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Foodborne Pathogens > Lecture 19: Mycotoxins > Flashcards

Lecture 19: Mycotoxins Flashcards

1
Q

what are mycotoxins

A

fungal metabolites which when ingested, inhaled or absorbed through the skin cause disease in humans and domestic animals including birds

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2
Q

T or F: the presence of spores indicates the presence of mycotoxins

A

False

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3
Q

T or F: mycotoxins may persist in food even after processing destroys the fungi that produce them

A

T

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4
Q

what are some effects of mycotoxins on health

A
  1. neurotoxins
  2. tetratogens
  3. nephrotoxins
  4. hepatoxins
  5. immunosuppressive agents
  6. carcinogens
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5
Q

name the 5 discussed mycotoxins

A
  1. aflatoxins
  2. ochratoxin A
  3. fumonisins
  4. deoxynivalenol
  5. zearalenone
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6
Q

what are the 4 naturally occuring aflatoxins

A

B1, B2, G1,G2

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7
Q

aflatoxins are named based on their?

A

fluorescence under UV light

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8
Q

when aflatoxins are ingested by lactating cows they are excreted as aflatoxins

A

M1 and M2

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9
Q

aflatoxins are produced by (2)

A

aspergillius flavus and aspergillus parasiticus

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10
Q

T or F: pasteurization destroys aflatoxin cells

A

True

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11
Q

aflatoxins can grow at pH between and aw of

A

2.1 and 11.2 and pH 0.8 ish

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12
Q

A flavus is associated with

A

food crops in tropical and warm temp areas of the world, associated with peanuts corn and tree nuts

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13
Q

T or F: a parasiticus is more geographically limited

A

T

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14
Q

T or F: mold growth on peanuts is aassociated with both a flavus and a parasiticus

A

T

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15
Q

major contributors to pre-harvest infection of a flavus in peanuts is

A
  1. high spore number
  2. plant stress (drought)
  3. high soil temp
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16
Q

control of a flavus spore numbers can be achieved by

A
  1. crop rotation
  2. irrigation
  3. bio control (fields inoculated with non toxic strains to compete with toxic strains)
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17
Q

aflatoxin can be reduced in peanuts by

A

manually sorting kernels after shelling

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18
Q

what happens to peanuts when ground is too dry

A

aspergillus grows and produces aflatoxin (discoloration)

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19
Q

T or F: aflatoxin removal by heat depends on the type of heat

A
  • Boiling and autoclaving doesn’t help (less than 25% of toxin destroyed)
  • Dry roasting removes up to 80%
  • The alkali process used to make peanut oil removes all aflatoxin
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20
Q

5 primary toxic effects of aflatoxin toxicity

A
  • acute
  • liver carcinogenicity
  • liver cirrhosis
  • immunosuppression
  • growth retardation
21
Q

explain how aflatoxins can cause liver carcinogenicity

A

in the liver, enzymes convert aflatoxin to epoxide. the epoxide binds to liver proteins leading to liver failure and epoxide binds DNA which is a precursor to liver cancer

22
Q

aflatoxin exposure before birth and during childhood is related to

A

stunted growth

23
Q

Aflatoxins have been shown to suppress cell mediated immune response

A

effects include
1. decrease in the phagocytic activity of macrophages, increased susceptibility to infection and reduced response to vaccines

24
Q

Ochratoxin A (OTA)

A
  • nephrotoxin that affect kidneys
  • has carnogenic properties
  • readily enters the blood stream through the intestine and can circulate for up to 3 weeks
25
Q

The mechanism of action of OTA is unclear but it is likely related to _____ metabolism

A

phenylalanine

26
Q

OTA is linked to which products

A

barley, wheat, meat, beer, wine, coffee, chocolate

27
Q

the tolerable weekly intake for ota is

A

100 ng/kg

28
Q

controlling OTA in food requires ____. name some methods used in prevent it in wine

A
  • proper irrigation
  • regular pruning
  • crop cover
  • fungiside application
29
Q

what is done to control ota in coffee

A
  • slow drying of coffee beans

- effective sun drying or mechanical dehydration provide effective control

30
Q

OTA is largely removed in the winemaking process when ___

A

solid fractions are removed

31
Q

fusarium species are produced by

A

aspergillus niger

32
Q

fusarium species are always present on ___

A

corn and sorghum, even in healthy kernels

33
Q

Fusarium verticilloides can grow on any standard mycological culture medium and produce ____ color

A

salmon or brownish violet on deep violet mycelia

34
Q

what can promote the colonization of corn by mycotoxins

A

stress which can be caused by drought stress, heat stress and insect predation

35
Q

name some health effects caused from fumonisins in humans and animals

A

-affect sphingolipid metabolism, cause depletion of sphingolipids– (inhibition of folarte binding)
- horses: equine leukoencephalomacia
-

36
Q

fumonisins to not grow below aw of

A

0.9

37
Q

what is nixtamalization

A

process where the corn is soaked and cooked in alkaline solution which remove almost all fumonisins

38
Q

T or F: when a product is processed above 150 deg C, fumonisins levels are decreases

A

T

39
Q

what is deoxynivalenol

A

produced by fusarium graminearum (only some produce DON) and F culmorum (all)

40
Q

F graminearum and F culmorum cause ______ in corn and _____ in wheat and barley

A

ear tot in corn and fusarium head blight in wheat and barley

41
Q

fusarium graminearum and fusarium columurm are disease that can occur as epidemics and require ____

A

airborne or insect borne spores, inoculation at susceptible time and appropriate moisture and temp

42
Q

DON inhibits ___

A

protein synthesis

43
Q

DON toxicosis is ____ but it does cause ___ symptoms and ____ in humans

A
  1. rare
  2. intestinal symptoms
  3. immunotoxicity in humans
44
Q

what are the main characteristics of zearalenone

A
  1. low acute toxicity
  2. metabolites possess estrogenic activity in agricultural animals
  3. produced by the same species of fusarium and generally under the same conditions
45
Q

vulvovaginitis and vaginal rectal prolapse in bigs is a sign of

A

zearalenone infection

46
Q

ZEA is considered — toxic (4)

A
  1. hepatoxic
  2. hematotoxic
  3. immunotoxic
  4. genotoxic
47
Q

what are considered the carcinogenic aflatoxins

A

B and G

48
Q

mold genera most commonly associated with food are

A

aspergillus, penicillum and fusarium

Foodborne Pathogens (15 decks)

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