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Foodborne Pathogens > Molds > Flashcards

Molds Flashcards

1
Q

What species produce aflatoxins?

A

Aspergillus flavus and Aspergillus parasiticus

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2
Q

Does pasteurization kill aflatoxins?

A

Yes

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3
Q

Where is Aspergillus flavus common?

A

Food crops in tropical and warm temperate areas of the world.

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4
Q

Where is Aspergillus parasiticus common?

A

Growth associated with peanuts , more geographically limited

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5
Q

What is a requirement for high levels of aflatoxins in peanuts?

A

Infection while nuts are in the ground

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6
Q

What are the major contributors to pre harvest infection?

A

high spore numbers
plant stress and drought (dry ground)
high soil temperatures

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7
Q

How can we control spore formation?

A

crop rotation
irrigation
biocontrol

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8
Q

How can we control aflatoxins in peanuts?

A

by manually sorting kernels after shelling

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9
Q

How can we know which peanuts are infected by aflatoxins?

A

they can be blanched to remove the skin. the infected ones are discolored

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10
Q

What removes all aflatoxins on peanuts?

A

alkali process used to make peanut oil.

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11
Q

What are the 5 primary effects of Aflatoxin toxicity?

A

1) Acute toxicity
2) Liver carcinogenicity (develops after consumption of low levels over long period of time)
3) Liver cirrohsis
4) Immunosuppression (cell-mediated)
5) Growth retardation in children

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12
Q

What does the liver convert aflatoxin to?

A

Epoxide

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13
Q

What is the accepted safe level of consumption of aflatoxins for humans?

A

15 ug/ kg

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14
Q

What is the level of aflatoxins in foods?

A

5 ug /kg

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15
Q

What are the 3 groups of fungi producing ochratoxin A ?

A

1) ocher colored aspergillus (Aspergillus ochraceus, Aspergillus westerdijikae, Aspergillus steynii)
2) black aspergilli
3) pencillium species

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16
Q

What organ does the ochra toxin target?

A

nephrotoxin

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17
Q

Where geographically are there people with high blood ochra toxin?

A

Northern Europe, North America, and Northern Asia

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18
Q

Although the mechanism of ochra toxin is unclear, what is probably related to?

A

phenylalanine

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19
Q

How long can the ochra toxin stay in the blood?

A

3 weeks

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20
Q

What is the tolerable ochra toxin intake?

A

100 ng/kg body weight

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21
Q

How is OTA controlled?

A

Rapid drying (sun drying or mechanical dehydration)

Growth can be prevented in grapes by:

  • proper irrigation
  • regular pruning (air flow)
  • use of crop cover
  • fungicide application
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22
Q

What are the effects of processing on ota with regards to fermentation for wines?

A
  • removed when solids are removed

- finished wine has 1-8 % of ota originally there

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23
Q

What are the effects of processing on ota with regards to coffee roasting?

A

enough roastin destroys the ota but highly contaminated batches are often destroyed

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24
Q

What are the effects of processing on ota with regards to cereal processing?

A

65% reduction of ota in milling
10% additional reduction in the oven
-higher in whole wheat bread (less grain is discarded)

25
Q

What species produce fumonisins?

A

Fusarium verticilloids, related species

Aspergillus niger

26
Q

Where are fumonisins always present?

A

kernel of corn and sorghum

Aspergillus niger : in grapes/raisins/coffee.
It also releases the ota toxin which has synergistics effects with the fumonisin.

27
Q

Is colonization of fumonisins on kernels symptomless? How can it become dangerous?

A

Yes

But when the plant is stressed (drought, heat, insects) it can lead to a disease in mycotoxin interaction

28
Q

How do fumonisins affect metabolism?

A

Affect sphingolipid metabolism

  • affects membrane proteins
  • inhibition of folate binding
29
Q

What is the dramatic disease in horses called and what toxin creates it?

A

equine leukoencephalomalacia by fumonin ingestion

30
Q

What do fumonisins do to pigs? to rats?

A

heart failure , liver cancer

31
Q

What do fumonisins do to humans?

A

esophageal cancer and neural tube defects (i.e spina bifida due to inhibition of folate binding)

32
Q

In the following countries: China, Iran, Northern Italy, Kenya, southern United States, corn consumption is high and so the people are exposed to high poisoning of which toxin?

A

fumonisins

33
Q

What do fumonisins contaminate?

A

corn preharvest

34
Q

What are some ways to control fumonisins?

A
  • rapid drying of harvested corn (they do not grow at aw below 0.9)
  • good agricultural practices (irrigation)
  • fumonisin resistant corn
35
Q

What is Nixtamalization?

A

corn is soaked and cooked in alkaline solution

  • removes almost all fumonisins
  • in Central America
36
Q

What are the fumonisin resistance to dry and wet milling?

A

survive , high levels in bran and germ

37
Q

What temperature decreases fumonisins?

A

heated above 150 (which is why cereals and snack foods are low in fumonisins)

38
Q

What species produce deoxynivalenol DoN?

A

Fusarium graminearum in corn and small grain (wheat / barley)
Fusarium culmorum in small grain (wheat / barley)

39
Q

What diseases does the deoxynivalenol toxin cause?

A

gibberella ear rot in corn and fusarium head blight in wheat and barley

-> always pathogenic to the plant

40
Q

What does deoxynivalenol require to cause disease?

A

require spores (airborn or insect born)
inoculation at susceptible times
appropriate moisture and temperature
usually occurs in the North

41
Q

What species produce zearalenone?

A

same species as DoN ( Fusarium graminearum and Fusarium culmorum)

42
Q

What is the toxicity like of zearalenone (ZEA) ?

A

low acute toxicity

43
Q

What toxin causes estrogenic metabolites in pigs, cattle, and sheep?

A

zearalenone (ZEA)

Also linked to early puberty in girls in Hungary and Italy

44
Q

What are the two diseases ZEA causes in pigs?

A 
vagina inflammation (vulvovaginitis) 
vaginal and rectal prolapse
45
Q

What is ZEA considered as in terms of toxicity?

A

hepatotoxic (liver)
hematotoxic (red blood cells)
immunotoxic
genotoxic (cancer)

46
Q

Are aflatoxins B and G carcinogenic?

A

yes

47
Q

Is aflatoxin M1 carcinogenic?

A

maybe

48
Q

Is ochratoxin carcinogenic?

A

maybe

49
Q

Are fumonisins carcinogenic?

A

maybe

50
Q

Are ZEA and DoN carcinogenic?

A

not evaluated

51
Q

What are the mold genera most associated with foods?

A

Aspergillus, Fusarium, and Penicillum

52
Q

What is a mycotoxin?

A

Fungal metabolite that when ingested/inhaled/absorbed through the skin can cause disease in humans and domestic animals

53
Q

T/F one species of fungus can produce several mycotoxins

A

true

54
Q

Does the presence of spores indicate mycotoxin?

A

no

mycotoxins occur as the result of fungal growth

55
Q

Are mycotoxins resistant?

A

Yes they usually persist in food even though the fungus does not survive the processing

56
Q

When does growth and toxin production occur?

A

Can occur during any point: growing, harvesting, drying, storage

57
Q

Are effects of mycotoxins acute?

A

Almost never acute, due mostly to accumulation of low levels over time
*this is why they are amongst the most neglected areas in medical science

58
Q

What are the four naturally occurring aflatoxins?

A

B1 B1 G1 G2

59
Q

What are aflatoxins excreted as in dairy cows?

A

M1 and M2

Foodborne Pathogens (11 decks)

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