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FDSC442 > 5- beer and wine > Flashcards

5- beer and wine Flashcards

1
Q

What is attenuation?

A

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

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2
Q

what is a hydrometer and what does it measure?

A

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

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3
Q

What is a refractometer and what does it measure?

A

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

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4
Q

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

A

dry sweet

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5
Q

what is malting ?

A

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

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6
Q

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

A

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

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7
Q

What are the two types of milling?

A

Wet milling Dry milling

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8
Q

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

A

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

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9
Q

After mashing, the malt in name ____

A

wort

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10
Q

What are the three types of hops?

A
  1. aroma hops 2. alpha hops 3. dual purpose hops
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11
Q

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

A

‘cold-shock’ prolonged lag period

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12
Q

how long is a normal lag phase?

A

6-15 hours

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13
Q

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

A

slow initial femrentation

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14
Q

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

A

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

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15
Q

what is fusel alcohol ?

A

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

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16
Q

T or F : Yeast can grow aerobically or anaerobically

A

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

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17
Q

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

A

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

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18
Q

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

A

48-60 hr

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19
Q

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

A

‘green beer’

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20
Q

What are the five steps of conditioning?

A
  1. flavour maturation 2. Clarification 3. Stabilization 4. Carbonation 5. Minimize O2
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21
Q

T or F : Pathogens are not an issue with brewing

A

t

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22
Q

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

A

2

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23
Q

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

A

40 hours

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24
Q

why is wine yeast more resistant to sulfite?

A

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

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25
Q

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

A

t

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26
Q

What is a stuck fermentation?

A

when there is a premature cessation of alcohol production in fermentation

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27
Q

name the cause of stuck fermentations (6)

A
  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)
28
Q

Is LAB good or bad for wine fermentations?

A

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.

29
Q

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

A

diacetyl compound

30
Q

T or F : only heterofermentative LAB can produce diacetyl

A

false, also the homofermentative

31
Q

what is gravity?

A

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)

32
Q

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

A

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

33
Q

what are the tools used to measure the gravity?

A

hydrometer and refractometer

34
Q

What is the terminal gravity?

A

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

35
Q

what is the problem of the gravity measured by the refractometer

A

the alcohol can distort the light

36
Q

what compound causes the bitterness in alcohol?

A

the isomerized alpha acid

37
Q

What is the bitterness?

A

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

38
Q

What is the ABV ?

A

the percentage of ethanol in the finished beer

39
Q

What is the formula of the ABV

A

OG - TG * 131.25

40
Q

What is the formula of the attenuation ?

A

OG -TG / OG

41
Q

what is the disaccharide mostly present in the wort before fermentation

A

maltose

42
Q

What will happen if the fermentation is exposed to oxygen?

A

the sugar up-take is diminished

43
Q

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?

A

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.

44
Q

What is flavour maturation?

A

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

45
Q

what is purging?

A

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

46
Q

What is clarification ?

A

the sedimentation of the yeasts in the green beer

47
Q

What is the stabilization step?

A

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

48
Q

What is the carbonation step?

A

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

49
Q

how do they minimize the oxygen in green beer

A

antioxidants

50
Q

What are the anaerobic beer spoilers?

A

LAB like pediococcus and lactobacillus

51
Q

___ 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.

A

zymomonas

52
Q

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

A

megasphaera

53
Q

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

A

pectinatus

54
Q

What are the primarly aerobic beer spoilers

A

are primarily AAB (Acetobacter and Gluconobacter)

55
Q

What are the process that happens in the wine fermentation

A
56
Q

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

A

in the stationnary phase

57
Q

during malolactic fermentation, the L-malic i converted to ___and ___

A

L-lactic acid and CO2

58
Q

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

A

Oenococcus onesie

59
Q

how does the sulfure dioxide inhibits the growth of microbes?

A

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

60
Q

What is the purpose of the campden crush tablet?

A

can sterilize
eliminate the chlorine
antioxidant

61
Q

What is a stuck fermentation?

A

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

62
Q

What are the causes of stuck fermentation?

A
  • 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)
63
Q

•There are three types of rice wine vinegar :

A
  • 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
64
Q

What is the dominant acetic acid bacteria in rice vinegar?

A

Acetobacteria

65
Q
A

FDSC442 (19 decks)

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