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Cicerone_Krasnor > Brewing Process > Flashcards

Brewing Process Flashcards

1
Q

What is the overall process of brewing beer?

A

1) Milling
2) Mashing
3) Lautering
4) Boiling
5) Whirlpool
6) Chilling
7) Aeration and pitching yeast
8) Fermentation
9) Lagering
10) Aging
11) Clarification
12) Carbonation
13) Packaging and pasteurization

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2
Q

What is the purpose of Milling?

A

Milling crushes grains, exposing starches and enzymes in the endosperm to hot water, allowing the process of conversion of starch to fermentable sugars to begin.

Note: Milling should leave husks largely intact to avoid astringency

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3
Q

What is malt called after it is milled?

A

Grist

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4
Q

What are the flavor impacts of over/under-milling on beer?

A

Under-milling: Prevents mashing from taking place, beer would taste mostly like water
Over-milling: Tannins leach out of husks, resulting in additional astringency. This is a mouthfeel effect, not a flavor

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5
Q

What is the primary objective of Mashing?

A

Activate enzymes in the malt to break down starches in the grist into simpler sugars that can be fermented by yeast (saccharification)

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6
Q

How does the brewer conduct mashing?

A

The brewer soaks the grist in hot liquor (water) for 30-60 minutes

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7
Q

At what temperatures is alpha amylase activity optimized and what kind of effect on the wort/beer does this enzyme have?

A

Alpha Amylase: 158 F
Alpha amylase leaves more dextrins intact and creates a less fermentable wort/fuller bodied beer

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8
Q

At what temperatures is beta amylase activity optimized and what kind of effect on the wort/beer does this enzyme have?

A

Beta Amylase: 140-149 F
Beta amylase converts more dextrins and creates a more fermentable wort/drier and crisper beer

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9
Q

How does the brewer terminate the mash phase?

A

The brewer will mash out. This involves raising the mash temperature to 176 F to stop enzymatic activity and increase the fluidity of the wort

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10
Q

Describe the basic types of mashing

A

Single infusion mash: Grist is mixed with hot liquor for 30-60 minutes for a single saccharification rest

Step mash: Temperature of the mash is raised in steps to activate enzymes at different temperatures to improve fermentability.

Decoction mash: Portions of the mash are removed and boiled then returned to the main mash to raise its temperature

Cereal mash: Performed for non-malted adjunct grains. Involves gelatinizing these grains to allow enzymatic access to their starches. Note: Flaked adjuncts do not require a cereal mash

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11
Q

What is the purpose of lautering?

A

Lautering separates the liquid wort from the grist providing a “clean” food source for yeast to ferment

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12
Q

Describe the lautering process

A

After mashing out:

1) Initiate wort run-off: The wort is allowed out of the mash tun through a slotted false bottom in the lautering vessel
2) Vorlauf (recirculation): Initial wort that runs out of the mash is recirculated through the mash filter bed until it comes out clear
3) Collection of wort for boiling: Once clear, the wort is collected in the boil kettle
4) Sparging: Once vorlauf is complete, 170F water is sprayed at the top of the mash for 20-40 minutes to rinse out remaining sugars. This is allowed to drain for 10-20 minutes

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13
Q

What are the major objectives of boiling?

A

1) Sterilize the wort to prevent off flavors/optimize yeast performance
2) Isomerize hop alpha acids to add bitterness
3) Drive off volatile off-flavors such as DMS
4) Concentrate wort to desired volume/gravity
5) Coagulate proteins to clarify beer
6) Develop desired colors and flavors

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14
Q

What are the primary flavor impacts of boiling?

A

1) Direct fired boils will add melanoidins via the Maillard process. This adds a rich malty and caramel/toffee taste

2) Isomerization of hop alpha acids into isoalpha acids allows them to dissolve in the wort, providing bitterness

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15
Q

What is the objective of whirlpooling?

A

Separate trub (malt, coagulated protein, polyphenols, hop debris) from the wort

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16
Q

Describe the whirlpool process

A

Wort is pumped from kettle to whirlpool tank through a tangential entry port, creating a whirlpool effect. The whirlpool spins for 15 minutes until it settles. Wort is removed via an outlet on the edge of the tank near the bottom allowing the wort to leave without the cone of trub collected in the center of the tank via centripetal force

17
Q

What is the purpose of chilling?

A

Wort is chilled to provide an optimal temperature for yeast performance. Rapid chilling minimizes conversion of SMM into DMS as well as development of non-desired microbes

18
Q

How is wort chilled?

A

Primarily through heat exchangers. Hot wort is pumped in one direction, cold water in another.

Coolships can also be used. These are large, flat, open-topped vessels which expose a large amount of beer surface area to cool air.

19
Q

What flavor issues are associated with wort chilling?

A

Chilling too slowly allows for the production of DMS and the proliferation of undesired microbes that can cause off-flavors such as sourness.

Improperly cleaned chillers can also result in microbial related off-flavors

20
Q

What is the purpose of wort aeration?

A

To provide oxygen for yeast cell growth

21
Q

When is wort aerated (timing)?

