Submitted to: Toxicological Sciences
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2006
Publication Date: 3/25/2007
Citation: Burns, T., Snook, M.E., Riley, R.T., Mitchell, T.R., Voss, K.A. 2007. Toxicological evaluation of Fusarium verticillioides culture material nixtamalized in the presence and absence of corn matrix. Toxicological Sciences. Abst. 726, p. 138. Interpretive Summary: Abstract - no summary required
Technical Abstract: Cooking-steeping corn in alkaline water (nixtamalization) reduces the amount of detectable fumonisin B1 (FB1) in masa and tortilla products. However, reductions might be overestimated if FB1 reacts with the corn matrix to form undetectable reaction products. The purpose of this study was to investigate if corn matrix facilitates the reduction of measurable FB1 during nixtamalization and reduces toxicity of the cooked material. Fusarium verticillioides culture material (CM) was nixtamalized in the absence (NCM) and presence (NCMC) of ground uncontaminated corn. Sham nixtamalization (cooking-steeping in water) of the CM without (SCM) and with corn (SCMC) was also done. Equivalent weights of each material were added to rodent chow and fed to male SD rats for 1 (n=3/group) or 3 weeks (n=5/group) to evaluate toxicity. Control groups were fed chow plus uncontaminated corn (UC), chow plus nixtamalized uncontaminated corn (NUC), or uncooked CM. FB1 concentrations of the diets were: UC = 0.15, NUC = 0.16, CM = 9.08, NCM = 2.08, NCMC = 0.49, SCM = 1.19 and SCMC = 0.95 ppm. Hydrolyzed FB1 concentrations were: UC = 0.07, NUC = 0.09, CM = 0.25, NCM = 1.27, NCMC = 1.60, SCM = 0.55 and SCMC = 0.37 ppm. No differences in body weights, food consumption or relative kidney weights were found during the feeding study. Apoptotic kidney lesions typical of fumonisins were found in all groups except UC and NUC. Compared to the CM group(mean apoptotic cell counts at week 3 = 207 ± 105 (SD)), fewer apoptotic renal epithelial cells were found in rats from all other groups. Furthermore, apoptosis counts in the NCMC group (22 ± 8) were less than those of the NCM group (44 ± 12). Apoptosis counts of the SCM and SCMC groups were similar, averaging 17 ± 5 and 19 ± 6. These findings suggest that the corn matrix facilitated reduction of measurable FB1, possibly through matrix binding, and further reduced toxicity of nixtamalized CM.