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United States Department of Agriculture

Agricultural Research Service

Title: A Method for Determining Kernel Moisture Content and Aflatoxin Concentrations in Peanuts

Authors
item Dorner, Joe
item Cole, Richard

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 11, 1996
Publication Date: N/A

Interpretive Summary: Preharvest aflatoxin contamination of peanuts is a primary concern for the U.S. peanut industry. Many research dollars are expended each year in efforts to determine how contamination occurs and how it can be prevented. It has been established that late-season drought stress with accompanying decreasing kernel moisture is required for contamination to occur. However, ,the association between reduced kernel moisture and aflatoxin contaminatio is not well understood because it has not been possible to measure kernel moisture and aflatoxin contamination in the same sample of peanuts. Methods to determine kernel moisture degrade aflatoxin. Therefore, this paper reports a method that enables the measurement of both kernel moisture and aflatoxin contamination in discrete samples of freshly harvested peanuts. Peanuts are weighed immediately after shelling, dried, and a water slurry is made by blending the peanuts in water. A portion of the slurry is oven dried for moisture determination and the remaining slurry is extracted after addition of methanol for aflatoxin determination. The slurry method compared well with an official method in determining kernel moisture, and recovery of aflatoxin with the slurry method averaged 97%. This method will aid research efforts to determine the role of kernel moisture loss during drought stress in preharvest aflatoxin contamination of peanuts.

Technical Abstract: A method was developed to enable the determination of kernel moisture content (KMC) and aflatoxin concentration in discrete peanut samples. Shelled peanuts were weighed to the nearest 0.01 g, and a water slurry was made by blending the peanuts for 2 min with 2.2 ml of water per g of peanuts. Ten g of the slurry was withdrawn and dried at 130 C for 3 h to determine KMC. Methanol was added to the remaining slurry and blended for an additional 1 min, and aflatoxins were quantitated with high performance liquid chromatography. Comparison of the slurry method with an official peanut moisture method showed good agreement between the two over a wide range of moistures. Recovery of aflatoxin B1 from spiked samples averaged 97% with an average CV of 3.6%. The method provides a way to determine both the KMC and the aflatoxin content in peanut samples without the degradation of aflatoxin that would occur using the official moisture method.

Last Modified: 10/21/2014
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