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Reduction of post-harvest losses in stored grains
SUMMARY OF MISSION REPORT UNDER
UNDP/FAO/THA/82/004
These were the most often observed practices at the farm level that contribute to the high level of aflatoxin. Harvesting and storing moist grain for a considerable time in mould infested storage bins summarise most often followed by Thai farmers. Changes in these areas should lower the aflatoxin contamination considerably. If the maize moisture content is high, every effort should be made to keep the grain as cool as possible.
Silo and exporters
By the time maize reaches terminal silo, the damage to the maize with respect to aflatoxin is history. The silos visited are well managed storage facilities and do not offer a conducive environment for fungal growth. The terminal silos practice sound and effective measures to prevent grain deterioration. It is this consultant's opinion and many commentors' that silo grading of income grain is not according to the official method established by the Thai government. The official grading standard seems to be subject to change without notice throughout the marketing system. The official grading standard is influenced by present supplies, demands and prices. Maize grades used, such as super A, by the terminal silos do not exist in the official grading standard published by the Thailand government.
Within the past five years, the terminal silos have greatly increased the storage and drying capacity, mainly to meet international maize standards required for moisture content. However, most of the
increased capacity is concentrated at or near point of export. If some of the drying capacity was centered inland near the major maize production area, a high percentage of the maize could be dried before mould growth occurs. The use of large highly efficient dryers, presently located at the end of the marketing system, could be very cost-effective method in reducing mould growth in Thai maize. Under the present system, moist maize is transported and then dried. The better system would be to dry the maize and then transport to the terminal silo. Under this system, the maize will be preserved before transporting. The installation of regional high efficient dryers should produce a high quality maize that is free of aflatoxin contamination and would demand a premium price on the international export market.
Exporter Importer Interface
Many exporters have commented that maize determined by analysis to be low in aflatoxin contamination at time of export, but when received by importer, had significantly higher level of aflatoxin (i.e. increased from 20 PPB to 100 PPB). This could be caused by a number of factors on the exporter side, improper sampling, improper analysis, or an increase in aflatoxin contamination anywhere along the exportimport interface. Due to tremendous economic gain or loss that can occur when the price of maize is related to level contamination, it is highly recommended that proper sampling and analysis be used before the Thai maize is exported.