Mycotoxins inactivation by extrusion cooking of corn flour

Abstract

Aims: To evaluate the effects of the extrusion cooking process on the inactivation of mycotoxins in corn flour.

Methods and results: Samples of corn flour experimentally contaminated with aflatoxin B1 (AFB1) (50 ppb) and deoxynivalenol (DON) (5 ppm) were extruded. The effects of three extrusion variables (flour moisture, extrusion temperature and sodium metabisulphite addition) were analysed according to a two-level factorial design. The process was effective for the reduction of DON content (higher than 95%) under all the conditions assessed, but was only partially successful (10-25%) for the decontamination of AFB1.

Conclusion: Extrusion cooking is effective for the inactivation of DON but is of limited value for AFB1, even if metabisulphite is added. More severe extrusion conditions are needed for the detoxification of AFB1.

Significance and impact of the study: As contamination with DON occurs mainly in the field prior to harvesting and that of AFB1 is normally produced during grain storage, maize is often contaminated with DON but not with AFB1. Under these conditions, the described extrusion process can be used for the detoxification of DON. The addition of sodium metabisulphite did not significantly affect the inactivation of AFB1. Extrusion cooking is therefore an appropriate treatment for vomitoxin-contaminated maize in countries where, because of the prevailing conditions, these are the only toxins present.