1
Q
What are the nine steps of beer brewing
A
- Malting
- Milling
- Mashing
- Wort separation
- Boiling
- Hop separation
- Wort cooling
- Fermentation
- Maturation/aging
2
Q
Milling
step two of beer brewing
A
Grinding your malted grain into cracked husks (NOT powder) to act as a filtering agent in wort separation (step 4)
3
Q
Mashing
step three of beer brewing
A
using milled barley to produce wort and solids
4
Q
Four mashing methods
A
- infusion mashing
- traditional decoction
- double mashing
- temperature programmed mashing
5
Q
Infusion mashing
A
- German, English, and Belgian ales
- required a perfeclty malted/ germinated grain
- grist floats and wort is pulled from the bottom
- no stirring
6
Q
Traditional decoction
A
- Bavarian and Czech beers
- can be performed more than once
- part of mixture is removed, boiled, and then returned
7
Q
Double mashing
A
- American
- Tun for cereal and for malt
8
Q
Temperature programmed mashing
A
- gives great control over mashing
- using heated coils
9
Q
Explain the starch iodine test used to test wort
A
Bright blue = iodine + amylose
light blue = iodine + amylopectin
brick red= iodine + limit dextrinases
10
Q
Explain the function of alpha amylase in mashing
A
cuts alpha 1-4 linkages in amylose and amylopectin
- heat stable
11
Q
Explain the function of Beta amylase in mashing
A
cuts amylose and amylopectin from non-reducing ends
- heat unstable
12
Q
Explain the function of limit dextrinases in mashing
A
cleaves amylose and amylopectin at alpha 1-6 linkages
- not heat stable
13
Q
In well mashed batches the wort is —- to —- fermentable sugars (—- and —-)
A
- 75%
- 78%
- Maltose
- Maltotriose
about 20% is non fermentable and not good on calories
14
Q
Brewers window
A
the ideal temperature where extractable fermentable sugars are at their height
- want soluble/ extractable amylose
15
Q
Endopeptidases
A
Cut amide bonds in proteins from the middle
- heat unstable
16
Q
Exopeptidases
A
cuts amide bonds in protiens from the ends
- heat stable
17
Q
What are the two main approaches to wort separation?
step four in beer brewing
A
- Lauter tun
- Mash filter
18
Q
Lauter tun (wort separation)
A
Grist sinks to bottom and acts as filter for wort
19
Q
Mash filter (wort separation)
A
- used by much smaller breweries because it cannot do the volume a lauter tun can
- uses a filtration system to separate wort and grist by pressure
20
Q
Sparging
A
Hot water sprayed over grist to release as much wort as possible
21
Q
Explain the purpose of wort boiling
fifth step in beer brewing
A
- unique to beer brewing and is not used in distilled products
- sterilizes the wort
- formation of trub
- extracts the bitterness of the hops
22
Q
Explain hops separation
sixth step in beer brewing
A
- hops added in early contribute to flavor, added in late contributes to aroma
- formation of iso-alpha acids that contribute to the bitterness
23
Q
What catalyzes the formation of iso-alpha acids in hops separation?
A
heat from the boiling
24
Q
What makes beers skunky?
A
When a beer is in a clear or green can interaction with sunlight forms a compound (isopentenyl mercaptan) that is actually found in skunk spray
25
Acterobacter
| fermentation, step eight of beer brewing
produces acetic acid
26
Lacobacillus/ pedioccocus
| fermentation, step eight of beer brewing
produces lactic acid
27
The three phases of yeast growth during mashing
1. aerobic/respiration
2. anaerobic/ fermentation
3. flocculation
28
What happens during the aerobic/ respiration portion of yeast growth?
Unsaturated fatty acids are formed and sterols are made for cell walls
29
What happens during the anaerobic/fermentation portion of yeast growth?
CO2 + ethanol is produced
30
What happens during the flocculation step of yeast growth?
the temperature is decreased and cells clump together
31
What are the three parts of maturation
| ninth and final step of beer brewing
1. carbonation
2. clarificiation
3. stabilization
32
How is carbonation performed during the maturation part of beer brewing?
