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unit 4 lesson 8 Flashcards

1
Q
A
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2
Q

What is the modern method for selecting hops?

A

Hops are often selected by variety and laboratory analyses, with physical examination also important.

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3
Q

What should hops ideally be free of?

A

Hops should be free of pests and diseases.

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4
Q

What are key physical characteristics to evaluate in hops?

A

Key characteristics include colour, lupulin presence, mould, cone damage, moisture, size, and signs of pests/disease.

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5
Q

What does brown discoloration in hops indicate?

A

Brown discoloration may indicate oxidation or windburn.

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6
Q

What should the aroma of hops be like?

A

The aroma should be characteristic of the variety with no cheesy or chemical notes.

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7
Q

What does a cheesy aroma in hops suggest?

A

A cheesy aroma suggests oxidation.

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8
Q

What is the purpose of evaluating hop pellets?

A

Pellets should be evaluated for colour, aroma, and ease of breaking apart.

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9
Q

What is the recommended sampling method for hops?

A

Take 10-15 g samples from every bale or 200 g samples from a set number of bales.

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10
Q

What is the Lead Conductance Value (LCV) used for?

A

LCV measures α-acids levels in hops.

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11
Q

How is the absorbance of hop extracts measured?

A

Absorbance is measured in the UV range at three different wavelengths.

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12
Q

What does the equation for α-acids concentration involve?

A

The equation involves absorbance values at specific wavelengths.

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13
Q

What is the purpose of High Pressure Liquid Chromatography (HPLC)?

A

HPLC separates and measures the concentration of hop acids.

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14
Q

What is the significance of the factors for calculating bitterness units?

A

The factors account for the perceived bitterness provided by different hop products.

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15
Q

What is HPLC used for in beer analysis?

A

HPLC is the most accurate method for determining levels of each acid and the total level of iso-α-acids in beer. It can also be used to determine the polyphenol content.

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16
Q

How is total essential oil content analyzed?

A

Total essential oil content is analyzed using steam distillation. 100 g of hops are added to 3 litres of water and steam distilled over three hours with 8 mL/min of distillate collected. After distillation, the volume of essential oils in the distillate trap is measured and reported as mL/100 g.

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17
Q

What is the process for analyzing essential oil components?

A

To analyze each component of the essential oils, 100 μL of distilled essential oil is mixed with 900 μL of pentane or hexane to produce a 10% solution. 1 μL of the 10% solution is injected into a gas chromatography (GC) column.

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18
Q

What does IBU stand for?

A

IBU stands for International Bitterness Units, a value calculated from the results of spectrophotometry of bitter substances extracted from beer into iso-octane.

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19
Q

How is perceived bitterness affected?

A

Perceived bitterness can be affected by factors such as the amount of residual extract in the beer, carbonation, alcohol level, polyphenol level and types, and even the person tasting the beer.

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20
Q

What are beer style guidelines?

A

Beer style guidelines provide a bitterness range that organizations feel some consumers might expect for a particular beer style.

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21
Q

When can hops be added during the brewing process?

A

Hops can be added at various points during the brewing process, affecting beer flavor and yield of essential oils and bitter substances.

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22
Q

What is dry hopping?

A

Dry hopping is the addition of hops, or hop products, after wort cooling.

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23
Q

What factors affect the effectiveness of dry hopping?

A

Factors include particle size of hop, condition of lupulin glands, temperature of the beer, concentration gradient, contact time, alcohol concentration, dose rates, process losses, yeast, and enzyme products.

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24
Q

What is in-tank dry hopping?

A

In-tank dry hopping involves adding hops to the fermentation or maturation vessel before or after filling, often using mesh sacks for whole hops.

