|Shier, William - UNIVERSITY OF MINNESOTA|
Submitted to: Asian-Pacific International Society on Toxinology Congress
Publication Type: Proceedings
Publication Acceptance Date: October 29, 2008
Publication Date: December 6, 2008
Citation: Shier, W., Abbas, H.K. 2008. The Case for Using Cultural Methods to Monitor Aflatoxin Contamination of Crop in Developing Countries. Asian-Pacific International Society on Toxinology Congress. 1:148. Interpretive Summary: Aflatoxin is a group of toxic materials produced by a fungus (mold) called Aspergillus flavus. This toxic compounds are the most common and worrisome mycotoxins globally. These toxic materials are regulated in almost all developed and some non-developed countries. This toxic material accumulation in agricultural crops takes place in before harvest, but it is found in after harvest products. In this work we developed simple, sensitive and economical cultural methods to evaluate crops to determine the amount of Aspergillus flavus (that produces aflatoxin). This will be of most help in developing countries, where food safety is of greatest concern.
Technical Abstract: 1. Background Aflatoxin is the most important mycotoxin problem worldwide. In developed countries the major problem with aflatoxin is the cost of regulatory compliance. Aflatoxin production occurs almost exclusively pre-harvest, but it is measured post-harvest and can be assumed to be constant because storage conditions are near ideal. In developing countries the major problem is chronic toxicity, including primary hepatocarcinoma and reduced immunity. Most aflatoxin production occurs post-harvest because storage conditions are often far from ideal, and the poorest people store the most contaminated crops under the worst conditions. 2. Material and methods In developing countries aflatoxin levels are generally determined only in crops intended for export, which are stored under near ideal conditions. The major health concern is with crops intended for domestic consumption. The case will be made that the greatest need is for an inexpensive, low-technology test to determine the amount of toxigenic Aspergillus flavus. We propose cultural methods in which a sample is ground, suspended in boiled water, diluted through aliquots of boiled water and used to inoculate a suitable starch-gelled medium in a glass Petri plate. The number of toxigenic A. flavus colonies can be counted after inducing a color change to red by alkalinization (Machida and Saito test), or estimated qualitatively by the amount of redness. 3. Results In developing countries most aflatoxin in foodstuffs is produced post-harvest during storage, so food safety risk in crops is primarily determined by the contamination level with viable toxigenic A. flavus. Estimating the number of toxigenic A. flavus propagules should allow triage of crops into 3 groups that are (1) heavily contaminated, which is not suitable for storage and should be consumed immediately; (2) moderately contaminated, which should be stored only during the dry season immediately following harvest; and (3) lightly or not contaminated, which can be stored during the rainy season until the next crop is ready for harvest. 4. Conclusions Reducing aflatoxin consumption in developing countries can be best achieved by developing and implementing locally-adapted cultural methods for assessing the infestation level by aflatoxigenic A. flavus, and teaching people only store longest the least contaminated food while consuming the most heavily contaminated food first.