittering / Aroma.
iii. Early Dry Hop – Aroma.
iv. Late Dry Hop – Aroma.
b) A hop back is a vessel that removes whole hops after wort boiling or is used to add hop flavour after the boil or after the whirlpool. Hot wort flows through the bed of hops and extracts hop aroma.
c) Any five of the following could be listed:
- Particle size of hop
- Condition of lupulin glands
- Temperature of the beer
- Concentration gradient between the compound in the beer around the particle and the surrounding beer
- Contact time
- Alcohol concentration
- Dose rates
- Process losses and process equipment.
d) CO2 extract should be kept at about 40°C and ethanol extract should be kept at about 50°C. Pellets should be kept as cool as possible to prevent resins becoming sticky in hot conditions.
e) The LCV is the Lead Conductance Value. The soft resin in the hops can be precipitated using lead acetate, where the precipitate is the α-acids and the solution is equivalent to the β-acids. An acidified lead acetate solution is slowly titrated into a hop solution (hop has been extracted with methanol) and the conductance or resistance of the solution is monitored. A graph of conductivity can be plotted against the volume of lead acetate solution added. The resulting curve, on extrapolation, allows the determination of the reaction end point or the lead conductance value of the hop solution.
