Date of Award

1998

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

School of Nutrition and Food Sciences

First Advisor

Douglas L. Park

Abstract

In the present project the use of ammoniation and fermentation as an integrated process was studied in order to give aflatoxin-contaminated corn an alternative use. Aflatoxin-contaminated corn can be fermented to obtain fuel alcohol and decontaminated distiller's dried solid grains (DDSG) can be used for animal feed. The efficacy of a fermentation process, with the inclusion of ammonium persulfate, for the decontamination of aflatoxin B$\sb1$-contaminated yellow corn was studied, as well as the effect of peroxides on the ethanol production. Addition of 2.0% ammonium persulfate decreased the aflatoxin B$\sb1$ levels by 87%. Peroxides did not have an effect on ethanol production. This process was not mutagenic in the Ames test using Salmonella tester strains TA98 and TA100 with metabolic activation. An isolation procedure based on thin layer chromatography technique was used to isolate factors that interfered with the mutagenic potential of AFB$\sb1.$ A dose-response type of relationship between a constant dose of AFB$\sb1$ and different concentrations of corn and corn fraction extracts were found in the Ames test. The corn fractions were found not to be toxic to either, Salmonella tester strain TA98 or TA100. Anti-mutagenic fractions isolated from corn were tested against 1-methyl-3-nitro-1-nitrosoguanidine (MNNG) to determine their activity on a direct acting mutagen. All corn fractions tested positive against MNNG in the Ames test using Salmonella tester strain TA100. Anti-mutagenic activity was tested in five different varieties of corn fractions. A dose-response effect was observed for all the corn fractions tested using two tester strains with S9. Four anti-mutagenic isolates were analyzed by MALDI-MS and GC-MS. MALDI-MS showed the presence of two groups of molecules or molecular fragments. The molecular mass of one group ranged from 250 to 370 m/z, the other ranged from 540 to 640 m/z. GC-MS showed the presence of a linoleic acid-like compound. The use of ammonium persulfate was shown to efficiently decontaminate AFB$\sb1$-contaminated corn during fermentation without affecting ethanol production. This research also found that corn has a number of compounds that may offer a protective effect against mutagenic events. One of these compounds may be linoleic acid or a linoleic acid-like compound.

ISBN

9780591997668

Pages

203

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