Molds

Question 1

What is a mycotoxin

Answer 1

A fungal metabolite that when ingestion, inhaled or absorbed, cause disease

Question 2

Mycotoxin production occurs only as a result of…

Answer 2

Fungal growth (not the presence of spores)

Question 3

Toxicity due to mycotoxins is…

Answer 3

Cumulative of a long period of time

Question 4

5 mycotoxins discussed in class

Answer 4

Aflatoxins, ochratoxin A, fumonisins, deoxynivalenol, zearalenone

Question 5

Symptoms of aflatoxicosis

Answer 5

Jaundice, fever, vomiting and anorexia

Question 6

4 naturally occurring aflatoxins

Answer 6

B1, B2, G1, G2

Question 7

How are aflatoxins named

Answer 7

Based on their fluorescence under UV light

Question 8

What happens when aflatoxins are eaten by lactating cows

Answer 8

They are excreted as aflatoxins M1 and M2

Question 9

What are two organisms that produce aflatoxins important in food

Answer 9

Aspergillus flavus and parasiticus

Question 10

What is the growth temp and Aw of A. flavus

Answer 10

T: 10-48C
Aw: depends on temp (decreases with increasing temp)

Question 11

How can A. flavus be destroyed

Answer 11

Pasteurization

Question 12

Where is A. flavus found

Answer 12

Common in food crops in tropical and warm areas (peanuts, corn, tree nuts)

Question 13

Where is A. parasiticus found

Answer 13

More associated with peanuts (more geographically limited than A. flavus)

Question 14

What is a prereq for high aflatoxin levels in peanuts

Answer 14

Aspergillus infection while the nuts are still in the ground

Question 15

What contributes to pre-harvest Aspergillus infection in peanuts

Answer 15

High spore numbers, drought, high soil temp

Question 16

Control strategies for Aspergillus

Answer 16

Crop rotation, irrigation, biocontrol (inoculating fields with non-toxic strains so they compete with each other)

Question 17

3 methods for removal of aflatoxin by heat and their effectiveness

Answer 17

1. Boiling/autoclaving - less than 25%
2. Dry roasting - up to 80%
3. Alkali process (peanut oil) - 100%

Question 18

5 primary toxic effects of aflatoxin

Answer 18

Acute toxicity, liver carcinogenicity, liver cirrhosis, immunosuppression, growth retardation in children

Question 19

What is the relation between hepatitis B and aflatoxin

Answer 19

If you have hep B, you are 30 times more likely to develop liver cancer

Question 20

How does aflatoxin cause liver cancer

Answer 20

NEED to have consumption of low levels over long period of time

1. Liver enzymes convert aflatoxin to epoxide
2. Epoxide binds liver proteins and causes liver failure
3. Epoxide binds DNA and is precursor for liver cancer

Question 21

What part of the immune system does aflatoxins suppress

Answer 21

Cell-mediated immune response

Question 22

3 effects of immunosuppression by aflatoxin

Answer 22

1. Decrease phagocytic activity of macrophages
2. Increased susceptibility to infection
3. Reduced response to vaccines

Question 23

What is the acceptable safe level of consumption of aflatoxin in humans

Answer 23

15ug/kg

Question 24

What 3 groups of fungi produce ochratoxin A

Answer 24

1. Ocher-color aspergilli
2. Black aspergilli
3. Penicillium

Question 25

What does OTA do

Answer 25

Is a nephrotoxin that affects kidney function and has carcinogenic properties

Question 26

How can you tell if someone has ingest OTA

Answer 26

Blood test, it has a long half life (3 weeks) in the blood

Question 27

What is the mechanism of OTA

Answer 27

Unclear, likely related to phenylalanine metabolism

Question 28

What are people in NA exposed to OTA from (fungi and products)

Answer 28

Penicillium verrucosum | Products include barely, wheat, coffee, wine, beer

Question 29

Where are OTA levels low

Answer 29

Tropical and subtropical regions

Question 30

What is the tolerable weekly intake of OTA

Answer 30

100ng/kg

Question 31

What control method prevents OTA production

Answer 31

Rapid drying (hard to do)

Question 32

What is a known fungi that produces OTA in wine

Answer 32

A. carbonarius

Question 33

4 control methods to prevent A. carbonarius growth in grapes

Answer 33

1. Proper irrigation 2. Air flow 3. Crop covers 4. Fungiside applications

Question 34

What can lead to OTA formation in coffee beans

Answer 34

Slow drying

Question 35

What can control OTA production in coffee beans

Answer 35

Effective sun drying or mechanical dehydration

Question 36

What fungi produces fumonisins

Answer 36

Fusarium verticilloides and F. proliferatum | Also A. niger

Question 37

Where are fusarium species always present

Answer 37

On corn and sorghum

Question 38

A. niger is associated with fumonisins in...

Answer 38

Grapes, raisins and coffee

Question 39

What is a concern of A. niger producing fumonisins

Answer 39

It can also produce OTA, and the co-occurrence of the two would be bad

Question 40

How do Fusarium colonized kernels start showing mycotoxin symptoms

Answer 40

When the plant is stressed (drought, heat of insect predation), it leads to a disease-mycotoxin producing interaction

Question 41

What do fumonisins do

Answer 41

They affect sphingolipid metabolism, cause depletion of complex sphingolipids and this interferes with the function of some membrane proteins (inhibition of folate binding)

Question 42

What does fumonisins cause in humans

Answer 42

Esophageal cancer and neural tube defects, like spina bifida in infants

Question 43

How can you prevent fungal growth in corn

Answer 43

Rapid drying (cannot live below Aw 0.9)

Question 44

What is mixtamalization

Answer 44

A process where the corn is soaked and cooked in an alkaline solution to remove almost fumonisins

Question 45

If a product is processed above __, fumonisins levels are decrease

Answer 45

150C

Question 46

What fungi produce deoxynivalenol (DON)

Answer 46

``` Fusarium graminearum (some) Fusarium culmorum (all) ```

Question 47

Where is F. culmorum found

Answer 47

Small grains (wheat and barely)

Question 48

What is the action of DON

Answer 48

Inhibits protein synthesis

Question 49

Where is DON production on corn the highest

Answer 49

Cooler, wet climate (like canada)

Question 50

What is a safe level of consumption of DON in human and bovine feeds

Answer 50

Human: 1mg/kg Bovine: 10mg/kg

Question 51

What are some control methods for DON

Answer 51

Fungicides, crop rotation, forecasting symptoms (to warn producers)

Question 52

What activity does zearalenone have in pigs, cattle and sheep

Answer 52

Estrogenic activity

Question 53

What are symptoms of ZEA in pigs

Answer 53

Vulvovaginitis and vaginal rectal prolapse

Question 54

What fungi produce ZEA

Answer 54

Same fusarium species that produce DON, F. graminearum and F. culmorum (generally under same conditions)

Question 55

4 toxic effects of ZEA

Answer 55

Hepatotoxic, hematotoxic, immunotoxic, genotoxic

Question 56

What are the 3 mold genera most commonly associated with food

Answer 56

Aspergillus, penicillum and fusarium