Ropiness in bread is caused by
Answer: A
Spores in the flour survive baking, because the centre of a loaf never much exceeds 100 degrees, and then germinate in the warm moist crumb to produce sticky brown threads and a fruity smell. Propionate and a slightly acid dough are the usual preventives.
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The commonest visible spoilage of bread is
Answer: B
Spores settle on the loaf after baking, from the air and from handling and slicing, and germinate wherever the surface is moist enough. Wrapping a warm loaf traps moisture and brings the mould on sooner rather than later.
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Bread mould commonly belongs to the genus
Answer: C
Rhizopus stolonifer is the familiar black bread mould, often with Penicillium and Aspergillus alongside it. The three named alternatives are bacteria, and none of them produces the visible fuzzy growth that spoils a loaf.
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Spores surviving in baked bread come mainly from
Answer: D
Grain is harvested from soil and carries spore-forming bacteria into the mill and so into the flour. Baking destroys vegetative cells throughout the loaf but not the spores, which is why rope arises from the crumb rather than the surface.
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Ergotism follows the consumption of grain infected with
Answer: A
The fungus replaces the developing grain of rye and some other cereals with a dark sclerotium rich in alkaloids, which cause burning pain, gangrene and convulsions. Historic epidemics of St Anthony's fire were caused by contaminated rye bread.
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Deoxynivalenol and zearalenone are mycotoxins associated chiefly with
Answer: B
Both are produced by Fusarium species and are correlated with wheat in particular, while T-2 and HT-2 toxins go with oats and the fumonisins with maize. The same moulds attack the crop in the field rather than in store.
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Fumonisins are Fusarium toxins associated particularly with
Answer: C
Correct answer: maize
Fumonisins are produced by Fusarium verticillioides and related species growing on maize, and they are the reason maize is the cereal most closely monitored for this group of toxins. They have been linked to oesophageal cancer in populations relying heavily on home-grown maize, and to fatal diseases of horses and pigs.
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Grain is kept below a defined moisture content in store in order to
Answer: D
Moulds need free water, and warm damp conditions are exactly what favour both their growth and the formation of mycotoxins. Drying before storage is therefore the single most effective control against aflatoxin and its relatives.
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Syrups and concentrated sugar solutions are spoiled chiefly by
Answer: A
Osmophilic yeasts tolerate the very high solute concentration that excludes ordinary organisms, so they ferment syrups, honey and concentrated juices. They are the reason a sugar solution is not self-sterilising however sweet it is.
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An organism described as osmophilic is one that tolerates
Answer: B
Osmophiles grow where the osmotic pressure created by dissolved sugar would dehydrate most cells, and they spoil syrups, jams and honey. Salt tolerance is described instead as halophilic, and the two groups are not the same.
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