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25
What is the purpose of a hop back?
Hop backs are vessels used for removing whole hops after the boil or adding late hop aroma by introducing additional whole hops after the boil.
26
How are hop oil products added in large breweries?
Large breweries use a hop dosing vessel, a flow meter, and a pump to dose hop oil products in-line upstream of a static mixer directly into the beer line.
27
What is the effect of temperature on dry hopping?
As temperatures increase, the energy in the beer increases, driving dissolution and diffusion, thus faster extraction of flavor compounds.
28
What is a centrifugal pump used for in brewing?
Centrifugal pumps are used to add modern oil products to a vessel under agitation.
29
When should iso-extract and reduced hop extract be added?
They should be dosed just before filtration or the final product tank (FPT) if the beer is unfiltered.
30
How can iso-extract and reduced hop extract be added to beer?
They can be pumped directly in-line into the beer or diluted before dosing.
31
What happens if iso-extract and reduced hop extract are added after filtration?
Haze may form because some products are not completely soluble.
32
What is hop utilisation?
Hop utilisation refers to the effectiveness of hops in contributing to the beer's flavor and bitterness.
33
What factors affect hop utilisation?
Factors include pH, boil time, wort gravity, trub, temperature, pressure, hop age, hop product, quantity of hops added, wort boiling system, hop α-acid levels, wort composition, and foaming.
34
How does pH affect hop utilisation?
Higher pH levels increase hop utilisation; a pH of 8-10 can provide 90% utilisation, while a standard wort pH of 5.2 is around 35%.
35
What is the effect of boil time on hop utilisation?
Longer boil times increase utilisation, up to a maximum of around 4 hours.
36
How does wort gravity influence hop utilisation?
Hop utilisation is greater in lower gravity worts.
37
What is the impact of trub on hop utilisation?
Excessive trub formation can lead to greater loss of hop acids, reducing utilisation.
38
How does temperature affect hop utilisation?
Higher wort temperatures improve isomerisation, which enhances hop utilisation.
39
What is the relationship between pressure and hop utilisation?
Higher pressure allows wort to boil at higher temperatures, increasing hop utilisation rates.
40
How does hop age affect utilisation?
α-Acid levels decrease as hops oxidise over time, reducing utilisation.
41
What is the difference in utilisation between hop cones and hop pellets?
Hop pellets have better utilisation than hop cones due to more efficient extraction of α-acids.
42
What is the effect of the quantity of hops added on utilisation?
Increased hop quantity can reduce utilisation due to saturation effects.
43
How does the wort boiling system affect hop utilisation?
A vigorous boil enhances hop utilisation.
44
How do hop α-acid levels influence utilisation?
Hops with higher α-acid levels generally have higher utilisation.
45
What is the effect of wort composition on hop utilisation?
Wort pH, gravity, and trub levels all influence hop utilisation.
46
How does foaming affect hop utilisation?
Foaming can lead to loss of α-acids and iso-α-acids, reducing utilisation.
47
What are example hop utilisations for different hop products?
Whole Hops: ± 25%, T90 Pellet: ± 30%, T45 Pellet: ± 35%, Hop Extract: ± 40%, Isomerised Kettle Extract: ± 70%, Isomerised Hop Pellet: ± 65%, Iso-Extract: ± 90%, Rho Iso-Extract: ± 90%, Tetrahydro Iso-Extract: ± 70%, Hexahydro Iso-Extract: ± 70%.
48
How can you estimate hop utilisation for a specific brewing stage?
Perform a brew with a single hop addition at the stage needed and measure the IBUs.
49
Why is knowing hop utilisation important for recipe development?
It dictates the IBUs achieved in the new beer.
50
How does changing hop addition at one stage affect subsequent stages?
It alters the utilisation at subsequent addition stages.
51
What are α-Acids?
The primary bittering compounds found in hops, converted to iso-α-acids during brewing to impart bitterness to beer.
52
What are β-Acids?
Compounds in hops that contribute to bitterness but are less soluble and less bitter than α-acids.
53
Define Biotransformation in brewing.
The chemical modification of hop compounds by yeast during fermentation, altering the aroma and flavor profile of the beer.
54
What are Bitterness Units (BU)?
A measure of the bitterness of beer, calculated based on the concentration of bitter compounds extracted from hops.
55
What is Cask Conditioning?
A traditional method of secondary fermentation in the cask, where beer undergoes further fermentation and maturation with added hops.
56
What is Cone Damage?
Physical damage to hop cones, affecting their quality and suitability for brewing.
57
What does Contact Time refer to in brewing?
The duration for which hops are in contact with the beer, affecting the extraction of flavor and aroma compounds.
58
What is Dry Hopping?
The addition of hops to beer after fermentation to enhance hop aroma without significantly increasing bitterness.
59
What are Essential Oils in hops?
Volatile compounds in hops that contribute to the aroma and flavor of beer.
