Management/Prevention of aflatoxin contamination.

Aflatoxins are secondary fungal metabolites that contaminate agricultural commodities and can cause sickness or death in humans and animals.

Risk of aflatoxin contamination of food and feed in Africa is increased due to environmental, agronomic and socio-economic factors. Management Prevention or management of aflatoxin contamination may be directed at both the process of contamination and the fungi causing contamination. The contamination process can be divided into two phases based on crop maturity (Cotty, 2001).

The first phase:

This occurs during crop development and is generally associated with physical damage to the crop typically by either physiologic stress or insect activity (Russell, 1982; Cotty, 2001). Crop components contaminated during the first phase often fluoresce a bright green-yellow as a result of kojic acid production in crop tissue by the aflatoxin-producing fungi (Zeringue et al., 1999). After maturation, the crops remain vulnerable to contamination, providing a window during which a second phase of contamination may occur (Bock and Cotty, 1999; Cotty, 2001). Exposure of the mature crop to both high humidity and temperatures conducive to aflatoxin producing fungi can result in both new crop infections and increases in the afla-toxin content of crop components already infected (Russell et al., 1976; Cotty, 1991).

The second phase:

This may occur prior to harvest in the field or after harvest during transportation, storage, or at any point until the crop is consumed.

NB: Hot dry conditions during crop development favor the first phase of contamination, whereas rain and high humidity with warm temperatures after crop maturation favor the second phase.

Solution:

Farming Management Information System that gathers real time data to help farmers identify and apply better crop management practices. Example in post- harvest management practices on storage duration, storage type, sorting on-farm management of aflatoxin contamination.

Reliable management practices must address both phases. Improving the resis-tance of cultivars to contamination is one method of simultaneously addressing both phases of contamination. Although proper cultivar selection and crop management can limit vulnerabil-ity to both phases, environmental changes can better even the best management practices and result in a highly contaminated crop (Wilson and Payne, 1994; Cotty et al., 2001).

When management procedures fail to prevent accumulation of unacceptable levels of aflatoxins, there are still options for the utilization of the contaminated crops. These options include detoxification. Chemical detoxification is a viable option for even very highly con-taminated crops, with ammoniation the detoxification method currently in the widest use. Ammoniation inactivates aflatoxins by hydrolysis of the lactone ring, which is followed by further breakdown. Ammoniation has been used in North America, Europe, and Africa on crops including maize, cottonseed, and peanut meal (Park et al., 1988; Bailey et al., 1994).

Following detoxification by ammoniation, the treated crop products are nutritionally valu-able for domestic animals, but are not suitable for human consumption.

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