The principal organ damaged by aflatoxin is the
Answer: A
Large doses cause acute aflatoxicosis, which is life threatening and acts chiefly through liver damage, and there is evidence that aflatoxins cause liver cancer in humans. The combination of acute toxicity and carcinogenicity is why limits are set so low.
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Ochratoxin A is found in
Answer: B
Produced by several Aspergillus and Penicillium species, it turns up in cereals, coffee, dried vine fruits, wine, grape juice and spices. Its wide distribution across stored plant products reflects how widespread the producing moulds are.
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Patulin is a mycotoxin associated particularly with
Answer: C
Produced by Aspergillus, Penicillium and Byssochlamys, patulin is often found in rotting apples, so it carries into juice made from windfall or bruised fruit. Sorting out rotten apples before pressing is the practical control.
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Spices are notable in food microbiology for carrying
Answer: D
Harvested and dried in the open, spices arrive with high spore counts from soil and dust, and though nothing grows in the dry powder the spores survive to be added to whatever food it seasons. That is why spices are a recognised source of spoilage in processed meats.
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Spices are commonly decontaminated by
Answer: A
Steam and water would spoil the product, so gamma irradiation or a permitted fumigant is used to bring the spore count down while leaving flavour and appearance intact. It is one of the most established applications of food irradiation.
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Most mycotoxins are not destroyed by ordinary cooking because they are
Answer: B
The toxins are small stable molecules, quite unlike the mould that made them, so heat that kills the fungus leaves the toxin behind. Prevention therefore has to stop contamination happening rather than rely on removing it later.
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Mycotoxin formation in stored produce is favoured by
Answer: C
Correct answer: warm, damp and humid conditions
Toxigenic moulds need moisture and warmth to grow, and mycotoxin production generally requires conditions even more favourable than growth itself. This is why drying grain promptly to a safe moisture content and keeping stores cool and ventilated is the whole of mycotoxin control - the toxins are heat-stable and cannot be removed once formed.
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Rancidity in nuts and fats produced by microbial action results from
Answer: D
Lipolytic organisms split the triglycerides and release free fatty acids, which give the characteristic taint. Oxidative rancidity is a separate, purely chemical process driven by oxygen and light rather than by organisms.
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Mayonnaise resists bacterial growth largely because of its
Answer: A
The acetic or citric acid brings the pH low enough to prevent growth, and commercial mayonnaise made with pasteurised egg is a stable product. Trouble arises when it is diluted into a salad, which raises the pH and adds nutrients.
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A salad made with mayonnaise becomes hazardous chiefly because the added ingredients
Answer: B
Correct answer: raise the pH and dilute the acid
Commercial mayonnaise is safe in itself because its vinegar and lemon juice bring it to around pH 3.8, well below what pathogens tolerate. Mixing it with chicken, egg or potato dilutes that acid and raises the pH into the range where Salmonella and Staphylococcus grow. The hazard is created by the combination, not by the mayonnaise.
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