Hops

Question 1

a-acids

Answer 1

Hop cones consists of 1-18% a-acids, which are the most important bittering compounds.

Question 2

Polyphenols

Answer 2

The plant material of the hop cone can be used to filter wort. It can also contribute proteins and polyphenols, which can help form haze I. Finished beer but can also impart an astringent flavour to the beer

Answer 3

Only female plants are cultivated, because they alone produce hop cones. Male plants must be eradicated from hop farms to prevent any pollen from being released and forming seeds in the female plants. These seeds contain lipids which can reduce the stability of the foam on the beer and make beer taste stale.

Question 4

Lupulin glands

Answer 4

Part of the hop containing the bitter resins (bittering) and essential oils (aroma)
-alpha scores comprise of 2-18% of the hop cone

Question 5

Isomerization

Answer 5

Occurs using heat during wort production, no chemical catalyst required

Question 6

Pre-isomerization

Answer 6

Occurs outside the brewery using heat and manesiun or potassium salt in an alkali solution, chemical catalyst required.

Question 7

Hop extract

Answer 7

Extracted components from hop pellets:
- alpha acids
-essential oils
-some polyphenols
Typically used for bittering, less for aroma (added at the start of the boil)

Question 8

Isomerized pellets

Answer 8

Tested in a heat chamber with chemical catalyst, increases hop untilisation from 30 to 65%
- pre isomerized pellets can be added later in the boil and in lower quantities.

Question 9

T90 hop pellet

Answer 9

Stands for type 90, which means that about 90% of the original bale mass ends up in the pellet

Question 10

T45 hop pellet

Answer 10

Are made by freezing the hood at -35*c before hammer milling then into fine articles and removing coarser leaf material, only 45% of the original bale mass ends uo int the pellet and the proportion of a-acid and of essential oil content is about double that found in T90.

Question 11

Hop pellets over whole hood

Answer 11

-have a known a-acid content
-storage is easier
-deteriorate more slowly
- less beer loss

Question 12

Non isomerised hop extract

Answer 12

Made by extracting the bitter and aromatic components from hop pellets or whole hops using either ethanol or liquid carbon dioxide as a solvent

Question 13

Advantages of using hop extracts

Answer 13

-has a known a-acid content
- storage is easier
- hop extract deteriorates very slowly over time.
- greatly improved hop utilisation
-minimal beer loss

Question 14

Isomerised pellets

Answer 14

In order to isomerise the hop pellets, a catalyst is added to the milled hops. The rest of the pelletisation process is similar to what we described earlier for non-isomerised hop pellets. The packaged pellets are held at a maximum temperature of 50°C for 8-14 days. This isomerises about 99% of the α-acids. This increases the hop utilisation percentage from about 30% for a non-isomerised pellet, to around 65% for an isomerised pellet.

Question 15

Isomerised kettle extract (IKE)

Answer 15

Magnesium salts are used as a catalyst

Question 16

Potassium isomerised kettle extract (PIKE)

Answer 16

Potassium is used instead of magnesium

Question 17

Astringency

Answer 17

More if a Phyisical sensation than a ‘flavour’. It has a drying, or ‘mouth puckering’ effect in the mouth.

Question 18

Key requirements for hop storage

Answer 18

-correct storage temperature (1-5C for whole hood and pellets and up to 15C for hot extracts)
-absence of light
- absence of oxygen (as much as possible)
-dry environment

Question 19

Isomerisation is

Answer 19

The conversation of alpha acids into iso-alpha acids, which required heat. This can be achieved in the brewhouse without chemical additions. If the hop product is pre isomerised outside the brewery then a chemical chatalyst is used.