Peanuts 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.)... 

Recently we completed an evaluation of the effectiveness of the Aflatest (Vicam) immunoaffinity column for analysis of corn, peanuts and peanut butter for aflatoxin (11). In this procedure the sample is extracted with Me0H/H20, filtered, and the extract diluted to <30% MeOH with water. An aliquot is then applied to the immunoaffinity column. The column is then washed with water and the aflatoxins eluted with methanol. Total aflatoxins are then determined by solution fluorometry with bromine (SFB), or individual toxins by reverse phase high performance liquid chromatography with post column I2 derivatization (PCD). In the collaborative study corn samples naturally contaminated with aflatoxins and samples of corn, peanuts and peanut butter spiked at 30, 20 and 10 ng/g, were analyzed by 24 collaborators. The results of this study are tabulated in Table V. 

Aflatoxins are potential carcinogens produced by certain molds that may be found in corn, peanuts, and other food items. They are colorless, odorless, and tasteless. The toxic nature of aflatoxins was made evident by a large turkey kill in England in 1960. One method of detecting... 

Risk assessment might be viewed simply as a means of organizing and analyzing all available scientific information that bears on the question at hand. If we are interested in understanding the nature and size of the health risk associated with, for example, aflatoxin in peanut products or trichloroethylene in drinking water, there are three types of information that must be evaluated. 

Most foods are not entirely safe, and I am including natural foods in this category. There are toxic chemicals in some foods, such as aflatoxin mold that grows on contaminated peanuts and causes liver cancer. Overuse of ordinary table sugar has been correlated with breast cancer. Overuse of high-fat, high-cholesterol foods increases the risk of heart disease, the number one cause of death in our country. Cancer researchers claim that as much as 30 percent of all cancers are diet related, and almost every food carries some level of carcinogens. 

The public s perception of toxicity and risk often differs from that found by scientific testing.16 The idea that natural 17 is better than chemical is overly simplistic. Many chemicals found in nature are extremely potent biologically. Mycotoxins are among these.18 Aflatoxins (1.4) were discovered when turkeys fed moldy ground nut (peanut) meal became ill and died. They are among the most potent carcinogens known. 

The impetus that stimulated scientific interest in myco-toxins evolved from the death of 100,000 turkey poults at 500 locations in England in 1960, which led to the discovery by British scientists of aflatoxin (a toxic metabolite of the fungus Aspergillus flavus Link ex Fr.) in the peanut meal fraction of the feed (2,3). Research soon demonstrated that aflatoxin is possibly the most potent, naturally occurring carcinogen ever utilized in animal studies (4). In addition, it can cause acute aflatoxicosis in animals and humans a case of the latter was cited in a CAST report (5). 

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). 

Food Analysis Preparative immunoaffinlty chromatography techniques are also applicable to the analysis of food samples for the presence of parent aflatoxins. To validate this method, naturally contaminated corn and peanut product samples were obtained and extracts made using methanol-water (60% 40%, vol/vol). An aliquot of extract was applied to the monoclonal antibody affinity column, aflatoxins eluted, and the product measured by reversed phase HPLC. In Figure... 

Is depicted the HPLC profile from a naturally contaminated peanut sample. This sample when analyzed contained 943 ppb (ug/kg) total aflatoxins. This chromatogram demonstrates that aflatoxins can be identified without any further deriv-atlzatlon by using a diode array detector after the affinity clean-up procedure and reversed phase HPLC. This detector obtains the spectrum of chromatographic peaks. Since as little as 2 ppb In the diet of rats (2) has been found to produce liver tumors following life time exposure, the levels of aflatoxins in the diets of people eating this level of contaminated foods would be of serious concern. 

Therefore, the fact that peanuts produce stilbene phytoalexins naturally in response to damage in the field but do not become contaminated with aflatoxin (indicative of A. flavus growth) until subjected to prolonged drought stress points toward a presumptive role for these compounds in the natural bioregulation of aflatoxin contamination. 

Occurrence of Aflatoxin Contamination After Cessation of Phvtoalexin Production. In view of the fact that stilbene phytoalexins are naturally produced in peanut kernels in response to fungal invasion and that these stilbenes possess antifungal activity against aflatoxigenic fungi, the question of how peanuts become contaminated with aflatoxin remains. Simply stated, how does A. flaws overcome this apparent natural defense mechanism of peanuts ... 

The evidence clearly supports the hypothesis that stilbene phytoalexins in peanuts are an important natural bioregulator of preharvest aflatoxin contamination. That evidence includes the facts that (1) stilbenes are naturally produced in field-damaged peanuts (2) stilbenes possess biological activity against A, flavus and A. parasiticus and (3) although invasion of peanuts by A. flavus and A. parasiticus can occur under any conditions, aflatoxin contamination does not occur until peanuts lose the capacity for phytoalexin production as a result of drought-induced kernel dehydration. 

It is unlikely that any single approach will provide a solution to the problem of preharvest aflatoxin contamination of peanuts. However, a multifaceted approach that could include enhancement of the natural bioregulative properties of stilbene phytoalexins might ultimately yield the solution to a serious and complex problem. 

The hazardous nature of mycotoxins was first associated with a disease (mycoroxicosis) in the mid-1950s (5), however, mycotoxin-associated diseases have been known for centuries. For example, aflatoxin was isolated and identified in 1961, following a 1960 incident in which 100,000 mrkey poults in the British Isles died from eating feed containing contaminated peanut meal (5). 

How do people view chemicals Studies have shown that people will accept a risk level of 1 in 10,000 from aflatoxin in order to eat peanut butter and reject a risk level of 1 in 1,000,000 for some synthetic chemical that has some benefit also associated with it. Natural is seen as less risky than synthetic or nonnatural. 

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