The effect of konjac glucomannan and Aloe vera gel concentration on physical and mechanical properties of edible film

Abstract

Glucomannan from konjac can be used as an ingredient for edible films. However, the use of glucomannan as an edible film has a high water vapour transmission rate and water solubility. Aloe vera is known to have the ability to reduce water vapour transmission and solubility, thus, it is suitable to improve these properties of glucomannan edible film. The purpose of this study was to determine the effect, interaction, and best treatment between three levels of glucomannan flour concentration (1%, 1.3%, 1.6%) and the addition of Aloe vera gel (0%, 5%, 10%) on the physical (thickness, water-solubility, optical transparency) as well as mechanical characteristics (tensile strength, elongation at break, water vapour transmission rate) of the edible film using randomized block factorial experimental design. The results showed that there were interactions between the concentration of glucomannan flour and the addition of Aloe vera gel on the elongation of the film. Glucomannan flour addition had a significant effect on thickness, solubility, tensile strength, and elongation of edible films. The addition of Aloe vera gel significantly affected the elongation of the edible film. The best treatment in this study was the treatment with 1.6% glucomannan flour and 10% Aloe vera gel which obtained a thickness value of 0.105 mm; tensile strength 0.854 MPa; elongation 9.53%; water solubility 54.72%; transparency 2.925 A.mm-1 ; and WVTR value 3.889 g.m-2 .day-1 .