The thick head of foam on a fermenting beer is known as
Answer: C
Krausen is the foam raised by vigorous fermentation and by yeast carried up with the gas, and its collapse signals that the most active phase is over. Trub is sediment, wort is the sugary liquid and grist is milled malt.
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Trub in brewing refers to
Answer: D
Correct answer: Protein and hop debris that settles out of the wort
Trub is the coagulated protein, polyphenol and hop material that drops out when the boiled wort is cooled. It is separated in a whirlpool or settling tank, since carrying it into the fermenter gives harsh flavours and makes the yeast harder to recover cleanly.
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Sparging in brewing is the operation of
Answer: A
Correct answer: Rinsing the grain bed to recover the remaining sugars
After the first wort has drained away, a good deal of sugar remains held in the wet grain. Sparging rinses the bed with hot water to recover it, and it must be judged carefully - sparging too far, or with water too hot, extracts tannins from the husks and gives an astringent beer.
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Lightstruck or skunky flavour in beer develops when
Answer: B
Light, particularly in the blue range, drives a reaction between riboflavin and the iso-alpha acids from hops that yields a thiol smelling strongly of skunk. Brown glass filters most of the offending wavelengths, which is why clear and green bottles are more vulnerable.
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Chill haze in beer is formed by
Answer: C
Complexes of protein and polyphenol become insoluble when the beer is chilled and redissolve as it warms, which distinguishes chill haze from a permanent or microbiological one. Stabilising treatments remove one partner or the other.
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Repitching in a brewery means
Answer: D
Yeast is cropped at the end of one fermentation and used to start the next, which is economical and gives consistency. It also demands careful monitoring, since yeast health and purity decline over successive generations.
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Which is a spoilage organism rather than a production organism?
Answer: A
Brettanomyces is unwanted in almost every context, giving volatile phenols and barnyard aromas, although a few traditional styles tolerate or even seek it. The other three are deliberately used organisms doing the jobs they are chosen for.
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Which pairing is correct?
Answer: B
Only the first pairing holds. Acetobacter spoils wine by making acetic acid, Botrytis is a vineyard fungus with nothing to do with hops, and Pediococcus is a beer spoilage organism rather than anything to do with malting.
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Beer and wine are both preserved to a degree by
Answer: C
Ethanol and acidity together exclude most organisms, which is why the spoilage flora of each is narrow and specialised. Neither drink is salty, neither is heated during fermentation, and many examples of both retain some sugar.
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Fortified wines such as sherry and port are made by
Answer: D
Correct answer: Adding distilled spirit to raise the alcohol content
Fortification adds grape spirit to bring the wine to 15 to 22 per cent, well above what yeast can survive. The timing determines the style: spirit added during fermentation arrests it and leaves the wine sweet, as in port, while spirit added after leaves it dry, as in a fino sherry.
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