19 - Molds Flashcards
Mycotoxins: _____________ which when ingested, inhaled, or absorbed through the skin can cause disease in humans and domestic animals, including birds.
fungal metabolites
Specific mycotoxins are produced by only ___________, usually a few species
specific fungi
T or F: a particular species of fungus may produce more than one mycotoxin
T
T or F: the presence of spores indicates the presence of mycotoxin
F
Mycotoxin production occurs only as a result of _________
fungal growth
Fungal growth and toxin production can occur at any point in the _________________
food production chain: growing, harvesting, drying, or storage
Mycotoxins are usually very ______ once formed and may persist in the food, even after processing destroys the fungi that produced them
stable
Molecular structures of mycotoxins ______ widely
vary
The effects of mycotoxins on health vary and include:
- neurotoxins
- teratogens
- nephrotoxins
- hepatotoxins
- immunosuppressive agents
- carcinogens
IMPORTANTLY, toxicity due to mycotoxins is almost never ______, effects are ___________ over a long period of time
acute
cumulative
T or F: the health effects of mycotoxins are among the most neglected areas in medical science
T
Name 5 mycotoxins:
- Aflatoxin
- Ochratoxin A
- Fumonisins
- Deoxynivalenol
- Zearalenone
Aflatoxin can cause _________ (Aflatoxicosis)
acute toxicity
Describe a typical aflatoxin outbreak:
India, consumption of contaminated corn, outbreaks occur when drought or famine cause exceptionally high levels of aflatoxins to be eaten at high-levels in substandard food
Name the 4 naturally occuring Aflatoxins:
- B1
- B2
- G1
- G2
- named based on their flurescence under UV light
When aflatoxins are ingested by lactating cows, they are excreted as aflatoxins ___ and ___
M1
M2
Aflatoxins are produced by (2):
- Aspergillus flavus
- Aspergillus parasiticus
Aspergillus flavus grows from _______
10-48C
What is the pH range of A.flavus:
2.1-11.2
The required aw of A.flavus depends on temperature, describe it:
A.flavus is better adapted to high temperatures so less water is required at higher temp and more water is required at lower temp
T or F: Pasteurization readily kills A.flavus cells
T
A.flavus is common in food crops in ______ and _____ temperate areas of the world
tropical
warm
A.flavus tends to be associated with peanuts, _________
corn and tree nuts (pistachios and Brazil nuts)
A.parasiticus is more _________ limited, its growth is associated with ________, and appears uncommonly elsewhere
geographically
peanuts
T or F: Under inadequate storage conditions, other grains may also permit growth and aflatoxin production
T
T or F: n peanuts it appears that Aspergillus infection while the nuts are still in the ground is a prerequisite for high levels of aflatoxins
T
If pre-harvest infection is ______ and nuts are dried quickly then aflatoxin free nuts can be produced
absent
What are major contributors to pre-harvest infections in peanuts?
- high spore numbers
- plant stress (drought)
- high soil temperatures
Control of spore numbers can be achieved by _________ and __________
crop rotation
irrigation
Biocontrol is also used as an effective strategy to reduce aflatoxin infection, explain:
- only 40% of A.flavus produce toxin
- fields are inoculated with non-toxic strains to compete with toxins
Aflatoxin can be reduced in peanuts by manually _______ kernels after shelling
sorting
If the ground is too ___ Aspergillus grows and produces aflatoxin (this causes discoloration)
dry
If peanuts are _______ to remove the skin they can be sorted to remove discolored kernels
blanched
Aflatoxin removal by heat depends on which type of heat: boiling and autoclaving ________________, dry roasting removes up to ______, the alkali process used to make peanut oil removes _________
doesn’t help (less than 25% of toxin destroyed)
80%
all aflatoxin
Aflatoxin toxicity have 5 primary toxic effects:
- acute toxicity (indian example)
- liver carcinogenicity
- liver cirrhosis
- immunosuppression
- growth retardation in children
T or F: liver carcinogenicity (less obvious) than acute toxicity is the development of liver cancer from the sustained consumption of lower levels of aflatoxin over longer priods of time
T
If you are infected with ____________________, you are 30 times more likely to develop liver cancer due to the consumption of aflatoxin (they are synergistic)
Hepatitis B
In the liver, enzymes convert aflatoxin to _________.
epoxide
Epoxide binds liver ________ leading to liver failure
Epoxide binds _____ which is a precursor to liver cancer
proteins
DNA
Aflatoxin exposure before birth and during childhood is associated with _________
