Molds Flashcards
What are Mycotoxins?
fungal metabolites which when ingested,inhaled or absorbed through the ksin cause disease in humans and domestic animals, including birds Toxocity is almost nevr acute- effects are cumulative over long periods of time
Do spores cause mycotoxin problems? Why or why not?
No, mycotoxins are only a form of fungal growth, but very stable and persist in food even after processes
What mycotoxin can cause acute toxicity?
Aflatoxin, resulting in aflatoxicosis → jaundice, fever, vomiting, anorexia
What produces Alfatoxin?
Aspergillus
Where is Aspergillus located?
A. flavus → peanuts, corn and tree nuts A. parasiticus → peanuts
Why is there often lots of Aspergillus growth? How can you reduce numbers?
Infection can occurs when peanuts are still in ground → high spores due to preharvest infection and high soil temperatures No aflatoxin if no infection and nuts dried quickly Crop rotation reduce spore numbers Biocontrol of non-toxic aspergillus to outcompete also works
How do you reduce Aflatoxin in peanuts?
Maunal sorting of kernel after sehlling. If ground is too dry, Aspergillus grows and produced aflatoxin → discoloration Blanched peanuts remove skin and then sorted base don discoloration Aflatoxin removal by heat depends on which types of heat Boiling and autoclaving reduce 25% Dry roasting removes 80% Alkali process for peanut oil completely removes aflatoxin
What are the toxic effect of Aflatoxins?
Acute toxicity Liver carcinogens→ liver enzymes convert aflatoxin to epoxise that binds to liver proteins and leads to liver failure LiverCirrhosis Immunosuppression Growth and retardation in Children Accepted SAfe level for consumption is 15 ug/kg
What fungi produce Ochratoxin?
Ocher-colored: Aspergillus ochraceus, A. westerdijkiae and A. steynii Black aspergilli: A. carbonarius, A. niger Penicillium: P.verrucosum and P. nordicum
What are the toxico effects of Ochratoxin A (OTA) toxicity?
OTA is a nephrotoxin that affects kidney function Carcinogenic properties Readily enters the blood stream through the intestine and can circulate for up to 3 weks Long half life→ can lead to detectable levels
What are some food that may contain OTA? What is the tolerable limit?
Barley, wehat, meat,beer, wine, coffee, cocoa, chocolate, dried vine fruits Lower in tropical and subtropical regions Tolerable weekly intake is 100ng/kg of body weight Cereal exposure is 8-17 ng/kg
What are some methods to control OTA? In Wine? In Coffee?
Rapid drying to prevent production In wine, A. carbonarius is a known OTA produce that infects prior to harvest Irrigation, regular pruning, crop cover, fungicide applications In Coffee, rarely on coffee beans at harvest, due to slow drying Sun drying or mech dehydration = good control
What effects do processing methods have on OTA?
Wine More in red than whtie wine, around 1-8% OTA from grape in final product Removed when solids are removed Coffee Dependent on temp of roasting 8-98% will be removed, highly contaminated samples will be discarded Cereals Bran and germ removal can affect OTA levels in flour milling→ 65% reduction in OTA
What produces Fumonisins?
Fumarium verticilloides, Aspergillus niger A. niger is associated with grapes, raisins, coffee→ also produces OTA Always presnet on corn and sorghum, even healthy ones
When are Fumonisins grown?
When the plant in stressed drought , heat insects
What does Fusarium affect?
Interferes with the function of some membrane proteins, including inhibition of folate binding humans→ esophageal cancer and neural tube defects
How do you control Fumonisins?
Good GAP Potential resistant corn Harvest should be dried rapidly toa bout fungal growth, most tested for levels
What is Nixtamalization
Process of soaking and cooking in alkaline solution - removed most fumonisins
What are some methods to remove Fumosariums in food?
Corn can be wet milled (starch, ger, fibre) Dry milled (bran, germs, meal, flour Fumonsins survive these processes there are higher concentration in bran and germ, >150C fumonisin lvl decreases
Explain Deoxynivalenol (DON).
Produced by Fusarium graminearum, culmorum F. graminearum- corn, F. g and F. c occurs in small grains (wheat and barley) These are always pathogens to the plant causing Gibberlla ear rot in the corn and Fusarim head blight in wheat and barley Epidemics Require airborne or insect borne spores, innoculationat susceptible time and appropriate moisture an temp More northern climates DON inhibits protein synthesis Toxicosis is rare but it does cause intestinal symptoms and immunotoxicity Incorn, more prevalent in cooler and wet climates Residues of crops were left in field → risk factors for contamination next year Crop rotation and forecasting systems USDA allows for 1mg/kg of DON in grains for humans consumption and 10mg/kg for feed Fungicides are be used to control DON production
What produces Zearalenone and what are the toxicities of the mycotoxin?
Produced by the same Fusarium species that produce DON, same conditions ZEA is considered Hepatotoxic Hematotoxic Immunotoxic Genotoxic (cancer) ZEA estrogenic activity has also been implicated in early puberty in girls- all effects poorly understood
What mold genera are most commonly associated with foods?
Aspergillus, Penicillum and Fusarium
Which Mycotoxins are carcinogenic?
Aflatoxin B+G= carcinogenic
Aflatoxin M1 = possibly carcinogenic
Ochratoxin = PC
Fumonisins = PC
Deoxynivalenol = Not evaluated
Zearalenone= EV
