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Characterization of deoxynivalenol producing mold, detection of deoxynivalenol and effects of heat on the mycotoxin
Abstract
Two methods for deoxynivalenol (DON) detection were compared, a thin layer chromatography (TLC) method and an enzyme-linked immunosorbant assay (ELISA) kit. The methods gave significantly (p $<$ 0.05) different results in analyzing 51 corn and wheat samples. The ELISA method showed higher concentrations of DON and higher recovery rates and was faster and used no organic solvents. The corn samples were analyzed for total internal mold infection which ranged from 3-100% and Fusarium infection which ranged from 0-81%. Wheat samples ranged in infection between 34-100% with Fusarium species (44-100%) and Alternaria species (0-40%) most common. Forty-nine isolates of F. graminearum were obtained and screened for DON, 3-acetyldeoxynivalenol (3-ADON) and 15-acetyldeoxynivalenol (15-ADON) production on rice. Production of DON and 15-ADON varied among isolates (0-38 $\mu$g/g DON and 0-19.4 $\mu$g/g 15-ADON) with no 3-ADON detected. Isolates were compared by randomly amplified polymorphic DNA (RAPD) analysis and showed two types. No correlation between RAPD patterns and DON production was observed. Sixteen isolates were compared for DON production on rice, corn and wheat at 25$\sp\circ$C and 35$\sp\circ$C. Higher production of DON and 15-ADON on rice and wheat occurred at 35$\sp\circ$C. Variation in mycotoxin production between the 16 isolates was observed. The effects of heat (100, 120 and 170$\sp\circ$C) and pH (4.0, 7.0 and 10.0) on DON in a buffer for 15, 30 and 60 minutes were tested. Deoxynivalenol was fairly stable at pH 4 and pH 7. At pH 10, DON was less stable with total destruction at 170$\sp\circ$C after 15 minutes. Spiked corn grits were extruded at different moisture contents (18, 22 and 26%), and temperatures (120, 140 and 160$\sp\circ$C), with mixing versus nonmixing in double screw extrusion. Moisture content and temperature effects on DON concentrations were not apparent. More DON was destroyed in the nonmixed extrusion (0-40%) than the mixed extrusion (0-27%). No destruction of DON was detected in extruded spiked dog food. Alpha-amylase addition to the extraction procedure improved recovery of DON from extruded corn grits, and pre-extruded and extruded dog food.
Subject Area
Microbiology|Food science
Recommended Citation
Wolf, Charlene Elizabeth, "Characterization of deoxynivalenol producing mold, detection of deoxynivalenol and effects of heat on the mycotoxin" (1995). ETD collection for University of Nebraska-Lincoln. AAI9611074.
https://digitalcommons.unl.edu/dissertations/AAI9611074