Which factor does NOT influence the course of a sauerkraut fermentation?
Answer: C
Salt, temperature and submersion each determine which organisms of the succession dominate and whether defects appear. The colour of the container has no bearing on any of it, since the fermentation happens in the dark beneath the brine in any case.
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Sauerkraut fermentation is usually complete when
Answer: D
Correct answer: Acid production stops because the sugar has been used up
The fermentation is substrate-limited: it ends when the bacteria have consumed the available sugar, at which point the acidity stops rising and the process is complete. Gas appearing marks the beginning rather than the end, and the salt dissolves within hours.
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In which product would you expect acetic acid rather than lactic acid to predominate?
Answer: A
Vinegar is made by acetic acid bacteria oxidising ethanol in the presence of air, so acetic acid dominates there. The three fermented vegetables are all lactic fermentations conducted without air, in which acetic acid is a minor product at most.
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A pickle described as genuinely fermented will contain
Answer: B
A fermented pickle is a living food: the acid is microbial in origin and a large population of lactic acid bacteria remains, held in check by the pH they created. A quick-process pickle is acidified and heated and holds neither.
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Why does a sauerkraut fermentation not usually require an added starter culture?
Answer: C
Cabbage carries its own population of lactic acid bacteria, and salting plus submersion selects them from among everything else present. Starter cultures are used to make the process faster or more consistent, not because it could not otherwise happen.
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Which best describes the relationship between the organisms of the sauerkraut succession?
Answer: D
Correct answer: Each changes the conditions so as to favour the next
Leuconostoc mesenteroides starts the fermentation and produces acid and carbon dioxide; the acidity it creates inhibits it and favours the more acid-tolerant Lactobacillus brevis, and then L. plantarum, which finishes the fermentation. Each species prepares the conditions for its successor and is displaced by them - a succession rather than a competition.
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Which practice is most likely to give a sauerkraut with poor flavour but no obvious spoilage?
Answer: A
A warm fermentation lets the acid-producing lactobacilli overtake the Leuconostoc stage, so the mixed products that round out the flavour are never made. The kraut is safe and sour but comparatively harsh and one-dimensional.
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Softening enzymes that damage pickles can remain active even after
Answer: B
The enzymes are separate from the organisms, so cleaning away the mould does not undo the damage its polygalacturonases can still do. This is why prevention, by removing blossoms and excluding air, matters more than dealing with visible growth later.
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Which statement about salt concentration in cucumber fermentation is correct?
Answer: C
Fermentation runs at around 6 per cent, storage brine is strengthened to 10 to 15 per cent so the stock keeps, and the pickles are then leached back to roughly 2 per cent to be edible. The concentration is managed at each stage rather than fixed.
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The most reliable way to judge whether a vegetable fermentation is safely preserved is to
Answer: D
Correct answer: Measure the pH and confirm it is sufficiently low
The pH is what actually determines safety, so it is what should be measured. Taste is subjective and unreliable, elapsed time says nothing about whether the fermentation succeeded, and an absence of visible growth is consistent with a batch that never acidified at all - which is the dangerous case.
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