Physical properties of tapioca-starch edible films: Influence of filmmaking and potassium sorbate

The effect of different gelatinization and drying techniques on physical properties of tapioca starch edible films containing sorbates were studied. Method 1 assayed involved 40 min of gelatinization (rate: 1.6 degrees C/min and 0.3 degrees C/min) and drying for a week. In this case, films showed the highest tensile stress, elastic modulus (E') and crystalline degree. When method 2 was applied, film forming solutions were gelatinized using constant heating rate (1.8 degrees C/min) and dried for a week. This technique, showed a reduced tensile stress and E'. Method 3 involved the same gelatinization procedure as method 2 but a faster drying was performed and a more viscous structure, increased moisture content, poorer water vapour barrier properties and less browning were attained. Solubility, in general, was not affected by technique used. The presence of potassium sorbate in the films affected their solubility, colour and mechanical properties. it can be concluded that gelatinization technique and drying method used to obtain edible films affected network characteristics determining changes in physical properties, potentially affecting film performance. (c) 2006 Elsevier Ltd. All rights reserved.