Cottonseed natural aflatoxins

All collaborators correctly identified naturally contaminated corn (101 ng/g) and raw peanut (69 ng/g) positive samples. No false positives were found for control samples containing <2 ng/g. Overall (excluding poultry feed) the average correct responses for spiked positive samples at 10, 20 and >30 ng/g levels were 52, 86 and 96%, respectively (see Figure 2). The method was rapid and simple and was adopted Official First Action by the AOAC as a screening procedure for aflatoxins at >20 ng/g in cottonseed and peanut butter, and >30 ng/g in corn and raw peanuts. (In this case the AOAC required a positive rate of 90% for acceptance.)... 

Although A. flavus will grow on almost any natural or processed substrate, aflatoxin occurs naturally primarily in corn, peanuts, cottonseed, grain sorghum, tree nuts, millet, copra, and figs (34). Substrate factors must be involved in contamination, since it is limited to a relatively small number of agricultural commodities. The restricted access of zinc has been proposed as an explanation for the inability of A. flavus to elaborate aflatoxin in soybeans (35). The availability of zinc for aflatoxin biosynthesis appears to be blocked by the presence of phytic acid in soybeans (36). 

In order to determine wdietfaer die aflatoxin content of the 80% medianol extracts remained stable over die 24 hour period between extraction and laboratory analysis, 3 extracts fixim naturally contaminated cottonseed were stored at 4 C for a period of 10 days. The extracts were analyzed on days 0, 1, 2, 3, 4, 5, 6, 7, and 10 bodi TlXl and immunochemical meth. Reductions in aflatoxin concentration were recorded as a percentage of that obtained from day zero (Figure 1). 

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