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Flavor retention enhancement in extrudates by internal application techniques
Abstract
Internal flavoring of extrudates was studied in detail to enhance flavor retention during extrusion cooking. The benefits of this method over traditional external flavor coating include manufacture of low fat, reduced calorie product with uniform flavor distribution and enhanced shelf life of the product. Normal corn starch was extrusion cooked in a C. W. Brabender twin screw extruder (Model PL 2000) at barrel section temperatures of 60-120-110-100$\sp\circ$C, screw speed of 100 rpm and starch moisture contents of 15 to 21% (db). Cinnamaldehyde, nonanoic acid, 3-octanone and eugenol, at concentrations of 1 to 5% (w/w), were either premixed with the feed, or injected into the compression zone of the barrel during extrusion. Retention of flavor compounds in the extrudates was analyzed using a Hewlett Packard GC (Model 5890). Radial expansion ratio, specific mechanical energy and flavor retained as percent of flavor in feed were determined. Radial expansion ratios of the extrudates were significantly lower when flavor was injected into the barrel (except for 3-octanone, which resulted in significant increase in radial expansion). Specific mechanical energies were not significantly different for the two methods of flavor addition, except for nonanoic acid (significantly higher when premixed with feed). Injection of flavor resulted in significantly higher retentions for all flavors studied as compared to direct addition of flavor prior to extrusion. Response surface plots for flavor retention indicated that higher recoveries were obtained when flavor was injected at 5% level into low moisture content of feed. Pre-blended extrudates of the above experiment were stored either at room temperature or at ${-}20\sp\circ$C and amount of flavor retained up to 90 days were studied. Flavor losses continued to occur during storage. Flavor losses were significantly higher at room temperatures. Use of pre-gelatinized starch (9 to 17% moisture (db), 5% flavor (w/w)) was studied to improve flavor retention. Flavor retention was significantly lower when pre-gelatinized starches were used as compared to raw starch. Flavor retention using pre-gelatinized starch could be improved by injecting the flavors. Retention of cyclodextrin complexed flavors in starch extrudates was studied. Flavor type significantly influenced specific mechanical energy requirements, radial expansion ratios and flavor retention of the extrudates. High retention levels of all flavor compounds (70 to 100% of initial levels) were obtained with cyclodextrin complexes. Food grade low boiling point liquids (acetone and isopropanol) were injected into the extruder barrel during extrusion of preblended starch (15% moisture (db) and 5% flavor (w/w)). Significantly higher flavor retentions were obtained compared to control. Thus, internal flavoring of extrudates by injection of the flavor compounds, by use of cyclodextrin complexed flavors or by injection of low boiling point liquids enhance flavor retention in extrudates.
Subject Area
Food science
Recommended Citation
Kollengode, Anantha Narayanan R, "Flavor retention enhancement in extrudates by internal application techniques" (1997). ETD collection for University of Nebraska-Lincoln. AAI9730275.
https://digitalcommons.unl.edu/dissertations/AAI9730275