60
What is Flame Ionization Detection (FID)?
A method used in gas chromatography to detect and quantify volatile compounds by measuring the ions produced in a flame.
61
What is Gas Chromatography (GC)?
A technique used to separate and analyze volatile compounds in a mixture, often used to profile essential oils in hops.
62
What is a Hop Back?
A vessel used to strain wort through whole hops after boiling, extracting hop oils and filtering out trub.
63
Define Hop Grist.
The amount and type of hops used in a brewing recipe, calculated to achieve the desired bitterness and aroma.
64
What is a Hop Pellet?
Compressed hop material formed into small pellets, easier to store and use than whole hops.
65
What is Hop Tea?
A method of evaluating hop aroma by steeping hops in hot water and smelling or tasting the resulting infusion.
66
What does Hop Utilization refer to?
The efficiency with which α-acids are converted to iso-α-acids during brewing, influenced by pH, boil time, and wort gravity.
67
What are Humulones?
The main α-acids found in hops, including humulone, cohumulone, and adhumulone.
68
What are International Bitterness Units (IBU)?
A standardized measure of beer bitterness, typically equivalent to 1 mg of iso-α-acids per liter of beer.
69
What are Iso-α-Acids?
The bitter compounds formed from α-acids during the boiling of wort, responsible for the bitterness in beer.
70
What is the Lead Conductance Value (LCV)?
A method for measuring α-acids in hops by monitoring the conductivity of a solution during titration with lead acetate.
71
What is Lupulin?
The yellowish powder found in hop cones, containing essential oils and resins responsible for bitterness and aroma.
72
What is a Maturation Vessel?
A tank used for the aging and conditioning of beer after fermentation, where dry hopping can also occur.
73
What are Polyphenols?
Compounds in hops and malt that contribute to flavor, mouthfeel, and stability of beer, affecting bitterness.
74
What is a Recirculation Loop?
A system used to circulate beer through hops or other materials to enhance extraction and mixing.
75
What is Spectrophotometry?
A method for measuring the absorbance of light by a solution, used to quantify α-acids, β-acids, and bitterness in beer.
76
What is Steam Distillation?
A technique for extracting essential oils from hops by passing steam through the hops and collecting the condensed distillate.
77
What is Trub?
The sediment formed during the brewing process, consisting of coagulated proteins, hop particles, and other solids.
78
What is Ultraviolet (UV) Light Absorbance?
A method for measuring the concentration of α-acids and β-acids in hops by their absorbance of UV light at specific wavelengths.
79
What are Aroma Compounds?
Volatile compounds in hops that contribute to the aroma of beer, including essential oils and other aromatic substances.
80
What are Bittering Hops?
Hops added early in the boil to impart bitterness to the beer, primarily through the conversion of α-acids to iso-α-acids.
81
What is Cold Crashing?
The process of rapidly cooling beer after fermentation to encourage yeast and other particulates to settle out, often used before dry hopping.
82
What are Cryo Hops?
A concentrated hop product created by separating lupulin from the hop cone, providing intense flavor and aroma with reduced vegetal matter.
83
What is First Wort Hopping?
The addition of hops to the wort as it is being collected from the mash tun, believed to enhance hop flavor and aroma.
84
What is Hop Aroma?
The characteristic smell of hops, which can include notes of citrus, pine, floral, spicy, and fruity, depending on the hop variety.
85
What is Hop Extract?
A concentrated form of hops, often used for bittering, that can be added at various stages of the brewing process.
86
What is a Hop Spider?
A mesh container used to hold hops during the boil, making it easier to remove them from the wort after boiling.
87
What is Iso-octane used for?
A solvent used in the spectrophotometric analysis of beer bitterness, extracting iso-α-acids from the beer for measurement.
88
What is Late Hopping?
The addition of hops towards the end of the boil or during whirlpooling to enhance hop aroma and flavor without adding significant bitterness.
89
What are Lupulin Glands?
The glands within hop cones that contain the resins and essential oils responsible for bitterness and aroma.
90
What is Oxidation?
A chemical reaction that occurs when hops or beer are exposed to oxygen, leading to off-flavors and reduced quality.
91
What are Pre-isomerized Hops?
Hops that have been processed to convert α-acids to iso-α-acids before being added to the wort, providing higher utilization rates.
92
What is Secondary Fermentation?
The fermentation that occurs after the primary fermentation, often in a separate vessel, where additional hops may be added for dry hopping.
93
What is the Utilization Rate?
The percentage of α-acids that are converted to iso-α-acids during the brewing process, affecting the final bitterness of the beer.
94
What is Whirlpooling?
A process where the wort is rapidly stirred after boiling to create a vortex, helping to separate trub and improve hop extraction.

IBD (15 decks)

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