Malting/germination process

Question 1

three main components to barley structure

Answer 1

husk
endosperm
aleruone layer

Question 2

role of the husk

Answer 2

protect seed and growing embryo

Question 3

why is the husk useful in brewing

Answer 3

it acts as a filter during wort separation

Question 4

role of the endosperm

Answer 4

bulk nutrients
-starch granules
-the source of fermentable sugars and amino acids

Question 5

role of the aleurone layer

Answer 5

-source of enzymes
-triggered by hormones produced by the growing embryo

Question 6

steps of malting

Answer 6

steeping: raise moisture content to trigger germination
Germination: controlled sprouting in grian beds with forced air
kiling: reduces moisture content and dries malt

Question 7

what happens if steeping is either too short or too long

Answer 7

too short: poor consistency
too long: mould and bacteria grow

Question 8

purpose of germination

Answer 8

control sprouting
release hydrolytic enzymes
modification of endosperm structure

Question 9

describe the steeping regime

Answer 9

-first immersion 6-16 hrs 32% water content
-air rest 12-24: expose embryo to O2 and removes CO2
-second immersion 10-20 hrs

Question 10

describe what is happening to the barley grain during steeping

Answer 10

-water enters through the microphyle and distributes through the starchy endosperm
-water activates the embryo which then produces gibberellic acid that migrates to the aleurone
-enzyme production is stimulated to breakdown the endosperm

Question 11

3 examples of diastatic enzymes

Answer 11

alpha glucosidase
alpha amylase
beta amylase

Question 12

which enzymes are most important

Answer 12

amylase

Question 13

how does starch exist in the endosperm

Answer 13

as large or small grnaules

Question 14

what is the difference in gelatinisation of large and small starch granules

Answer 14

small granules require a higher temperature

Question 15

what is gelatinisation temperature important

Answer 15

reaching the right temp is important during mashing for the conversion to fermentable sugars

Question 16

describe amylose shape

Answer 16

linear chains
alpha 1,4 linkages

Question 17

describe amylopectin shap

Answer 17

short chains
alpha 1,6 glucose links between branches

Question 18

which is the major starch degrading enzyme

Answer 18

alpha amylase

Question 19

describe how amylase degrades starch

Answer 19

random places in the middle of amylose and amylopectin

Question 20

what does endo-amylase mean

Answer 20

attacks in the middle of amylose/amylopectin molecules

Question 21

what does the endoamylase alpha amylase release

Answer 21

maltose and maltotriose
dextrins

Question 22

optimum conditions for alpha amylase

Answer 22

pH 5.5
70C

Question 23

describe the behaviour of beta amylase

Answer 23

starts at one end and chops off two glucose units at a time

Question 24

what does beta amylase release

Answer 24

maltose

Question 25

optimal conditions for beta-amylase

Answer 25

pH 5.2 60C

Question 26

which amylase is the most thermostable

Answer 26

alpha

Question 27

what is the principle sugar in the mash and at what percentage

Answer 27

maltose 45%

Question 28

what is the principle sugar in the mash and at what percentage

Answer 28

maltose 45%

Question 29

what is the principle sugar in the mash and at what percentage

Answer 29

maltose 45%

Question 29

what is the principle sugar in the mash and at what percentage

Answer 29

maltose 45%

Question 30

what are the two major cell-wall polysaccharides?

Answer 30

beta-glucans pentosans

Question 31

structure of beta glucans

Answer 31

glucose straight chain linked by beta-glycosidic linkages

Question 32

what enzymes are needed for the hydrolysis of beta-glucans

Answer 32

B-glucanase

Question 33

where are beta-glucans mainly found

Answer 33

cell wall (make up 75% of it)

Question 34

what are pentosans

Answer 34

sugar polymers

Question 35

describe pentosans shape

Answer 35

backbone of xylose and side chains of arabinos

Question 36

what must happen to cell wall polysaccharides during brewing to make a desirable product

Answer 36

must be degraded into soluble products

Question 37

if the beta glucna is not properly broekn down what happens

Answer 37

increases the viscosity slows wort sepaeration reduces beer filtration rate can cause sediment/haze in beer

Question 38

when is B-glucasnase produced

Answer 38

germination

Question 39

why do brewers often start mash at 45-50C

Answer 39

B-glucanase + proteinases are very heat sensitive

Question 40

what is proteolysis important for

Answer 40

prevention of beer haze generation of amino acids for yeast growth

Question 41

role of proteinases

Answer 41

attack hordeins in the middle of protein molecule to release short linear peptides

Question 42

role of carboxypeptidases

Answer 42

chop AA of the chains one by one