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unit 4 lesson 4 Flashcards

1
Q

What are the key chemical components of hops?

A
  • Polyphenols
  • Total resins
  • Essential oils

These components play a crucial role in beer flavor and aroma.

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2
Q

Where are the lupulin glands found?

A

In the hop cone

Lupulin contains the total resins and essential oils.

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3
Q

What are the two types of total resins in hops?

A
  • Soft resins
  • Hard resins
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4
Q

What compounds are included in soft resins?

A
  • α-acids
  • β-acids
  • Uncharacterised components
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5
Q

What is the purpose of the lead conductance value test?

A

To quantify the amount of each component in hops

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6
Q

What are the homologs of α-acids?

A
  • Humulone
  • Cohumulone
  • Adhumulone
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7
Q

What are the homologs of β-acids?

A
  • Lupulone
  • Colupulone
  • Adlupulone
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8
Q

Why are α-acids important in hops?

A

They are isomerised during wort boiling into soluble and bitter iso-α-acids.

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9
Q

What is isomerisation?

A

The transformation of one molecule into another with the same atoms but a different arrangement.

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10
Q

What are the isomerised forms of humulone?

A
  • cis-isohumulone
  • trans-isohumulone
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11
Q

Which α-acid has the highest solubility?

A

Cohumulone

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12
Q

What factor has the greatest impact on hop utilisation?

A

pH

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13
Q

At what pH level can hop utilisation reach 90%?

A

8-10

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14
Q

What effect does boil time have on hop utilisation?

A

Longer boil times increase utilisation, up to a maximum of around 4 hours.

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15
Q

True or False: β-acids undergo isomerisation during wort boiling.

A

False

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16
Q

What are hulupones believed to contribute to in beer?

A

Synergise the bitterness of iso-α-acids

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17
Q

What are oxidised α-acids called?

A

Humulinones

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18
Q

How do humulinones affect beer bitterness?

A

They increase bitterness during dry hopping.

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19
Q

What is the major portion of the total hard resin fraction derived from?

A

β-acid derived hard resins

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20
Q

What is xanthohumol?

A

The bulk of the β-acid derived hard resin fraction

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21
Q

Fill in the blank: The hop cone is made up of _____.

A

[chemical components such as lipids, resins, acids, oils, proteins, etc.]

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22
Q

What happens to α-acids during the brewing process?

A

They decrease as hops are oxidised over time.

23
Q

What is the typical hop utilisation percentage in standard brewing?

24
Q

What is the relationship between hop age and α-acid levels?

A

α-Acid levels decrease as hops age.

