Aflatoxin guide for corn production program

1. AFLATOXIN IN CORN

2. BEWARE
A silent killer is on the loose. Silently,
potently, mycotoxins creep into the food
chain creating economic and health
hazards.
The problem is -----
Not many are aware of their existence.
Mycotoxins do not belong to the more
popular poisons.

3. MYCOTOXINS . . .
 produced by fungi
when they grow in
grains and other
substrate
produce harmful effects
to animals and man

4.  derived from the Greek words “MYKES”
(fungus) and “TOKSIKON” (poison)
 toxic products of microscopic fungi or
molds that have serious adverse effects in
humans and animals
 toxic, carcinogenic, mutagenic, teratogenic
and estrogenic metabolites

5.  can be produced in storage under conditions
favorable for growth of toxigenic fungi
 It is estimated that there are about 20,000 to
300,000 unique mycotoxins and only a
relative few (<50) have been well
characterized.
 Can cause death or chronic ill health
resulting from damage kidneys and liver.

6. Toxigenic fungi
 are fungi that produce mycotoxins
 Do not produce mycotoxins after
ingested by animals and humans.
 Grow in corn, cereal, soybeans,
sorghum, peanuts, silage and other
food and feed crops or hay in the field in
grain during transportation.
Fungus

7. THE FUGUS
• present in the environment
* air
* soil
* decaying vegetation
* contaminated facilities
(storage bins, cribs,
transport vehicle)
• can be spread thru the conidia spores by :
* air * insects
* mites * higher animals
* facility personnel

8. Toxins Producing Fungi Common
Substrate
Susceptible
Species
Aflatoxin A . Flavus
A . Parasiticus
Corn. Peanuts,
cotton seed,
surghum etc.
Mammals, fish,
bird, man
Ochratoxin A . Ochraceus
P. Viridicalum
Corn, barley,
legumes
Swine, cattle
Vomitoxin F . Graminearum Corn Swine
Fumonisins F . Moliniforme
Fusarium spp
Corn Mammals, birds,
man
T-2 Toxin F . Sporotrichioides
Fusarium spp.
Corn, cereals Mammals
Zearalenone F . Graminearum
F . Roseum
Corn, cereals Swine
IMPORTANT MYCOTOXINSIMPORTANT MYCOTOXINS

9. PROPERTIES OF AFLATOXIN
• Naturally occurring toxin produced by fungi/molds
• 4 aflatoxins produced by different kinds of fungi
Aflatoxin B1 (AFB1) – most toxic
- produced by Aspergillus flavus
and Aspergillus parasiticus
Aflatoxin B2 (AFB2) – less toxic than AFB1
- produced by A. flavus and A.
parasiticus
Aflatoxin G1 and Aflatoxin G2 – less toxic; produced
only by A. parasiticus
• AFB1 and AFB2 = exhibit blue flourescence under UV
AFG1 and AFG2 = exhibit green flourescence under UV

10. Stable;
•not destroyed during processing or heating even up to 260o
C.
• heating under pressure inactivates aflatoxin by 50%
• even if the mold is killed during heating, the aflatoxin may
still be present
• irradiation with 5-10 kG will kill the fungi but will not
completely decompose aflatoxin
• When AFB1 and AFB2 are ingested by lactating cows, about
1.5% is hydroxylated and excreted in the milk as AFM1 and
AFM2 compounds of lower toxicity than the AFB1 and
AFB2 but significant because of the widespread consumption
of cow’s milk by infants.

11. NOT USED IN HUMANS!!!
•because of its stability, aflatoxin is NOT converted to
another substance or compound needed by the animal
or human body for growth and development but is
filtered and accumulates in the liver.

12. Agricultural Commodities
Susceptible to Aflatoxin
Corn
Cassava
Peanut
Copra

13. Relative Distribution of Aflatoxin in
Different Milled Fraction
23.25%
9.85%
4.56%
62.24%
"Sungo"(Bran +
Germ Fraction)
"Tahop" (bran)
Grits (Starchy
endosperm)
"Tiktik" (Floured
corn)

14. Effects of Aflatoxins In Poultry
• 50% reduction in growth
rate
• 30% reduction in feed
conversion efficiency
• fewer and smaller eggs are
produced by laying hens
• Downgrading of carcasses
• Altered immunity which
increases susceptibility to
disease
• Increased mortality rate

