EFFECT OF CITRIC ACID ADDITION ON AFLATOXIN DEGRADATION AND ON FUNCTIONAL PROPERTIES OF EXTRUDED SORGHUM PRODUCTS

Sorghum flour contaminated by aflatoxin at a concentration of 140 mu g-kg super(-1) was extrusion-cooked in a single screw extruder with a temperature profile of 60-80-100 degree C. The moisture content (MC) of the flour was adjusted to 20, 25 and 30% by adding aqueous citric acid (CA) at concentrations of 0, 0.5, 1, 2, 4 and 8N. The temperature profile in combination with the MC and CA concentrations significantly affected the extent of aflatoxin reduction in the extruded sorghum; the maximum percentage of aflatoxin reduction was 35.5%. In extruded sorghum prepared with high MC and CA concentrations, the highest valuesin color difference ( Delta E) and smallest values of viscosity were found. The expansion index was favored by higher MC and CA concentrations. The highest cutting force values were found in extruded products prepared with a higher MC, but there were no significant differences between those values and the different CA concentrations evaluated. Using moderate extrusion conditions in combination with higher concentrations of CA, products were obtained with acceptable pH, color, viscosity, as well as with good textural and functional properties.