The finished acidity of good sauerkraut is usually about
Answer: C
Around 1.5 to 2 per cent lactic acid, with a pH near 3.5, is enough to preserve the cabbage and give the characteristic sharpness. Ten per cent is far beyond what these organisms can reach, and the dominant acid is lactic rather than acetic.
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Fermentation temperature affects sauerkraut chiefly by
Answer: D
A cool fermentation near 18 degrees favours the full succession and gives the best flavour, while warm conditions let the lactobacilli overrun the early stage and produce a harsher product. Temperature selects among the organisms rather than acting on the cabbage itself.
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Pink discolouration of sauerkraut is caused by
Answer: A
Certain Rhodotorula yeasts carry red pigments and colour the kraut when they are able to grow. They are favoured by too much salt, or by salt spread unevenly, because that holds back the lactic acid bacteria that would otherwise outcompete them.
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Soft sauerkraut is usually the result of
Answer: B
Enzymes that hydrolyse pectin dissolve the material holding the plant cells together, and the shreds lose their texture. The usual underlying cause is too little salt or too high a temperature, either of which delays acid formation and lets the responsible organisms grow.
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Slimy sauerkraut arising during the middle of the fermentation is
Answer: C
Dextran formed from sucrose by Leuconostoc makes the brine ropy, but other lactic acid bacteria commonly consume it as fermentation proceeds and the texture recovers. Sliminess that persists is a different matter and points to pectin breakdown.
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Dark discolouration of sauerkraut is most often associated with
Answer: D
Correct answer: Exposure of the kraut to air during fermentation
Air at the surface allows oxidation of the plant tissue and lets film yeasts and moulds grow, and both darken the kraut. Keeping the shredded cabbage below its own juice, weighted down and covered, is the whole of the remedy - and it is the same measure that keeps the fermentation anaerobic for the lactic acid bacteria.
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Genuine dill and salt-stock pickles are produced by
Answer: A
A genuine pickle is fermented: cucumbers are held in brine while lactic acid bacteria acidify it over days to weeks. Pouring vinegar over unfermented cucumbers makes a fresh-pack or quick-process pickle, which is acidified rather than fermented and tastes quite different.
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Cucumbers for fermentation are normally brined at a salt concentration of about
Answer: B
A starting brine near 6 per cent restrains spoilage organisms and the softening enzymes while still permitting the salt-tolerant lactic acid bacteria to work. The concentration is often raised during long storage and reduced again before the pickles are packed.
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Salt-stock cucumbers held in storage for months are kept in brine of about
Answer: C
Once fermentation is complete the brine is strengthened to 10 to 15 per cent so the stock keeps for many months until it is needed. It is then leached back down to roughly 2 per cent before the pickles are finished and packed, since nobody could eat them at storage strength.
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The lactic acid bacteria that ferment brined cucumbers come mainly from
Answer: D
The traditional process is a natural fermentation relying on organisms already present on the fruit and the vessels, with salt selecting among them. Starter cultures are used in some modern controlled fermentations but the classical process needs none.
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