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Food 1130: Traditional alcoholic beverages > Beer part 3: Boiling > Flashcards

Beer part 3: Boiling Flashcards

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1
Q

What is the hop plant related to?

A

Nettle

Hemp

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2
Q

What part of the hop plant is used in brewing?

A

Dried flowers of the female plant

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3
Q

When did hops become the main flavouring agent of beer and who were they used by?

A

13-15th Century

Used by Egyptians

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4
Q

When were hops banned in ale?

A

1471

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5
Q

What happened when hops were allowed in English beer?

A

Strong and sweet unhopped beer was sold alongside it for 100 yrs

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6
Q

What are the 3 main functions of the hop?

A
  • To preserve beer
  • To counter malt sweetness with bitterness
  • to provide aroma and flavour
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7
Q

What type of plants are hops and what growing conditions do they require?

A

Climbing plants grown on wire supports

Require 13 hrs of sunlight a day - only grown in narrow zone around the world

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8
Q

Where are the main UK hop growing areas?

A

Kent
Hereford
Worcester

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9
Q

When are hops harvested and what happens to them?

A

Once a year in autumn, then dried in storage like most flowers

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10
Q

How are hops dried?

A

In oast houses, kilns or sun dried

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11
Q

What temperatures are used to dry hops and why?

A

Below 71 C

They can supply volatile aromatic oils - a compromise between loss of oils and drying times gives temps used for drying

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12
Q

What happens to hops after drying?

A

Packed into 7’ by 2’ pockets

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13
Q

Which countries are the main producers of hops?

A

Germany

USA

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14
Q

Which countries produce specific in demand hops?

A

Czech Republic
UK
New Zealand

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15
Q

How can you by dry hops and why?

A
  • Crushed and processed into pellets
    -Compacted as dry cones a
    = vacuum sealed in foil bads
  • This is done to protect the alpha acids from oxygen and protect them from exposure to light (speeds up deterioration)
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16
Q

What temperature are hops that lose their aromatic oils straight after harvest stored at?

A

-3 C

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17
Q

When is the use of whole hops preferred?

A

If you need better control over the hopping process - particularly if using a hopback or during dry hopping

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18
Q

Give 4 advantages of pellet hops

A
  • Less storage space required
  • Cheaper (maybe lower quality?)
  • Extraction efficiences improve (10% more bittering compounds)
  • Easier to clean equipment afterward
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19
Q

What happens to hops once open to the air?

A
  • degenerate rapidly

- most resultant ‘off’ flavours are lost on boiling

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20
Q

What are the different hop classifications?

A

Bittering (>40 types)
Aroma (>90 Types)
both bittering and aroma (>130 types)

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21
Q

Why are new varieties of hops being developed?

A

For disease resistance or better bittering qualities - also have excellent aromas

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22
Q

How are hops quantified?

A

By their content of alpha acids

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23
Q

Why do the beta acids in hops need to be monitored?

A

They add ‘off’ tastes when oxidised

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24
Q

What is the source of bitterness in hops?

A

Alpha acids

Concentration used to indicate degree of biterness

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25
Q

What is the most prevalent form of alpha acid in hops?

A

Humulone

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26
Q

What happens to alpha acids in hops?

A

They are isomerized into iso-alpha acids by the application of heat - these are the bitter compounds in beers

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27
Q

What are the flavour of cohumulone and humulone?

A

Harsher flavour
Soft flavour
- debatable on which is best

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28
Q

How is alpha acid concentration determined?

A

By extraction

- it will vary from season to season depending on growing conditions

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29
Q

What happens to alpha acids over time in storage?

A

They lose strength slowly

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30
Q

What do hops contain as well as alpha acids?

A

Beta acids

Essential oils - the aroma compounds

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31
Q

What happens to beta acids when hops are boiled?

A

They do not change form but do form bitter compounds when oxidised

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32
Q

What are the 4 main hop essential oils?

A

Myrcene
Humulene
Caryophyllene
Farnesene

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33
Q

What is myrcene?

A

Hop essential oil
- floral, grassy or citrus aromas in beer, generally 50% of the oils in hop cone.
Used in perfumery

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34
Q

What is humulene?

A

Hop essential oil
- woody, earthy and herbal aromas, better at withstanding high temps than myrcene. Present in high concentrations in noble hop varieties.