A

Wort is aerated after is has been chilled, usually as it is sent to the fermenter. Aerating hot wort (hot side aeration) causes faster oxidation and related off-flavors

22
Q

What is the general fermentation process

A

1) Yeast perform aerobic fermentation, consuming oxygen and other nutrients and dividing. This creates many esters and phenols as well as off-flavors
2) Once O2 has been consumed, yeast begin anaerobic fermentation where sugars are metabolized (primary fermentation). They produce CO2 and ethanol.
3) The yeast conduct secondary fermentation, processing compounds other than simple sugars. This can remove off flavors such as diacetyl and acetaldehyde
4) Once food sources are consumed, the yeast go dormant, flocculate, and sink

23
Q

What are the primary differences between ale and lager fermentation?

A

Temperature: ale yeast prefer to ferment at 65F or higher, lager yeast at 33-58F.

Location: Ale yeast float during primary fermentation, lager yeast tends to sink

Flavor: Ale yeast produce more esters, phenols, and fusel alcohols

24
Q

What equipment is used for fermentation?

A

Jacketed cylindroconical fermenters with glycol coolant pumps

25
Q

What are the primary inputs and outputs of fermentation?

A

Inputs: Sugars, Oxygen
Outputs: Carbon dioxide, Ethanol

26
Q

What are the objectives of lagering?

A

Lagering allows yeast to clean up undesired fermentation by-products such as diacetyl and acetaldehyde. It provides time for sulfur, tannins, proteins, and other compounds to fall out of solution. It allows additional time for remaining sugars to be attentuated

27
Q

What are the temperatures and durations used for lagering?

A

Temperature: 31-38F
Duration: Varies. Generally 2-4 weeks. Stronger beers such as doppelbocks may be lagered for 12 weeks

28
Q

What are the flavor impacts of lagering?

A

Lagering produces very smooth, clean beers (concerning yeast flavors) with high clarity and crisp finishes

29
Q

In which cases are beers aged?

A

1) High ABV beers may be smoothed via aging
2) Used liquor barrels can impart additional flavors via aging
3) Mixed fermentation ales need time to conduct slower fermentations

30
Q

What vessels are used for aging and what impact do they have on flavor?

A

Stainless steel: Neutral flavor impact. Impervious to light and oxygen

New wood: Intense woody flavor. Tend to add vanilla/coconut flavor via vanillins. Aging for too long can add a tannic raw wood character

Used wood: Can impart flavors from whatever was held in the container before, or treatment related flavors such as toastiness/charring.

31
Q

How does used wood tend to impart its particular flavors to an aged beer?

A

Residual liquids can impart flavor.

Treatments such as toasting/charring of the wood can impart flavors via the wood itself.

Microflora such as brett or pediococcus bacteria can produce flavorful compounds

32
Q

What methods are used to clarify beer?

A

Filtration: Mechanical filtration

Centrifuging: Separates solids from liquid

Finings: Adding fining agents which bind and precipitate compounds out of the solution

Settling/lagering/aging: Holding the beer in a bright tank to allow yeast and other compounds to flocculate and fall out of solution on their own

33
Q

How do brewers carbonate beer?

A

1) Capture CO2 produced during fermentation
2) Force carbonation through a carbonation stone and an external CO2 tank
3) Secondary fermentation: Adding sugar and potentially fresh yeast directly into the serving vessel

Modifications to carbonation level can be conducted while in a bright tank prior to packaging

34
Q

In what units is carbonation measured?

A

Volumes (Vol CO2/Vol liquid) or g/L

35
Q

What are typical carbonation levels for ales, lagers, real ales and German/Belgian wheat beers?

A

Ale: 1.5-2.6 Volumes
Lager: 2.5-2.7
Real Ale: 1-1.5
Wheat beers: 3-3.5

36
Q

What are the sensory impacts of carbonation in beer?

A

-Carbonic acid is created when CO2 dissolves in water. This adds acidity, zing, and tingle
-Carbonation cleanses and refreshes the palate while eating
-Carbonation creates bubbles as it leaves solution. This reveals aromatic compounds

37
Q

What are the primary beer packaging types and their associated benefits?

A

Draft: Claimed to have superior taste and texture compared to alternatives
Bottles: Allows for bottle conditioning
Cans: Logistically efficient. Better than bottles at protecting from air and light.
Casks: Allows for cask conditioning
Bright Tanks: Does not require an additional packaging step

38
Q

What is Cap-on-foam packaging?

A

The concept that packagers should cap/seal vessels while foam is coming out of the top to minimize space in the head for remaining oxygen. This is usually conducted via counterpressure filling and CO2 purging

39
Q

What is pasteurization and how does it impact beer flavor and stability?

A

Pasteurization is the process of heating beer to 140 F for several minutes to kill living organisms. This prevents microbial related off-flavors from developing, but the heat involved increases the rate of chemical processes involved in staling/oxidation, leading to more rapid development of associated off-flavors. Pasteurized beer has double the shelf life as compared to non-pasteurized beer

Cicerone_Krasnor (9 decks)

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