CO2 is trapped with the green beer and forced to saturate into the liquid
33
How is clarification performed during the maturation step of beer brewing?
centrifuging, filtering, etc.
- cooled to remove tannins/proteins
34
How is stabilization performed during the maturation step of beer brewing?
sterilizing the beer to remove bacteria and removal of reductants
35
---- causes degredation of beer flavors by formation of ---- ----
1. oxygen
2. hydroxyl
3. radicals
36
How do we identify radicals in a degrading beer?
by electron paramagnetic resonance
37
Why do we add adjuncts?
1. stabilization of a beer
2. for flavor
3. to get a better foam
4. to make a light beer
38
Equation to convert standard reference method/lovibond to european brewing convention
SRM *1.97 = EBC
39
Specific gravity
the density of a solution compared to pure water
- specific gravity = degree plato* 0.004 +1
- degree brix= 231.61(specific gravity * 0.9977)
| ex: 1.015 is 1.015 times denser than pure water
40
Original gravity
the specific gravity before fermentation
41
Final gravity
the specific gravity after fermentation
42
ABV%=
(original gravity - final gravity) *132.715
43
International bitterness units (IBU)
the concentration of iso-alpha-acids in ppm
| calculated by UV-Vis, mass spec., HPLC, and fluorescence
44
# True or false?
Bubbles make compounds more volatile?
True!
- this is why it is so important to have the right amount of head in a beer
45
# True or false?
Distilled spirits are less regulated than beer and wines?
False, distilled spirits are more regulated by law, definition, and taxes
46
Distillation is a --- technique
purification
47
What are the components of a moonshine distillery?
1. moonshine still
2. thumper keg
3. worm box
48
What are the three types of stills we discussed?
1. pot still
2. column still
3. hybrid still
49
Pot still
- used for scotch whisky, tequila, and rum
- one distillation: 80-120 proof
- second distillation: 140-170 proof
50
Column/ Coffey still
- many different plates where each plate essentially gives its own distillation
- constant refluxing where components are separated by boiling point
- rectification and stripping sections
51
Explain the rectification section of a column still
this is where concentration of the liquid occurs
- top part of the column
52
Explain the stripping section of a column still
this is where components or compounds are removed
- bottom of the column still
- coldest part
53
Hybrid still
pot still and column still
54
Azeotrope
when a mixture of two or more susbtances behaves as a pure substance such that the components of the mixture cannot be separated
- found at the top of vapor curve where the two curves come together
| ex: water and ethanol, methanol and water
55
Using the example of a vapor curve, why is it so difficult to make a vodka without a column still?
We notice that the more distillations you do the smaller the change in proof. So, vodka at 92% ABV is very difficult because it requires many distillations and that is best done in a column still.
56
Heads
compounds with a lower bp than ethanol
57
Hearts
ethanol, or the liquid you want to collect and age
58
Tails
compounds with a higher bp than ethanol
59
Thin stillage
liquid stillage, can be collected, purified and reused
60
Dry stillage
solids, can be used to feed livestock for nutritional benefit
61
Scotch whisky
- must be made in Scotland
- uses barrels for caramel coloring
62
American whiskey/ Bourbon
- Must be made in the united states
- one of the most regulated/ strictly defined
63
Legal definition of american whiskey/bourbon
must be produced in the US, at least 51% corn, new charred oak barrel container, distilled to < 160 proof and bottled >80 proof
64
During barrel aging what determines the color and flavor of an alcohol?
the char of the barrel determines the color while oxygen reactions with primary alcohols creates the different flavors
65
What kind of transitions and what wavelength is UV and Vis?
