摘要：The objectives of this research are to determine the effect of microencapsulation on d-limonene retention in starch extrudates and the effect of incorporating encapsulated d-limonene on extruder operation and extrudate properties.Two set of extrusion experiments were carried out in a twin screw extruder (16 mm diameter screw;40:1 L/D ratio) using corn starch as a food matrix.In one set of experiments,d-limonene was encapsulated in -cyclodextrin.In the other experiments,d-limonene was encapsulated with sodium caseinate.Using a Central Composite Design,three variables were studied: level of encapsulated d-limonene in the feed material,extruder screw speeds and barrel temperatures.Another set of experiment with unencapsulated d-limonene was also performed.Measured parameters included extruder operation parameters (torque and die melt pressure),extrudate properties (expansion ratio and hardness) and d-limonene retention.All variables contributed significantly to the d-limonene retention and extrudate properties.-Cyclodextrin capsules gave higher d-limonene retention (average of 92.2%) than the sodium caseinate capsules (67.5%).A higher expansion ratio was observed from the extrudates containing sodium caseinate capsules than those with -cyclodextrin (average of 1.87 and 1.38,respectively).Extrudates containing -cyclodextrin capsules had a lower hardness (average of 1.14 N/mm2) than those with sodium caseinate capsules (average 2.34 N/mm2).Without encapsulation,retention of d-limonene was the lowest (average of 8.0%),extrudate hardness was the highest (average of 3.38 N/mm2) but expansion ratio was the highest (average of 2.1).
