Effects of salep, glycerol and sunflower oil on potato starch-based edible film

Starch is one of the most abundant carbohydrate biopolymers with excellent film-forming properties. However, it has a poor resistance to water vapour and poor mechanical properties. The objective of this studt was to determine the effects of glycerol, oil and salep on the film properties of starch. Edible films based on mixtures of starch and salep (an Iranian gum) were prepared and their properties (mechanical and optical charactersitics, solubility, and water vapor permeability (WVP)) investigated. The mixtures were as follows: potato starch and salep (1-5%), potato and glycerol plasticizer (10-40%), and potato and sunflower oil (0-20%). The results showed that the physical and mechanical properties of potato starch-based edible films were affected by the their contents of salep, glycerol, and sunflower oil. The salep gum increased tensile strength, elastic modulus, and C*, but reduced elongation at break and L*, while glycerol reduced tensile strength, elastic modulus, and UV transparency but increased elongation at break, L*, opacity, solubility and WVP. On the other hand, sunflower oil decreased elongation at break, tensile strength, elastic modulus, UV transparency, solubility, and water vapor permeability, but it increased opacity. Based on the findfings, it can be concluded that the optimum contents of salep, glycerol, and sunflower oil in potato starch-based edible films are 3%, 32%, and 8%, respectively.