Properties of laminated films from whey powder and sodium caseinate mixtures and zein layers

Corn zero-stearic acid films were laminated to whey powder (WP) and sodium caseinate (SC) mixture (WSM) films. WSM films were prepared at three mass ratios of WP and SC (50:50, 60:40, and 70:30 in w/w) by casting method. WSM films with poor mechanical and barrier properties were produced as the whey powder ratio of WSM increased from 50:50 to 70:30. Corn-zein lamination improved the mechanical and water barrier properties of WSM films by increasing tensile strength (TS) from 4.7-14.5 to 14.0-26.8 MPa and by decreasing water vapor permeabilities (WVP) from 0.432-0.490 to 0.386-0.422 ng m/m(2) s Pa. However, elongations of corn-zein laminated films were reduced from 64.5-128.0 to 2.6-4.5%. Mechanical and water barrier properties of corn-zero laminated WSM films were affected by the mass ratio of whey powder to sodium caseinate in WSM films. Addition of stearic acid zip to 10 g/100 g of corn zein decreased TS and WYP of laminated films to approximately 12 MPa and 0.36 ng m/m(2) s Pa regardless of mass ratio in WSM film. However, no significant differences in TS and WVP were found with further addition of stearic acids. (C) 2002 Elsevier Science Ltd. All rights reserved.