25
What are hard resins primarily derived from?
Oxidation of soft resins ## Footnote Hard resins can be categorized into α-acids and β-acids, which transform into uncharacterised soft resins and then into hard resins.
26
What is the major component of β-hard resin?
Xanthohumol ## Footnote Xanthohumol is mostly lost during the brewing process and is isomerised into isoxanthohumol during wort boiling.
27
List some health problems that xanthohumol has been used to combat.
* Cancer * Inflammation * Viruses * Bacteria * Osteoarthritis * Diabetes * Atherosclerosis * Cellular damage due to free radicals ## Footnote Although beneficial, xanthohumol levels in beer are very low.
28
What percentage of polyphenols is typically found in hops?
Approximately 4% ## Footnote This percentage can fluctuate between 3-8% depending on the hop variety.
29
What are polyphenols also referred to as?
Tannins ## Footnote Tannins are a specific type of polyphenol.
30
What key role do polyphenols play in beer?
They complex with protein to form the bulk of beer haze and act as antioxidants. ## Footnote Polyphenols also affect beer mouthfeel and astringency.
31
What are the three categories of components found in hop oil?
* Hydrocarbons * Oxygenated fraction * Sulphur compounds ## Footnote Each category contributes differently to beer aroma and flavor.
32
What is the main hydrocarbon component of essential oil in hops?
β-myrcene ## Footnote β-myrcene comprises 30-70% of the total oil content and is thought to be the main contributor to the aroma of fresh hops.
33
True or False: Terpenes and terpenoids are the same.
False ## Footnote Terpenes are hydrocarbons, while terpenoids include compounds containing oxygen and are therefore not classified as hydrocarbons.
34
What is the aroma description of α-humulene?
Woody, piney ## Footnote α-humulene is a main sesquiterpene found in hops.
35
Fill in the blank: The oxygenated fraction of hop oil includes compounds that are more _______ and less likely to evaporate.
Polar ## Footnote The addition of oxygen to hydrocarbons results in a more polar compound.
36
What compounds are thought to contribute to noble hop aroma?
* Oxygenated products of α-humulene * β-caryophyllene ## Footnote These compounds can change in concentration as hops age.
37
What are polyfunctional thiols known for?
Imparting desirable fruity and tropical aromas ## Footnote Interest in these compounds has grown among brewers who dry hop.
38
What is the significance of the flavour threshold?
It is the minimum concentration at which the taste or aroma of a substance can be perceived. ## Footnote Some sulphur compounds have extremely low flavour thresholds.
39
What happens to geraniol during fermentation?
It decreases dramatically as it is converted into β-citronellol. ## Footnote This conversion is facilitated by yeast activity.
40
What role do esters play in beer flavor?
They are relatively soluble and contribute to dry and late hopped beer flavor. ## Footnote Yeast activity can encourage their formation from precursors.
41
What is the aroma description of linalool?
Floral, spicy ## Footnote Linalool is found in over 200 plants and contributes to fruity, hoppy aromas in beer.
42
What are some unpleasant sulphur compounds mentioned?
Cooked vegetable, musty, onion-like, cheesy ## Footnote Examples include polysulphides like dimethyl trisulphide, dimethyl tetrasulphide, and methyl methylthiomethyl disulphide
43
What are polyfunctional thiols known for in brewing?
Imparting desirable fruity and tropical aromas ## Footnote They are particularly of interest to brewers who dry hop
44
What does 'polyfunctional' mean in the context of polyfunctional thiols?
Having two or more functional groups ## Footnote Functional groups include thiol (S-H), carbonyl (C=O), hydroxyl (OH), ester (O-C=O)
45
What is the initialism for 3-mercapto-4-methylpentan-1-ol?
3M4MPol ## Footnote It is also known as 3-sulphanyl-4-methylpentan-1-ol
46
What descriptors are associated with 4-mercapto-4-methylpentane-2-one?
Ribes, blackcurrant, muscat-like, fruity ## Footnote Its initialism is 4-MMP (4MSP)
47
What are cysteinylated and glutathionylated precursors?
Compounds of interest bound to glutathione or cysteine ## Footnote They are known as cysteine S-conjugates and glutathione S-conjugates
48
What enzyme is responsible for converting polyfunctional thiol precursors into free thiols?
Cysteine S-conjugate β-lyase ## Footnote It catalyses the lysis of the carbon-sulphur bond between the thiol and cysteine
49
What is the aroma of S-methyl thiohexanoate?
Pineapple ## Footnote It is another sulphur compound with a fruity aroma
50
True or False: Sulphur compounds are significant in dry hopped beers.
True ## Footnote Their volatility means they are mostly significant in dry hopped beers unless produced by biotransformation of precursors
51
What is a key point about hop essential oils during brewing?
Most are lost during normal brewing processes ## Footnote What you smell in raw hops is unlikely to be what you smell in beer due to these losses
52
What should you be careful about when using certain compounds in brewing?
Small amounts can have a large effect on flavour and aroma ## Footnote This highlights the importance of precise measurements and selections
53
What should you be able to do regarding hop selection for beer?
Choose hops based on a hop analysis and intended final beer flavour ## Footnote This is a core outcome of understanding hop chemistry

IBD (15 decks)

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