COLLECTION AND CHARACTERIZATION OF VOLATILE COMPOUNDS RELEASED AT THE DIE DURING TWIN-SCREW EXTRUSION OF CORN FLOUR

A specially designed collection apparatus was used to collect the volatile compounds released at the extruder die during twin screw extrusion of corn flour. The collected volatile compounds were analyzed using GCMS. Among the 91 compounds identified, furans, pyrazines, pyridines, thiazoles, thiophenes and pyrrolizines were the major aroma compounds released at the die of the extruder during processing. Two sensory significant proline-specific Maillard reaction products, 5-acetyl-2,3-dihydro-1H-pyrrolizine and 5-propionyl-2, 5-dihydro-1H-pyrrolizine were identified. Several carotenoid decomposition products such as alpha-ionone, dihydro-beta ionone, beta-ionone and dihydroactinodiolide were also identified. The volatile compounds released at the extruder die were compared with the volatiles recovered by purge and trap analysis of the extrudates. The volatile profiles show significant differences in their chemical composition and provide additional information on possible mechanisms of flavor generation during extrusion cooking.