44G-18 |
Optimization of extrusion conditions to degrade aflatoxins in peanut meal |
F. K. SAALIA, Department of Food Science and Technology, University of Georgia, Griffin, GA 30223 and R. D. Phillips. Following the success of ammonia and other nucleophillic reagents in the chemical degradation of aflatoxins, it was hypothesized that lysine could be used to degrade aflatoxins during extrusion cooking of contaminated peanut meal. The use of lysine, a nutritionally limiting amino acid, would improve the protein nutritional quality of the product. Our objective was to optimize extrusion conditions for the decontamination of aflatoxins in peanut meal using lysine as a nucleophile. Both naturally contaminated and laboratory-spiked (roasted) peanut meals were used. A laboratory scale single-screw extruder was run at the constant maximum screw speed of 135rpm. A response surface design with 3 factors (feed moisture, barrel temperature, and die diameter) was used to study the effects of extrusion on aflatoxin degradation. Aflatoxin levels in the peanut meal were determined before and after extrusion using HPLC procedures with florescence detection. The nutritional quality of the decontaminated extrudates was evaluated by determining the FDNB-available lysine, in vitro-digestibility, and the possible formation of lysino-alanine. The safety of the product was assessed by feeding it to turkey poults. Extrusion of naturally contaminated peanut meal at 40% Moisture and 150°C afforded 59% reduction of total aflatoxins. Much higher levels of reduction, up to 91% was achieved in the artificially contaminated peanut meal, at 20% Moisture, with an orifice die of 2.5mm internal diameter. Aflatoxin degradation was negatively but significantly correlated with extrudate throughput (r=0.648, p<0.05). In vitro digestibility and the FDNB-available lysine of the extrudates were not very different from the starting roasted peanut meal. The results point to extrusion cooking with lysine as a promising direction in the aflatoxin decontamination effort. A fast and reliable processing method to decontaminate aflatoxins in peanut meal will stimulate the utilization of the crop, and greatly benefit the peanut industry
Session 44G, Toxicology & Safety Evaluation
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