Aflatoxins are deadly

By Sosimo. Ma. Pablico

Never take aflatoxins for granted.  Worldwide, these are known to be deadly.

Helen R. Calica, supervising science research specialist of BPRE (Bureau of Postharvest Research and Extension), said that aflatoxins are the most widely known among the mycotoxins because of their acute and chronic toxicity in animals.  Aflatoxins have been reported to produce four effects: acute liver damage, liver cirrhosis, stimulation of tumors, and other genetic effects.

Calica reported that in 1960, the first effect of aflatoxins was realized following the death of 100,000 young turkeys in England.  A high incidence of liver disease in ducklings in Kenya was also found.  Scientists soon established that the causes of these problems were the common molds Aspergillus flavus and Aspergillus parasiticus.

In 1974, an outbreak of hepatitis due to aflatoxins affected 400 individuals in India, resulting in the death of 100 or one-fifth of the affected individuals, the BPRE expert added.  The outbreak was traced to corn heavily contaminated with Aspergillus flavus.

She added that aflatoxins were also suspected as the cause of   Reye’s syndrome, a common cause of death of South East Asian children.  In 1971, exactly 23 Thai children died of the Reye’s syndrome and scientists found significant levels of aflatoxins in their livers. In Czechoslovakia and New Zealand, aflatoxins were also found during the autopsy in the livers of children who have died from Reye’s syndrome.

Likewise, 125 Kenyans died in 2004 after eating corn contaminated with aflatoxins.  Nearly 200 others were treated after eating similar material.  The deaths were associated mainly with homegrown corn that were not treated with fungicides or were not properly dried before storage.  It was reported that due to food shortages at that time, Kenyan farmers harvested corn earlier than normal to prevent thefts from their fields.  The corn kernels were more susceptible to aflatoxin infection because these were not fully mature.

Calica said aflatoxins remain as a problem in developing countries.  She said scenarios all over the world, as reported by the Food and Agriculture Organization, are alarming especially in the Philippines because of the prevailing high temperature and relative humidity, which favor fungal growth.  Moreover, heavy rains coincide with the peak harvest months of staple cereals, particularly corn.  As a result, high moisture in the grains leads to aflatoxin formation.

Unfortunately, many farmers in the Philippines are not aware of the deadly effects of aflatoxin.  In Isabela, for instance, we passed by piles and piles of corn still with their husk being exposed to continuous rains towards the end of last August.  On our way to Brgy. Dinganen, Buldon, Shariff  Kabunsuan in early  September, we also passed by a good number of sacks filled with corn still in the cob, that were stored outside the farmer’s  house.  Consequently, the corn was exposed to aflatoxin contamination.

Filipino farmers suffer financial losses because of the rapid deterioration of wet grains caused by the growth of molds, technically known as mycotoxin, a poisonous substance produced by the fungi Aspergillus  flavus and Aspergillus parasiticus.             

The market price of contaminated corn is greatly reduced, resulting in low economic gain.  Thus, BPRE recommends MACS (Maize Aflatoxin Control System) as the best approach to prevent aflatoxin contamination.

MACS is an integrated set of technologies, which aims to produce aflatoxin-safe corn. and minimize fungal infection and aflatoxin contamination.  It is designed to reduce postharvest losses and address the need for good quality corn that is highly acceptable in the domestic and global market.

In the farm, good agronomic practices reduce the susceptibility of corn grains to mold infection while still in the farm.  Observe the following:

Avoid stress causing condition to crops.  Poor irrigation, lack of fertilizer and poor pest management make the crop more susceptible to mold attack.  Protect your harvest from rainfall.  Harvesting should be done during fine weather conditions.  Harvested corn must be in volumes that could be dried immediately for two days after harvest.  Harvest corn as soon as it reaches optimum maturity. Use bags and baskets during harvest to protect the crop from fungal infection.

After harvest, dry the corn immediately to lower the moisture content to 14 percent. Drying is a strategic intervention because high moisture is favorable to fungi.  Sundrying, if unreliable, takes 2 to 3 days to dry the corn kernels.  Any delay in drying would allow the growth and production of aflatoxin.

To minimize wounds or injuries, corn should be harvested and shelled only when matured.  Good shelling results in clean kernels with less brokens. Cracked or broken kernels provide entry points for mold contamination and growth. Use shelling machines that do not damage the kernel and those that produce clean shelled corn.  Corn should be free from impurities.  It should be kept clean to prevent insect infestation.

Corn should have 14 percent moisture content during storage to avoid aflatoxin contamination. Good storage facilities and practices minimize fungal infection and rewetting of the grains.

To prevent infestation of pests like insects, birds, rodents, fungi and bacteria during storage, follow integrated pest management to preserve grain quality.  It involves the combination of physical, biological and chemical controls.

(For past columns, click http://sundaypunch.prepys.com/archives/category/opinion/harvest-time/ Readers may reach columnist at spablico@yahoo.com . For reactions to this column, click “Send MESSAGES, OPINIONS, COMMENTS” on default page.)

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