SeungRan Yoo1, John M Krochta. 1. Department of Food Science and Technology, University of California, Davis, 374 Old Davis Road, Davis, CA 95616, USA.
Abstract
BACKGROUND: Films made from different protein (P) or polysaccharide (PS) materials have widely different properties. The objective of this study was to determine whether whey protein isolate (WPI)-PS blended films possess a combination of properties intermediate and possibly superior to WPI or PS film alone. RESULTS: Oxygen permeability (OP) and tensile strength (TS) for PS-WPI blended films were intermediate between the OP and TS properties of pure methycellulose (MC), hydroxypropylmethylcellulose (HPMC) or sodium alginate (SA) film and pure WPI film. Starch-WPI blends gave the weakest films. Water vapor permeability values for all pure and blended films were similar. Blended films made of MC, HPMC or SA with WPI had lower transparency than pure MC, HPMC, SA or WPI films. Differential scanning calorimetry thermograms obtained from the blended films exhibited a single glass transition temperature (T(g) ) at an intermediate value between the T(g) values of the pure films. CONCLUSIONS: Whether properties of PS-WPI blended films are intermediate to properties of the pure PS and WPI film depends on the particular PS and specific property. In the case of MC or HPMC with WPI, the blended films reflect the higher TS of the PS and lower OP of the WPI.
BACKGROUND: Films made from different protein (P) or polysaccharide (PS) materials have widely different properties. The objective of this study was to determine whether whey protein isolate (WPI)-PS blended films possess a combination of properties intermediate and possibly superior to WPI or PS film alone. RESULTS:Oxygen permeability (OP) and tensile strength (TS) for PS-WPI blended films were intermediate between the OP and TS properties of pure methycellulose (MC), hydroxypropylmethylcellulose (HPMC) or sodium alginate (SA) film and pure WPI film. Starch-WPI blends gave the weakest films. Water vapor permeability values for all pure and blended films were similar. Blended films made of MC, HPMC or SA with WPI had lower transparency than pure MC, HPMC, SA or WPI films. Differential scanning calorimetry thermograms obtained from the blended films exhibited a single glass transition temperature (T(g) ) at an intermediate value between the T(g) values of the pure films. CONCLUSIONS: Whether properties of PS-WPI blended films are intermediate to properties of the pure PS and WPI film depends on the particular PS and specific property. In the case of MC or HPMC with WPI, the blended films reflect the higher TS of the PS and lower OP of the WPI.