Effects of plasticizers on thermal properties and heat sealability of sago starch films

Sago starch films were plasticized with sorbitol, glycerol, or a combination of sorbitol/glycerol (1:1, 1:3, and 3:1 ratios) and the effects on the thermal properties and heat sealability of the films were investigated. Films were sealed with an impulse heat sealer at a dwell time of 1 s and temperature of 110 ± 10 °C. Thermal properties of the films (determined using a differential scanning calorimeter) showed that onset temperatures (To) of sorbitol-plasticized films were significantly lower than those of glycerol-plasticized films. All films were heat sealable, but sorbitol-plasticized films exhibited better heat sealability than did the glycerol type. The highest seal strength was obtained with a 3:1 combination of sorbitol/glycerol. In summary, the type of plasticizer governed the heat sealability as well as the seal strength of starch films.