CBI Apprentice flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Ale fermentation profile

Top-fermenting Saccharomyces cerevisiae at roughly 16-24 C produces fruity esters and a relatively fast fermentation, giving ales their characteristic complex, warm-fermented flavor profile.

Lager fermentation profile

Bottom-fermenting Saccharomyces pastorianus at roughly 7-13 C ferments slowly and cleanly, producing crisp beers with low ester levels, followed by a cold lagering period for clarity and smoothness.

IBU definition

International Bitterness Units measure isomerized alpha acids in beer, where one IBU equals one milligram per liter. Higher values indicate more perceived bitterness, though malt sweetness balances it.

SRM and EBC

SRM and EBC are color scales for beer. EBC is approximately SRM multiplied by 1.97, so a beer measuring 10 SRM reads about 20 EBC.

Apparent attenuation

The percentage of original gravity that yeast consumed, calculated as (OG minus FG) divided by OG times 100. High attenuation yields a dry finish; low attenuation leaves residual sweetness.

ABV from gravity

Alcohol by volume can be estimated by subtracting final gravity from original gravity and multiplying the difference by 131.25, using specific gravity readings taken before and after fermentation.

Crystal malt contribution

Crystal and caramel malts are kilned while moist, converting starch to unfermentable dextrins. They add body, residual sweetness, and amber-to-brown color rather than fermentable sugar.

Mash pH target

Brewing mash pH should sit near 5.2 to 5.5 at mash temperature. Water alkalinity is the main driver, and excess alkalinity is corrected with acid or calcium salts.

Sulfate-to-chloride ratio

Sulfate accentuates hop bitterness and dryness while chloride rounds malt sweetness and body. Adjusting the ratio steers perception toward hoppy or malty character without changing gravity.

Hop alpha acids

Alpha acids are the hop resins that become bitter only after heat isomerizes them during the boil. Beta acids contribute little bitterness fresh but oxidize into harsh compounds in storage.

Yeast pitching rate

The number of viable yeast cells added per volume of wort. Underpitching stresses yeast, slowing fermentation and increasing ester, fusel, and diacetyl off-flavors.

Adjunct grains

Unmalted cereals such as rice, corn, and sugar lighten body and color. They require sufficient enzyme power from base malt or a cereal cooker to convert their starch.

Beta-amylase rest

A mash rest near 62-65 C favors beta-amylase, producing more fermentable sugars and a drier, more attenuated beer with less residual body.

Alpha-amylase rest

A mash rest near 70-72 C favors alpha-amylase, producing unfermentable dextrins that raise body, sweetness, and mouthfeel in the finished beer.

Kettle boil functions

A 60-90 minute boil sterilizes wort, isomerizes hop alpha acids, drives off DMS precursors, and coagulates proteins into hot break for later removal.

Diacetyl rest

Holding fermentation slightly warmer near the end of primary lets yeast reabsorb diacetyl, the buttery off-flavor formed during fermentation, before the beer is cooled and packaged.

Dry hopping

Adding hops in the cellar after fermentation extracts aroma compounds without adding bitterness, because no heat isomerizes the alpha acids present in the hops.

CIP verification

Clean-in-place effectiveness is confirmed by visual inspection plus ATP swabs or microbiological plating, ensuring chemical concentration, temperature, contact time, and flow were adequate.

Dissolved oxygen target

Finished beer should typically hold dissolved oxygen below roughly 50 parts per billion. Packaging is the largest pickup point and drives staling and cardboard flavors.

Lightstruck flavor

Riboflavin-mediated photodegradation of iso-alpha acids produces a skunky aroma. Brown glass and cans block the damaging wavelengths; green and clear glass do not.

Chill haze

Reversible protein-polyphenol haze that appears when beer is cold and redissolves on warming. Permanent haze that persists indicates colloidal instability and possible quality problems.

Trans-2-nonenal

The classic cardboard or papery stale flavor of oxidized beer. It forms as fatty acids oxidize over time, especially when dissolved oxygen and storage temperatures are high.

Diacetyl off-flavor

A buttery or butterscotch flavor from fermentation. Yeast reabsorbs it if given warmth and time before cooling; premature chilling leaves it in the finished beer.

Acetaldehyde off-flavor

A green apple or grassy flavor from an intermediate in alcohol fermentation. It is reduced by healthy yeast and adequate conditioning before packaging.

Draught balance formula

Required applied pressure in psi equals static lift in feet times 0.5 plus line resistance, with roughly 1 psi per foot of 3/16-inch beer line as a working rule.

FOB valve function

A foam-on-beer valve stops beer flow when a keg empties and prevents foam from entering the line. It must be reset after each keg change.

Keg coupler types

Couplers are type-specific, such as D, S, A, G, and U. Using the wrong type causes leaks or no flow, so the coupler must match the keg valve.

Draught line cleaning

Beer lines should be cleaned at least every two weeks with an approved line-cleaning chemical followed by thorough rinsing, since residue harbors wild yeast and bacteria.

CO2 asphyxiation risk

Carbon dioxide is heavier than air and accumulates in cellars and fermentation rooms. Gas monitoring and ventilation are required before entering confined spaces.

Caustic chemical safety

Sodium hydroxide is corrosive and requires goggles, face shield, gloves, and apron. Acid must never be added to caustic without control, because the reaction is violent.

Sanitizer contact time

Sanitizers must contact a clean surface for the full labeled contact time. Organic soil inactivates sanitizer, so cleaning always precedes sanitizing.

TTB brewery regulation

In the United States, the TTB regulates brewery permits, label approvals, and federal excise tax determination, while state and local authorities separately license and inspect premises.