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FDSC 442 > Beer, Wine, Cider, Vinegar > Flashcards

Beer, Wine, Cider, Vinegar Flashcards

1
Q

Beer

A

solution of water, CO2 and alcohol flavoured by carbs, proteins, minerals
-hops, yeast, grains

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2
Q

Brewing

A

process of preparing beverages from grains that have sprouted, and their fermentation process

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3
Q

how is gravity calculated?

A

using a hydrometer or refractomer

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4
Q

What can alter the attenuation?

A

attenuation: how complete the fermentation process is

- sugar type, mashing method, composition of the wort, type of yeast

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5
Q

high apparent attenuation vs low apparent attenuation

A

high: dry beer
low: sweet beer

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6
Q

malting

A

the process where the grains soak in order for them to germinate.

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7
Q

what is the purpose of malting

A

turn the food reserves in the grain into sugars convenient for use in the fermentation.

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8
Q

what should the moisture content of the grains be at the start and during storage? (malting)

A

no higher than 20%

during drainage, CO2 and air are pumped through (CO2 promotes germination)

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9
Q

milling

A

process where the malt is broken down into smaller, more fermentable sizes.

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10
Q

mashing

A

ground malt is mixed with brewing water. A fermentable extract is produced that will support yeast.

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11
Q

what are the steps to making beer

A

malting, milling, mashing, addition of hops, fermentation, post-fermentation additions

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12
Q

Yeasts - beer. What conditions are preferable or negative?

A

too cold - lag period
too much - competition and stress
not enough - lag period
temp to high - fusal alcohols are produced

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13
Q

can spores survive the brewing process?

A

yes, but not likely to germinate due to lack of nutrients.

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14
Q

fermentation - phases

A

lag phase, exponential phase (high production of CO2 and ethanol)

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15
Q

wine fermentation - phases

A

lab phase: a few hours
growth phase: (24-36hr)
stationary phase: long time

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16
Q

malolactic fermentation

A

L-malic acid is converted to L-lactic acid and CO2

LAB: Oenococcus onesie

17
Q

what is special about wine yeast?

A

reciprocal translocation between chromosome 8 and 16

-direct relationship with the number of repeats and sulfite tolerance

18
Q

what can cause a 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
19
Q

malt vinegar

A

starch converted to maltose

maltose converted to ale, which is aged

20
Q

cider vinegar

A

made with apple juice through a double fermentation of alcohol and acetic acid in the same barrel.

21
Q

traditional balsamic vinegar

A

conversion of sugars to ethanol via yeast

at least 12 years of aging

22
Q

rice vinegar

A

produced by a static surface fermentation
final acidity is 10%
acetobacter is used (AAB)

23
Q

Colour

A

measured using spectrophotometer or tristimulus

24
Q

bitterness

A

measured in bitterness units, which relates to ppm isomerized alpha acid

25
Q

at what moisture content do grains begin to germinate?

A

42-46%

26
Q

are anaerobic or aerobic conditions favourable in beer?

A

yeast are both aerobic and anaerobic. anaerobic conditions are favourable because sugar uptake is increased

27
Q

why does production of alcohol by yeast slow and stop?

A
  • Budding requires cell wall synthesis which cannot happen in anaerobic conditions, therefore eventually growth must cease
  • Eventually the level of ethanol present becomes toxic to yeast
  • When fermentation slows the yeast cells flocculate and sediment out (which causes growth to slow even further)
28
Q

esters

A

cause fruity flavour, are caused by the esterification of ethanol

29
Q

what are the 5 considerations during conditioning?

A

Flavour Maturation: The yeast remove undesirable compounds such as H2S, acetaldehyde, and diacetyl. This process is called purging.
Clarification: Green beer can contain 1 x 107 cells per mL. This would block your filter during filtration. Thus, the beer is allowed to settle so that yeast can be removed by sedimentation.
Stabilization: To prevent a non-biological precipitate to form during storage. Stabilizers are added to remove the precursors of this precipitate.
Carbonation: CO2 is more soluble at reduced temperatures, so a top pressure of CO2 is maintained in conditioning tanks.
Minimize Oxygen: Oxygen is low in green beer. If O2 finds its way back in, antioxidants are added

30
Q

are pathogens and issue with brewing?

A

nope. low pH, low nutrients, high ethanol content

31
Q

Anaerobic Beer Spoilers

A

LAB, turbidity, acid notes, and unwanted flavours

32
Q

Aerobic Beer Spoilers

A

are primarily AAB (Acetobacter and Gluconobacter) they will result in the oxidization of ethanol to acetic acid. There will be a “raft” of surface growth in the beer that will lead to generalize turbidity, and the infected beer may have a “ropiness” quality.

33
Q

grape must

A

At the start of the wine making process grapes are crushed and the grape must contains a yeast flora similar in numbers and composition of the grapes pre-harvest

34
Q

what is the role of sulfur dioxide in wine making?

A

Sulfur dioxide is added to kill natural species and allow wine specific Sc (which are resistant to sulfur dioxide) to carry out the fermentation, but despite the addition of sulfur dioxide several different species of yeast participate in the process
-SO2 can inhibit the growth of microbes by rupturing disulfide bridges in proteins, and reactions with cofactors. It can also deaminate cytosine to uracil which increases the likely hood of fatal mutations

35
Q

campden tablet

A
  1. used to sterilize. has very low levels of sodium metabisulfate, which traps oxygen and prevents it from harming the ferment.
  2. eliminate free chlorine
    3.
36
Q

what is a stuck fermentation?

A

when there is a premature cease in alcohol production.

37
Q

wine spoilage organisms:

A

LAB spoils some wine and adds flavour to others.

AAB is considered spoilage with off-flavours etc.

38
Q

what produces diacetyl?

A

homo and hetero LAB

FDSC 442 (19 decks)

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