Effects of Drying Temperature on Fumonisin Recovery From Feeds

Abstract

Abstract A number of corn and feed samples submitted for fumonisin analysis contain high levels of moisture. The high moisture content can interfere with grinding during sample preparation and, if samples are held at room temperature, may promote fungal, bacterial, and/or other microbial growth. To inhibit possible sample deterioration, wet corn and feed samples routinely are stored in a freezer. Prior to grinding, the sample, or a representative portion, is dried. Using a fumonisin-positive, rain-soaked, pelleted mixed feed, we found that prolonged drying at temperatures above 50°C results in decreased fumonisin recoveries. Therefore, we carried out a study to assess the effect of drying times and temperatures on recoveries of fumonisins FB1 and FB2. A fumonisin-positive corn sample and the pelleted mixed feed were dried for various periods up to 24 h at 30°, 50°, or 110°C. Duplicate samples were dried for 0, 0.25, 0.5, 1, 2, 4, 8, or 24 h at each temperature. Samples were extracted with solvent, and an aliquot of each extract was cleaned up with Cie Sep-Pak cartridges. Extracts were derivatized with fluorescamine and analyzed by liquid chromatography with fluorescence detection. During the 24 h drying period, recoveries of fumonisins FB1 and FB2 from samples dried at 110°C exhibited a nonlinear decrease. Recoveries from samples dried at 30° and 50°C showed no real change.