STORY LEAD:
A Ratio Process Makes It Easier To Detect Aflatoxin Levels
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ARS News Service
Agricultural Research Service, USDA
Sarah Tarshis, (301)504-1611, isst@ars-grin.gov
July 12, 1999
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One bad nut can spoil the whole bunch, thanks to aflatoxin, a carcinogen
that can contaminate peanuts and other commodities. Federal food safety
regulations create a need to find the most efficient aflatoxin detection
method possible. Such methods can be time-consuming and expensive.
So Thomas B. Whitaker of the Agricultural Research Service has been
researching methods of accurately estimating aflatoxin levels in peanut lots
to better ensure appropriate handling. He developed a new method of
detection that may reduce economic loss for handlers and farmers while also
preserving quality.
Whitaker's method of detecting aflatoxin in a lot is to measure the
aflatoxin levels in the high-risk peanuts. Peanuts that are damaged, loose
shelled or small are labeled high- risk. An estimated ratio of aflatoxin in
high-risk peanuts to aflatoxin in the lot determines the aflatoxin of the
entire lot. Whitaker found that a five-to-one ratio accurately assesses the
aflatoxin levels. For example, if a high-risk sample has an aflatoxin
contamination level of 100 parts per billion (ppb), the entire truckload
will probably average 20 ppb--the Food and Drug Administration's legal limit
for food quality safety. The ratio was derived over a wide range of
concentration in many lots, according to Whitaker.
The current method of detecting aflatoxin in peanuts can cause farmers and
handlers to lose profits because of inaccuracy. When a truckload of peanuts
is brought from a farm to the buyer, it is sampled and visually examined for
moldy kernels that indicate the lot may be contaminated by aflatoxin. If
even one moldy kernel is found, the entire truckload is classified as a
low-grade status that could result in profit loss. The ratio method might be
used to replace or complement the current method of visual analysis.
A story on the research is in the July issue of Agricultural Research
magazine and on the web at:
http://www.ars.usda.gov/is/AR/archive/jul99/pea0799.htm
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Scientific contact: Dr. Thomas B. Whitaker, ARS Market Quality and Handling
Research Unit, Raleigh, N.C.; phone (919) 515-6731, fax (919) 515-7760,
whitaker@eos.ncsu.edu.
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