Its about mycotoxins and its effects on spoiling of grains.

1. The Bio deterioration of grains and the risk
of mycotoxins
Praveen Kumar
Department of Agricultural & Food Engineering
IIT Kharagpur
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2. Contents
– Bio deterioration of grains.
– Molds and mycotoxins.
– The significance of mycotoxins.
– The interaction of mycotoxins.
– The control of mycotoxins .
– The segregation of contaminated grains .
– Sampling and analysis .
– Conclusions .
– References .
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3. • The condition of stored grains is determined by a complex
interaction between grain and the variety of macro and
micro organisms.
• Insects , mites , rodents birds and microorganisms which
may attack it .
• Grains provide an abundant source of nutrients and the
natural consequence is the spoilage of the grains caused by
organisms.
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Bio deterioration of grains

4. • The extent of contamination by moulds is largely
determined by the temperature of the grain and the
availability of water and oxygen.
• The interaction between grain temperature and moisture
content also affects the extent of mould colonisation.
• Insects and mites (arthropods) can, of course, make a
significant contribution towards the bio deterioration of
grain, through the physical damage and nutrient losses
caused by their activity.
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5. Bio deterioration of grains
• In general, grain is not infested by insects below a
temperature of 17°C whereas mite infestations can occur
between 3 and 30°C and above 12 per cent moisture content .
• The metabolic activity of insects and mites causes an increase
in both the moisture content and temperature of the infested
grain.
• Arthropods also act as carriers of mould spores and their
faecal material can be utilised as a food source by moulds.
Furthermore, moulds can provide food for insects and mites
but, in some cases, may also act as pathogens. 5

6. • Another important factor that can affect mould
growth is the proportion of broken kernels in a
consignment of grain.
• Mould growth is also regulated by the
proportions of oxygen, nitrogen and carbon
dioxide in the intergranular atmosphere.
• Many moulds will grow at very low oxygen
concentrations; a half of linear growth,
Interactions between the gases and the prevailing
water activity also influence mould growth
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7. Moulds and mycotoxins
• In ecosystem the growth of micro organisms is due
to the nutrient availability and micro
environmental changes with time.
• Grains are predominantly contaminated by those
moulds requiring high water activities (at least 0.88
aw) for growth.
• Stored grains will support moulds which grow at
lower moisture levels.
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8. • The rate of mould growth is also determined by the ability
of the micro-organism to compete with other species.
• Some species, including those of Aspergillus, Penicillium
and Fusarium, can occur both in the field and in storage.
• Some secondary metabolites produced by moulds are
highly toxic to animals, humans and plants. These so-called
are 'mycotoxins'.
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9. Mycotoxins
• Mycotoxins are the metabolites ( by – product ) of the growth
of moulds.
• They have very real toxic side effects to other plants and
animals.
• They are also generally less selective of the hosts they attack
and can cross plant species .
• Fusarium , Penicillium and, Aspergillus are the most important
mycotoxins producing fungal genera .
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• They are low molecular weight compounds with diverse
chemical structures and biological properties.
• Toxigenic (mycotoxins-producing) Aspergillus moulds can occur
both before and after harvest.
• Fusarium and Penicillium moulds occur predominantly before
and after harvest .
• Aspergillus is associated with the tropics and Penicillium with
temperate climates, Fusarium moulds occur world wide.
• Temperature and moisture can greatly affect the growth rate
of fungi as well as the types and amount of mycotoxins
produced.

11. The major mould and mycotoxins
Mould species Mycotoxins produced
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Aspergillus parasiticus Aflatoxins B1, B2, G1, G2
A. Flavus Aflatoxins B1, B2
Fusarium sporotrichioides T-2 toxin
F. Graminearum deoxynivalenol (vomitoxin)
Zearalenone
F. Moniliforme fumonisins
Penicillium verrucosum ochratoxin A

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The significance of mycotoxins
• The significance of mycotoxins is difficult to asses due to
extremely small amount of toxic chemical in the diet .
• There are several risks of mycotoxins ,these are :
• Risk to human health.
• Their effect on animal health .
• Impact on livestock production and productivity
• Legislation ( when it exists) .
• Demand of the food industry of for high quality raw
materials.
• Mycotoxins are not easily detectable , when health problems
arise all possible involvement are investigated and then after
when no symptoms are found then only mycotoxins are
tested.

13. • The existence of legislation requires an agreed policy for
testing and control to be implemented , at present there is no
limit for mycotoxins in raw cereals .
• However , regulations are to be introduced in 2 to 3 years for
Aflatoxins and ochratoxin A in raw cereals .
• The mycotoxins have attracted worldwide attention, over the
past 30 years.
• Firstly because of their perceived impact on human health.
• Secondly, economic losses occurring from condemned
foods/feeds and decreased animal productivity.
• Thirdly, serious impact of mycotoxins contamination on
internationally traded commodities.
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The Aflatoxins
• Aflatoxins are group of mycotoxins produced by Aspergillus ,
mainly A. parasiticus and A.flavus .
• They are common fungal contaminants of nuts but are also
found in many other feedstuffs e.g. corn , tree nuts , rice and
wheat.
• Aflatoxins B1 , B2, G1 and G2 are four naturally occurring
forms of Aflatoxins , B1 being the most potent prevalent .
• Chemical structure of Aflatoxins.

