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

Abstract

Corn zein-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/m2 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-zein laminated WSM films were affected by the mass ratio of whey powder to sodium caseinate in WSM films. Addition of stearic acid up to 10 g/100 g of corn zein decreased TS and WVP of laminated films to approximately 12 M Pa and 0.36 ng m/m2 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. © 2002 Elsevier Science Ltd. All rights reserved.