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35
Q

What is caryophyllene?

A

Hop essential oil

- woody spicy and earthy aroma, present in low concentrations

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36
Q

What is farnesene?

A

Hop essential oil
Very low concentration 1-10% of total oils, woody, citrusy and herbal aromas.
Generally only found in noble hop varieties.

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37
Q

What are the main reasons for boiling? (9)

A
  1. Sterilisation of the wort to provide non-competitive environment for the yeast
  2. Termination of all enzymatic activity - the boil in effect fixes the composition of the wort.
  3. Extraction of essential oils, polyphenols and preservatives from the hops
  4. Utilisation of hops for beer flavour profile: - for bittering from isomerisation - aroma properties if added at end of the boil
  5. Reduction in volume of wort to correct for any dilution from sparging
  6. Removal of protein and tannins by encouraging coagulation and so precipitation
  7. Decomposition/loss of undesirable volatile compounds.
  8. Enhancement of the colour of the wort (10% of proteins/sugars undergo maillard reaction)
  9. COmpletion of chemical reactions from mashing so lowering ph
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38
Q

What are kettle adjuncts?

A

Wort extenders

- adjuncts added during the boil to increase the alcoholic content. At least 10% conc they will not affect flavour

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39
Q

Give examples of kettle adjuncts

A 
Honey
Rice syrup
Corn syrup
Candi sugar
Or starch derived syrups e.g. maltose and malt extract
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40
Q

What is the efficiency of kettle adjuncts?

A

100%

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41
Q

When should kettle adjuncts be added and why?

A

Hop utilisation is affected by the gravity of the boil so better to add them towards end
- but leave time to sterilize - 15 mins

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42
Q

What adds flavour to the boil?

A

Hops through resins and essential oils

- they add bitterness and aroma

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43
Q

When should hop essential oils be added?

A

towards end of boil as the aroma will be lost after 5-10 mins of boiling

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44
Q

When should bittering hops be added to the boil?

A

At the start - if relying on aroma not bitterness then add additional at the end, but both can be added at the start

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45
Q

What is dry hopping?

A

When dry hops are added to the finished beer in the fermentation vessel - get no bitterness as there is no heat

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46
Q

What is hop-back?

A

When hops installed in-line between boiling and cooling process, ensures essential oils aren’t lost.

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47
Q

Generally when are hops added?

A

At start of boil for bittering and a few at the end for aroma

48
Q

What regarding hops causes bitterness?

A

Hop resins (containing alpha and beta) alpha acids

49
Q

What properties do the alpha acids found in hop resin provide to the beer?

A
  • Preservation, as mild antiseptic, prevents bacterial spoilage
  • Not bitter themselves are important to bitter taste, they’re insoluble at room temp so need to be boiled
50
Q

What happens to alpha acids when boiled?

A

Undergo a chemical transformation (isomerization) to more soluble and bitter iso alpha acids

51
Q

What does isomerisation cause?

A

Increased water solubility

52
Q

Why is a relatively long boiling time required?

A

As it’s not particularly efficient way of isomerising due to the pH of the wort.

53
Q

What is utilisation in the boil?

A

When the yield increases with alkalinity - so the wort pH (5.2-5.6) is not ideal - less than 50% of the alpha acids will be converted within the 2 hr boil.

54
Q

What happens to beta acids during the boil?

A

They don’t isomerise, they have a negligible effect on beer flavour. They contribute very slightly to beer’s bitter aroma.

55
Q

What happens to beta acids in the long term?

A

They may oxidise into compounds that can give beer off-flavours of rotten veg, cheese or cooked corn. - so ratio fo beta to alpha acids is often monitored

56
Q

What are hop extracts?

A

Mainly just alpha acids and essential oils - can be added instead of whole hops or pellets - similar to use of malt extracts

57
Q

What is a hot break?

A

The coagulation of proteins during the boil.
Solids are known as hot trub and traditionally removed by filtering through the spent hop bed after boil - can be carried out during ‘hop back’

58
Q

How long is the boil time of IPA?

A

30-90 mins

59
Q

How long is the boil time of pale ale?

A

60 mins

60
Q

How long is the boil time of pilsner?

A

60-90 mins

61
Q

How long is the boil time of porters and stouts?

A

60-90 mins

62
Q

How long is the boil time of Black Lager?

