46I-9 |
Reduction of aflatoxins in contaminated corn by extrusion cooking |
F. K. SAALIA and R. D. Phillips. Department of Food Science and Technology, University of Georgia, 1109 Experiment Street, Griffin, GA 30223 Corn is a popular food and feed commodity in many communities throughout the world, but its susceptibility to aflatoxin contamination provides a potential health hazard to both human consumers and animals. The objective was to determine extrusion conditions that can be used to reduce aflatoxins in contaminated corn, and also add value to the product. Effects of extrusion conditions and added nucleophile on aflatoxin destruction in corn were studied using a 2X2X2X4 factorial design. Independent variables were: moisture (18% and 35%), pH (natural and pH9) extruder barrel temperature (150°C and 200°C) and nucleophile addition (no nucleophile, lysine, sodium metabisulfite, cysteine).Yellow corn was "spiked" with mixed aflatoxin standards (Sigma) at 150ug/kg for B1 and G 1and 45ug/kg for B2 and G2. The nucleophile was added at 0.5% of the weight of the corn meal. Samples were extruded using a Wayne (yellow jacket) laboratory scale single screw extruder equipped with 2.5mm diameter die, a 1:5 compression ratio screw and run at a speed of 150rpm. At steady state the residence time distribution (RTD) of material flow through the barrel was determined by the colorimetric method. Aflatoxins were extracted with methanol: water (70:30 v:v), and quantified using HPLC procedures (Waters 2690) with fluorescence detection (Waters 474) The mean residence time was 85 seconds at 150°C and 18% Moisture. The throughput of extrudates under these conditions was 4.34 (+/-0.27) kg/H. Treatments with metabisulfite and cysteine offered the least degradation of aflatoxins during extrusion, ranging from 15% reduction to above 40%. The best conditions for aflatoxin reduction were treatments at 35% moisture and pH9, with or without lysine. Under these conditions 62% reduction in total aflatoxins was achieved. A successful extrusion method to reduce aflatoxins in corn would not only reduce the potential health hazard, but also add economic and nutritional value to the product.
Session 46I, Toxicology & Safety Evaluation
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