Starch-methylcellulose-whey protein film properties

Four % (wt/wt) aqueous solutions were prepared at corn starch:methylcellulose:whey protein isolate (CS:MC:WPI) ratios of 2:2:2, 1:2:3, 2:1:3, 2:2:0, 1:2:0 and 2:1:0. Glycerol (gly) was used as a plasticiser at CSMCWPI:gly ratios of 2:1, 2.5:1 and 3:1. CS-MC-WPI blend films were stronger than CSWPI films and had lower oxygen permeability (OP) than MCWPI films. The highest tensile strength (TS) of blend films was 8.01 +/- 3.41 MPa, at CS:MC:WPI ratio of 2:2:0 and CS-MC-WPI:gly ratio of 3:1. Lowest OP value was 45.05 +/- 7.24 cm(3) mu m m(-2) per day kPa(-1), at CS:MC:WPI ratio of 2:2:2 and CS-MC-WPI:gly ratio of 3:1. OP values were predictable based on relative amounts of components. However, TS and elastic modulus properties of the CS-MC-WPI blend films did not reflect the relative amounts of the components. All of CS-MC-WPI films were translucent indicating some degree of immiscibility among the CS, MC and WPI. These results indicate the influence of complex molecular interactions among the components.