Effect of stearic acid on thermal, barrier and morphological properties of salep-based edible film

The objective of this research was to investigate the feasibility of edible film made from salep in which the hydrophobicity of film was modified by using stearic acid as a lipid agent. In addition its mechanical, thermal, permeability and color changes of film were analyzed. For this purpose, edible composite films were prepared from salep, stearic acid, and tween 80 in emulsion form using an ultra turax apparatus. The water vapor permeability (WVP) of the emulsified films was reduced by fatty acid addition. Also the permeability to oxygen of the emulsified films was lower than that of a salep film without fatty acid, but the difference was not significant in higher concentration of stearic acid. Scanning electron microscopy (SEM) was also used in order to analyze films microstructure. Finally, differential scanning calorimetry showed that the glass transition temperature (Tg) of the salep film was 12 °C and was considerably affected by stearic acid concentration.