A

60-90 mins

63
Q

How long is the boil time of Tripel?

A

60-120 mins

64
Q

What is continuous hopping?

A

Developed by dogfish head brewery with the 90 min IPA.

  • hops are added continuously throughout boil to balance bitterness, flavour and aroma.
  • Leads to less bitter more intensely flavoured beer
65
Q

What do many homebrewers do instead of continuous hopping?

A

Add at 2 min intervals

66
Q

What is whirlpooling?

A

A post boiling method to add hop oils (no more addition of bittering as it’s below isomerisation temp)

67
Q

How is whirlpooling done?

A
  • Spraying wort tangentially to surface to get wort spinning
    OR
  • hand stirred after hops added
    The hops are added and the spinning continued until the hops are well dispersed throughout the volume
    Spinning is stopped and the trub will collect at bottom - leave to settle for 15 mins and then cool to form cold break
68
Q

What is a cold break?

A
  • Hot wort is cooled before fermentation to 210C using heat exchanger.
  • Rapid cooling causes more protein/tannin precipitation. Heat from exchanger used elsewhere in the brewery.
69
Q

What happens if beer is cooled too slowly?

A

Cold break won’t form and proteins will stay in beer = chill haze in final beer
- Although chill haze doesn’t effect flavour, the proteins that compose it can cause long term stability issues.

70
Q

What do home brewers use to get a cold break?

A

Water baths/ice but heat exchanger is best option

71
Q

What happens industrially to the heat recovered by the heat exchanger during the cold break?

A

Reused in other systems around brewery e.g. to heat next batch of wort

72
Q

What is the wort called following the addition of hops?

A

Bitter wort

73
Q

What is the hot and cold break aided by the addition of - give detail?

A

Copper finings

  • derived from seaweed
  • added towards end of boil
  • called Copper finings as added to the copper kettle to fine out the precipitates
74
Q

What is left after the boiling and cooling process?

A

Separated cool wort (now bitter or hopped wort)
spent hops
protein
(all left in kettle)

75
Q

What happens to 85% of the hop material added during the beer making process?

A

Disposed of

  • can’t be used as animal feed due to residual bitterness
  • Generally used as fertiliser/compost
  • Currently trials being performed to extract further essential oils from the spent hops to create insect repellent
76
Q

What is a measure of bitterness?

A

IBU - international bitterness units

77
Q

What is barley wine?

A

type of beer that has alcoholic strength similar to wine (12-14%)

78
Q

What is another variation of barley wine?

A

Wheat wine

79
Q

How many main types of barley wine are there?

A

2

80
Q

Describe American barley wine

A

hoppy and bitter

  • boil time for wort is normally 2 hours to ensure the characteristic sugar caramelisation occurs
  • Light brown in colour
81
Q

Describe English barley wine

A

May not contain hops

  • dark brown/black
  • Wort prior to boiling and fermentation will usually contain 320g/l of sugars
82
Q

What is an IPA

A

Indian pale ale - most popular style of craft beer worldwide

83
Q

How did IPA’s come about?

A

Pale ales = originally lightly hopped made using lightly roasted pale malts

  • 1822 Tsar of Russia introduced a tariff on English imports (inc. beer), so English brewers turned to India as new market
  • Beers had to be strongly hopped to survive long journey
84
Q

What is an IPA classes as now?

A

Strongly hopped pale ale with an alcohol percentage between 5 and 9.7%

85
Q

What were imperial stouts?

A

Strong dark beers developed by English brewers for the Russian imperial court

  • Very high ABV level (10-12%), often hopped
  • Very strong flavours - pale ale backbone, around 10% flaked barley and then additional malts added for flavour (chocolat, caramel, black patent etc)
86
Q

What are imperial IPAS?

A
  • aka double/triple IPAs are high alcohol IPAs between 8-11% ABV, IBU usually over 100
  • Heavier in hop flavours than English barley wines
87
Q

How are fruit beers made?

A

Macerated fruit can be added during the boil or cut up finely and added to the mash to add flavour compounds to the beer

88
Q

What fruits are usually added for fruit beers?

A

Stone fruits
Berries
Citrus

89
Q

Give examples of fruit beers

A
  • Framboise such as Raspberry porters
  • Pecheresse such as peach lambics
  • Grapefruit IPAs
  • Cherry stouts
90
Q

What are Radlers/Shandy?

