EFFECTS OF DRYING TEMPERATURE ON FUMONISIN RECOVERY FROM FEEDS

A number of corn and feed samples submitted for fumonisin analysis con tain high levels of moisture. The high moisture content can interfere with grinding during sample preparation and, ii samples are held at ro om temperature, may promote fungal, bacterial, and/or other microbial growth. To inhibit possible sample deterioration, wet corn and feed sa mples routinely ave stored in a freezer Prior to grinding, the sample, or a representative portion, is dried. Using a fumonisin-positive, ra in-soaked, pelleted mixed feed, we found that prolonged drying at temp eratures above 50 degrees C results in decreased fumonisin recoveries. Therefore, we carried out a study to assess the effect of drying time s and temperatures on recoveries of fumonisins FB1 and FB2. A fumonisi n-positive corn sample and the pelleted mixed feed were dried for vari ous periods up to 24 h at 30 degrees, 50 degrees, or 110 degrees C. Du plicate samples were dried for 0, 0.25, 0.5, 1, 2, 4, 8, or 24 h at ea ch temperature. Samples were extracted with solvent, and an aliquot of each extract was cleaned up with C-18 Sep-Pak cartridges. Extracts we re derivatized with fluorescamine and analyzed by liquid chromatograph y with fluorescence detection. During the 24 h drying period, recoveri es of fumonisins FB1 and FB2 from samples dried at 110 degrees C exhib ited a nonlinear decrease, Recoveries from samples dried at 30 degrees and 50 degrees C showed no real change.