Figure 1. Structures of important aflatoxins.
Aflatoxin Mx dicatum and other Pénicillium species. Ochratoxin A (OA) is the major mycotoxin in this group (Fig. 4). It has believed to cause endemic kidney disease in swine and poultry in Denmark and Sweden. When the hogs were fed diets containing 200 ppb OA, their kidneys became pale and swollen. The proximal tubules and interstitial cortical fibrils were observed to undergo atrophy (187). The toxin has been implicated in causing the human disease known as Balkan endemic nephropathy (187,188). Occurrence and toxicology of the toxin were recently reviewed (179,189).
Mycotoxin Occurrence in the Food Supply. It is possible for feeds and foods to become contaminated with mycotox-ins prior to harvest, during the interval between harvest and drying and during storage. There are some mycotoxins that are only produced in the field (ie, ergot). Mycotoxins can, therefore, be considered to occur naturally in raw agricultural products, processed foods and imported products (190).
There are a number of documented occurrences of mycotoxins in raw products (190-194), processed foods (195202) and imported products (191,192,199). Most of the information available is for the aflatoxins with less infor mation available for ochratoxin A, trichothecenes, and zearalenone. An extensive review was published that described the effects of food processing on selected toxins (200). The stability of the mycotoxins during food processing is affected by a number of factors such as the type of food, the type of processing used, the additives, moisture content, and the amount and type of contamination (189). The mycotoxins display different degrees of variability in foods under processing conditions. It has been demonstrated that the aflatoxins are stable to moderately stable in the majority of processes. However, they are unstable when alkaline conditions and oxidizing steps are used. DON is stable during bread baking, while ergot alkaloids have been shown to be partially destroyed (190).
Although a number of mycotoxins could be identified in imported foods and feeds, the FDA only routinely tests for aflatoxins. Under the FDA compliance programs, the FDA tests about 300 samples of imported foods (eg, almonds, brazil nuts, peanuts and peanut products, sesame seeds, sunflower seeds, nutmeg, coffee beans, marzipan, corn-meal and flour, cocoa products) and about 200 feed samples (eg, corn, mixed feeds, cottonseed meal, copra pellets, and sorghum). Summaries of analyses from 1982 to 1996 are
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