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Title: Evidence for fumonisin-corn matrix binding during nixtamalization.

Author
item BURNS, TANTIANA - TOX PROG/UGEORGIA, ATHENS
item Snook, Maurice
item Mitchell, Trevor
item Voss, Kenneth

Submitted to: Toxicological Sciences
Publication Type: Abstract Only
Publication Acceptance Date: 12/7/2007
Publication Date: 3/16/2008
Citation: Burns, T., Snook, M.E., Mitchell, T.R., Voss, K.A. 2008. Evidence for fumonisin-corn matrix binding during nixtamalization. Toxicological Sciences. March 16-20, 2008. Seattle, WA.

Interpretive Summary: Abstract - no summary required.

Technical Abstract: Fumonisins are mycotoxins produced by Fusarium verticilliodes. They are found in corn and corn-based foods. Nixtamalization (cooking in alkaline water) reduces detectable fumonisins; however, their concentrations in foods can be underestimated if fumonisin-matrix binding occurs. The purpose of this study was to determine if fumonisin FB1 (FB1) binds to the corn matrix during nixtamalization. A modification of the method of Park et al. (Food Addit. Contam. 21: 1168-78, 2004) was used in which (a) free fumonisins were quantified by HPLC; (b) protein bound fumonisins (FB1 plus hydrolyzed FB1 (HFB1)) were then extracted with sodium dodecyl sulfate (SDS) and quantified as HFB1 following base hydrolysis of the extract; and (c) the remaining (residual) bound fumonisins were quantified as HFB1 after the SDS-extracted residue was base hydrolyzed. Whole kernel corn (23 + 11.5 ppm = 32.3 + 15.9 nmol/g FB1; 0.33 + 0.10 ppm = 0.81 + 0.25 nmol/g HFB1) and nixtamalized and sham nixtamalized samples (base omitted) of the corn were evaluated. About five fold more (nmol/g) protein bound fumonisin was detected in the nixtamalized samples (0.40 + 0.20 ppm detected as HFB1 = 0.98 + 0.49 nmol/g) than in the uncooked (0.17 + 0.12 nmol/g) or sham nixtamalized (0.17 + 0.05 nmol/g) corn. Residual bound fumonisins in the nixtamalized samples (0.32 + 0.17 ppm detected as HFB1 = 0.79 + 0.42 nmol/g) were about 10 to 15 times more than in the uncooked (0.05 + 0.01 nmol/g) or sham nixtamalized (0.07 + 0.01 nmol/g) corn. This indicates that fumonisins bound to the matrix during nixtamalization, but that the amount of binding was low: protein bound plus residual bound fumonisins detected were only about 5 to 10% of the amounts of free FB1 plus HFB1 in the uncooked, nixtamalized (3.31 + 1.08 ppm = 4.59 + 1.50 nmol/g FB1; 4.79 + 0.47 ppm = 11.8 + 1.16 nmol/g HFB1), and sham nixtamalized (11.0 + 3.22 ppm = 15.3 + 4.47 nmol/g FB1; 0.13 + 0.16 ppm = 0.32 + 0.39 nmol/g HFB1) corn.