Effect of moisture content, lactic acid addition and extrusion conditions on reduction of beta-aflatoxins in milled sorghum (Sorghum L. Moench)

摘要

Sorghum flour contaminated with beta-aflatoxins at a level of 140 +/- 7.34 ng/g was extrusion-cooked in a single screw extruder under two different conditions: moderate (ME) and severe (SE). The difference in the processing conditions was in the temperature profile of the barrel sections of the extruder: 60-80-100 degrees C for ME and 80-150-200 degrees C for SE, respectively. The flour moisture content (MC) was adjusted at 20, 25 and 30% by means of aqueous lactic acid (LA) at concentrations of 0, 0.5, 1.0, 2.0, 4.0 and 8.0 N. The effect of the three extrusion variables (temperature profile, MC and LA concentration) was analysed as a completely randomized factorial design 2 x 3 x 6. The barrel temperature profile, in combination with the MC and LA concentration, significantly affected the extent of aflatoxin reduction in the extruded sorghum. The recovered aflatoxin decreased with an increase in MC and LA concentration, in both temperature-profiles evaluated. The SE condition produced higher aflatoxin degradation rates (from 16.38 to 67.09%) than the ME condition (up to 19.79%).