Handling and aflatoxin contamination of white maize in Costa Rica.
Mora, M.; Lacey, J.;
Mycopathologia Year: 1997 Vol: 138 Issue: 2 Pages: 77-89 Ref: 17 ref.
1997
บทคัดย่อ
The examination of >3000 samples of maize collected from all regions of Costa Rica during 1985-88 at different stages, from the growing crop and storage to final sale, and at different water contents, is reported. Contamination with Aspergillus flavus was frequent and approx. 80% of samples contained >20 ng/g aflatoxins. Mean contamination with aflatoxins in the Brunca Region was >274 ng/g while that in other regions was <70 ng/g. Except in the Brunca region, where it averaged 376 ng/g, contamination of grain from commercial sources was slightly less than of that from farms (less than or equal to 15 ng/g). Samples kept on the cob after harvest contained almost no aflatoxin while shelled samples were frequently highly contaminated. Experiments were performed in the Brunca and Huetar Atlantic Regions, using 34 experimental maize crops to study in detail the development of A. flavus and aflatoxin from before harvest, through postharvest treatment before drying and through storage for 6 months. A. f
lavus was isolated more frequently from maize shelled immediately after harvest than from that kept on the cob until it could be dried, and from more samples from the Brunca Region than from the Huetar Atlantic Region. Samples harvested with more than or equal to 18% water content often contained >70% of grains infected with A. flavus but sometimes there were few grains infected. As in the initial survey, more aflatoxin contamination developed in shelled maize than in that handled on the cob during the period from harvesting to drying, especially if the delay was >5 days, and more in Brunca than in Huetar. Shelled grain contained 400-800 ng/g aflatoxin in Brunca but <100 ng/g in Huetar while grain kept on the cob contained <30 ng/g, even with >18% water content. The incidence of Fusarium spp. exceeded 50% except where A. flavus colonized >80% of grains.