A

Beers where fruit syrup is added after the boil

91
Q

What other flavours can be added during the boil?

A

Citrus, herbs, spices

- This maximises the essential oils that end up in wort - generally added at end of boil

92
Q

Give example of a citrus IPA and explain how flavour is added

A

Citrus IPA has lemon zest and crushed juniper berries added at five minutes

93
Q

Give an example of a scottish heather beer and how it is made

A

Viking heather ale adds heather at the start of the boil to ensure the woody flavour is transferred to the wort

94
Q

Give an example of a christmas ale and how it’s made

A

Great lakes christmas ale adds honey at 15 mins and cinnamon sticks at 5 mins

95
Q

What is mead?

A

It is made from fermented watered-down honey

96
Q

How is the alcohol content of mead controlled?

A

By adjusting the honey/water ratio

also controls sweetness and flavour

97
Q

What is honey (in terms of sugar)?

A

The most concentrated natural sugar source on planet (82%)

98
Q

How is flavour of the mead influenced in relation to the bees?

A

The floral source of the bees imparts flavour to the honey and the resulting mead, honey colour also determines final colour.

99
Q

What type of honey yields a better mead?

A

Single source

100
Q

What proportion of mead is honey and what is water?

A

Non-chlorinated water makes up to 65% of final product but ratios are generally 1-1.5kg honey to 2L water

101
Q

How is mead actually made?

A

Honey is dissolved in water and boiled 15-20 mins, skimmed (bacteria removed) and added to sterilised vessel.

  • Flavours can be added here
  • Fermentation started once honey mix is cooled by addition of mead or champagne yeast.
102
Q

What does mead need in order to mature?

A

TIME

103
Q

What 4 things does boiling the mead need to ensure?

A
  • Everything is sterilised before yeast is pitched so there are no other organisms present that the yeast must compete with for nutrients
  • Good mixing of the honey and water
  • To ensure yeast nutrient if using is dissolved
  • To extract any flavour compounds from additional ingredients
104
Q

Why might sulfides be added to mead and what are the effects?

A

Because boiling can destroy some of the flavour of the honey, however some people react to sulphites

105
Q

In general what do meads need the addition of in order for the yeast to propagate?

A

Yeast nutrient

- otherwise there won’t be sufficient nitrogen for the yeast to propagate

106
Q

What is mead?

A

Traditional honey wine

107
Q

What is malomel?

A

Mead flavoured with fruit juice

108
Q

What is metheglin?

A

Mead flavoured with spices e.g. cinnamon, cloves, corriander

109
Q

What is Tej?

A

Spontaneously fermented Ethiopian honey wine flavoured with buckthorn.

110
Q

What is Meade?

A

Wine flavoured with unfermented honey

111
Q

How long are meads generally aged for and why?

A

1-2 years, will mellow and improve with age

112
Q

How does the yeast selected effect the mead?

A

It will determine the strength and sweetness of the result: Champagne yeast = dry mead
Ale yeast = Sweet mead

113
Q

How is alcoholic ginger beer made?

A

Ginger doesn’t contain enough sugar for fermentation
Sugar source needs to be added to ginger ‘wort’ for yeast to eat- e.g. dextrose/cane juice
Additional flavour is added with citrus and spices

114
Q

What are the rough ratios for alcoholic ginger beer?

A

200g sliced root ginger (or mix of crystallised)
400g sugar
5 litres water
- should yield about 5% alcohol (600g sugar = 7.5%)

115
Q

How is alcoholic ginger beer produced?

A

Boil water, flavours and ginger together for 15 mins, then stir sugar off heat.
Add to sterile container and add yeast to start fermentation

116
Q

Summarise hops and boiling (6)

A
  • Boiling important in beer making process as it ensures that essential oils will be extracted from hops and bitter alpha acids converted to iso form so they can be extracted from wort
  • Bittering hops added at start and aroma hops added towards end or using hop back/dry hopping
  • Boiling ensures wort is sterilised prior to pitching of the yeast
  • Boiling and cooling precipitates proteins so hazes can be avoided
  • IBU is what is used to calculate bitterness level of beer
  • Kettle adjuncts and other flavours are added towards end of boil to reduce flavour loss and reduction in hops utilisation but still ensure sterilisation

Food 1130: Traditional alcoholic beverages (9 decks)

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