Mashing BioChemistry

Question 1

What does the term ‘saccharide’ refer to?

Answer 1

A sugar

Comes from the medieval Latin word for sugar.

Question 2

What are monosaccharides?

Answer 2

Single sugar molecules

Question 3

Define polysaccharides.

Answer 3

Many sugars

Strictly speaking, any molecule composed of more than one sugar is a polysaccharide.

Question 4

What does the suffix ‘ose’ indicate?

Answer 4

Sugar

Question 5

What is a glucan?

Answer 5

A polymer formed from monomers of glucose

Question 6

What does the prefix ‘gly’ refer to?

Answer 6

Glucose

Comes from the Greek word glykys.

Question 7

What are the two forms of starch?

Answer 7

• Amylose
• Amylopectin

Question 8

True or False: All starch in nature contains both amylose and amylopectin.

Answer 8

True

Question 9

What are dextrins?

Answer 9

Smaller polysaccharides formed when larger polysaccharides are broken down

Question 10

What are amyloplasts?

Answer 10

Large and small granules in which starch exists

Question 11

What are the structural forms of starch within granules?

Answer 11

• Amorphous (unstructured)
• Semicrystalline
• Crystalline

Question 12

Amylose typically makes up what percent of starch?

Answer 12

Amylose typically makes up 18-33% of starch (by weight)

Question 13

Is amylose soluble in cold water?

Answer 13

The tight packing of the molecule means that it is insoluble in cold water and has a higher density than amylopectin

Question 14

Any cereal starch that is not amylose is what?

Answer 14

Amylopectin

Question 15

Amylopectin makes up what percentage of starch?

Answer 15

67-81%

Question 16

Describe some traits of amylose

Answer 16

Straight and helical
Minor component of starch
Insoluble
Stains blue with iodine
Single non reducing end

Question 17

Describe some traits of amylopectin

Answer 17

Branched molecule
Major component of starch
Soluble
Stains reddish brown with iodine
Multiple non reducing ends

Question 18

What are some impacts of NSP’s like Pentosans and b-glucans

Answer 18

Increase wort viscosity (slowing wort separation)
Reduce extract efficiency
Block filters
Form hazes and precipitates in beer

• Wheat contains higher levels of pentosans (70% of wall polysaccharides), so they become much more significant in mashes containing wheat

Question 19

Above a certain level, lipids are detrimental to beer. They are thought to:

Answer 19

Reduce foam potential

Reduce flavour stability

Play a part in the cause of gushing (over foaming when opened) in beer

Varying fatty acid levels causes inconsistent ester formation during fermentation

Question 20

The extraction of lipids during mashing is increased by:

Answer 20

Using finer grist

Increased agitation

Producing turbid (cloudy) worts

Thinner mashes (high water: grist ratios)

Question 21

What are polyphenols in brewing?

Answer 21

Natural grain/hop compounds (like tannins) that affect beer bitterness, astringency, and clarity

Question 22

Where do polyphenols mainly come from in brewing?

Answer 22

Primarily grain husks (especially barley) and hops

Question 23

Why are moderate polyphenols beneficial?

⸻

What happens if too many polyphenols are extracted?

Answer 23

They help beer stability and clarity by forming complexes with proteins, aiding trub formation.

⸻

Excess polyphenols cause harsh bitterness, mouth-drying astringency, and haze (cloudiness

Question 24

What brewing mistakes increase polyphenol extraction?

Answer 24

Mash or sparge water that’s too hot, too high in pH, sparging too long, or over-crushed malt

Question 25

Ideal sparging conditions to prevent polyphenol issues?

Answer 25

Sparge with water below ~77°C (170°F), maintain pH below ~6.0, avoid over-sparging

Question 26

Polyphenols combine with proteins to form xxxxxxx during wort boiling and xxxxxx in beer

Answer 26

Polyphenols combine with proteins to form trub during wort boiling and haze in beer

Question 27

Polyphenols are also said by some to impart an _________ palate to beer, but there is also evidence that some polyphenols can increase palate fullness.

Answer 27

Polyphenols are also said by some to impart an astringent palate to beer, but there is also evidence that some polyphenols can increase palate fullness. It is possible that there are good and bad polyphenols in this regard.

Question 28

Above a certain _________ (or beyond a specific _____ range), the chemical structure (shape) of the enzyme can be permanently changed, and can no longer catalyse reactions. This is called ________ .

Answer 28

Above a certain temperature (or beyond a specific pH range), the chemical structure (shape) of the enzyme can be permanently changed, and can no longer catalyse reactions. This is called denaturation.

