27-9 |
Glycerol effect on compression-molded whey protein film properties |
R. SOTHORNVIT1, C. W. Olsen2, T. H. McHugh2, and J. M. Krochta3. (1) Dept. of Food Engineering, Kasetsart Univ., Kamphaengsaen, Faculty of Engineering, Nakornprathom, 73140, Thailand, (2) Processed Foods Research Unit, USDA-ARS-Western Regional Research Center, 800 Buchanan St., Rm. 1107, Albany, CA 94710-1105, (3) Dept. of Food Science & Technology, Univ. of California, Davis, 1 Shields Ave., 237 Cruess Hall, Davis, CA 95616 Compression molding is a novel fast method to form whey protein isolate (WPI) film compared to the time-consuming traditional solvent casting technique. Our objective was to determine the effect of compression molding conditions (temperature and pressure) and glycerol content on film water vapor permeability (WVP) and mechanical properties. WPI powder and 30, 40 or 50% (w/w) glycerol content (Gly) were thoroughly mixed. Films were formed by pressing WPI-Gly mixture at a temperature in the range 104-140oC and pressure in the range 0.81-2.25 MPa for 2 min in a Carver Press. The Modified Cup Method and an Instron machine were used to determine film WVP and mechanical properties, respectively. Films made from WPI-Gly mixtures at 104oC had higher WVP, but films made from WPI-Gly mixtures at 140oC had WVP similar, to films from solvent casting. Molding temperature and pressure did not significantly affect film elastic modulus (EM), tensile strength (TS) and % elongation (% E) (p>0.05). Increasing the Gly content of compression molded films decreased EM, similar to solvent cast WPI films. Compression molded WPI film TS and % E were greater than values from solvent cast films with same amount of Gly. The compression molding method consumes less time for film formation and produces films with properties similar to solvent cast films. These results indicate the possibility of forming pouches for milk powders and other dry foods and ingredients by the extrusion process.
Session 27, Food Packaging: General
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