Effect of Gelatinization Temperature and Time on Properties of Edible Canna Starch Films Formed by Solvent Casting Technique

Abstract

The aims of this research are to study chemical composition of edible canna starch (Thai-purplevariety) and effects of gelatinization temperature (80, 100 and 121°C) and time (5, 20 and 60 min) onproperties of edible canna starch films formed by solvent casting technique. Amylose and phosphoruscontents of Thai-purple canna starch were 27.93% and 454 ppm, respectively, whereas ash, protein andlipid contents were negligible. An increase in the gelatinization temperature resulted in a considerablechange in swelling and disintegration of starch granules. However, the swelling was not significantly differentwhen the gelatinization time was extended. Films of edible canna starch were smooth and translucentand a few cracks at the edges were found. Thickness of the films was in the range of 35 to 46 μm. Gelatinizationat 121°C for 20 min under pressure gave the smoothest film with a B-type crystalline structure.Tensile strength of the films gelatinized at 80°C increased when the time of gelatinization increased (from43.50 to 50.93 MPa), but those at 100°C were not different (about 50 MPa). On the other hand, elongationand oxygen permeability decreased from 8.90 to 5.92% and 0.294 to 0.021 cm3•μm /m2•d•kPa, respectively,when gelatinization temperature and time increased. Water vapor permeability tended to decrease when thegelatinization temperature increased. Solubility of the films in water was in the range of 0.66 to 1.15%.

Keywords : Edible Canna Starch / Starch Film / Gelatinization / Film PropertiesAbstract1 Graduated