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FDSC442 > Lecture 4: Beer wine and Cider > Flashcards

Lecture 4: Beer wine and Cider Flashcards

1
Q

define beer

A

a solution of water, alcohol, and carbon dioxide that is flavored by carbohydrates, proteins, minerals and different aromatic compounds that it aquires from malt, hops and yeast

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2
Q

define brewing

A

its the combined process of preparing beverages from the infusion of grains that have undergone sprouting and subsequent fermentation of the sugary solution produced, by yeast - where a proportion of the carbohydrates is converted to ethanol and carbon dioxide

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3
Q

How can you know how alcoholic your final brew will be?

A

gravity density of the wort. It is a measure of calculating the amount of dissolved substances, largely sugars that will be converted into alcohol.

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4
Q

gravity can be expressed as ____. State how you would calculate.

A

Plato or original gravity. Using hydrometer or refractometer

OG=ratio of density relative to pure water.

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5
Q

Gravity reading of 1.040 results in what %ABV

A

4.0% (last significant digit)

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6
Q

Hydrometer

A

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

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7
Q

Refractometer

A

measures the original gravity only. based on the refractive properties of sugar. alcohol distorts the reading.

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8
Q

is how much gravity is left after the fermentation is finished and can be used to calculate the alcohol content of the finished beer (or wine or cider)

A

Terminal gravity

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9
Q

How do you calculate %ABV

A

ABV= (OG-TG) * 131.25

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10
Q

What 4 measurements are important in beer. Provide small defintions for each.

A
  1. ABV = % ethanol in the finished beer
  2. Colour; measured using spectrophotometer. Tristimulus is used to assess the colour
  3. Bitterness; measured in BU which relates to ppm of isomerized alpha acid
  4. attenuation; measures how complete a fermentation is; (OG-TG)/OG
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11
Q

How can attenuation in beer be altered?

A
  • sugar type
  • mashing method
  • composition of wort
  • type of yeast
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12
Q

High attenuation signifies ____ beer while ____ apparent attenuation signifies ___ beer

A

dry beer, low and sweet beer

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13
Q

Malting

A

the process of allowing the grain to germinate (soak in water)

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14
Q

what is the purpose behind malting of barley?

A

to transform the food reserves in the grain into substrates that are convienent for fermenting in the brewery

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15
Q

Explain the process of malting

A
  1. moisture content of grains at the start should not be more than 20%
  2. to commence the malting of the grains, are soaked –> at 42-46% moisture germination starts
  3. intermittent periods of drainage when air is blow through
  4. CO2 is dispersed to promote germination
  5. air blown and grains are turned slowly in drums
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16
Q

Define Milling.

A

the process that breaks down malt into smaller fermentatable sizes

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17
Q

What are the two types of milling

A

wet and dry

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18
Q

Define Mashing

A

process where ground malt is mixed with brewing water such that fermentable extract is produced that will suppport the growth of yeast.

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19
Q

What is produced after mashing

A

wort

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20
Q

what is added to the wort to iniate fermentation?

A

Saccharomyces cerevisae

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21
Q

What is the issue with adding too much or too little Sc to the wort?

A

too little = slow initial fermentation

too much = competition between yeasts and poor growth

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22
Q

yeast stress in beer fermentation can lead to ____

A

fusel alcohol production

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23
Q

yeasts can grow under what conditions?

A
  • aerobically or anaerobically
  • anaerobic conditions are essential for the production of alcohol by yeast, sugar up-take is diminished in the prescne of oxygen
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24
Q

why doesnt fermentation proceed for as long as possible in anaerobic conditions and as long as hexoses are available

A
  • budding requires cell wall synthesis which cant happen under anaerobic conditions
  • ethanol at high levels becomes toxic to yeasts
  • when fermentation slows the yeast cells floculate and sediment out
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25
Q

what happens during the exponential growth phase

A

yeast density can increase 4-6 fold. at this stage yeast are at their highest level of utilizing sugars and producing ethanol + co2.

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26
Q

how are esters formed in beer? what kind of taste do they impart to the beer?

A

esterification of ethanol. they impart a fruity taste

27
Q

during the exponential growth phase, a considerable amount of heat is producd and cooling is needed to keep the temp down to 20-22 deg C. What can happen if this is not respected?

A

high fusel alcohol will be produced –> off flavors

28
Q

Post fermentation: what are 5 considerations during conditioning? (FC,C,S,C,MO)

A
  1. flavour maturation
  2. clarification
  3. stabilization
  4. carbonation
  5. minimize oxygen
29
Q

Flavour maturation

A

yeast remove undesirable compounds like acetaldehyde, diacetyl and H2S. purging

30
Q

Clarification

A

settle so that yeasts can be removed by sedimentation

31
Q

What is done to prevent non biological precipitate to form during storage?

A

stabilizers are added to remove precursors of this precipitate

32
Q

Oxygen is ___ in green beer.

A

low

33
Q

T or F: Pathogens are an issue with brewing

A

F

34
Q

T or F: wort and beer are prone to spoilage microorganisms. why or why not

A

T; provide nutrient rich, oxygenated environment

35
Q

why isnt beer a good media for bacteria?

