Flavor, Haze, Foam

Question 1

Which hop variety will have the most bittering potential?

Answer 1

Simcoe will have the most bittering potential due to the lowest iso-cohumulone.

Question 2

What is “umami” in common terms?

Answer 2

Savory

Drinkability

Question 3

What is “kokumi” in common terms?

Answer 3

Rich tasting

Delicious

Question 4

What flavor characteristics are attributed to Sulfate?

Answer 4

Dryness and astringency

Question 5

What flavor characteristics are attributed to Chloride?

Answer 5

Fullness and body

Question 6

What is a flavor unit?

Answer 6

Total measured/Flavor theshold

(60 mg DMS/30 mg threshold = 2 flavor units)

Question 7

Excess FAN results in more or less higher alcohols produced

Answer 7

More

Question 8

Stronger wort increases or decreases ester formation

Answer 8

Increases

Question 9

A temperature rise of 3-4 degress on fermentation will have what effect on VDKs and higher alcohols?

Answer 9

Will increase rate of utilization for VDKs

Will increase production of higher alcohols

Question 10

What is the commercial enzyme “Maturex” (Acetolactate decarboxylase) used for?

Answer 10

To prevent the production of diacetyl

Question 11

The Synebrychoff method is a much faster method (compared to the natural process) to remove VDKs from green beer. Why is it not used in industry?

Answer 11

It is too complex to use practically.

Ferment, centrifuge, heat green beer to 80C for 20 minutes, cool, flow through immobilized yeast

Question 12

Which VDK is produced by pediococcus? What is often the cause of this contamination?

Answer 12

Pediococcus produces diacetyl but not pentanedione.

It is a contamination often caused by dirty draft dispense lines.

Question 13

What reaction is methionine sulphoxide reductase enzyme used for?

Where is this enzyme found?

Answer 13

Converts DMSO to DMS.

It is found in both ale and lager yeasts.

Lager fermentations will convert more DMSO to DMS due to lower temperatures.

Question 14

Perceived DMS increases or decreases with the concentration of 2-Phenyl ethanol (2-PE)?

Answer 14

Decreases

Question 15

Which cereal grain does Ferulic acid come from?

Answer 15

Wheat cell walls

Question 16

What is a better method for measuring sourness than pH?

Answer 16

Titratable acidity gives a better indication of sourness

Question 17

What is invisible haze? How do you avoid measuring invisible haze?

Answer 17

Haze that can’t be seen but there are particles in solution that will deflect light to the 90 degree detector.

Detect forward scatter at 13 or 30 degrees to avoid measuring the invisible haze.

Question 18

What is chill haze?

Answer 18

A haze that forms when beer is chilled to 0C but which returns to solution when the beer is returned to 20C.

Particle size of 0.1 to 1 micron

Question 19

What is permanent haze?

Answer 19

Haze that is present at all temperatures.

Particle size of 1 to 10 microns

Question 20

What is the method of chill haze formation proposed by Karl Siebert?

Answer 20

At low temps, 2 ended polyphenols will bridge between proline molecules to form long chains resulting in haze.

Once the temp increases, the molecules break apart.

Question 21

Where do the haze forming proteins originate?

Answer 21

Mostly hordein derived

Rich in proline

Albumin and globulin also in chill haze but only after those derived from hordein

Question 22

What is PVPP and what is it used for?

Answer 22

Polyvinylpolypyrrolidone

Binds polyphenols and tannins because it has a similar structure to proline. Removes haze as a result.

Comes as a single use powder or a regenerable sheet

Question 23

What is silica gel and what is it used for?

Answer 23

Highly purified sand that is processed into a gel.

Selective for haze forming proteins.

Can be used as a tank dosing method or as a filter aid substitute.

Question 24

What is tannic acid and what is it used for?

Answer 24

It increases precipitation of solids in beer to remove haze.

Dosed in-line on the way to the filter.

Question 25

Papain can be used to reduce haze in beer. What is a negative attribute of it that prevents it from being used more?

Answer 25

It also hydrolyzes the foam proteins

Question 26

What is Brewers Clarex and what is it used for?

Answer 26

Prolyl endoproteinase

Eliminates the haze forming prolyl proteins and leaves the foam proteins

Added to the fermentor

Additional benefit is using it to produce gluten reduced beers

Question 27

Why is Irish Moss added to the kettle?

Answer 27

Promotes precipitation of proteins to reduce haze

Question 28

What are the 3 factors influencing nucleation?

Answer 28

1. Nucleation sites
2. Temperature (Solubility of gas decreases as temp increases)
3. CO2 content

Question 29

Which is more soluble? N2 or CO2?

Answer 29

CO2 is more soluble

N2 results in a more stable foam since it is less soluble

Question 30

What are the 4 impacts of nitrogen with respect to foam?

Answer 30

1. Improved foam stability
2. Smoother mouthfeel
3. Less harshness
4. Less hop aroma

Question 31

What are 3 foam negative components?

Answer 31

1. Ethanol
2. Lipids
3. Detergents

Question 32

Which proteins retain foam better? Hydrophobic or hydrophillic?

Answer 32

Hydrophobic

Question 33

Interpret the graph

Answer 33

Increasing the hydrolyzed hordein concentration squeezes out the better foam stabilizing albumins

Question 34

Describe what is happening in the picture:

Answer 34

The hydrophobic side chains of the iso-alpha-acids bind with the proteins. Then a divalent metal cation (such as zinc) binds the iso-alpha-acids together to form a stable foam. This results in lacing of the beer glass.

Higher bitterness = higher lacing