Evaluation and Characterization of Reaction Products from Ozonated Aflatoxin Contaminated Corn

Project Overview

Project Type: Graduate Student
Funds awarded in 2002: $10,000.00
Projected End Date: 12/31/2006
Region: Southern
State: Louisiana
Graduate Student:
Major Professor:
Joan King
LSU Agricultural Center

Annual Reports


  • Agronomic: corn


  • Crop Production: tissue analysis
  • Soil Management: toxic status mitigation


    Ozonation of clean corn, AFB1-contaminated corn, and pure AFB1 was carried out to evaluate the formation of reaction products. Results of TLC and HPLC analyses of aflatoxin in the model system showed seven possible reactions products. Results also indicated that the products formed are water-soluble. Further study to isolate and identify these compounds was conducted but no data were generated. Although these compounds are present in the model system, attempts to determine their presence in ozonated corn did not get any positive result. The presence of other materials in the extracts interferes with the analysis.


    Aflatoxins are a group of closely related bis-dihydrofurano secondary metabolites that have been epidemiologically implicated as environmental carcinogens in humans. They are considered one of the most toxic compounds that have ubiquitously contaminated cereal grains, oilseed crops and milk worldwide (CAST, 1989). Aflatoxins are produced primarily by Aspergillus flavus Link: Fr. and A. parasiticus Speare. These fungi have the capability of invading various agricultural commodities such as corn, peanuts, cottonseed, and various tree nuts, during maturation in the field and/or after harvest while the products are stored.
    The aflatoxin that has caused the most concern is AFB1. It has been a focus of considerable research since its discovery because of its widespread occurrence, its prevalence among the four naturally occurring aflatoxins, and its acute toxicity and carcinogenicity (McKenzie et al., 1997). Human exposure to aflatoxins can be from direct consumption of contaminated commodities, or consumption of foods from animals previously exposed to aflatoxins through feeds. Exposure to aflatoxin B1 is generally considered a major factor in the high incidence of hepatocellular carcinoma, a malignant neoplasm of hepatic cells, commonly referred to as primary liver cancer. Apart from its effect on health, aflatoxin contamination also impacts the agricultural economy through the loss of produce and the time and cost involved in monitoring and decontamination efforts. It is estimated that as much as one-quarter of the world’s yearly food and feed crops are contaminated with mycotoxins (FAO, 1996). The Council for Agricultural Sciences and Technology (1989) estimated that in the United States alone, twenty million dollars is lost annually on peanuts contaminated with aflatoxins.
    In an effort to limit human exposure to these toxins, prevention and control programs have been continuously being studied and established. These include monitoring of commodities susceptible to aflatoxin contamination, the establishment of limits and regulations that are legally enforced, and decontamination procedures designed to remove or inactivate the toxicant in food or feed (Park, 1993). Methods to decontaminate aflatoxin-affected foods and feed are constantly being studied and evaluated in order to optimize those that already exist, or to obtain more efficient and safer methods.
    The most rational and practical approach to control human and animal exposure to aflatoxin contamination is by prevention (Park, 1993). However, prevention is not always possible under certain agronomic and storage practices (Samarajeewa, et al., 1990). Once the contamination has occurred, other control measures must be established and applied to reduce the risk of exposure to these toxins. Some of the necessary approaches include physical, chemical or biological removal, or use of chemical or physical inactivation. The use of chemical treatments to decontaminate aflatoxin-containing commodities is currently the most practical approach. Although these chemical treatments are effective, through their direct and indirect interaction with either mold or aflatoxins, however, decontamination products are still the points of contention and extensive investigations. The numbers of chemicals that are effective without leaving deleterious residues or without excessive damage to nutrients appear to be small. For foods, in addition to nutrients retention, it is essential that odor and flavor, color, texture, and functional properties be acceptable to consumers (Goldblatt and Dollear, 1977).
    One method of decontamination for aflatoxin-affected commodities that has been a focus of attention is ozonation, a physical/chemical oxidation method. Several studies undertaken previously have established the effectiveness of ozonation as a decontamination process. It has been found to be effective in reducing aflatoxin levels by as much as 95%. However, few or limited studies have been done on the potential toxicity and possible carcinogenicity of ozone-aflatoxin reaction products. These aspects are very important in assessing the suitability and acceptability of the ozonation process.

    Project objectives:

    General Objective
    To determine the safety of the ozonation procedure to reduce aflatoxin hazards in corn.

    Specific Objectives
    1.To evaluate the formation and distribution of ozone-aflatoxin and ozone-corn reaction products.
    2.To characterize and identify ozone-aflatoxin and ozone-corn reaction products.
    3.To determine the mutagenic potential of reaction products using the Salmonella / microsomal mutagenicity assay.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.