A

low ph, ethanol concentration and largely devoid of nutrients

36
Q

T or F: spores can make it into canned beer and germinate

A

F; they will not likely germinate

37
Q

cause turbidity, acid notes and unwanted flavours in Beer

A

LAB; pediococcus and lactobacillus

38
Q

Effect of zymonas in beer

A

infects cask-conditioned beers resulting in cider sickness, where there is secondary fermentation with much frothing, a loss of sweetness and off-odours due to hydrogen sulfide and acetaldehyde production

39
Q

effect of megasphaera

A

produces hydrogen sulfide in beer producing rotten egg smell. cannot tolerate more than 2.8% abv so only effects low alcohol beers

40
Q

effect of pectinatus in beer?

A

rapidly converts finished beer into propionic acid, acetic acid, succinic acid, lactic acid and hydrogen sulfide given beer rotten egg smell

41
Q

aerobic beer spoilers mainly include

A

AAB (acetobacter and gluconobacter)
oxidize ethanol into acetic acid. This results in a raft; surface growth in the beer that will lead to generalize turbidity and ropiness quality.

42
Q

What is added to most fruit wines

A

sugar cane

43
Q

what are superior wines?

A

They are vintage wines and cannot be blended with other wines. non vintage wines are generally blended so that wine makers can still have an acceptable product even in bad years

44
Q

Explain the simple/general wine making process

A

sampling –> harvest –> crushing –> fermentation –> blending –> stabilization –> aging –> filtration — bottling

45
Q

Explain the process for making red wine

A
  1. crushing + adding sulfur dioxide –> obtain juice and skins
  2. innoculate with yeast
  3. maceration and partial fermentation
  4. pressing
  5. completion of alcoholic fermentation followed by racking off yeast lees
  6. wine –> malolactic fermentation
  7. aging in oak barrels
  8. finding, clarification and packaging
46
Q

Explain the process for making white wine

A
  1. crushing –> addition of sulfur dioxide
  2. pre-fermentation treatments settling
  3. pressing (removal of skins)
  4. juice
  5. inoculation with yeasts optional
  6. racking off yeast lees
  7. malolactic fermentation oak barrels
  8. aging
  9. fining, clarification and packaging
47
Q

explain the fermentation (phases) involved in wine fermentation

A

lag phase –> few hours
short growth phase
long stationary phase during which most of the alcohol is converted to sugar

48
Q

what is malolactic fermentation?

A
  1. its not important in all wines but it helps in the taste development. during this process L-malic acid is converted is converted into L-lactic acid and carbondioxide. Several LAB can carryout this reaction but commercial strains of oenococcus onesie are generally used
49
Q

what are the management conditions used to make sure brewing Sc dominate the fermentation and other yeasts are removed in wine

A
  1. sulfiting
  2. anerobic conditions
  3. rapid and complete exhaustion of sugars
50
Q

what is the purpose of adding sulfur dioxide to wine?

A

kill natural species and allow wine specific Sc (which is resistant to sulfur dioxide_ to carry out fermentation.

It can inhibit growth of microbes by rupturing disulfide bridges in proteins and reactions with cofactores. It can also deaminate cytosine to uracil which increases the likelihood of fatal mutations.

51
Q

what leads to sulfite resistance in wine yeast?

A

reciprocal translocation between chromosome 8-16.

translocation results in dominant allele sulfite pump –> SSU!-R1 which is expressed at high level and leads to sulfite resistance

52
Q

what is the function of campden tablets?

A
  1. sterilize wine –> sodium metabisulfite
  2. eliminate free chlorine
  3. antioxidizing agent when transferring wine between containers (sodium metabisulfite traps oxygen and prevents harm)
53
Q

what is the function of potassium sorbate in wine?

A

halt yeast and preserve wine

54
Q

what is a stuck fermentation?

A

problem during wine fermentatiwhere there in premature cessation of alcohol production in the fermentation

55
Q

causes of stuck fermentations?

A
  1. nutrient deficiency
  2. inhibitory substances
  3. killer toxins
  4. low ph
  5. pesticides
  6. temp (too low or too high)
56
Q

why compound is produced by LAB in wine which may indicate signs of spoilage at high concentrations?

A

diacetyl

57
Q

what are 3 signs that wine has been spoiled?

A
  1. mold growth
  2. slime and ripiness
  3. taste like vinegar (AAB)
58
Q

what is added to cider to prevent contamination with AAB?

A

sulfur dioxide

59
Q

what is malt vinegar

A

is made from malting barley which results in the conversion of starch to maltose. the maltose is converted to ale and then turned into vinegar which is then aged. it is typically light brown in color

60
Q

what is cider vinegar

A
  1. made from apple juice through a double fermentation with alcohol and acetic acid fermentation in the same barrel by naturally occuring yeast and acetic acid bacteria
61
Q

process of making traditional balsamic vinegar?

A

is made only in modena italy with cooked grape; 3 step process

  1. conversion of sugars to ethanol by yeast
  2. oxidation of acetic acid by AAB
  3. 12 years of aging in a barrel
  4. final product = dense, dark brown and sweet/sour taste
62
Q

rice vinegar

A

made from fermented rice wine
produced via static surface fermentation
acidity = 10%
Acetobacteria

63
Q

3 types of rice wine vinegar (KKK)

A
  1. komesu
  2. kurosu
  3. kasuzu

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