Effects of the free and pre-encapsulated calcium ions on the physical properties of whey protein edible film

Effects of the free and the pre-encapsulated calcium ions on the physical properties of the whey protein isolate film were studied for improving calcium content in the edible films. At pH 8, the film-forming process was hindered by serious protein aggregation and gelation caused by 0.5% (w/w) free calcium ions added in an 8% whey protein isolate solution. If the calcium ions were pre-encapsulated in the protein microparticles (contained 17% Ca2+) using spray drying method, and then added in the film-forming solution prepared using the same protein, the calcium content could be doubled (1%, w/w) without significant effects on the physical properties of the film. The calcium release ability (55% at pH 1.2, 32% at pH 7.4 and more than 75% with the enzymes) of the film was also investigated.