Effect of sugar on starch edible film properties: plasticized effect.

The effect of some sugars (maltose, sucrose, and d-allulose) on different starch sources (normal corn, normal rice, waxy corn and waxy rice) to produce edible film was studied. Films were prepared using 3% (w/w) starch and 20% (w/w) sugar as a plasticizer. The relative crystallinity of films increased with addition of sugars and extended storage. The thickness of films was increased with addition of sugar. The morphology of films surface became homogeneous with sugars. Sugars decreased breaking stress and increased breaking strain immediately after preparation and during storage. The flow behavior of all the starch film suspensions showed shear-thinning properties determined using the Power law model. The apparent viscosity of the suspensions changed during the drying process resulting from the added sugar and starch type. Adding sugar as a plasticizer showed different effects on the crystallization, the thickness, the morphology of the film surface, the mechanical properties of the film and the flow behavior during drying. Both types of sugar and starch that could interact and inhibited starch chain mobility due to size of sugar, hydroxyl group, and hydrogen bond.