Effect of storage upon aflatoxin levels in peanut materials

The effect of storage upon aflatoxin levels in naturally contaminated peanut materials has been studied. The materials were selected to have levels in excess of those found in the trade to emphasize the possible loss during storage. The stimuli for this effort were: (A) a late 1969 report of the possible regeneration of aflatoxins in a commercial meal, and (B) the general lack of information on the long term stability of aflatoxins in commercial peanut products. Samples of deoiled peanut meal, natural peanut meal, raw peanut butter, and roasted peanut butter were held at 73 F and 50% relative humidity exposed to air for 2 years. Three of the four samples were identical to those used in the first International Aflatoxin Check Series. The samples were withdrawn from storage at 0, 6, 12, and 24 months and analyzed in comparison to materials retained at 0 F. Analysis was by the Contaminants Branch procedure (Association of Official Analytical Chemists Method 26.015-020) with the six participating Laboratories (four U.S., one Canadian, and one Danish) using visual and densitometric measurement. A single mixed aflatoxin standard was used throughout the program via retention at 0 F. No statistically significant changes in aflatoxin levels were noted in any of the commodities as a function of either time or temperature of storage throughout the 2 years of the study.