UV and Vis are electronic transitions
- UV: 180-380 nm
- Vis: 380-780 nm
66
What kind of transitions and wavelength is NIR and IR
Both are vibrational transitions
- NIR: electronic, 0.78-2.5 um
- IR: rotational, 2.5-5.0 um
67
Summarize a UV- Vis absorbance instrument
- follows beers law of absorbance
- more conjugation increases absorbance
- want to pick a solvent with no background noise so analyte signal is not overshadowed
68
Three limitations to Beers law
1. Work with solutions with a concentration <0.01 M
2. No stray/outside light
3. Monochromatic light only (importance of gratings)
69
Why is NIR a better option than regular IR for testing beer?
Beer has a high water content which can degrade IR sample holders and produce distracting peaks on the spectra. NIR detects the distinct methyl group with little influence from other compunds such as water.
- Beer is also too complicated of a matrix for regular IR analysis
- NIR gives very accurate ethanol readings
70
Three steps of electrothermal atomization
1. Dry the sample
2. Ash the sample
3. atomize sample to Mo
71
Summarize an atomic absorbtion instrument
| M^(n+) (aq) ---- Mo (g)
- Inexpensive
- Can only do one metal at a time because the source is atom dependent and source needs to be switched each time
- LOD: ppm
72
Summarize an atomic flame emission instrument
| M^(n+) (aq) --- M*(g) + hv
- inexpensive
- only for alkali metals
- change in the flame color can represent what alkali metal is present
- LOD: ppm
73
A grating/ monochromator is essential for most instrumentation but why is it particulalry important for AES?
because you want to narrow/ reject all flame light possible
74
Summarize an induced coupled plasma emission instrument
| M^(n+) (aq) --- M*(g) + hv
- Expensive
- fast with multiple metal detection
- LOD: ppb
75
Summarize an induced coupled plasma mass spectrometry instrument
| M^(n+) (aq) --- M+(g)
- The most expensive
- can detect isotopes which other instruments cannot
- LOD: ppt (best/ lowest detection limits)
76
How do we use VIS to test for color in beer?
- the color of beer comes from the drying step of malting
- a reaction of an amine + carbohydrate gives the yellow color of beer
- abs. at 430 nm
77
How do we test for IBU using UV?
- extract beer using an isooctate to detect iso-alpha acids
- abs at 275
78
Why is testing for IBU using UV not a selective test?
Because lots of things absorb at 275 nm so there can be lots of background
79
How do we use VIS to test for carbohydrates in beers?
- Using anthrone colorimetry where a blueish green complex is formed that can be detected
- this method can tell the difference between a regular beer and a light beer
80
How do we test for proteins using UV or VIS?
By detecting the aromatic amino acids like tryptophan and tyrosine
- abs at 280 nm
81
How do we test for phenolics in beer using VIS?
By testing for pH and color to determine the amount of phenolics present
82
Why is Ca an important metal in beer?
It is important for amylase activity
| we saw this in lab 2 (EDTA data)
83
Why is Mg an important metal in beer?
Mg is beneficial to yeast in small amounts but gives a sour or bitter taste in high amounts
84
Why is K an important metal for beer?
potassium is required for yeast growth but is salty at high concentrations
85
Boltzmann distribution
N* /N = (g* /g)e^(- delta E/kT)
- highly dependent on temperature
- tells us the distribution of exicted state and ground state molecules
86
Five types of adjuncts
1. Raw Cereals (Barley and wheat)
2. Raw grits (corn, rice sorghum)
3. Flaked (corn, rice, barley, oats)
4. Syrups (corn, wheat, barley)
5. Malted cereals
87
Hydrometer
floats in the liquid, read meniscus to get a value of Brix or Plato
88
Refractometer
the sugar in the solution refracts light that gives the value of specific gravity or in Brix
89
How do you choose a wavelength range for linearity of Beers law from a plot of abs vs. wavelength?
Choose where there is a peak/ slop is zero because that produces a linear abs. vs concentration curve
90
Why is ICP a better choice than flame, using the Boltzmann distribution?
ICP excites more molecules to N * or the higher energy level excited states. The greater the number of atoms in the excited state the lower the LOD and sensitivity
CHM 436 (fermentation)
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