Malt

Question 1

Describe the components of a barley kernel. And the role they play in the malting/ brewing process

Answer 1

Husk, Pericarp and testa, Scutellum, Aleurone layer, Embryo, Endosperm

Question 2

Husk

Answer 2

Dry outer shell (cellulose and lignin, as well as silica, and polyphenols)
- protects embryo inside
- forms a filter bed during wort separation.

Question 3

Pericarp and testa

Answer 3

Layer below husk
- pericarp restricts water uptake
- testa has a waxy coating that limits water uptake and prevents nutrients leaving the grain.

In the beer it contributed to mouthfeel, can form haze when combined with proteins, and can reduce the rate at which beer goes stale.

Question 4

Gibberellic acid

Answer 4

Plant hormone produced by the embryo
- increases enzymes that break down the compounds to nutrients that feed the barley embryo

Question 5

Scutellum

Answer 5

“Shield”
- enables nutrients to move between the endosperm and embryo

Question 6

Aleurone layer

Answer 6

Layer below pericarp and testa
- responds to gibberellic acid (plant hormone) by secreting enzymes into starchy endosperm.
- breakdown compounds into nutrients, fed to embryo by scutellum.

Question 7

Embryo

Answer 7

Precursor to new barley plant
- nutrients (lipids, sucrose, proteins) stored here.
- at the base of the kernel and would become a new barley plant it or germinated and was allowed to grow.

Question 8

Starchy Endosperm

Answer 8

Main food storage: starch cells contained in cell walls made up of carbohydrates and proteins.
- during malting, enzymes break down starch call walls & starch into nutrients for the embryo
- malting controlled so enzymes are available for saccharification & B-glucan breakdown

Question 9

Two row barley

Answer 9

-plumper grain
- higher starch:protein ratio
- more commonly used
- contains sufficient enzymes, protein and husk material and has higher extract potential.

Question 10

Six row barley

Answer 10

• higher malt enzyme content, more effective saccharification
• higher protein content
• more husk = better filter bed
• more enzymes that help convert starch into sugar

Question 11

Malting process

Answer 11

Steeping, Germination, kilning

Question 12

Steeping

Answer 12

Ensures that all kernels reach the ideal moisture level to start germination.
- wet stand @20*C
- dry sand to prevent o2 loss
- repeat till 43-46% moisture

Question 13

Chitting

Answer 13

Term used to describe the appearance of the tip of the first root at the end of the grain

Question 14

Germination

Answer 14

Grain allowed to grow under controlled conditions
- 16-21*, 42-47% moisture
- enzymes released, cell walls & B-glucans dissolved, proteins broken down
- aims to achieve a complete and uniform modification
- takes 3-5 days

Question 15

Modification

Answer 15

The breakdown of the endosperm cell walls, protein matrix and small starch granules. Modification of the term we fine the changes in the barley kernel that occur as it is turned into malt.

Question 16

Kilning

Answer 16

Stops germination
- 50* dries malt
- up to 90* to develop colour and flavour
- heat converts SSM (formed during germination) into DMS

Question 17

Moisture content

Answer 17

Barley-<18%
Steeping- 42-46%
Germination- 42-47%
Kilning -3-5%

Question 18

Phyisical changed to the barley kernel during malting

Answer 18

• an increase in moisture lever triggers growth of the embryo, which starts to grow chits and rootlets

Question 19

Biochemical changes during malting

Answer 19

• the level of sugar in the embryo drops which causes the embryo to secrete gibberellic acid (GA)
  -GA is released by the embryo and moved to the Aleurone layer where it stimulates enzyme production.
• enzymes are secreted by the aleurone layer into the endosperm
  -Enzymes help break down both the endosperm cell walls and the protein matrix meaning that the starch granules are exposed. The proteins are broken down into amino acids
• enzymes help break down the small starch granules, producing sugar
• the sugars and amino acids are transported to the embryo to use as it grows.

Question 20

Malt storage

Answer 20

Can be stored in bags or bulk silos
-bagged malt is sealed to reduce uptake of moisture and prevent insects and birds getting in.
- should be kept inside to avoid birds, moisture, insects, and temp fluctuations.
- best stored below 30*C
-silos can be used to store bull malt, must be cleaned before they are filled, once filled should be completely emptied before re-filling.

Answer 21

High protein levels mean malt has lower extract, may not malt consistently,

Question 22

Barley grains contain

Answer 22

65% starch, 7-12% protein, 2-3% lipids and a range of minerals, enzymes and vitamins

Answer 23

Malt provided enough lipids for our yeast but not so much that the quality of beer is effected

Answer 24

Steeping is usually 40-56 hours

Question 25

Biochemical changes

Answer 25

Dimethyl sulphide (DMS) smells of cooked sweetcorn and can be produced during the malting process. It is an off-flavour if present in most beers. DMS is formed when S-methyl methionine (SMM) is heated. SMM is produced by the embryo during germination. DMS is volatile so evaporates when it is heated. The maltster must ensure that as much SMM as possible is converted into DMS and evaporates during kilning. If not, there is a risk that DMS will form when the wort is boiled in the brewhouse. Levels of SMM and DMS are usually measured after the malting process and we can specify the level we want in our malt.

Question 26

Malt modification

Answer 26

Malt used to brew lager traditionally had more enzyme potential (diastatic power), but was under modified. In under modified malts, the protein matrix and endosperm cell walls are not completely broken down. This means that the starch is still locked inside. Under-modified malt can also lead to high β-glucan levels in the wort, which leads to slow wort separation and beer filtration. β-glucans can also form haze in the beer. Undegraded proteins can cause similar problems. When brewing with under modified malt we need to use different temperature stands when mashing to breakdown the β-glucans and proteins which are keeping the starch locked inside the endosperm cell walls. We will describe the different mashing methods in more detail in the Mashing lesson.

Question 27

Dinethyl suphate is produced

Answer 27

From SMM when heat is applied, suck a kilning