Brewing Process

Question 1

What is the overall process of brewing beer?

Answer 1

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

Question 2

What is the purpose of Milling?

Answer 2

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

Question 3

What is malt called after it is milled?

Answer 3

Grist

Question 4

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

Answer 4

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

Question 5

What is the primary objective of Mashing?

Answer 5

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

Question 6

How does the brewer conduct mashing?

Answer 6

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

Question 7

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

Answer 7

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

Question 8

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

Answer 8

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

Question 9

How does the brewer terminate the mash phase?

Answer 9

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

Question 10

Describe the basic types of mashing

Answer 10

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

Question 11

What is the purpose of lautering?

Answer 11

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

Question 12

Describe the lautering process

Answer 12

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

Question 13

What are the major objectives of boiling?

Answer 13

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

Question 14

What are the primary flavor impacts of boiling?

Answer 14

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

Question 15

What is the objective of whirlpooling?

Answer 15

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

Question 16

Describe the whirlpool process

Answer 16

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

Question 17

What is the purpose of chilling?

Answer 17

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

Question 18

How is wort chilled?

Answer 18

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.

Question 19

What flavor issues are associated with wort chilling?

Answer 19

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

Question 20

What is the purpose of wort aeration?

Answer 20

To provide oxygen for yeast cell growth

Question 21

When is wort aerated (timing)?

Answer 21

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

Question 22

What is the general fermentation process

Answer 22

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

Question 23

What are the primary differences between ale and lager fermentation?

Answer 23

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

Question 24

What equipment is used for fermentation?

Answer 24

Jacketed cylindroconical fermenters with glycol coolant pumps

Question 25

What are the primary inputs and outputs of fermentation?

Answer 25

Inputs: Sugars, Oxygen Outputs: Carbon dioxide, Ethanol

Question 26

What are the objectives of lagering?

Answer 26

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

Question 27

What are the temperatures and durations used for lagering?

Answer 27

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

Question 28

What are the flavor impacts of lagering?

Answer 28

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

Question 29

In which cases are beers aged?

Answer 29

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

Question 30

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

Answer 30

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.

Question 31

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

Answer 31

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

Question 32

What methods are used to clarify beer?

Answer 32

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

Question 33

How do brewers carbonate beer?

Answer 33

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

Question 34

In what units is carbonation measured?

Answer 34

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

Question 35

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

Answer 35

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

Question 36

What are the sensory impacts of carbonation in beer?

Answer 36

-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

Question 37

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

Answer 37

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

Question 38

What is Cap-on-foam packaging?

Answer 38

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

Question 39

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

Answer 39

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