engleski

Enzymatic conversion of corn starch in twin screw extruder

Investigation of thermomechanical gelatinization and enzymatic liquefaction processes of starch in the twin screw extruder showed the possibility of using extruder as an integral part of the continuous process of starch hydrolysis. The influence of barrel temperature of the last section of extruder (106-154 oC), moisture content in the extruder (33-57 %), screw rotation rate (170-230 min-1 ) and concentration of a-amylase Termamyl 120L added in extruder (10-30 mL kg-1 d.m. starch) on the degree of starch hydrolysis in the extruder, on the residual enzymatic activity present in freeze-dried extrudates, on the solubility of extrudates in cold water and on the temperature of the extrudates at the outlet of extruder were investigated. The experiments were carried out in accordance with the Compositional Orthogonal Plan of experiment, 2exp.3. Optimization of the process of native corn starch hydrolisis in extruder, showed that maltodextrins of dextrose equivalent, DE =10 and high solubility in cold water, 70-85 %, could be produced at the following conditions: moisture content in the extruder, 55 %, barrel temperature of the last section of extruder, 110 oC, screw rotation rate, 175 min-1, concentration of a-amylase, Termamyl 120L in the extruder, 20 mL kg-1 d.m. starch and corn starch feed rate, 20 kg h-1.

Corn starch; extrusion cooking; gelatinization; liquefaction; enzymatic hydrolysis

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