Lecture 14- Mycotoxins Flashcards
What are Mycotoxins?
filamentous fungi that can develop on food commodities and produce chemical toxins
What are the toxins formed from?
Secondary products produced by fungus
Aspergillus, Fusarium & Penicillin
What causes mutations in the DNA?
Neurotoxins
What do some of these secondary metabolites do?
T2- leakiness in intestines
Where are many mycotoxins found?
cereals because ther are mostly attacked by fungus, not bacteria
Are mycotoxins easy to destroy?
Yes, difficult, heat stable
What are the major classes of mycotoxins?
- Aflatoxins (B1, B2, M1, M2, G1 and G2)
- Ochratoxins (ochratoxin A, OTA)
- Trichothecenes (deoxynivalenol – DON, T2 and HT-2)
- Fumonisins (FB1, FB2, FB3 and patulin, a mycotoxin that occurs mainly in apples & apple products)
- Zearalenone (ZEN)
The if the food chain?
Pre-harvest -> Harvest-> Post harvest -> Processing-> Distribution-> Marketing -> Consumption
Where can toxins contaminate?
Field fungi
Storage fungi
What do Aflatoxins contaminate?
Sorghum, Soy, corn, wheat, barley
What do trichothecenes contaminte?
Barley, oats, sorghum, soy, Corn, wheat
What does Zearaleone contaminate?
Wheat, sorghum, corn, barley
What are the method of control?
Physical, Chemical and biological
What materials can be used to absorb mycotoxins?
: silicon – clay powders ( fed to animals, binds to toxins and is excreted)
What are some of the physical methods?
Grinding, heat treatment, irradiatin degradation, inorganic absorption
What are the chemical methods?
alkilization, ozone degradation
Are chemical methods always feasable?
No
What are the biological methods?
microbial adsorption, microbiocaldegradation, biological degration
–> enzymes
What is a con of control?
Energy required
When can UV rays be applies?
only decontaminate the surface
What arr the Characteristics of Aspergillus Fiavus and parasiticus?
Soluble in polar organic solvents
Poorly soluble in water
Stable in neutral solution, resistant to strong acids, reapid decomposition in alkaline solution
Produce flruoresence, destructive for low concentration
Stable in 200C, decomposed at 268C
What is ZEN (Fusarium graminearum)
Insoluble in water, slightly soluble in hexane, soluble in alkali
Stable in neutral and acid
Ester bond will open in alkaline (high concentraion)
Blue-green fluoresence
Melting point is 161C
What is Deoxynivalenol (DON)?
Easily soluble in wate rand polar insoluble in hexane and diethyl ether Sensitive to alkaline Stable in neutral and acid Existing aborption peak under short wave UV Decomposed under high UV Reisitant to heat Stable in 120C for 1hr Decomposed at 170C for 15mins under pH10
Which toxins are hard to detroy with normal cooking?
DON
ZEN
AFB
What happens to aflatoxins once they are in the body?
They become more toxic
Effect of Aflatoxin
Carcinogen
Effect of Citrinin?
Nephrotoxic
Effect of Fumonosin
Carcinogen
Hepatogen
Trichothedecenes effect
Cytoxic
Immunosuppresive
Effect of ochratoxin
Carcinogen
Nephrotoxin
Hepatoxin
Tetratoxin
Effect of Patulin
Carcinogen
Immunotoxin
Genetoxin
Zearalenone
Esterogen activity
Potential caricnogen and tetragenic
Steps of mycotoxin analysis
Sampling
Pre treatment
Clean up
Detection
What happens during sampling?
- Mycotoxin-sampling plan defined by a mycotoxin test procedure & defined accept/reject limit
- Traditional approaches may not be adequate (since pop could be heterogeneous)
- Number of containers sampled can vary from ¼ (less than 20 metric tons) to the square root of the total number of containers for large lots (>20 metric tons)
- Whole primary sample must be ground and mixed so that the analytical test portion has the same concentration of toxin as the original sample
What ar ehte pre-treatment methods?
Liquid -liq extraction Supercritical fluid extraction Solid phase extraction Solid phase concentration Solid Phase micro extraction