15. Effects of Aflatoxins on Human Health
A correlation has been established between per
capita corn intake and the incidence of Primary Liver
Cancer (PLC) in the Philippines
Aflatoxins have been linked with
the occurrence of various chronic
diseases in humans, such as Indian
childhood cirrhosis, chronic
gastritis, kwashiorkor, Reye’s
Syndrome

16. Effects of Aflatoxins In Pigs
 Toxicity has been reported in suckling pigs, growing and
finishing pigs, and breeder stock
 Effects of aflatoxin depends upon age of animal, diet,
concentration of aflatoxin and length of exposure
 Pigs are more resistant to dietary levels of aflatoxin up
to 300ppb fed from the time of weaning to marketing
 Most important impacts of aflatoxicosis are increased
mortality rates, decreased weight gain ,decreased feed
conversion efficiency

17. Maximum tolerated levels of aflatoxin in foodstuff in
Asian Countries
Country Commodity Tolerance(ug/kg)
Aflatoxin B1
People’s Maize and maize products 20
Republic Peanut and peanut products 20
of China Rice, other edible oil 10
Taiwan Cereals (rice,maize,peanuts,
wheat, barley
sorghum, legume, etc.)
50
Hongkong Peanut and peanut products 20 (including
aflatoxin M1,M2)
India All foods 30
Japan All Foods 10

18. THE AFLATOXIN
CONTAMINATION IN CORN

19. Afla Contamination Process
Sound Grains Moldy Grains
Aspergillus Mold
Mold Infection
Mold Growth

20. Afla Contamination Process
Factors for Fungal Growth
Mold Infection
Mold Growth
• Infection by Aspergillus mold
• High moisture content on the grain
• Favorable relative humidity
• Near ambient temperature

21. Afla Contamination Process
Favorable Conditions for Afla Formation
Mold Infection
Mold Growth
• Deep penetration of mold to the
carbohydrate
• Above 14% MC, particularly 17%-25%
• Above 85% relative humidity
• 25o
C to 30o
C temperature
+ Aflatoxin Formation

22. Afla Build-Up Pattern
LEGEND
Harvesting
Shelling
Drying
Trader’s Level
Wholesaler’sLevel
Miller’s Level
Feed Product
LEGEND
Harvesting
Shelling
Drying
Trader’s Level
Wholesaler’sLevel
Miller’s Level
Feed Product
After Drying
38 ppb
After 2 Days
20 ppb
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 40 42 44 46
Days After Harvest
60
20
40
50
10
30
A
F
L
A
T
O
X
I
N

23. The Environment Favorable for the Growth of A.
flavus and Aflatoxin Contamination in the Corn Ear
• Air/soil temperature = 10-35o
C (favors
germination of sclerotia in the soil).
•Kernel moisture = 13-30%
•Relative Humidity = 62-99%
•pH = 2-9
• drought stress, nitrogen stress, shading
• rotting plant residues
• presence of vectors (mites, weevils, beetles,
animals) for spore dispersal.
• Air !!! (A. flavus is an obligate aerobe).

24. EVENTS LEADING TO AFLATOXIN
CONTAMINATION IN THE CORN EAR
Spore
carriers
moist silk
Decaying corn residue
high To
, RH,
drought
N deficiency,
Shading, poor root
development
Corn laden with
fungus and aflatoxin

25. The Challenge is …
How can we minimize aflatoxin
contamination in corn?

26. Postharvest operations that favor the
production of aflatoxin
 Storage in plastic sack or spreading on floor with
shed for more than 3 days for shelled corn with
moisture content of 18 % and above
Shelling ear corn with moisture content ranging
from 26% and above favors the growth of aflatoxin
forming fungi
Storage of unevenly dried corn grains, i.e., pockets
of skin dry (15%-17% M. C.) grains are present in the
lot, favors aflatoxin production

27. Other Conditions that Favor Aflatoxin
Formation
Corn moisture content between 22% to 18% produce
high amount of aflatoxin
Damaged corn grains favor the growth of the
aflatoxin forming fungi
 growth of the aflatoxin forming fungi is favored
in the presence of impurities e.g. cobs
 Stress condition of the plants before harvest such as
insect infestation, drought condition and lack of
fertilization

28. Prevention of Aflatoxin
Contamination in Corn
• Harvest corn at full maturity
• Dry corn ears before shelling; the moisture content
should be below 18 - 21% before shelling is done to
prevent mechanical damage
• Dry the shelled corn uniformly to 14% within two
days from shelling
• Prevent contaminating dried from fresh corn grains
• Prevent insect infestation in storage
• Prevent microbial growth during storage

29. An important note for the public

30. THANK YOU!