5- beer and wine

Question 1

What is attenuation?

Answer 1

is a way to measure how complete a fermentation process is.

Question 2

what is a hydrometer and what does it measure?

Answer 2

: A weighted glass tube with a scale on the inside which stops at the relative density of the liquid being measures

Question 3

What is a refractometer and what does it measure?

Answer 3

Measures the original gravity only, based on the refractive properties of sugar. Alcohol distorts the readings

Question 4

High apparent attenuation signifies a ___ beer, while low apparent attenuation signify a ____ beer.

Answer 4

dry sweet

Question 5

what is malting ?

Answer 5

Is the process of allowing the grain to germinate (usually by soaking them in water)

Question 6

What is miling and what is the goal of this step?

Answer 6

Milling is a process that breaks down the malt into smaller more fermentable sizes

Question 7

What are the two types of milling?

Answer 7

Wet milling Dry milling

Question 8

what is mashing and what is the goal of this step?

Answer 8

Mashing is the process where ground malt is mixed with brewing water, such that a fermentable extract is produced that will support the growth of yeast

Question 9

After mashing, the malt in name ____

Answer 9

wort

Question 10

What are the three types of hops?

Answer 10

1. aroma hops 2. alpha hops 3. dual purpose hops

Question 11

Temperature is also important. If the wort is more than 5C cooler than the yeast a ____ will result and this will result in a _____

Answer 11

‘cold-shock’ prolonged lag period

Question 12

how long is a normal lag phase?

Answer 12

6-15 hours

Question 13

what is the result of adding too little yeast in the fermentation of beer?

Answer 13

slow initial femrentation

Question 14

what is the result of adding too much yeast in the fermentation of beer?

Answer 14

too much competition between yeast and poorer growth and production of fusel alcohol

Question 15

what is fusel alcohol ?

Answer 15

alcohol with more than two carbons and that don’t taste good.

Question 16

T or F : Yeast can grow aerobically or anaerobically

Answer 16

true, but the anaerobic conditions are essential for the production of alcohol by yeast.

Question 17

why do you need to control the temperature when the yeast are converting sugars to alcohol?

Answer 17

If the temperature gets too high higher alcohols (propanol, iso-amyl alcohol, or iso-butyl alcohol) will be produced, and this will impart off-flavours

Question 18

Exponential growth lasts for ____hours, after which growth is decelerated before the cells reach stationary phase

Answer 18

48-60 hr

Question 19

Immediately after the fermentation beer is called ____ and must still be conditioned before packaging

Answer 19

‘green beer’

Question 20

What are the five steps of conditioning?

Answer 20

1. flavour maturation 2. Clarification 3. Stabilization 4. Carbonation 5. Minimize O2

Question 21

T or F : Pathogens are not an issue with brewing

Answer 21

t

Question 22

In wine fermentation most of the sugars are consumed within ___ days

Answer 22

2

Question 23

wine fermentation : Dissolved CO2 peak around _____ there shouldn’t be no dissolved CO2 when you finish your fermentation.

Answer 23

40 hours

Question 24

why is wine yeast more resistant to sulfite?

Answer 24

reciprocal translocation between chromosome 8 and 16 This translocation resulted in a dominant allele of the sulfite pump

Question 25

T or F : Campden Tablets can eliminate free chlorine from water solutions

Answer 25

t

Question 26

What is a stuck fermentation?

Answer 26

when there is a premature cessation of alcohol production in fermentation

Question 27

name the cause of stuck fermentations (6)

Answer 27

1. Nutrient deficiency (nitrogen, vitamins, or minerals) 2. Inhibitory Substances (acetic acid, lactic acid, excessive sulfur dioxide) 3. Killer toxins (toxins produced by yeasts against other yeasts) ph to low (\<3) 4. Pesticides remain on grapes from field 5. Temperature (too low at the beginning, or too high during the ferment)

Question 28

Is LAB good or bad for wine fermentations?

Answer 28

LAB have an interesting relationship with wine. The growth of some LAB in wine produces desirable traits (malolactic fermentation), while the growth of some species just causes spoilage.

Question 29

What is the compound produced by LAB that can have a buttery aroma at low concentration but a nutty aroma (spoilage) at high concentration

Answer 29

diacetyl compound

Question 30

T or F : only heterofermentative LAB can produce diacetyl

Answer 30

false, also the homofermentative

Question 31

what is gravity?

Answer 31

density of the wort, or a way of calculating the amount of dissolved substances, largely sugars that will be converted into alcohol (it is your first look at how alcoholic your final brew will be)

Question 32

how can you estimate the final ABV from the original gravity?

Answer 32

you take the significant digit. for example 1.040 will have 4% ABV.

Question 33

what are the tools used to measure the gravity?

