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Removal of Aflatoxin Contaminated Peanuts from a Process Stream


Nuts, corn, rice, some spices and coffee are foods susceptible to mold attack under certain conditions. For these foods, molds exist which may produce a deleterious toxin, named aflatoxin. Aflatoxin may cause liver trauma, including cancer in rare cases. Moreover, its presence will cause foreign buyers to reject the food. Among nuts, and particularly among peanuts, this toxin is found, if at all, in very few nuts in a lot, maybe 1in 1000 or 10,000 nuts. On the other hand, the aflatoxin level in these few nuts may be quite high, leading to a high overall average concentration in the lot. The rarity of contamination suggests that sorting methods, i.e., removal of the contaminated nuts from a process stream, may be a very effective method for limiting this toxin. What is needed is a sorter which can, at high speed and high volume, recognize and remove contaminated peanuts. Unfortunately, high contamination levels are not always visible externally. Nevertheless, we are now attempting to develop such a sorter.

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The first step requires the collection of a reasonable size sample of whole, but contaminated, nuts along with a sample of uncontaminated nuts. The next step is to establish properties, principally transmission of light or similar radiation, which can look inside the nut and which are sensitive to contamination. Next, detectors must be found which can react at adequate speed for sorting. Such detectors are expected to be available from the semiconductor industry. And, finally, a sorter, based on these principles, must be constructed. We are well along in the first step, selecting a set of contaminated nuts without damaging them. The present project is designed to carry out the remaining steps.

Schatzki, Thomas
USDA - Agricultural Research Service
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