stunted growth (also observed in birds and other mammals) *mechanism is unknown
__________________ have been shown to suppress the cell- mediated immune response.
Effects include: ________________(3)
Aflatoxins
- decreases in the phagocytic activity of macrophages
- increased susceptibility to infection
- reduced response to vaccines
The accepted safe level of aflatoxin consumption in humans is ________
15ug/kg
Ochratoxin A is produced by 3 well defined groups of fungi:
1- The ocher-colored aspergilli
2- The black aspergilli
3- Penicillium species
Ochratoxin A is a _____________ that affects kidney function
nephrotoxin
T or F: OTA also has carcinogenic properties
T
OTA readily enters the blood stream through the intestine and can circulate for up to __________
3 weeks
T or F: As a result of the long half-life most people who regularly consume OTA in food will have detectable levels in their blood
T (mostly in Northern Europe, Northern North America, and Northern Asia)
The mechanism of action of OTA is still unclear, but it is likely related to _____________ metabolism
phenylalanine
People in North America are probably exposed to OTA via ________________ OTA production
P.verrucosum
Products involved with exposure of OTA include:
- barley
- wheat
- meat
- beer
- wine
- coffee
- cocoa
- chocolate
- dried vine fruits
OTA intake is much lower in ________ and ___________ regions
tropical and subtropical
The tolerable weekly intake of OTA is __________ of body weight
100 ng/kg
T or F: rapid drying is difficult but it prevents OTA production
T
____________ is a known producer of OTA especially in Wine
A. carbonarius
Levels of OTA in wine are generally low because:
fermentation stops fungal growth (production of alcohol)
OTA producing fungal growth can be prevented by:
- proper irrigation
- regular pruning (air flow)
- use of crop cover
- fungiside applications
Slow drying of coffee beans can lead to ___________
OTA formation, effective sun drying or mechanical dehydration provide effective control
OTA is largely removed in winemaking process when solid fractions are removed, _____ wines maintain OTA more than _____
red
white
Dependent on the temperature of roasting _____ of OTA will be removed in coffee
8-98%
______ and ____ removal can affect OTA levels in flour
bran
germ
________ to produce white flour creates 65% reduction in OTA
Milling
A further 10% decrease in OTA is observed after _______
backing
T or F: whole wheat bread shows less of a reduction in OTA since less of the grain is discarded
T
Fumonisins are produced by _____________________
- Fusarium verticilloides
- Fusarium proliferatum
- A.niger
T or F: Fusarium species are always present on corn and sorghum, even in healthy kernels
T
A.niger is associated with fumonisins in _________________
grapes, raisins and coffee
*this is of particular concern since A.niger can also produce OTA, the co-occurence of OTA and fumonisins is scary
Fumonisins is associated with which color?
Fuschia
Levels of F. verticillioides and F. proliferatum are influenced by _______ during or near harvest
climate
T or F: Colonization of the kernel is usually symptomless, but when the plant is stressed it leads to a disease- / mycotoxin producing interaction
T
Stress can be caused by:
- drought stress
- heat stress
- insect predation
Fumonisins affect________________ metabolism, and cause depletion of complex sphingolipids
his interferes with the function of some membrane proteins, including the inhibition of ____________
sphingolipid
folate binding
There is a dramatic disease in horses called ___________________
- it rapidly progresses and turns the horse brain to mush
- if feed contains more than 10mg/kg of fumonisin there is a risk of developing this disease
equine leukoencephalomalacia
In pigs fumonisin in feed leads to ________
In rats ____________
in humans, _____________ and ___________ in infants
heart failure
liver cancer
esophageal cancer, and neural tube defects such as spina bifida in infants (probably due to inhibition of folate binding)
Harvested corn should be rapidly dried to avoid fungal growth (Fusarium species do not grow below ____), this level of drying can occur in the field before harvest if the field is not over irrigated
Aw 0.9
T or F: most corn lost are inspected for fungal damage, and tested for levels of fumonisins
T
What is nixatmalization?
- Process used in central america
- Corn or other grains are soaked and cooked in an alkaline solution
- This process removes almost all fumonisins
- Processed products in these areas such as tortillas and other corn products are essentially fumonisin free
If product is processed above ______, fumonisin levels are decreased (breakfast cereal, snack)
150C
Deoxynivalenol (DON) is produced by Fusarium __________, F. _______
graminearum
culmorum
T or F: Only some F. graminearum produce DON and all F. culmorum produce DON
T
F. graminearum occurs in ____, and F. gaminearum and F. culmorum occur in _________, especially wheat and barley
corn
small grains
DON inhibits ____________
protein synthesis
DON toxicosis is rare, but it does cause _____________ and __________ in humans
intestinal symptoms
immunotoxicity
T or F: DON production on corn is the most prevalent in cooler and wet climates
T (Canada and Argentina are where rates are highest)
USDA allows ________ of DON for grains for human consumption and _______ for bovine feed
1 mg/Kg
10 mg/Kg
__________ can be used to control DON production, __________ helps reduce the risk
Fungicides
irrigation
T or F: Forecasting systems have been developed in Canada to warn producers when the weather poses a DON production risk
T
T or F: ZEA is produced by the same Fusarium species that produce DON, and generally under the same conditions
T
Zearalenone has a __________ toxicity
low acute
Zearalenone metabolites possess estrogenic activity in agricultural animals:
- pigs
- cattle
- sheep
Symptoms of ZEA in pigs include:
- vulvovaginitis
- vaginal and rectal polapse
ZEA is considered:
- hepatotoxic (toxic to the liver cells)
- ___________ (toxic to red blood cells)
- ________________
- ______________ (may be involved in cancer)
hematotoxic
immunotoxic
genotoxic
ZEA estrogenic activity has also been implicated in _________ and ___________ of girls in Hungary and Italy
early puberty
advanced growth
Out of all mycotoxins, which one are considered carcinogenic?
-Aflatoxin B and G
___________, _________, and__________are the mold genera most commonly associated with foods
Aspergillus
Penicillum
fusarium
Toxigenic molds are mostly found as contaminates of ________ foods
plant derived
T or F: Developed countries tend to have regulations on the allowable levels of mycotoxins in foods
T