15. The Ochratoxins
• The ochratoxins are produced by numerous Aspergillus and
Penicillium supplement , including A.ochraceus and
Penicillium verrucosum.
• Ochratoxins are found principally in cereal grains but also in
animal by-products because of their binding with plasma
proteins and long half life in animal tissues .
• There are four ochratoxins homologues : A, B , C and D. A is
the most prevalent whereas , A & C are most toxic .
• Chemical structure of Ochratoxins.
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16. Tremor genic mycotoxins
• Tremor genic mycotoxins are produced by Penicillium ,
Aspergillus , and claviceps .
• They are rarely found in feed ingredients but are usually
produced during food spoilage .
• Dogs are exposed to tremor genic mycotoxins when eating
mouldy garbage ,such as dairy product , nuts , grains.
• More than 20 mycotoxins have been classified as tremor gens.
• Most tremor genic mycotoxins are neurotoxic indole alkaloids.
• Penitrem A causes slight salivation , vomiting , ataxia and
tremors in dogs . 16

17. The interaction of mycotoxins
• The complex ecology of mould growth and mycotoxin
production can produce mixtures of mycotoxins in food and
feed grains, particularly in cereal .
• The co-occurrence of mycotoxins can arise through a single
mould producing more than one toxin.
• The co-occurrence of mycotoxins can affect both the level of
mycotoxin production and the toxicology of the contaminated
grain.
• The presence of trichothecenes may increase the production
of Aflatoxins in stored grain .
• To date, little is known about this particularly important area
of mycotoxicology.
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18. The control of mycotoxins
• Since the occurrence of mycotoxins is a consequence of bio
deterioration, to mitigate the effect of spoilage the agents like
temperature, moisture and pests should be controlled.
• Humid climate ,excess rainfall and moist weather lead to
mould contamination and mycotoxin production in grains.
• Considerable effort has been expended on the development
of crop strains which are resistant to mould growth or
mycotoxin production.
• Breeding programmes have focused, for example, on the
development of Aspergillus/Aflatoxins resistant varieties of
maize and groundnuts, with limited success.
• However, despite the best efforts of the agricultural
community, mycotoxins will continue to be present in a wide
range of foods and feeds.
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19. The Segregation of Contaminated Grains
• There are basically two methods of controlling mycotoxins:
• The segregation of contaminated grains and,
• The Detoxification of Mycotoxins.
The segregation of contaminated grains :
• The identification and segregation of contaminated
consignments is pursued through the implementation of
quality control .
• The consignment is accepted or rejected on the basis of the
analysis of representative samples of the food or feed.
• Acceptable levels of mycotoxin contamination are specified by
individual customers, commercial agreements and regulators .
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20. • The mycotoxin content of grains can be further reduced
during processing.
• Automatic colour sorting, often in combination with manual
sorting, is widely used to segregate kernels of abnormal
appearance during the processing of edible grade groundnuts.
• Mycotoxins can also be concentrated in various fractions
produced during the milling process.
• Zearalenone and deoxynivalenol, for example, are reportedly
concentrated in the bran fraction during the milling of cereals.
• the stability of mycotoxins during processing will depend
upon a number of factors including grain type, level of
contamination, moisture content, temperature and other
processing agents.
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21. The Detoxification of Mycotoxins
• Ammonia, as both an anhydrous vapour and an aqueous
solution, is the detoxification reagent, for the destruction of
Aflatoxins.
• The nature of the reaction products of the ammonisation of
aflatoxin is still poorly understood.
• The formal approval of the ammonisation process by the USA
Food and Drug Administration is still awaited.
• Commercial processes have not been developed for the
detoxification mycotoxins.
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22. Sampling and analysis.
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• The control of the mycotoxin problem comprises :
• The identification of the nature and extent of the problem by
the implementation of surveillance studies .
• The regular monitoring of foods and feeds as part of a quality
control programme.
• The introduction of improved handling procedures, which
address the identified problems.
• The distribution of aflatoxins (and, presumably, other
mycotoxins) in grains is highly skewed, it is important that
great care is taken to collect a representative sample .

23. Conclusions.
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• The mycotoxins described in this chapter, as symptoms of bio
deterioration, are acutely toxic, carcinogenic,
immunosuppressive and oestrogenic.
• The potential immunosuppressive role of mycotoxins in the
aetiology of human disease is an especially important issue
which requires further careful study.
• Every effort must be made to minimise the occurrence of
mycotoxins in food and feed grains.
• Undoubtedly, the implementation of improved handling and
quality control procedures will have a significant effect on the
incidence of mycotoxins in important foods and feeds
throughout the world.

24. References
• Maxwell C K Leung, Gabriel Diaz – Llano, and Trevor K. smith.
Department of animal and poultry science, university of
Guelph, Guelph, Ontario, Canada.
• Naresh magan, David aldred, applied mycology group
carnfield health, Carnfield University, silsoe campus, Bedford.
• K .A . Scudamore , KAS mycotoxins , 6 fern drive , Taplow
maidenhead , Berkshire .
• Black, Kevin. “Aflatoxins in Corn” (Dec. 1996) Online.
Internet. 20, February , 1997.
• Cheeke, Peter R., Lee R. Shull. ed. Natural Toxicants in Feeds
and Poisonous Plants. Westport: AVI Publishing 1988
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Thank you