Answer 33

hydrometer and refractometer

Question 34

What is the terminal gravity?

Answer 34

it is how much gravity is left after the fermentation is finished

Question 35

what is the problem of the gravity measured by the refractometer

Answer 35

the alcohol can distort the light

Question 36

what compound causes the bitterness in alcohol?

Answer 36

the isomerized alpha acid

Question 37

What is the bitterness?

Answer 37

Is the level of bitterness you taste when you drink beer. It is measured in bitterness units (BU) which relates to ppm isomerized alpha acid

Question 38

What is the ABV ?

Answer 38

the percentage of ethanol in the finished beer

Question 39

What is the formula of the ABV

Answer 39

OG - TG \* 131.25

Question 40

What is the formula of the attenuation ?

Answer 40

OG -TG / OG

Question 41

what is the disaccharide mostly present in the wort before fermentation

Answer 41

maltose

Question 42

What will happen if the fermentation is exposed to oxygen?

Answer 42

the sugar up-take is diminished

Question 43

why is there still sugar that can be left after the alcoholic fermentation and why are the yeast not fermenting all the sugar into alcohol?

Answer 43

because in the absence of oxygen, there is no budding and so no growth of yeasts and eventually they will die because of the too high level of ethanol.

Question 44

What is flavour maturation?

Answer 44

The yeast remove undesirable compounds such as H2S, acetaldehyde, and diacetyl. This process is called purging

Question 45

what is purging?

Answer 45

the removl al of the undersirable compounds like H2S, acetaldehyde and diacetyl during the maturation by the yeast

Question 46

What is clarification ?

Answer 46

the sedimentation of the yeasts in the green beer

Question 47

What is the stabilization step?

Answer 47

To prevent a non-biological precipitate to form during storage. Stabilizers are added to remove the precursors of this precipitate

Question 48

What is the carbonation step?

Answer 48

adding CO2 to the beer at low temperature because CO2 is more soluble at lower temp

Question 49

how do they minimize the oxygen in green beer

Answer 49

antioxidants

Question 50

What are the anaerobic beer spoilers?

Answer 50

LAB like pediococcus and lactobacillus

Question 51

\_\_\_ Infects cask-conditioned beers resulting in ‘cider sickness’ where there is a secondary fermentation with much frothing, a loss of sweetness, and off-odours due to hydrogen sulfide and acetaldehyde production. Due to failure in the cask-washing regime.

Answer 51

zymomonas

Question 52

Produces hydrogen sulfide in beer producing “rotten egg” smell. Cannot tolerate more than 2.8% ABV so only affects low alcohol beers.

Answer 52

megasphaera

Question 53

rapidly converts finished beer into propionic acid, acetic acid, succinic acid, lactic acid, and hydrogen sulfide giving the beer a “rotten egg” smell

Answer 53

pectinatus

Question 54

What are the primarly aerobic beer spoilers

Answer 54

are primarily AAB (Acetobacter and Gluconobacter)

Question 55

What are the process that happens in the wine fermentation

Answer 55

Question 56

during wine fermentation, in which phase most of the sugar are converted into ethanol

Answer 56

in the stationnary phase

Question 57

during malolactic fermentation, the L-malic i converted to \_\_\_and \_\_\_

Answer 57

L-lactic acid and CO2

Question 58

what are the commercial strains that are used for the wine malolactic fermentation

Answer 58

Oenococcus onesie

Question 59

how does the sulfure dioxide inhibits the growth of microbes?

Answer 59

SO2 by rupturing the disulfide bridges in proteins and between co-factors and enzymes. It can also deaminate cytosine to uracil and increase the likelyhood of fatal mutation

Question 60

What is the purpose of the campden crush tablet?

Answer 60

can sterilize eliminate the chlorine antioxidant

Question 61

What is a stuck fermentation?

Answer 61

•when there is a premature cessation of alcohol production in the fermentation

Question 62

What are the causes of stuck fermentation?

Answer 62

* Nutrient deficiency (nitrogen, vitamins, or minerals) * Inhibitory Substances (acetic acid, lactic acid, excessive sulfur dioxide) * Killer toxins (toxins produced by yeasts against other yeasts) * ph to low (\<3) * Pesticides remain on grapes from field * Temperature (too low at the beginning, or too high during the ferment)

Question 63

•There are three types of rice wine vinegar :

Answer 63

* Komesu is produced from polished rice grains, is pale amber in color, and is sued for sushi and seaweed salad * Kurosu is produced from unpolished rice grains, is dark black and is used as a table condiment or a healthy drink * Kasuzu is produced from sake lees, 210 different acetic acid bacteria were isolated from a traditional fermentation

Question 64

What is the dominant acetic acid bacteria in rice vinegar?

Answer 64

Acetobacteria