Tuesday, November 14, 2006

Enhanced Aflatoxin Sorption by Modified Clays.

William Jaynes, Richard Zartman, and Wayne Hudnall. Texas Tech Univ, Plant and Soil Science Dept, Lubbock, TX 79409-2122

Aflatoxins are toxic metabolites produced by Aspergillus fungi.  Cancer and deaths in humans and animals can result from aflatoxin ingestion.  Clay minerals, such as montmorillonite, when added to animal feeds have been shown to effectively bind aflatoxins and reduce aflatoxicosis.  Clay minerals modified by treatment with organic cations have been shown to more effectively remove weakly-soluble organic contaminants from water than the untreated clay.  Aflatoxin B1 (AfB1) is the most abundant and most toxic of the aflatoxins, all of which are weakly-soluble in water.  Clay minerals treated with organic cations or other compounds might more effectively bind aflatoxins in feed and reduce or prevent aflatoxicosis.  In this study, the AfB1 sorptive capacities of reference clay minerals and surface-modified clay minerals were compared.  AfB1 sorption by Novasil plus, a commercial clay product demonstrated to reduce aflatoxicosis when added to animal feeds, was also examined.  The relatively toxic and commonly used organic cations, hexadecyltrimethylammonium (HDTMA) and trimethylphenylammonium (TMPA) were used to prepare organoclays.  Organoclays were also prepared using the nutritional supplement, carnitine.  The AfB1 sorption capacities followed the order SWy-carnitine = SWy-TMPA >> SWy = Novasil plus > SAz-carnitine > SWy-HDTMA.  SWy-carnitine was 4 to 5 times more effective than Novasil plus. Of the carnitine organoclays, low-charge SWy-carnitine was a much better AfB1 sorbent than high-charge SAz-carnitine. These sorption characteristics suggest that AfB1 is retained via clay surface adsorption, not by partitioning into the cation-derived organic phase. Modified clays prepared using non-toxic organic cations, such as carnitine, might be used in animal feeds to more effectively prevent aflatoxicosis.

Handout (.pdf format, 119.0 kb)