Question 29

Fill in the blank spots

Answer 29

Question 30

What types of products does α-Amylase produce?

Answer 30

Di and trisaccharides and dextrins ## Footnote It does not produce products at the end of glucose chains

Question 31

What is the optimum temperature range for α-Amylase?

Answer 31

70-75°C ## Footnote This enzyme is heat stable

Question 32

What is the primary role of α-Amylase in starch processing?

Answer 32

Starch liquefaction and extract yield ## Footnote Often referred to as the liquefaction enzyme

Question 33

How does β-Amylase differ in its action compared to α-Amylase?

Answer 33

Works on the ends of glucose chains and is slower acting ## Footnote β-Amylase is inhibited and inactivated at lower temperatures

Question 34

What is the optimum temperature range for β-Amylase?

Answer 34

63-65°C ## Footnote This enzyme is heat labile

Question 35

What temperature range inactivates β-Amylase?

Answer 35

68-70°C ## Footnote It is called heat labile due to its inactivation at lower temperatures

Question 36

What is the significance of β-Amylase in fermentation?

Answer 36

Defines wort fermentability ## Footnote It is also known as the enzyme of saccharification

Question 37

What is the role of proteases in yeast nutrition?

Answer 37

Proteases help provide the FAN for yeast but can reduce foam stability and beer body if overactive. ## Footnote FAN stands for Fermentable Amino Nitrogen, which is critical for yeast health during fermentation.

Question 38

What is the difference between endoproteases and exoproteases?

Answer 38

Endoproteases catalyse hydrolysis at specific points within the protein molecule; exoproteases act at the ends of the amino acid chains.

Question 39

What do carboxypeptidases and aminopeptidases produce?

Answer 39

They produce the majority of soluble nitrogen required for yeast nutrition.

Question 40

What is the optimum temperature for protease enzymes?

Answer 40

Around 50°C.

Question 41

What happens to protease enzymes during kilning?

Answer 41

Many are denatured due to heat sensitivity.

Question 42

What does β-glucan solubilase catalyse?

Answer 42

The hydrolysis of protein cross-links between strands of β-glucan molecules.

Question 43

What is the optimum temperature for β-glucan solubilase?

Answer 43

60°C.

Question 44

What issue can arise from the activity of β-glucan solubilase during mashing?

Answer 44

It can release long chains of glucose residues that increase wort viscosity.

Question 45

What happens in gelatinization during mashing?

Answer 45

Starch grains absorb water, heat up, and swell (soften), making them accessible to enzymes

Question 46

What happens during liquefaction in mashing?

Answer 46

Enzymes (α-amylase) break softened starch into smaller pieces, turning mash thinner and easier to handle

Question 47

What is saccharification in mashing?

Answer 47

Enzymes (β-amylase and others) convert smaller starch pieces into fermentable sugars (like maltose and glucose). Saccharification means to turn into sugar

Question 48

What is gelatinisation?

Answer 48

The process where heat causes starch granules to swell and disrupt their structure, allowing water to form a gel ## Footnote Gelatinisation is crucial in cooking for thickening sauces and making foods like spaghetti and rice edible without breaking teeth.

Question 49

What is the initial effect of water entering the starch granule during gelatinisation?

Answer 49

Water first enters the amorphous parts of the starch granule, causing it to swell ## Footnote This is the beginning of the gelatinisation process.

Question 50

What occurs to the crystalline regions of the starch granule during gelatinisation?

Answer 50

Crystalline regions become amorphous as water moves in ## Footnote This transformation is essential for the starch to dissolve and form a gel.

Question 51

What is the role of amylose during gelatinisation?

Answer 51

Amylose chains from the amorphous regions start to dissolve in the water ## Footnote This contributes to the formation of the gel structure.

Question 52

What is the effect of temperature on gelatinisation?

Answer 52

Higher temperatures cause greater movement and strain on bonds, facilitating gelatinisation ## Footnote This is evident when boiling spaghetti; it continues to soften beyond the initial gelatinisation temperature.

Question 53

What factors affect gelatinisation temperatures in cereals?

Answer 53

Variety of cereal, harvest differences, structure of starch granule, proportions of amylose and amylopectin ## Footnote These factors lead to variability in gelatinisation temperatures.

Question 54

What happens to viscosity in the mash after starch gelatinisation?

Answer 54

Viscosity rapidly declines due to ɑ-amylase catalysing the hydrolysis of starch chains ## Footnote This decline is crucial for the efficiency of extraction recovery.