1. Aflatoxins 50 years after: still unsolved challenge
Slaven Zjalić,
Department of ecology, agronomy and aquaculture, University of Zadar, Croatia

2. Aflatoxins are secondary metabolites produced by some moulds belonging to Aspergillus section Flavi secreted on the growing media
Aflatoxins have no odor and no taste
Through whole human history aflatoxins were present in food and feed

3. Discovered only in the past century after the outbreak of Turkey X desease in UK in 1960
In different farms more than turkeys and ducklings died
The only thing in common was peanut based feed

4. Since then different fungal species were reported as aflatoxin producers
Almost all important aflatoxin contaminations are caused only by 2 species:
Aspergillus flavus and Aspergillus parasiticus

5. Moulds produce 4 aflatoxins B1, B2, G1, G2
More than 70% of produced aflatoxins
Aspergillus flavus
Aspergillus parasiticus

6. When iradiated with UV light aflatoxins have fluorescence blue (B) or green (G)

7. Toxicity of aflatoxins: B1> B2 >G1 >G2
Aflatoxins have cytotoxic and genotoxic effects: immune suppression, terratogenic, mutagenic, carcinogenic
Toxicity of aflatoxins:
B1> B2 >G1 >G2
Aflatoxicosis
Chronic
Acute (rare)
Cytotoxicity
Interference with metabolic processes in the cell
Genotoxicity
Mutagenic and carcinogenic effects, suppression of immune system

8. Toxicity is specie –related, sometimes sex related within the same specie
LD 50 mg kg-1 body weight
rabbit
0.3
duckling
0.43
rat
male
female
5.5 – 7.5
17.9

9. In the same organism different tissues are differently affected by aflatoxins
Detoxifications of animal cells from aflatoxins is operated by cytochrome P450 family
In mammalians part of AFB1 is transformed in less toxic M1 secreted by milk

10. Aflatoxins are persistent molecules
Intoxication
Primary
Consumption of contaminated plants or their parts (seeds, fruits)
Secondary
Consumption of animals fed by contaminated feed or their products (milk, eggs)

11. Due to their toxicity the legislations of almost all the countries have limited the concentration of aflatoxins in food and feed commodities EU
mg kg-1
USA
China
Almonds
8 (B1)
12 (tot)
20 (tot)
30 (tot)
Animal feed
2 (B1)
20 (B1)
Milk
0.05 (M1)
0.5 (M1)
0.5
Infant formulae
0.025 (M1) -
Spices
5 (B1)
10 (tot)

12. Contamination with aflatoxins is a worldwide problem
Different commodities can be contaminated: cereal seeds, spices, dry fruits, meat products, cheese
Aflatoxigenic moulds requires relatively low aw (>0.7)
Contamination can occur in preharvest, in field, and postharvest period during any phase of transformation process or stocking

13. Oxidative stress is considered a prerequisite for aflatoxin biosynthesis
Oily seeds, at same humidity, have higher aw and lipid oxidation triggers aflatoxin biosynthesis

14. For contamination in field high temperatures and high humidity, preceded by drought or insect attack are needed
In Europe contamination with aflatoxins were considered more a problem of import or bad conservation
Due to global climatic changes in some years aflatoxin contamination in field is a serious problem in some European countries

15. 2003 and 2012 were “black” years for aflatoxin contamination in Europe
Currently Gafta (Grain and Feed Trade Assosiation) has signalized reported high levels of aflatoxins in maize grains from:
Spain, Italy, Serbia, Bulgaria, Romania

16. Role of aflatoxins still not clarified
Response to a stress, especially oxidative stress
Major growth of mould doesn’t mean higher production of aflatoxins
Gens are clustered, part of the signaling network that regulates expression of the cluster described

17. No method for total prevention of their presence in food and feed has been achieved
Control can be divided in:
prevention
detoxification
adsorption

18. good agriculture practice (avoiding stress, quick postharvest drying)
Prevention
good agriculture practice (avoiding stress, quick postharvest drying)
use of fungicides
use of antioxidants and organic acids
use of natural products (plant and fungal extracts)
Aflatoxins produced on maize seeds treated and non with BHA
control
BHA

19. Decontamination
removal of husks can significantly lowers the quantity of aflatoxins
chemical treatments
use of microbial enzymes

20. Adsorption
different hydratated sodium calcium aluminosilicates (HSCAS) used to adsorb aflatoxins in animals

21. Conclusions
Aflatoxins represent high health hazard for humans and animals
No method for total prevention of their presence in food and feed has been achieved
Nevertheless the presence of aflatoxins in food and feed in EU countries is under control